NOAA Professional Paper NMFS 20

Deep-sea emergence of red tree 

corals (Primnoa pacifica) in 

Southeast Alaska glacial fjords

Robert P. Stone 

Jennifer Mondragon

December 2018
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NOAA Professional Paper NMFS 20

Deep-sea emergence of red tree corals 

(Primnoa pacifica) in Southeast 

Alaska glacial fjords

Robert P. Stone 

Jennifer Mondragon

December 2018

U.S. Department of Commerce

Seattle, Washington
Cover image

The NOAA Ship John N. Cobb cruises about a quarter mile from the face of 

Lamplugh Glacier in 1992. Lamplugh is one of a only a handful of tidewater 

glaciers remaining in Glacier Bay today. (Photo courtesy of Commanding Officer 

John Bortniak, NOAA Corps.)

Suggested reference

Robert P. Stone and Jennifer Mondragon. 2018. Deep-sea emergence of red tree

corals (Primnoa pacifica) i n S outheast A laska g lacial f jords. NOAA P rofessional

Paper NMFS 20, 33 p. https://doi.org/10.7755/PP.20

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Disclaimer

The findings and conclusions in this report are those of the author(s) and do not

necessarily represent the views of the National Marine Fisheries Service (NOAA).
CONTENTS

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Materials and methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Field operations—investigations by scuba divers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Field operations—investigations by remotely operated vehicle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Field operations—physical oceanography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Distribution of red tree corals—Glacier Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Distribution of red tree corals—Holkham Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Depth of red tree corals and Lithothamnion—Glacier Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Depth of red tree corals and Lithothamnion—Holkham Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Species composition and associations—Glacier Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Species composition and associations—Holkham Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Growth rates—Glacier Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Oceanography—Glacier Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Oceanography—Holkham Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Appendix Table 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Appendix Table 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Appendix Table 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Appendix Table 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

iii

1

Deep-sea emergence of red tree corals (Primnoa 

pacifica) in Southeast Alaska glacial fjords

Robert P. Stone (contact author)1

Jennifer Mondragon2

Email address for contact author: bob.stone@noaa.gov

1 Auke Bay Laboratories

Alaska Fisheries Science Center

National Marine Fisheries Service, NOAA

17109 Point Lena Loop Road

Juneau, Alaska 99801

2 Alaska Regional Office

National Marine Fisheries Service, NOAA

709 West 9th Street

Juneau, Alaska 99801

Abstract—Red tree corals (Primnoa pacifica) were found thriving in 

shallow-water areas of 2 large glacial fjord systems in Southeast Alaska during scuba surveys. Corals were 

found at depths as shallow as 9 m in 

Muir Inlet, Glacier Bay, in 2004 and 

2005 and as shallow as 6 m in Tracy 

and Endicott arms, Holkham Bay, in 

2006. These observations represent 

a depth range extension for the species—red tree corals typically occur 

at depths greater than 130 m in the 

Gulf of Alaska and elsewhere where 

they form extensive thickets. The 

red tree coral is an important pioneer species in the primary succession of recently deglaciated habitats. 

The emergence of red tree corals in 

shallow-water areas of these glacial 

fjords likely occurs because yearround oceanographic conditions (low 

temperature, higher than normal surface salinity, and low ambient light 

levels) are similar to those found in 

their more typical depth range. Glacier Bay was formed beginning in 

1794 by rapid glacial retreat, and 

a deglaciation record has been meticulously documented during the 

past 130 years. This record provides 

a chronosequence that we used to 

study the succession of red tree corals into the bay and it presented an 

opportunity to evaluate the accuracy 

of a method previously used to age 

the corals. In situ access to shallowwater populations provided an invaluable opportunity to examine reproductive and recruitment processes 

and genetic connectivity of the most 

important coral species in the North 

Pacific Ocean. The information from 

these examinations provides important insights into the ability of this 

species to recover from disturbance 

and to colonize protected areas established to mitigate the effects of 

human activities.

Introduction

Corals in the genus Primnoa are large, 

structure-forming gorgonians distributed in the northern boreal Pacific and 

Atlantic oceans and subantarctic Pacific Ocean (Cairns and Bayer, 2005). 

In Alaska, red tree corals (Primnoa 

pacifica) have a broad distribution 

and are dominant biotic elements of 

benthic habitats in the Gulf of Alaska (GOA) where they form extensive 

thickets (i.e., large aggregations) in 

some areas and at depths between 150 

and 250 m (Stone et al., 2014). Colonies tend to be located on high- to 

moderate-relief bedrock (Stone et al., 

2014; Masuda and Stone, 2015) and 

provide structural habitat for many 

commercially important species, particularly rockfish (Sebastes spp.), including gravid females and juveniles 

(Krieger and Wing, 2002; Stone et al., 

2014).

Red tree corals are highly susceptible to disturbance from fishing activities because of their large size and arborescent morphology (Krieger, 2001; 

Stone et al., 2014). They are also common bycatch in Alaska fisheries for 

demersal species and research stock 

assessment surveys (Krieger, 2001; 

Heifetz, 2002). Furthermore, estimated growth rates are slow (Krieger, 

2001; Andrews et al., 2002), and consequently disturbed thickets are likely 

slow to recover or may be chronically 

affected. Observations made from a 

submersible in the GOA indicate that 

some thickets have been disturbed by 

past fishing activities (Stone et al., 

2014). In June 2006, the North Pacific 

Fishery Management Council designated as habitat areas of particular 

concern 5 small areas (total area of 46 

km2) known to support thickets in the 

eastern GOA (Federal Register, 2017). 

This regulation prohibits the use of all 

bottom-contact fishing gear in these 

habitat areas of particular concern in 

an effort to protect sensitive habitats.

In 2003, biologists discovered red 

tree corals in shallow water (<25 m 

depth) during videographic habitat 

surveys in Glacier Bay National Park 

and Preserve, Southeast Alaska (Fig. 

1). These observations supported anecdotal reports by fishermen of deep-sea 

emergence of red tree corals in other 

glacial fjords in Southeast Alaska; 

reports that were subsequently confirmed in the fjords of Holkham Bay 

(Fig. 1). We define deep-sea emergence 

as a phenomenon whereby organisms 

that typically dwell in the deep sea are 

able to exist in shallow-water areas because of unusual oceanographic conditions there.
2 Professional Paper NMFS 20 

Figure 1

Map of Southeast Alaska showing the location of the 4 study areas in the East and West arms of Glacier Bay and Tracy 

and Endicott arms of Holkham Bay.

The purpose of this study was to document deep-sea 

emergence of red tree corals by determining the areal extent and depth distribution of the corals in several glacial 

fjord systems in Southeast Alaska. We examine the role 

of physical oceanographic processes in coral distribution 

and the potential use of an accurate deglaciation record 

to corroborate estimated growth rates for the species.

Glacier Bay is a system of deep glacially derived fjords 

with 2 main fjords—Muir Inlet (hereafter referred to as 

the East Arm) and the West Arm (Fig. 2). Glacier Bay 

was completely glaciated when discovered by Captain 

George Vancouver in 1794. Glaciers have continuously 

retreated since that time (Matthews and Quinlan, 1975), 

but glacial retreat in the 2 arms, beginning in 1860, has 

not occurred at the same rate (Fig. 2). Glacial retreat in 

the West Arm initially occurred much more rapidly—the 

entire fjord was deglaciated by 1890 except the 2 uppermost inlets (Powell, 1990). Glaciers in the East Arm have 

retreated at a more constant rate and the main glacier, 

Muir Glacier, grounded (i.e., rested completely on land 

with no direct calving into the sea) at the head of the 

fjord in 1993 (Hunter and Powell, 1995). The only remaining tidewater glacier in the East Arm is the McBride 

Glacier; however, both the Muir and Riggs glaciers, although now grounded, provide substantial volumes of 

glacial meltwater into the upper reaches of the fjord. 

There are 3 major tidewater glaciers in the West Arm 

(Johns Hopkins, Lamplugh, and Margerie), and several 

grounded glaciers in the upper reaches of the fjord provide substantial volumes of glacial meltwater. Glacial retreat in both fjords has exposed extensive areas of new 

habitat devoid of sedentary marine life (Carney et al., 

1999).

The entrance to the East Arm is guarded by a broad 

sill (or moraine) at a depth of 55 m and several deeper 

intermediate sills. The entrance to the West Arm has a 

much more complex bathymetry with no obvious sill. 

The physical oceanography of Glacier Bay has been described by Matthews and Quinlan (1975) and Etherington et al. (2007) and by Reisdorph and Mathis (2014) 

with special regard to pH chemistry. The upper reaches 

of both arms have steep vertical walls, above and below 

sea level, consisting of well-worn schist and areas of plutonics (Greene1). 

Holkham Bay is also a system of deep, glacially derived fjords. The bay has 2 main fjords—Tracy and Endicott arms, both with tidewater glaciers at their heads 

(Fig. 3). The U.S. Congress designated the area as Tracy 

Arm-Fords Terror Wilderness in 1980, and it is managed 

by the U.S. Forest Service. Much less is known regarding 

the chronology of glacial retreat and the physical and 

oceanographic settings of the fjords in this area. The 2 

main fjords were largely deglaciated as long ago as the 

1 Greene, G. 2016. Personal commun. Univ. Calif., 1850 Research 

Park Dr., Ste. 300, Davis, CA 95618–6134.
3

Figure 2

Map of Glacier Bay, Southeast Alaska, showing the historic extents of glaciation. Yellow lines indicate the year and location of glacial extent. 

late 1800s (Fig. 3), but the tidewater glaciers in both 

Tracy Arm (Sawyer and South Sawyer glaciers) and Endicott Arm (Dawes Glacier) have undergone a more rapid 

retreat during the past few decades (Molnia, 2008). Since 

1948 the Sawyer, South Sawyer, and Dawes glaciers have 

all retreated more than 3 km (an average rate of 50 m/

year) (McNabb, 2013), and the Sawyer Glacier reportedly grounded in July 2017. Both arms of Holkham Bay 

are guarded by very narrow, shallow sills (<40 m depth) 

formed by terminal moraines at their entrances. Many 

areas of both arms have steep vertical walls, both above 

and below sea level, consisting principally of well-worn 

graywacke and granodiorite (Greene1).

Materials and methods

Field operations—investigations by scuba divers

During 2 research cruises (24–27 April 2004 and 17–22 

April 2005), scuba divers conducted reconnaissance surveys at 14 locations in each arm of Glacier Bay (Fig. 4). 

In 2004, dives were restricted to the East Arm, but in 

2005 dives were made in both the East and West arms. 

During 2 research cruises (22–27 March 2006 and 1–3 

May 2008) scuba divers conducted reconnaissance surveys at 20 locations in Tracy Arm (Fig. 5A) and at 2 

locations in Endicott Arm (Fig. 5B). Dive sites were selected on the basis of 3 criteria: 1) the presence of hard, 

exposed bedrock along the shoreline, 2) the presence of 

relatively steep bathymetry, and 3) the location allowing a somewhat systematic design along the axes of the 

fjords. The first 2 criteria were based on the known habitat requirements of red tree corals (Stone et al., 2014; 

Masuda and Stone, 2015). The third criterion was considered necessary to establish a timeline gradient among 

dive sites and to maximize the areal coverage of reconnaissance surveys.

At each dive site (Appendix Table 1), divers swam 

generally between the 20 and 30 m isobaths, and if red 

tree corals were observed, the divers swam vertically 
4 Professional Paper NMFS 20 

Figure 3

Map of (A) Tracy Arm and (B) Endicott Arm in Holkham Bay, Southeast Alaska, showing the historic extents of glaciation. Yellow lines indicate the year and location of glacial extent. 

between a depth of approximately 30 m and the surface to establish the depth distribution of corals. A differential global positioning system was used to mark the 

beginning and end of each dive transect. At sites where 

red tree corals were found, additional dives were made 

often to measure the length of the largest colonies, collect samples for taxonomic verification, and collect video footage of the corals and habitat. Divers noted the 

habitat at each site, including type of substrate and associated flora and fauna.

Field operations—investigations by remotely 

operated vehicle

Video observations were recorded in Holkham Bay (Fig. 

5, A and B) with a Phantom XTL remotely operated vehicle (ROV; Deep Ocean Engineering, San Jose, CA) at 

7 sites in Tracy Arm and a single site in Endicott Arm 

during the May 2008 research cruise and at 3 locations 

in each arm during a June 2014 research cruise (for identification of sites where the ROV was used, see Appendix Table 1). The ROV was deployed from a small skiff 

at each site, and then it slowly traversed up the vertical 

wall. The ROV was operated through a 168 m neutrally 

buoyant umbilical attached to a control console. Nonlinear joystick controls on the console allowed maneuvering the ROV both vertically and horizontally (maximum cruise speed of 1.3 m/s). Depth and heading were 

displayed on a real-time viewing monitor and aided in 

navigation. A differential global positioning system was 

used to mark the beginning and end of each dive transect. The ROV was equipped with two 150 W lights; 3 

thrusters; a low-light, high-resolution video camera (12:1 

zoom); and a stainless steel crash frame. The camera was 

mounted with the imaging plane directed at a 45° angle 

and recorded a pair of parallel laser marks (10 cm apart) 

projected onto the seafloor or fjord wall to provide a reference for area of view and size of fauna.
5

Figure 4

Map of sites in Glacier Bay, Southeast Alaska, where red tree corals (Primnoa pacifica) were present or absent. Surveys were 

conducted by scuba divers in 2004 and 2005. Numbers assigned to sites are indicated.

Field operations—physical oceanography

Conductivity, temperature, and depth (CTD) instruments 

(Sea-Bird Scientific, Bellevue, WA) were used to collect 

oceanographic profiles of the water column during each 

survey period (Appendix Table 2). During the surveys 

in 2004 and 2005, oceanographic data were recorded at 

stations established in the East Arm, West Arm, and central Glacier Bay and in Icy Strait near Point Couverden 

(Fig. 6). Oceanographic data also were recorded at several locations in Tracy and Endicott arms in Holkham Bay 

(Fig. 7) during the surveys conducted in March 2006, 

May 2008, and June 2014, and during a survey completed in 26–28 March 2007 to collect samples for genetic 

analysis. An instrument was lowered to various depths 

at an average rate of 1.5 m/s, and it measured depth, 

temperature, and salinity every 0.5 s. All depth measurements presented in this paper are adjusted to mean lower 

low water. 

During several surveys, the instrument array included 

additional sensors to measure dissolved oxygen, photosynthetically active radiation (PAR), turbidity, and pH. 

Dissolved oxygen was measured in milliliters per liter 

(Appendix Tables 3 and 4) and converted to percent saturation by using the solubility of oxygen in seawater as 

a function of temperature, barometric pressure, and salinity (USGS2). Photosynthetically active radiation designates the spectral range or wave band of solar radiation 

(400–700 nm) that photosynthetic organisms, such as 

coralline algae, are able to use in the process of photosynthesis, and it was used to calculate the euphotic depth 

(i.e., the depth where light intensity falls to 1% of that 

at the surface). Turbidity was measured in nephelometric 

turbidity units and is essentially the cloudiness of seawater or the degree to which light is scattered by particles 

(principally sediment and phytoplankton) suspended in 

seawater. 

Several additional oceanographic instruments were deployed at specific sites during the study period. A Minilog 

12-TR miniature microprocessor-controlled temperature 

logger (VEMCO, Bedford, Canada) was deployed on a 

live red tree coral colony at a depth of 18 m at Site 5 in 

the East Arm of Glacier Bay. Deployed between 22 April 

2005 and 14 June 2006, the logger recorded data every 6 

h and had an accuracy of ±0.1°C. Four daily temperature 

2 USGS (U.S. Geological Survey). 2011. Change to solubility 

equations for oxygen in water. Off. Water Qual. Tech. Memo. 

2011.03, 11 p. [Available from https://water.usgs.gov/admin/

memo/QW/qw11.03.pdf.]
6 Professional Paper NMFS 20 

Figure 5

Map of (A) Tracy Arm and (B) Endicott Arm in Holkham Bay, Southeast Alaska, showing 

the location of sites where red tree corals (Primnoa pacifica) were present or absent during 

surveys conducted by scuba divers or with a remotely operated vehicle (ROV) in 2006, 2008, 

and 2014. Numbers assigned to sites are indicated.

measurements were recorded every 6 h and averaged to 

derive a mean daily temperature. We also deployed a 

DST CTD compact microprocessor-controlled temperature, depth, and salinity recorder (Star-Oddi, Gardabaer, 

Iceland) on a live red tree coral colony at a depth of 15 m 

at Site 15 in Tracy Arm, Holkham Bay. The logger was 

deployed between 9 September 2010 and 4 January 2012, 

recorded data every 6 h, and had an accuracy of ±0.1°C. 

Four daily temperature measurements recorded every 6 h 

were averaged and presented as mean daily temperature.

An Argonaut-MD Doppler current meter (Sontek, 

San Diego, CA) equipped with an internal compass was 

moored at a depth of 11 m in a red tree coral thicket at 

Site 15 in Tracy Arm. The meter was deployed between 

10 March 2011 and 3 January 2012 and programmed to 

record average current velocity and direction every 10 

min. Three acoustic transducers generated short pulses 

of sound at known frequencies that propagated through 

the water and were reflected back to the meter, where 

the frequency change, or Doppler shift, was measured. 

The meter is capable of recording current velocity (±0.5 

cm/s) and heading (±2°) of a 1 m cell of water 0.5 m 
7

Figure 6

Map of Glacier Bay, Southeast Alaska, showing the location of stations where oceanographic data were collected in 

2004 and 2005. Numbers assigned to stations are indicated.

below the meter once per second. However, to preserve 

memory space for data, the current meter was programmed to record average velocity and direction (based 

on 180 observations) every 15 min. Magnetic current 

headings were converted relative to true north. 

Results

Distribution of red tree corals—Glacier Bay

Approximately 2220 and 3133 m of seafloor (i.e., fjord 

wall) was traversed and visually examined by divers 

during the Glacier Bay surveys in 2004 and 2005, respectively. The width of the transect and the exact area 

observed was difficult to determine because underwater 

visibility was highly variable between sites and ranged 

approximately from 1 to 6 m. Red tree corals were 

found at 7 dive sites in the upper reaches of the East 

Arm (Fig. 4), within 22.6 km of the head of the fjord 

(Table 1). Colonies generally were found in small patches and were most dense (up to approximately 0.3 colonies/m2) at Sites 5 and 7 (Fig. 4). All colonies were attached to stable bedrock. Detailed taxonomic examination of specimens collected at several locations revealed 

that the corals were all Primnoa pacifica. The largest 

colony (153 cm maximum length or height) observed in 

the East Arm was at Site 7 located 17.7 km from the 

head of the fjord. No red tree corals were observed in 

the lower East Arm (Sites 9–14) or at any of the 14 sites 

in the West Arm.
8 Professional Paper NMFS 20 

Figure 7

Map of Tracy Arm and Endicott Arm in Holkham Bay, Southeast Alaska, showing the location of stations where 

oceanographic data were collected in 2006, 2007, 2008, and 2014. Numbers assigned to stations are indicated.

Distribution of red tree corals—Holkham Bay

During the Holkham Bay surveys in 2006 and 2008, divers examined approximately 2804 and 530 m of seafloor 

(i.e., fjord wall), respectively. An additional 1931 m of 

seafloor was surveyed with the ROV in 2008 and 2014. 

Red tree corals were found at 15 of the 23 dive sites 

and 12 of the 13 ROV sites in Holkham Bay (Fig. 5). 

Detailed examination of specimens collected at several 

locations revealed that the corals were principally Primnoa pacifica with several colonies of Primnoa pacifica 

var. willeyi present at a few sites in Tracy Arm. All corals were attached to stable bedrock. Red tree corals were 

present in shallow-water areas only in the upper reaches 

of Tracy and Endicott arms, within approximately 3.3 

km of the glacial termini in Tracy Arm and within 3.7 

km of the Dawes Glacier in Endicott Arm (Table 1). Red 

tree corals were not observed in shallow water at sites in 

lower Tracy Arm greater than 24.4 km from the glacial 

termini. At 2 sites in upper Tracy Arm (Sites 4 and 6) 

red tree corals were actually found beneath the seasonal 

ice mélange and fast ice, which is present approximately 

from December through March in typical years. However, corals were not found in shallow water at the 2 

sites closest to Sawyer Glacier (Sites 1 and 2, Fig. 5), and 

both of those sites had a thick surface layer of glacial 

sediment and evidence of significant iceberg scour.

Colonies were generally found in small patches and 

were most dense (approximately 0.5 colonies/m2) at Sites 

14 and 15 (Fig. 5A) in Tracy Arm and at Sites 33 and 34 

(approximately 0.2 colonies/m2) in Endicott Arm (Fig. 

5B). The largest colony (280 cm length) observed in Tracy Arm was at Site 15, and the largest colony observed 

in Endicott Arm (150 cm length) was observed at Sites 

32 and 34 (Table 1). 

Depth of red tree corals and Lithothamnion—

Glacier Bay

Red tree corals were observed at depths between 9 and 35 

m (the maximum depth sampled during any scuba dive). 

Coralline algae (Lithothamnion sp.) were generally scarce 

at depths in the East Arm where red tree corals were 

present. The depth distributions of coralline algae and 

red tee corals were typically disjunct with little overlap, 

and coralline algae showed a clear pattern of increasing 

maximum depth with distance from the head of the fjord 

(Table 1). In the West Arm, coralline algae were more 

common and extended to considerably greater depths 

compared with sites in the East Arm at similar distances 
9

Table 1

Maximum length and minimum depth of red tree corals (Primnoa pacifica) and maximum depth of encrusting 

corralline algae (Lithothamnion sp.) at sites surveyed in 3 study areas in Southeast Alaska: East Arm (Muir 

Inlet) of Glacier Bay in 2004 and 2005 and Tracy and Endicott arms of Holkam Bay in 2006 and 2008. The 

distance of each site from the head of the fjord is given. Refer to Figures 4 and 5 for locations of sites surveyed 

by scuba divers or with a remotely operated vehicle.

Distance from Maximum length Minimum depth Maximum depth of

head of fjord of red tree corals of red tree corals Lithothamnion sp. 

Site (km) (cm) (m) (m)

East Arm, Glacier Bay

1 1.32 55 14.0 0

2 5.24 – – 5.0

3 11.40 40 21.6 8.0

4 11.63 20 16.2 8.0

5 15.98 144 9.1 6.0

6 17.66 89 10.7 6.0

7 17.67 153 17.4 6.0

8 22.58 21 21.6 6.0

9 24.41 – – 12.0

10 26.00 – – 15.0

11 27.21 – – 15.0

12 33.13 – – 22.0

13 35.71 – – 22.0

14 47.62 – – 25.0

Tracy Arm, Holkham Bay 

1 1.07 – – 0

2 2.06 – – 0

3 3.28 100 17.7 0

4 4.90 130 9.1 11.9

5 5.33 92 14.6 11.9

6 5.82 160 14.6 11.9

7 6.06 120 11.9 11.9

8 6.23 175 52.4 12.5

9 6.43 236 13.4 12.8

10 6.40 130 13.7 12.8

11 9.38 105 11.9 16.2

12 9.36 120 12.2 16.2

13 13.43 192 23.8 14.0

14 14.33 275 7.9 13.1

15 14.51 280 10.7 18.3

16 15.96 170 21.6 19.2

17 17.71 110 22.6 20.1

18 19.68 110 25.3 22.9

19 21.94 30 70.1 22.9

20 24.03 133 47.9 21.3

21 24.40 200 24.7 24.7

22 24.39 211 35.7 22.3

23 25.75 – – 22.3

24 26.02 140 78.6 23.2

25 28.84 – – 22.9

26 29.31 – – 25.6

27 29.82 – – 26.2

28 32.14 – – 25.9

29 37.17 – – 27.0+

30 48.45 – – 27.0+

Endicott Arm, Holkham Bay 

31 3.70 – – 6.1

32 6.80 150 30.2 14.9

33 7.80 148 9.1 13.4

34 7.90 150 11.0 11.9

35 8.60 30 55.8 12.8

36 10.00 120 16.5 14.3
10 Professional Paper NMFS 20 

from the head of the fjord. For example, coralline algae 

were found to depths of 12 m at Site 19 (4.6 km from the 

head of the fjord) compared with a depth of only 5 m at 

Site 2 (5.2 km from the head of the fjord), to depths of 

14 m at Site 17 (12.3 km from the head of the fjord) compared with a depth of only 8 m at Site 4 (11.6 km from the 

head of the fjord), and to depths of 19.8 m at Site 23 (22.6 

km from the head of the fjord) compared with a depth of 

only 6 m at Site 8 (22.6 km from the head of the fjord). 

Coralline algae were observed to a maximum depth of 25 

m in both the East (Site 14) and West (Site 25) arms, the 

sites farthest from the heads of the fjords. 

Depth of red tree corals and Lithothamnion—

Holkham Bay

Red tree corals were observed at depths as shallow as 

5.8 and 12.2 m in Tracy and Endicott arms, respectively, 

and generally were found deeper with increasing distance 

from the head of the fjord (Table 1). Observations made 

with an ROV revealed that red tree corals were distributed to depths well beyond those surveyed by scuba divers. 

Colonies were observed in Tracy Arm at depths to 59 

m (Site 8), 30 m (Site 9), 64 m (Site 13), 84 m (Site 14), 

70 m (Site 19), 74 m (Site 20), 80 m (Site 22), and 79 m 

(Site 24). Corals were not present in surveys at depths 

to 84 m at Site 23 in Lower Tracy Arm. The habitat at 

this site, deeper than the depth of coralline algae cover 

(22 m), was not optimal coral habitat, as it was heavily 

silt-laden with few bedrock exposures and of low relief. 

Red tree corals were present to a depth of 96 m in Endicott Arm. Coralline algae were generally scarce at sites in 

both arms where red tree corals were present, typically 

at depths just shallower than those of corals or at the 

same depth, and had a clear pattern of increasing depth 

with distance from the head of the fjord (Table 1). Coralline algae were observed at a depth of 27 m in Tracy 

Arm and at 14.3 m in Endicott Arm, the sites farthest 

from the heads of the fiords.

Species composition and associations—Glacier Bay

Similar benthic communities were found in both the East 

and West arms of Glacier Bay, but the along-fjord gradient of community composition was different for the 

2 fjords. Red tree corals were found only in the upper 

portion (22.6 km from the head of the fjord) of the East 

Arm where benthic communities were apparently much 

less diverse. Bedrock in the upper reaches of the East 

Arm was typically covered with a veneer of silt but, 

where it was exposed, provided suitable substrate for 

small patches of coralline algae (Fig. 8A), the calcareous 

tube worm (Serpula vermicularis), and the thatched barnacle (Semibalanus cariosus). Other taxa present in these 

low-diversity habitats included the blue mussel (Mytilus 

edulis), the brachiopod Laqueus californicus, the barnacle Chirona evermanni, the great puncturella (Cranopsis 

major), the chevron-tentacle anemone (Cribrinopsis fernaldi), and the shiny orange sea squirt (Cnemidocarpa finmarkiensis). Species associated with red tree corals in the 

East Arm included the shortscale eualid (Eualus suckleyi) 

and the spiny lebbeid (Lebbeus groenlandicus).

An encrusting stoloniferan coral, Sarcodictyon incrustans, was found at many of the sites where red tree 

corals were present, at depths as shallow as 15 m, and 

often formed mats measuring over 0.5 m2 (Fig. 8B). The 

stoloniferans were clearly associated with red tree corals 

and were often in close proximity to their bases. Other 

sedentary invertebrates found in close proximity to red 

tree corals were several hexactinellid sponges, including 

Aphrocallistes vastus (Fig. 8C), Heterchone calyx (Fig. 

8D), a species of Staurocalyptus, and the demosponge 

Haliclona urceolus. Haliclona urceolus is common in areas of the North Atlantic and Arctic oceans, but this record is only the second one from the North Pacific Ocean 

(Lehnert and Stone, 2016; incorrectly listed as H. rosea). 

We observed A. vastus and H. calyx at depths of 20 and 

21 m respectively, with the latter observation representing a new minimum depth record for the species (Stone 

et al., 2011). 

Species richness markedly increased at dive sites 

greater than 22.6 km from the head of the fjord. The gigantic anemone (Metridium farcimen); anemones of the 

genus Urticina; the sea peach (Halocynthia aurantium); 

the spiny sea squirt (Halocynthia igaboja); the common 

basket star (Gorgonocephalus eucnemis); sea stars, including Lethasterias nanimensis, Crossaster papossus, 

Stephanasterias albula, Solaster paxillatus, and Solaster 

endeca; sea cucumbers, including Cucumaria frondosa 

japonica and Synallactes challengeri; the green falsejingle 

(Pododesmus macrochisma); the Oregon triton (Fusitriton oregonensis); and the spiny lithode crab (Acantholithodes hispidus) were observed only in those shallowwater areas farther out from the head of the fjord where 

red tree corals were not present. Juvenile light dusky 

rockfish (Sebastes variabilis) were observed only at Site 

14 near the mouth of the East Arm using the interstices 

of large fractured bedrock as refuge (Fig. 8E).

The same general species composition and pattern of 

distribution was observed in the West Arm except for the 

notable absence of both red tree corals and the encrusting stoloniferan S. incrustans. Hexactinellid sponges, 

including A. vastus and H. calyx, were again observed 

at depths as shallow as 20 and 21 m, respectively. An 

increase in species richness occurred at Site 24, which is 

located 23.2 km from the head of the fjord.

Species composition and associations—Holkham Bay

Species associated with red tree corals in Tracy Arm 

included the brachiopod Laqueus californicus and the 
11

barnacle Chirona evermanni, and individuals of both 

species were often completely overgrown with coenenchyme if previously attached to bare sections of axial 

skeleton. Other associates included the shortscale eualid, 

the spiny lebbeid, and the scaled crab (Placetron wosnessenskii). Other species found in the same habitat as red 

tree corals included the hexactinellid sponges A. vastus, 

H. calyx, 2 undescribed species of Acanthascus, and 1 

undescribed species of Staurocalyptus (Reiswig3). The 

stoloniferan coral S. incrustans that was common in the 

East Arm of Glacier Bay was not observed anywhere in 

Holkham Bay. Other fauna observed during scuba surveys were similar to those observed in Glacier Bay: the 

calcareous tube worm, the chevron-tentacle anemone, 

and the shiny orange sea squirt in the same depth range 

as red tree corals; and the calcareous tube worm, the sea 

peach, the blue mussel, the thatched barnacle, the great 

puncturella, and the green sea urchin Strongylocentrotus 

droebachiensis at shallower depths. We observed A. vastus and H. calyx at depths of 19 and 21 m, respectively, 

with the former observation representing a new minimum depth record for the species. 

Species richness in Tracy Arm appeared to increase 

markedly at Site 25 located 28.8 km from the head of 

the fjord. The change in community structure was similar to that observed in the 2 arms of Glacier Bay, and 

many of the same species were present, including the sea 

stars (Lethasterias nanimensis, Leptasterias sp., Henricia

sp., Pteraster tesselatus), the common basket star, the 

feather star Florometra serratissima, and the sea cucumber Synallactes challengeri. Observations were geographically limited in Endicott Arm (3.7–10 km from the head 

of the fjord), but the species observed were consistent 

with those seen at the sites in Tracy Arm at similar distances from the head of the fjord. 

Growth rates—Glacier Bay

The chronosequence provided by the known glacial retreat in the East Arm (Fig. 2) allowed us to calculate 

the minimum (i.e., slowest) growth rate for red tree corals present there (Table 2). Assuming that corals settled 

the year the habitat was deglaciated, we calculated minimum growth rates for corals at each site where they 

were present; minimum growth rates were 0.31–2.39 

cm/year (Table 2). In addition, we used the growth rate 

(1.60–2.32 cm/year) estimated by Andrews et al. (2002) 

for the species in presumably optimal open-ocean habitat to calculate a range of potential years of recruitment 

(Table 2). We suggest that the higher growth rates we 

estimated from the year of deglaciation corroborate 

those estimated by Andrews et al. (2002) and represent 

3 Reiswig, H. 2008. Personal commun. Dep. Biol., Univ. Victoria 

and Nat. Hist. Sect., R. B.C. Mus., P.O. Box 3020, Stn. CSC, 

Victoria, BC, Canada V8W 3N5.

recruitment to the substrate soon after deglaciation and 

that the smaller colonies (i.e., those for which we suggest a slower growth rate) are from variable or delayed 

recruitment events thereafter. We do note, however, that 

this scenario assumes that growth rates for all colonies 

would be the same, a reasonable assumption given that 

all colonies would be equally subjected to the variables 

that presumably constrain growth (i.e., temperature and 

food supply).

Oceanography—Glacier Bay

Average daily temperatures for the entire deployment period (from 22 April 2005 to 14 June 2006) of the temperature logger at Site 5 in the East Arm ranged from 

4.5°C (27 April 2006) to 7.8°C (8 August 2005) (Fig. 

9A). The range for all temperatures measured during the 

deployment of the logger at Site 5 was 4.1°C (19 March 

2006) to 7.8°C (17 September 2005). The mean annual temperature (from 22 April 2005 to 21 April 2006) 

at Site 5 in the East Arm was 6.4°C. General seasonal 

trends were 1) cooling in early November at the time of 

an obvious water column mixing event and 2) warming 

beginning in early May. The CTD casts made during surveys (Table 3) confirmed these temperatures at a depth 

of 18 m at Site 5. The CTD data (Table 3) from the lateApril 2004 survey indicated that temperatures were stable in the East Arm and slightly cooler at depths below 

~15 m in central Glacier Bay and Icy Strait. The CTD 

data (Table 3) from the survey conducted in late-April 

2005 indicate unstable temperatures at depths shallower 

than 20 m in both the East and West arms and slightly cooler temperatures in surface waters in comparison 

with temperatures in central Glacier Bay and Icy Strait. 

Below a depth of ~15 m, temperature slightly decreased 

with depth. No major temperature gradient was apparent from the head to mouth of either fjord during the 

survey periods.

The CTD data (Table 4) from the survey conducted 

in 2004 indicate slightly lower salinity in surface waters 

within the East Arm, stable salinities at depths below 

~15 m, and slightly higher salinities at all depths at stations outside the fjord. The CTD data (Table 3) from the 

survey conducted in 2005 indicate slightly lower salinity 

in surface waters (depths <20 m) within the East and 

West arms, stable salinities at depths below ~15 m, and 

higher salinity at all depths at the station in Icy Strait. 

No major salinity gradient was apparent from the head 

to mouth of either fjord during the survey periods.

The CTD data (Table 5) from the survey completed 

in 2004 indicate high oxygen saturation levels (Table 5) 

at all depths at stations within the East Arm and central 

Glacier Bay. Very high saturation levels in shallow water at some stations, particularly at Station 1, were likely due to localized phytoplankton blooms. Saturation 
12 Professional Paper NMFS 20 

Figure 8

(A) A large patch (upper left) of coralline algae (Lithothamnion sp.) growing near a colony of red tree coral (Primnoa pacifica) at a depth of 18 m in Tracy Arm, Holkam Bay, Southeast Alaska. (B) A patch of a stoloniferan coral, Sarcodictyon 

incrustans, at a depth of 22 m in the East Arm (Muir Inlet), Glacier Bay, Southeast Alaska. (C) The glass sponge Aphrocallistes vastus at a depth of 24 m in the East Arm. (D) The glass sponge Heterochone calyx at a depth of 24 m in the East 

Arm. A spiny lithode crab (Acantholithodes hispidus) takes refuge in the sponge’s atrium. (E) Juvenile light dusky rockfish 

(Sebastes variabilis) were observed in shallow water (17 m depth in this photo) only at Site 14 near the mouth of the East 

Arm. (F) A group of heavily calcified basal plates and stumps of red tree corals at a depth of 20 m in Tracy Arm. The colonies were likely removed as a result of iceberg scour. Small coral recruits are visible on some of the plates. (G) A school of 

capelin (Mallotus villosus) at a depth of 75 m in Tracy Arm. (H) Juvenile walleye pollock (Gadus chalcogrammus), which 

were sometimes associated with red tree corals during the winter months in Tracy Arm (20 m depth). (I) Egg mass of a great 

sculpin (Myoxocephalus polyacanthocephalus) at a depth of 18 m in the East Arm. The sculpin, not pictured, was guarding 

several egg masses deposited on the colony. (J) A blue king crab (Paralithodes platypus) using a large red tree coral as cover 

at a depth of 18 m in Tracy Arm.
13

Figure 8 (continued)

levels steadily decreased with depth, particularly to 50 

m, and were highest in central Glacier Bay and in Icy 

Strait. The CTD data (Table 5) from the survey conducted in 2005 indicate very different scenarios in the 2 

fjords. Saturation levels were much lower, but stable, in 

shallow water (depths <15 m) in the East Arm than in 

the West Arm, central Glacier Bay, and Icy Strait (Table 

5). The high saturation levels measured in shallow water outside the East Arm were undoubtedly due to localized phytoplankton blooms. Contrastingly, saturation 

levels in deeper waters (depths >20 m) were consistently 

higher in the East Arm than at other stations within 

Glacier Bay. No major oxygen saturation gradient was 

apparent from the head to mouth of either fjord during 

the survey periods.

The CTD data (Table 6) from the survey conducted 

in 2005 indicate a strong gradient of decreasing euphotic depth from the head to mouth of the East Arm. Euphotic depth near the head of the fjord was only 2.8 m 

and increased steadily to 12.7 m near the mouth of the 

fjord (Table 6). The CTD data for the West Arm indicate a complicated scenario with unusually deep euphotic depths in the upper reaches of the fjord (Stations 8, 

9, 10, and 11). Beginning at Site 12, the same pattern 

observed in the East Arm continued with increasing euphotic depth farther out the fjord. The euphotic depth 

at the stations in central Glacier Bay and Icy Strait was 

considerably deeper than the euphotic depth in either 

fjord.

Oceanography—Holkham Bay

Water currents were generally bidirectional with the 

strongest currents (up to 12 cm/s) flowing out-fjord 

with a weaker reciprocal current flowing in-fjord. The 

mean annual temperature (from 10 September 2010 to 

09 September 2011) at Site 15 in Tracy Arm was 4.4°C, 

considerably colder than for a 1-year period in the East 

Arm of Glacier Bay. Average daily temperatures for the 

entire deployment period (from 9 September 2010 to 4 

January 2012) ranged from 3.1°C to 6.3°C (Fig. 9B). 

The range for all temperatures measured during the deployment was from 2.8°C (18 February 2011) to 6.5°C 

(28 November 2011). General seasonal trends were 1) 

cooling in early December and 2) warming beginning in 

early May. The CTD casts made during survey periods 
14 Professional Paper NMFS 20 

Table 2

Estimated minimum growth rate and years of recruitment of the largest red tree corals (Primnoa pacifica) 

observed at sites in the East Arm (Muir Inlet) of Glacier 

Bay, Southeast Alaska. Divers measured colony lengths 

during the survey conducted in 2004. Minimum growth 

rate was calculated on the basis of the coral recruiting 

to the substrate in the year of deglaciation. Estimates 

of the years of recruitment are based on the published 

growth rate of 1.60–2.32 cm/year (Andrews et al., 2002) 

for corals in presumably optimal open-ocean habitat. 

Maximum Minimum

colony Year of growth Years of

Site length (cm) deglaciation rate (cm/y) recruitment

1 55 1978 2.12 1970–1980

3 40 1961 0.93 1979–1987

4 20 1960 0.45 1991–1995

5 144 1942 2.32 1914–1942

6 89 1942 1.44 1948–1966

7 153 1940 2.39 1908–1938

8 21 1937 0.31 1991–1995

from the survey completed in March 2007 indicate much 

colder water temperatures at all stations and depths in 

Tracy Arm in comparison with temperatures recorded 

in 2006. The CTD data (Table 7) from the survey conducted in 2008 indicate cooler temperatures at depths 

shallower than 40 m, relatively stable temperatures in 

deeper water, and an obvious gradient of increasing temperature in surface waters (depths <40 m) from the head 

to the mouth of the fjord. The CTD data from the survey 

performed in 2014 indicate a mixing water column with 

cooler surface waters at all stations, except for obvious 

warming at Station 10 nearest the mouth of the fjord. 

Again, there was a gradient of slightly higher temperature in surface waters (depths <40 m) from the head to 

the mouth of the fjord.

In Endicott Arm, CTD data (Table 7) from the surveys conducted in 2006 and 2007 indicate a well-mixed 

water column with stable temperatures. No major temperature gradient was observed from the head to mouth 

of the fjord during either year. The CTD data (Table 

7) from the survey completed in 2008 are very similar 

to those from Tracy Arm and indicate cooler surface 

waters (depths <40 m), relatively stable temperatures in 

deeper water, and an obvious gradient of increasing temperature in surface waters from the head to the mouth 

of the fjord. The CTD data (Table 7) from the survey 

performed in 2014 are also similar to data recorded in 

Tracy Arm and indicate a mixing water column with 

cooler surface waters at the uppermost station only (Station 11). A strong gradient of increasing temperature 

in surface waters (depths <20 m) from the head to the 

mouth of the fjord was evident.

Figure 9

(A) Mean daily water temperature recorded between 22 April 2005 and 14 June 2006 at a depth of 18 m at Site 5 in the 

East Arm (Muir Inlet) of Glacier Bay, Southeast Alaska, and (B) mean daily water temperature recorded between 9 September 2010 and 4 January 2012 at a depth of 15 m at Site 15 in the Tracy Arm, Holkham Bay, Southeast Alaska. Water 

temperature was recorded every 6 h with a temperature logger attached to a coral colony at both sites.

(Table 7) confirmed these temperatures at a depth of 15 

m at Site 15. 

The CTD data (Table 7) from the survey conducted 

in 2006 indicate that temperature was stable in Tracy 

Arm but warmer at depths below 15 m, particularly near 

the head of the fjord. There was a gradient of increasing 

temperature in surface waters (depths <20 m) from the 

head to the mouth of the fjord. The CTD data (Table 7) 
15

The salinity cell on the DST CTD recorder failed during the first month of deployment, possibly as a result 

of fouling; consequently, no long-term (i.e., year-round) 

salinity data were recorded. The CTD data (Table 8) 

from the surveys conducted in 2006 and 2007 indicate 

that salinity was slightly lower in surface waters (depths 

<15 m) of Tracy Arm then relatively stable to a depth of 

120 m. There was a slight gradient of increasing salinity 

from the head to the mouth of the fjord. The same general pattern was observed during the survey completed in 

2008, although salinity was slightly lower at all depths 

to 120 m. The CTD data (Table 8) from the survey performed in 2014 indicate steadily increasing salinity to a 

depth of 120 m. There was no obvious gradient from the 

head to the mouth of the fjord.

Salinity in Endicott Arm followed the same general 

pattern observed in Tracy Arm during all 4 surveys but 

generally was slightly higher at all depths. The CTD data 

(Table 8) from the surveys conducted in 2006 and 2007 

indicate that salinity was slightly lower in the immediate 

surface waters (depths <5 m) of Endicott Arm then relatively stable to a depth of 120 m. Salinity at all stations 

in Endicott Arm and at all depths were higher than salinity values recorded in Tracy Arm. The CTD data (Table 

8) from the survey completed in 2014 indicate steadily 

increasing salinity to a depth of 120 m. There was no 

obvious gradient from the head to the mouth of the fjord 

during any survey.

The CTD data (Table 9) from the survey conducted 

in 2006 indicate low oxygen saturation levels at all stations and at all depths in Tracy Arm except for the immediate surface waters (depths <5 m) at the lower fjord 

stations. Saturation levels steadily decreased with depth, 

and a gradient of increasing saturation levels from the 

head to the mouth of the fjord was not evident. Contrastingly, saturation levels were high at all stations and 

at all depths during the surveys completed in 2007 and 

2008. The same general patterns of oxygen saturation 

were found in Endicott Arm during all 3 surveys.

Measurements of PAR were recorded during the surveys conducted in 2008 and 2014 (Table 10). The PAR 

data from the survey completed in 2008 indicate an apparent gradient of decreasing euphotic depth from the 

head to mouth of Tracy Arm. Euphotic depth near the 

head of the fjord was only 8.6 m with highly fluctuating 

measurements, likely due to localized plankton blooms, 

throughout the fjord. However, the euphotic depth was 

greatest near the mouth of the fjord (22.3 m). The PAR 

data for Endicott Arm indicate an even more complicated scenario—with shallow euphotic depths in the upper 

Table 3

Water temperature (°C) measured at stations in Glacier Bay, Southeast Alaska, during surveys conducted in 2004 (24–27 

April) and 2005 (17–22 April). Depths are adjusted to mean lower low water. Station numbers refer to those in Figure 6 and 

Appendix Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2004 1 5.21 5.04 4.88 4.75 4.70 4.68 4.65 4.64 4.64 4.63 4.63 4.64 4.64 4.64

2004 4 4.85 4.80 4.74 4.69 4.65 4.64 4.64 – – – – – – –

2004 5 4.90 4.84 4.80 4.76 – – – – – – – – – –

2004 7 4.88 4.82 4.78 4.75 4.71 4.69 4.65 4.64 4.64 4.67 4.70 4.68 4.69 4.71

2004 17 5.19 4.88 4.85 4.82 4.79 4.75 4.82 4.91 4.97 4.98 5.00 5.01 5.02 5.00

2004 18 4.85 4.81 4.77 4.79 4.80 4.76 4.75 4.74 4.76 4.79 4.89 4.89 4.92 4.96

2005 1 5.42 5.23 5.05 4.85 4.79 4.78 4.78 4.78 4.78 4.79 4.79 4.79 4.79 4.79

2005 2 4.88 4.85 5.02 4.85 4.78 4.78 4.78 4.79 4.79 4.79 4.79 4.79 4.79 4.80

2005 3 5.48 5.19 5.01 4.81 4.78 4.78 4.78 4.78 4.78 4.78 4.78 4.79 4.79 4.79

2005 6 5.53 5.19 5.06 4.89 4.80 4.78 4.77 4.78 4.78 4.78 4.79 4.79 4.79 4.80

2005 7 5.12 5.02 4.97 4.88 4.86 4.78 4.78 4.79 4.79 4.80 4.80 4.80 4.81 4.81

2005 8 4.73 4.73 4.76 4.76 4.79 4.77 4.80 4.80 4.79 4.79 4.78 4.77 4.76 4.74

2005 9 4.86 4.84 4.76 4.75 4.79 4.80 4.81 4.81 4.80 4.79 4.78 4.76 4.75 4.75

2005 10 4.29 4.38 4.70 4.79 4.81 4.81 4.81 4.80 4.80 4.77 4.76 4.76 4.75 4.75

2005 11 4.77 4.79 4.74 4.77 4.80 4.81 4.81 4.81 4.80 4.79 4.78 4.77 4.76 4.76

2005 12 5.01 5.01 4.98 4.80 4.75 4.78 4.80 4.80 4.80 4.77 4.76 4.75 4.75 4.75

2005 13 5.02 4.94 4.88 4.82 4.79 4.79 4.78 4.77 4.77 4.76 4.76 4.76 4.77 4.76

2005 14 5.21 5.10 5.01 4.86 4.78 4.79 4.78 4.78 4.77 4.77 4.77 4.77 4.77 4.76

2005 15 5.35 5.12 4.95 4.90 4.83 4.80 4.80 4.79 4.78 4.78 4.78 4.78 4.78 4.79

2005 16 5.23 5.07 4.93 4.86 4.79 4.78 4.77 4.77 4.77 4.76 4.76 4.77 4.77 4.77

2005 17 5.44 5.14 5.02 4.99 5.00 4.81 4.81 4.84 4.88 4.90 4.90 4.97 5.02 5.04

2005 18 4.67 4.67 4.66 4.66 4.66 4.53 4.47 4.47 4.49 4.43 4.48 4.51 4.52 4.57
16 Professional Paper NMFS 20 

Table 4

Salinity measured at stations in Glacier Bay, Southeast Alaska, during surveys conducted in 2004 (24–27 April) and 2005 

(17–22 April). Depths are adjusted to mean lower low water. Station numbers refer to those in Figure 6 and Appendix Table 

2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2004 1 30.33 30.56 30.71 30.76 30.80 30.81 30.82 30.83 30.83 30.84 30.84 30.85 30.85 30.85

2004 4 30.47 30.62 30.73 30.77 30.81 30.83 30.83 – – – – – – –

2004 5 30.51 30.61 30.68 30.73 – – – – – – – – – –

2004 7 30.52 30.65 30.72 30.75 30.80 30.81 30.83 30.84 30.85 30.86 30.87 30.87 30.87 30.88

2004 17 30.37 30.67 30.74 30.78 30.84 30.89 30.95 30.97 30.99 31.00 31.00 31.00 31.01 31.01

2004 18 31.08 31.18 31.19 31.22 31.27 31.39 31.47 31.68 31.72 31.83 32.01 32.06 32.11 32.14

2005 1 29.91 30.16 30.46 30.90 30.96 30.98 30.99 31.00 31.01 31.02 31.02 31.02 31.02 31.02

2005 2 29.91 30.36 30.52 30.80 30.96 30.98 30.99 30.99 31.00 31.00 31.01 31.01 31.02 31.03

2005 3 29.79 30.42 30.64 30.89 30.97 30.99 31.00 31.01 31.01 31.02 31.02 31.02 31.03 31.04

2005 6 29.81 30.31 30.64 30.84 30.97 30.99 31.01 31.02 31.03 31.03 31.04 31.04 31.04 31.05

2005 7 30.55 30.68 30.75 30.85 30.87 30.99 31.00 31.02 31.02 31.03 31.03 31.03 31.04 31.04

2005 8 30.44 30.55 30.65 30.68 30.87 30.96 31.03 31.06 31.07 31.08 31.09 31.09 31.10 31.11

2005 9 30.41 30.53 30.73 30.84 30.94 31.02 31.05 31.07 31.08 31.09 31.10 31.11 31.11 31.12

2005 10 30.14 30.64 30.86 30.94 31.01 31.04 31.05 31.06 31.07 31.08 31.10 31.10 31.11 31.11

2005 11 30.45 30.64 30.73 30.85 30.98 31.03 31.04 31.05 31.07 31.07 31.09 31.09 31.10 31.10

2005 12 30.46 30.64 30.73 30.86 30.95 31.01 31.05 31.06 31.08 31.11 31.11 31.12 31.12 31.12

2005 13 30.62 30.77 30.88 30.96 31.02 31.05 31.07 31.08 31.09 31.09 31.10 31.11 31.11 31.12

2005 14 30.17 30.50 30.78 30.92 31.02 31.03 31.05 31.07 31.08 31.09 31.09 31.09 31.10 31.11

2005 15 29.89 30.56 30.80 30.88 30.94 30.99 31.02 31.03 31.05 31.06 31.07 31.08 31.09 31.11

2005 16 30.34 30.61 30.85 30.97 31.02 31.06 31.08 31.08 31.09 31.10 31.11 31.12 31.12 31.12

2005 17 30.49 30.68 30.79 30.87 30.98 31.00 31.03 31.06 31.08 31.08 31.10 31.11 31.12 31.13

2005 18 30.93 30.96 30.96 30.97 31.00 31.15 31.23 31.29 31.33 31.45 31.54 31.67 31.77 31.87

reaches of the fjord (Stations 12 and 13) but also at Station 15 farther out the fjord near the mouth, again likely as a result of a localized phytoplankton bloom. The 

PAR data from the survey conducted in 2014 are more 

straightforward with a clear gradient of deeper euphotic 

depth from the head to the mouth of both fjords (Table 

10). 

Measurements of turbidity (the degree to which light 

is scattered by particles suspended in seawater) were 

recorded during only the cruise that occurred in 2014 

(Table 11). Because high concentrations of particulate 

matter affect light penetration, measurements of turbidity are relevant to euphotic depth. A moderately strong 

decreasing turbidity gradient from the head to mouth of 

both fjords was evident, and a consistent decrease in turbidity with depth at all stations was observed.

Measurements of pH also were recorded during the 

cruise that occurred in 2014 (Table 12). The pH was 

stable (7.77–8.34) at all depths and at all stations in 

both fjords but slightly higher in Tracy Arm. The pH 

was slightly higher in surface waters (depths <5 m) from 

the head to mouth of both fjords and steadily decreased 

with depth at all stations.

Discussion

Our observations of red tree corals thriving at shallow 

depths in fjords in Southeast Alaska represent a major 

depth range extension for this keystone species. Distributional data for Primnoa in Alaska waters were first 

summarized by Cimberg et al. (1981), and on the basis of limited data available at the time they reported 

that Primnoa ranged from Amchitka Island in the Aleutian Archipelago to Dixon Entrance on the border with 

British Columbia, Canada. They also reported a very 

broad bathymetric distribution for Primnoa in Alaska 

waters ranging from 10 to 800 m. We now know from 

expert examination of specimens, including those collected during this study, that red tree corals are distributed at depths between 6 and 573 m in Alaska waters 

(Stone and Cairns, 2017). Furthermore, we know from 

extensive research surveys conducted with submersibles 

and from bycatch records of fisheries surveys completed 

in the eastern GOA and the Inside Passage of Southeast 

Alaska that red tree corals typically occur at depths between 127 and 365 m (Krieger and Wing, 2002; Stone 

et al., 2014) and are extremely rare at shallower depths 
17

aside from those observations reported here for the 

emerged populations in the glacial fjords. 

The results of extensive research through surveys conducted by scuba divers in the shallow waters of Southeast Alaska and elsewhere (senior author, personal observ.) indicate that deep-sea emergence of red tree corals 

is a rarity in Alaska and is limited to a few glacial fjords 

where oceanographic conditions are unusually optimal 

to support corals. The validity of the shallow (<127 m) 

depth records reported by Cimberg et al. (1981) are 

questionable. Many of these records are based on anecdotal information, nonexpert identifications, and collections made with spatially imprecise sampling equipment 

(i.e., fishing gear). 

Several gorgonian species closely resemble each other 

superficially and can be easily mistaken for red tree corals. This problem is particularly the case with the shallow-water acanthogorgiid gorgonian Calcigorgia spiculifera, which is the most common shallow-water gorgonian in Alaska (Stone et al., 2017). Additionally, some 

records reported by Cimberg et al. (1981) are based on 

fisheries bycatch specimens that may have been collected 

at their original location and discarded at sea only to be 

recollected as bycatch at a new location. Such a translocation was apparently the case for one specimen reported in Cimberg et al. (1981) that was collected in shallow 

water and identified by an acknowledged expert in octocoral taxonomy. The specimen in question was collected 

during the 1940s near Petersburg, Alaska, by a shrimp 

trawler at a depth of 21–30 m. In July 1999, scuba divers (senior author, personal observ.) determined that the 

collection site was a vast, sandy seafloor with high current — habitat that red tree corals do not inhabit. The 

location was, however, in an area where local fishermen 

reportedly cleaned their nets of debris after fishing in 

nearby deeper water. There is one confirmed record of a 

red tree coral collected at a depth of 64 m in Jack Bay, 

Prince William Sound (Cairns and Bayer, 2005), which 

was strongly glacially influenced when the specimen was 

collected in 1941. However, we propose that the majority of the 30 records of Primnoa compiled by Cimberg et 

al. (1981) for shallow water (depths <127 m) were likely 

C. spiculifera.

Deep-sea emergence has been reported previously 

for only a few coral species worldwide. The gorgonians 

Paramuricea placomus and red trees (Primnoa resedaeformis) emerge from deep waters to depths of 28 and 

32 m, respectively, in Norwegian fjords (Strömgren, 

1970). The spider hazards (Lophelia pertusa), a colonial 

azooxanthellate scleractinian coral, also emerges in these 

Table 5

Oxygen saturation (%) measured at stations in Glacier Bay, Southeast Alaska, during surveys conducted in 2004 (24–27 

April) and 2005 (17–22 April). Depths are adjusted to mean lower low water. Station numbers refer to those in Figure 6 and 

Appendix Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2004 1 136.8 114.9 102.6 94.4 91.4 93.2 94.0 94.7 95.1 95.4 95.5 95.9 95.9 96.1

2004 4 94.1 96.6 93.4 92.6 94.3 94.9 95.2 – – – – – – –

2004 5 99.8 94.8 93.2 91.3 – – – – – – – – – –

2004 7 115.9 100.3 94.7 92.7 92.7 91.9 92.4 92.9 93.6 94.1 94.4 94.6 94.6 94.5

2004 17 122.1 114.6 105.5 101.5 97.8 96.4 96.9 97.8 98.3 98.7 99.0 99.3 99.3 99.3

2004 18 110.6 105.6 100.2 97.9 95.1 91.9 85.9 80.7 75.9 71.8 66.6 64.9 63.8 62.7

2005 1 64.4 67.6 72.1 72.3 71.7 71.3 71.0 70.7 70.3 69.6 69.4 68.2 68.2 67.3

2005 2 66.8 68.0 68.7 70.1 65.6 64.9 64.7 65.0 65.1 65.1 65.1 65.6 66.0 66.3

2005 3 – – – – – – – – – – – – – –

2005 6 70.1 74.7 76.9 76.6 76.4 76.1 75.9 75.8 75.6 75.5 75.3 75.3 75.2 75.0

2005 7 75.1 76.7 77.0 76.9 76.5 75.6 75.4 75.0 74.7 74.6 74.6 74.4 74.4 74.3

2005 8 113.4 86.9 76.9 70.3 67.0 64.4 63.4 63.1 63.1 63.2 63.2 63.2 63.3 63.3

2005 9 110.0 86.6 73.8 66.7 62.8 61.5 60.7 60.7 60.6 60.7 60.7 60.7 60.8 60.8

2005 10 113.8 86.1 69.3 62.8 60.7 60.5 60.5 60.5 60.3 60.3 60.3 60.3 60.3 60.3

2005 11 146.7 99.8 76.5 67.9 63.1 61.5 61.3 61.3 61.3 61.3 61.3 61.3 61.2 61.2

2005 12 156.1 101.9 83.0 68.9 63.3 61.2 60.7 60.6 60.6 60.7 60.7 60.6 60.8 60.8

2005 13 180.0 104.2 83.9 66.9 62.5 61.6 61.0 60.9 60.9 60.8 60.9 61.0 61.2 61.2

2005 14 170.0 114.9 96.6 71.6 63.4 61.5 60.7 60.6 60.3 60.3 60.3 60.3 60.3 60.3

2005 15 135.4 107.7 86.7 74.4 67.0 64.8 63.4 62.9 62.9 62.9 62.9 62.9 63.1 63.5

2005 16 – – – – – – – – – – – – – –

2005 17 180.9 178.7 110.5 91.2 77.2 72.1 69.6 68.6 68.6 68.5 68.8 69.2 69.3 69.7

2005 18 – – – – – – – – – – – – – –
18 Professional Paper NMFS 20 

Table 6

Photosynthetically active radiation and euphotic depth (the depth where light intensity falls to 1% of that at the sea surface) 

measured at stations in Glacier Bay, Southeast Alaska, during a survey conducted in 2005 (17–22 April). Depths are adjusted 

to mean lower low water. Station numbers refer to those in Figure 6 and Appendix Table 2.

Depth (m)

Station 0 5 10 15 20 30 40 50 Euphotic depth

1 141.00 0.50 0.08 0.05 0.04 0 0 0 2.85

2 357.70 7.33 0.92 0.26 0.04 0 0 0 3.30

3 278.51 7.18 1.34 0.42 0.19 0.06 0.04 0 7.70

6 103.00 1.39 0.24 0.09 0.05 0.04 0 0 5.40

7 136.50 2.44 0.84 0.35 0.08 0.04 0 0 12.72

8 200.00 20.32 4.72 1.70 0.72 0.15 0.05 0 14.20

9 176.20 14.77 3.28 1.16 0.54 0.14 0.05 0 12.76

10 13.71 2.21 0.58 0.27 0.14 0.54 0 0 20.40

11 26.59 2.93 0.51 0.17 0.08 0 0 0 12.60

12 84.69 0.87 0.13 0.05 0 0 0 0 5.15

13 32.96 1.11 0.24 0.09 0.05 0 0 0 8.55

14 31.91 0.29 0.04 0 0 0 0 0 4.85

15 147.40 4.18 0.40 0.12 0.06 0 0 0 6.88

16 84.70 5.05 0.73 0.24 0.18 0.05 0 0 9.64

17 37.19 5.65 2.30 1.08 0.46 0.13 0.06 0.04 23.47

18 417.40 14.36 13.33 12.21 10.62 2.46 0.60 0.16 28.30

same fjords to minimum depths of 52 m (Strömgren, 

1971). Deep-sea emergence has also been observed for 

black corals (Antipatharia) in the southern fjords of New 

Zealand (Grange et al., 1981; Grange, 1985), where an 

endemic species, Antipathes fiordensis, is also found at 

unusually shallow depths (5–40 m), and for the cockscomb cup coral (Desmophyllum dianthus), a solitary 

azooxanthellate scleractinian coral, to depths of 8 m 

in the fjords of southern Chile (Försterra and Häussermann, 2003). None of these studies specifically mention 

the roles, or even the presence, of tidewater glaciers and 

fjord bathymetry (e.g., sills) in deep-sea emergence of the 

corals, but several do implicate oceanographic controls, 

such as unusual stenothermal and stenohaline conditions, a shallow maximum extension of the surface low 

salinity layer, and reduced transparency of the water.

The emerged populations of red tree corals found in 

this study appear to be disjunct from populations outside the fjords but likely extend into much deeper waters 

within the fjords. We confirmed the presence of red tree 

corals to depths of more than 100 m in Tracy and Endicott arms in Holkham Bay, and they have been observed 

at depths of more than 100 m in lower Glacier Bay 

(Waller4). Therefore, it is likely that these populations 

have crept into the fjords and only emerge to shallow 

depths near the heads of the fjords where oceanographic 

conditions are favorable.

4 Waller, R. 2016. Personal commun. Sch. Mar. Sci., Darling Mar. 

Cent., Univ. Maine, 193 Clarks Cove Rd., Walpole, ME 04573.

Red tree corals that have emerged in glacial fjords are 

likely living at the edge of their physiological tolerance 

to the environmental conditions there, and this condition 

is likely particularly true for colonies residing 1) nearest 

the glacier face where siltation and turbidity are seasonally very high and 2) at the shallowest depths where the 

water mass can reach temperatures above 7.5–8.0°C for 

extended periods. During our early surveys, we noted 

2 obvious ecomorphs that were identified as “typical” 

and “atypical” growth forms of P. pacifica (Cairns5). 

The atypical form differs from the typical form described 

by Cairns and Bayer (2005) and further examined by 

Cairns (2011) in that “it has very slender branches and 

sometimes whorled calyces.” Our observations indicate 

that the atypical colonies appear to be in relatively poor 

health with much less coenenchyme and far fewer polyps. We found atypical colonies in all 3 fjords where 

red tree corals were present in shallow water, sometimes 

interspersed with typical colonies, but atypical colonies 

were generally more common at shallower depths and at 

sites nearer the heads of the fjords. Furthermore, atypical forms have never been observed at the deepwater 

sites studied in the eastern GOA (Stone et al., 2014). We 

suggest that atypical colonies are ecomorphs responding 

phenotypically to the physiological stress of residing at 

the edge of optimal or tolerable habitat.

5 Cairns, S. D. 2005. Personal commun. Dep. Invert. Zool., Natl. 

Mus. Nat. Hist., Smithson. Inst., P.O. Box 37012, MRC 163, 

Washington, DC 20013-7012.
19

Table 7

Water temperature (°C) measured at stations in Holkham Bay, Southeast Alaska, during surveys conducted in 2006 (22–27 

March), 2007 (26–28 March), 2008 (1–3 May), and 2014 (7–9 June). Depths are adjusted to mean lower low water. Station 

numbers refer to those in Figure 7 and Appendix Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2006 1 3.10 4.02 4.64 4.90 5.07 5.23 5.31 5.28 5.23 5.19 5.17 5.11 5.10 5.09

2006 2 3.56 4.34 4.62 4.87 5.25 5.28 5.26 5.22 5.19 5.15 5.13 5.08 5.07 5.04

2006 3 3.69 4.38 4.92 5.16 5.31 5.32 5.28 5.24 5.20 5.16 5.10 5.08 5.07 5.06

2006 6 4.38 4.90 5.08 5.22 5.29 5.26 5.22 5.20 5.17 5.14 5.11 5.09 5.07 5.06

2006 7 4.86 5.23 5.28 5.29 5.29 5.24 5.21 5.18 5.16 5.15 5.12 5.08 5.06 5.04

2006 8 4.81 5.20 5.28 5.27 5.24 5.20 5.14 5.14 5.12 5.04 5.02 4.99 4.96 4.96

2006 9 4.66 4.91 5.25 5.27 5.23 5.20 5.18 5.16 5.13 5.08 5.06 4.97 4.97 4.91

2006 10 4.90 4.97 5.00 5.11 4.79 4.74 4.72 4.75 4.75 4.75 4.75 4.78 4.81 4.83

2006 11 – – – – – – – – – – – – – –

2006 12 5.06 5.42 5.59 5.58 5.57 5.55 5.54 5.53 5.51 5.50 5.49 5.49 5.48 5.47

2006 13 5.45 5.58 5.60 5.60 5.58 5.52 5.50 5.47 5.45 5.44 5.44 5.43 5.43 5.42

2006 14 5.59 5.62 5.62 5.63 5.63 5.53 5.52 5.49 5.47 5.46 5.44 5.41 5.40 5.35

2006 15 5.54 5.58 5.61 5.54 5.54 5.49 5.49 5.49 5.47 5.43 5.32 5.32 5.31 5.28

2006 16 5.40 5.26 5.11 5.08 5.06 5.03 4.96 4.94 4.94 4.92 4.92 4.92 4.91 4.91

2007 1 2.43 3.04 3.31 3.56 3.73 4.04 4.02 3.97 3.95 3.95 3.94 3.92 3.90 3.89

2007 2 3.07 3.30 3.32 3.74 3.89 4.00 4.03 3.97 3.95 3.94 3.94 3.93 3.92 3.89

2007 3 3.13 3.29 3.70 3.75 3.89 4.03 3.98 3.95 3.94 3.92 3.93 3.93 3.92 3.87

2007 6 2.99 3.43 3.70 3.87 4.04 3.96 3.95 3.95 3.93 3.92 3.91 3.90 3.89 3.88

2007 7 3.14 3.41 3.92 3.98 4.02 4.01 3.97 3.94 3.93 3.90 3.89 3.86 3.86 3.85

2007 8 3.20 3.51 3.76 3.93 4.04 4.01 3.97 3.94 3.92 3.86 3.89 3.89 3.85 3.84

2007 9 2.99 3.56 3.83 3.88 3.88 3.97 3.88 3.83 3.81 3.79 3.76 3.76 3.77 3.73

2007 10 3.63 3.66 3.76 3.88 3.85 3.85 3.77 3.75 3.75 3.74 3.72 3.72 3.73 3.75

2007 11 – – – – – – – – – – – – – –

2007 12 4.16 4.46 4.56 4.51 4.47 4.44 4.40 4.36 4.35 4.34 4.33 4.24 4.22 4.16

2007 13 4.22 4.36 4.53 4.57 4.48 4.43 4.39 4.36 4.23 4.18 4.13 4.11 4.08 4.06

2007 14 4.37 4.53 4.52 4.32 4.15 4.12 4.09 4.07 4.03 4.02 4.03 4.01 3.99 3.98

2007 15 4.40 4.44 4.47 4.47 4.42 4.35 4.28 4.21 4.14 4.11 4.06 4.04 4.03 4.02

2007 16 4.37 4.35 4.17 4.09 4.02 3.95 3.92 3.91 3.91 3.91 3.91 3.90 3.90 3.90

2008 1 2.29 2.95 3.02 3.18 3.46 3.60 3.78 3.88 3.91 3.93 3.95 3.95 3.96 3.97

2008 2 2.62 2.95 3.13 3.28 3.57 3.75 3.86 3.90 3.92 3.94 3.95 3.98 3.99 3.99

2008 3 2.53 2.98 3.11 3.30 3.58 3.82 3.89 3.92 3.93 3.94 3.95 3.96 3.97 3.98

2008 6 2.94 3.14 3.28 3.46 3.68 3.83 3.92 3.93 3.94 3.94 3.95 3.96 3.97 3.98

2008 7 2.92 3.17 3.31 3.47 3.68 3.87 3.92 3.94 3.94 3.95 3.96 3.97 3.98 3.98

2008 8 2.94 3.16 3.31 3.52 3.71 3.78 3.89 3.94 3.95 3.95 3.96 3.96 3.97 3.98

2008 9 4.41 4.09 3.99 3.96 3.93 3.94 3.95 3.95 3.95 3.95 3.97 3.98 4.00 4.01

2008 10 4.43 4.15 4.11 4.11 4.02 4.01 4.05 4.06 4.08 4.13 4.26 4.26 4.31 4.32

2008 11 – – – – – – – – – – – – – –

2008 12 3.54 3.58 3.65 3.85 3.95 4.04 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.12

2008 13 3.77 3.61 3.75 3.93 3.97 4.09 4.12 4.12 4.12 4.12 4.12 4.12 4.12 4.13

2008 14 4.36 4.27 4.15 4.15 4.15 4.14 4.14 4.13 4.11 4.12 4.13 4.13 4.13 4.13

2008 15 4.75 4.26 4.18 4.14 4.15 4.14 4.13 4.13 4.13 4.14 4.14 4.15 4.15 4.15

2008 16 4.87 4.74 4.57 4.49 4.41 4.39 4.34 4.33 4.32 4.26 4.21 4.23 4.24 4.27

2014 1 4.13 4.21 4.34 4.48 4.67 4.84 5.08 5.20 5.17 5.15 5.11 5.07 5.04 4.98

2014 2 4.19 4.26 4.47 4.53 4.71 4.76 5.18 5.20 5.16 5.12 5.08 5.06 5.04 4.97

2014 3 4.19 4.23 4.35 4.49 4.64 4.84 5.17 5.17 5.13 5.08 5.08 5.02 5.01 4.97

2014 6 4.23 4.33 4.37 4.43 4.55 4.55 4.91 5.18 5.15 5.10 5.08 5.05 5.01 4.99

2014 7 4.28 4.23 4.32 4.40 4.48 4.70 5.16 5.20 5.16 5.11 5.06 5.03 5.01 4.99

2014 8 4.23 4.26 4.31 4.31 4.58 5.13 5.20 5.12 5.10 5.04 5.01 4.97 4.93 4.90

2014 9 4.25 4.24 4.28 4.35 4.71 5.21 5.22 5.16 5.12 5.08 5.02 4.99 4.97 4.95

2014 10 6.52 6.44 5.80 5.42 5.22 5.33 5.33 5.23 5.08 5.05 5.02 4.98 4.95 4.91

2014 11 4.87 4.94 5.15 5.36 5.68 5.58 5.49 5.39 5.34 5.18 4.97 4.81 4.71 4.72

2014 12 4.92 5.03 5.07 5.43 5.75 5.68 5.54 5.38 5.32 5.26 5.12 4.94 4.82 4.74

2014 13 4.94 5.01 5.46 5.68 5.75 5.60 5.50 5.45 5.38 5.30 5.21 5.07 4.88 4.79

2014 14 – – 5.85 5.86 5.72 5.54 5.48 5.41 5.30 5.21 5.13 5.04 4.88 4.80

2014 15 5.52 5.73 5.87 5.74 5.61 5.45 5.39 5.32 5.22 5.10 5.01 4.93 4.76 4.74

2014 16 6.91 6.38 6.13 5.99 5.45 5.32 5.18 5.15 5.12 5.07 5.06 5.04 5.01 5.02
20 Professional Paper NMFS 20 

Table 8

Salinity measured at stations in Holkham Bay, Southeast Alaska, during surveys conducted in 2006 (22–27 March), 2007 

(26–28 March), 2008 (1–3 May), and 2014 (7–9 June). Depths are adjusted to mean lower low water. Station numbers refer 

to those in Figure 7 and Appendix Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2006 1 30.40 30.67 30.80 30.91 31.01 31.00 31.05 31.08 31.11 31.13 31.14 31.16 31.17 31.18

2006 2 30.36 30.65 30.81 30.91 31.03 31.05 31.09 31.12 31.13 31.15 31.16 31.18 31.18 31.19

2006 3 30.41 30.65 30.88 30.96 31.02 31.05 31.08 31.10 31.13 31.16 31.18 31.18 31.19 31.19

2006 6 30.60 30.88 30.91 30.98 31.05 31.07 31.11 31.12 31.13 31.15 31.16 31.17 31.18 31.18

2006 7 30.91 30.99 31.04 31.05 31.06 31.11 31.12 31.14 31.15 31.16 31.17 31.17 31.18 31.19

2006 8 30.80 31.00 31.03 31.05 31.07 31.10 31.14 31.15 31.16 31.18 31.18 31.18 31.18 31.19

2006 9 30.70 30.84 31.03 31.05 31.09 31.12 31.13 31.15 31.15 31.16 31.16 31.16 31.17 31.16

2006 10 30.89 30.97 31.03 31.05 31.00 31.03 31.05 31.06 31.08 31.08 31.10 31.12 31.15 31.16

2006 11 – – – – – – – – – – – – – –

2006 12 31.13 31.25 31.30 31.32 31.35 31.36 31.37 31.37 31.38 31.40 31.40 31.40 31.41 31.42

2006 13 31.23 31.28 31.32 31.34 31.35 31.37 31.39 31.41 31.42 31.44 31.44 31.44 31.44 31.44

2006 14 31.17 31.26 31.29 31.31 31.34 31.35 31.37 31.40 31.41 31.42 31.42 31.42 31.43 31.43

2006 15 31.14 31.24 31.26 31.29 31.33 31.35 31.38 31.39 31.40 31.40 31.40 31.40 31.41 31.41

2006 16 30.90 31.06 31.22 31.25 31.27 31.30 31.39 31.41 31.42 31.44 31.44 31.45 31.46 31.49

2007 1 30.82 31.07 31.20 31.28 31.38 31.43 31.45 31.47 31.49 31.49 31.49 31.50 31.50 31.49

2007 2 31.03 31.17 31.16 31.34 31.39 31.43 31.44 31.47 31.49 31.49 31.50 31.50 31.50 31.50

2007 3 31.07 31.16 31.29 31.32 31.36 31.44 31.46 31.48 31.49 31.49 31.50 31.50 31.50 31.49

2007 6 31.00 31.17 31.30 31.35 31.44 31.47 31.48 31.49 31.49 31.49 31.49 31.49 31.49 31.49

2007 7 31.03 31.13 31.35 31.38 31.43 31.45 31.47 31.48 31.49 31.49 31.49 31.49 31.49 31.49

2007 8 31.04 31.16 31.29 31.35 31.42 31.45 31.46 31.47 31.46 31.47 31.48 31.48 31.48 31.49

2007 9 30.69 31.16 31.30 31.24 31.41 31.45 31.45 31.46 31.46 31.46 31.47 31.47 31.47 31.48

2007 10 31.17 31.19 31.27 31.35 31.39 31.43 31.45 31.46 31.47 31.47 31.48 31.48 31.48 31.49

2007 11 – – – – – – – – – – – – – –

2007 12 31.41 31.54 31.59 31.59 31.59 31.60 31.60 31.60 31.60 31.60 31.60 31.60 31.60 31.59

2007 13 31.48 31.51 31.57 31.58 31.59 31.60 31.60 31.60 31.59 31.59 31.59 31.59 31.59 31.59

2007 14 31.19 31.42 31.56 31.56 31.56 31.56 31.56 31.57 31.57 31.57 31.57 31.57 31.57 31.57

2007 15 31.28 31.44 31.54 31.58 31.59 31.59 31.58 31.58 31.58 31.58 31.57 31.57 31.57 31.57

2007 16 31.26 31.42 31.49 31.50 31.52 31.53 31.56 31.57 31.57 31.57 31.58 31.58 31.58 31.59

2008 1 30.35 30.84 30.89 30.94 31.09 31.16 31.23 31.26 31.27 31.30 31.31 31.32 31.33 31.34

2008 2 30.68 30.84 30.92 31.00 31.15 31.22 31.25 31.26 31.28 31.30 31.32 31.34 31.35 31.36

2008 3 30.58 30.87 30.93 30.99 31.14 31.22 31.26 31.27 31.29 31.31 31.32 31.33 31.34 31.35

2008 6 30.86 30.95 31.00 31.08 31.17 31.22 31.27 31.28 31.30 31.31 31.32 31.33 31.34 31.35

2008 7 30.80 30.95 31.01 31.07 31.16 31.23 31.25 31.27 31.29 31.30 31.32 31.33 31.34 31.35

2008 8 30.72 30.80 30.96 30.99 31.10 31.16 31.22 31.26 31.29 31.30 31.32 31.32 31.33 31.34

2008 9 30.87 31.01 31.03 31.12 31.21 31.23 31.26 31.29 31.30 31.30 31.32 31.33 31.34 31.35

2008 10 30.87 31.09 31.19 31.23 31.26 31.28 31.29 31.30 31.31 31.34 31.36 31.37 31.38 31.38

2008 11 – – – – – – – – – – – – – –

2008 12 30.95 31.03 31.13 31.24 31.29 31.34 31.38 31.39 31.40 31.40 31.40 31.41 31.42 31.42

2008 13 30.95 31.06 31.15 31.25 31.31 31.36 31.39 31.39 31.40 31.41 31.42 31.42 31.43 31.43

2008 14 30.77 30.93 31.19 31.24 31.32 31.35 31.36 31.39 31.40 31.42 31.42 31.43 31.43 31.43

2008 15 30.65 31.00 31.12 31.23 31.33 31.35 31.38 31.39 31.40 31.41 31.41 31.42 31.42 31.42

2008 16 30.94 31.13 31.23 31.28 31.35 31.38 31.40 31.41 31.42 31.45 31.47 31.49 31.50 31.51

2014 1 29.14 29.40 29.67 29.94 30.29 30.69 31.07 31.17 31.25 31.30 31.38 31.44 31.49 31.56

2014 2 28.99 29.56 29.95 30.03 30.44 30.72 31.03 31.20 31.29 31.36 31.42 31.46 31.49 31.57

2014 3 29.07 29.35 29.71 30.11 30.38 30.88 31.03 31.23 31.29 31.36 31.40 31.48 31.52 31.58

2014 6 29.08 29.65 29.74 29.93 30.56 30.58 30.78 31.04 31.20 31.29 31.35 31.39 31.46 31.51

2014 7 28.64 29.35 29.70 30.00 30.36 30.69 30.93 31.06 31.19 31.28 31.35 31.41 31.44 31.47

2014 8 29.03 29.58 29.83 29.87 30.51 30.84 31.08 31.23 31.28 31.36 31.41 31.48 31.52 31.57

2014 9 29.25 29.53 29.82 30.19 30.61 30.91 31.03 31.17 31.24 31.31 31.39 31.42 31.46 31.51

2014 10 28.99 29.24 29.94 30.56 30.74 30.89 30.95 31.07 31.32 31.35 31.39 31.44 31.48 31.52

2014 11 29.44 29.71 30.12 30.63 31.13 31.27 31.38 31.49 31.55 31.61 31.67 31.70 31.74 31.75

2014 12 29.41 30.01 30.07 30.63 30.94 31.15 31.33 31.50 31.56 31.59 31.64 31.69 31.73 31.76

2014 13 29.36 30.02 30.52 30.70 31.03 31.24 31.37 31.43 31.50 31.57 31.61 31.65 31.72 31.74

2014 14 – – 30.61 30.76 31.07 31.28 31.56 31.44 31.53 31.59 31.64 31.67 31.72 31.74

2014 15 29.80 30.48 30.79 30.97 31.19 31.37 31.42 31.48 31.58 31.65 31.69 31.71 31.76 31.76

2014 16 28.14 30.03 30.40 30.59 31.17 31.33 31.48 31.53 31.56 31.60 31.62 31.64 31.68 31.70
21

Table 9

Oxygen saturation (%) measured at stations in Holkham Bay, Southeast Alaska, during surveys conducted in 2006 (22–27 

March), 2007 (26–28 March), and 2008 (1–3 May). Depths are adjusted to mean lower low water. Station numbers refer to 

those in Figure 7 and Appendix Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2006 1 37.06 36.79 36.12 33.24 33.40 33.36 33.32 33.29 33.26 33.22 33.22 33.19 33.30 33.16

2006 2 53.23 51.82 50.17 50.09 50.72 50.90 51.04 52.38 51.36 50.67 50.76 50.57 51.40 51.76

2006 3 94.09 65.14 58.66 55.27 54.01 53.87 66.30 60.69 55.84 56.06 54.90 55.27 54.85 54.71

2006 6 92.94 79.87 69.09 64.51 62.28 58.39 55.70 60.14 52.33 51.86 51.72 51.54 51.40 51.26

2006 7 83.99 70.18 65.05 63.39 60.61 57.09 55.14 52.19 51.36 50.94 50.76 50.57 50.57 50.38

2006 8 89.99 65.20 61.72 60.47 64.02 59.94 56.29 54.35 53.80 53.42 53.83 53.09 53.04 52.89

2006 9 81.52 68.62 67.62 61.17 59.03 58.34 56.76 53.02 51.72 51.67 51.35 51.25 51.25 51.20

2006 10 94.23 78.31 66.68 63.14 61.15 59.80 60.35 56.30 54.65 53.83 53.42 53.06 52.42 52.20

2006 11 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0

2006 12 78.40 62.72 56.81 53.87 62.41 53.87 49.95 48.92 48.92 49.34 49.34 48.78 48.88 48.88

2006 13 86.97 66.88 61.91 57.42 56.95 54.38 52.14 50.13 49.85 49.44 49.30 49.11 48.41 48.27

2006 14 80.80 61.63 57.00 53.78 54.96 50.74 51.30 49.34 48.88 48.60 48.46 47.85 48.13 43.32

2006 15 80.02 62.82 57.42 54.24 53.96 51.25 51.39 48.51 47.90 47.99 47.99 48.13 47.57 47.57

2006 16 81.85 75.73 65.55 63.20 61.62 58.44 58.66 54.19 53.37 52.54 52.54 52.54 51.85 51.44

2007 1 100.10 100.10 100.10 100.10 100.00 100.10 100.10 100.00 100.10 100.10 100.00 100.00 100.10 100.10

2007 2 100.20 100.10 100.10 100.20 100.00 95.96 96.10 96.00 100.10 100.10 100.10 100.10 100.10 100.10

2007 3 100.30 100.00 100.20 100.20 100.10 100.10 100.00 100.10 100.10 100.10 100.10 100.10 100.10 100.10

2007 6 100.20 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.10

2007 7 100.10 100.00 100.10 100.10 100.10 100.10 100.00 100.10 100.10 100.10 100.10 100.00 100.00 100.10

2007 8 100.10 100.20 100.00 100.00 100.00 100.00 100.00 100.10 100.10 100.00 100.10 100.10 100.10 100.10

2007 9 100.10 100.10 100.10 100.00 100.10 100.10 100.00 100.00 100.00 100.10 100.00 100.00 100.10 100.10

2007 10 100.20 100.10 100.20 100.10 100.00 100.10 100.10 100.00 100.10 100.10 100.10 100.10 100.10 100.00

2007 11 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0

2007 12 100.00 100.20 100.00 100.10 100.10 100.10 100.20 100.10 100.10 100.10 100.00 100.10 100.00 100.00

2007 13 100.00 100.00 100.20 100.00 100.10 100.00 100.10 100.10 100.10 100.00 100.10 100.00 100.10 100.00

2007 14 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.00 100.10 100.10 100.10 100.10 100.10 100.10

2007 15 100.10 100.30 100.00 100.10 100.10 100.10 100.10 100.00 99.93 100.00 100.00 100.10 100.10 100.10

2007 16 100.20 99.91 100.10 100.00 100.10 100.00 100.10 100.10 100.10 100.10 100.10 100.10 100.10 100.10

2008 1 100.00 100.10 100.10 100.10 100.10 100.10 100.00 100.00 100.10 100.10 100.10 100.10 100.10 100.10

2008 2 100.10 100.00 100.10 100.10 100.10 100.10 100.20 100.10 100.00 100.10 100.10 100.10 100.10 100.10

2008 3 100.10 100.10 99.89 100.10 100.10 100.10 100.00 99.99 100.10 100.10 100.10 100.10 100.10 100.10

2008 6 100.10 99.98 99.95 100.10 100.00 100.20 99.99 100.10 100.10 100.10 100.10 100.10 100.10 100.10

2008 7 99.73 100.10 100.10 99.85 99.87 100.00 99.99 100.10 100.10 100.10 100.10 100.10 100.10 100.10

2008 8 100.00 100.10 100.10 100.20 100.10 100.00 100.00 100.10 100.10 100.10 100.10 100.10 100.10 100.10

2008 9 100.10 100.00 100.10 99.99 99.99 99.99 100.10 100.10 100.10 100.10 100.10 100.10 100.00 100.00

2008 10 100.10 100.10 100.20 100.10 100.10 100.00 100.10 100.10 100.10 100.00 100.10 100.10 100.10 100.10

2008 11 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0 –.0

2008 12 100.10 100.10 100.10 100.10 100.10 100.10 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

2008 13 100.10 100.10 100.20 100.10 100.10 100.10 100.00 100.00 100.00 100.00 100.00 100.00 100.10 100.10

2008 14 100.10 100.10 100.20 100.00 100.00 100.00 100.10 100.10 100.00 100.00 100.10 100.10 100.10 100.10

2008 15 100.10 100.10 100.20 100.20 100.30 100.20 100.20 100.30 100.30 100.30 100.30 100.30 100.00 100.00

2008 16 100.10 100.00 100.10 100.10 100.00 100.00 100.10 100.10 100.10 100.00 100.00 100.10 100.10 100.20

Glaciated fjords in Southeast Alaska typically have 

different oceanographic and physical properties than 

non-glaciated inlets, including lower temperatures, smaller ranges in salinity and dissolved oxygen, higher sedimentation levels (Pickard, 1967; Carney et al., 1999), 

and seasonal events of enhanced carbonate mineral saturation (Reisdorph and Mathis, 2014). The environmental conditions found in emerged populations of shallowwater red tree corals in the glacial fjords are similar to 

those in deeper water on the continental shelf where 

large populations of red tree corals are located. The 

optimal temperature range for red tree corals in Alaska appears to be between 3.0°C and 7.5°C. Cimberg et 

al. (1981) suggested that the lower depth limit and geographical distribution for red tree corals corresponded 

with a mean spring temperature (typically March, April, 

and May) of 3.7°C (i.e., they prefer or are tolerant of 

temperatures above 3.7°C). We measured annual mean 
22 Professional Paper NMFS 20 

Table 10

Photosynthetically active radiation and euphotic depth (the depth where light intensity falls to 1% of that at the surface) 

measured at stations in Holkham Bay, Southeast Alaska, during surveys conducted in 2008 (1–3 May) and 2014 (7–9 June). 

Depths are adjusted to mean lower low water. Station numbers refer to those in Figure 7 and Appendix Table 2. En dashes 

(–) indicate no measurements.

Depth (m)

Year Station 0 5 10 15 20 30 40 50 Euphotic depth

2008 1 206.63 4.99 0.72 0.13 0 0 0 0 8.60

2008 2 493.55 13.56 3.12 0.86 0.21 0 0 0 12.18

2008 3 416.13 9.03 1.97 0.47 0.08 0 0 0 10.37

2008 6 371.55 27.69 7.62 2.31 0.72 0 0 0 16.72

2008 7 214.06 3.03 0.88 0.28 0.05 0 0 0 10.55

2008 8 263.15 6.41 1.30 0.50 0.16 0 0 0 8.40

2008 9 140.61 7.29 1.43 0.40 0.10 0 0 0 11.31

2008 10 195.02 27.82 9.02 4.41 2.19 0.51 0.06 0 22.30

2008 11 – – – – – – – – –

2008 12 531.63 2.81 0.39 0 0 0 0 0 8.08

2008 13 451.72 4.24 0.58 0.18 0 0 0 0 9.22

2008 14 153.77 22.59 4.65 1.35 0.51 0.03 0 0 15.84

2008 15 129.35 0.98 0.01 0 0 0 0 0 6.12

2008 16 91.56 5.67 0.76 0.16 0 0 0 0 11.65

2014 1 22.18 0 0 0 0 0 0 0 4.45

2014 2 172.20 0 0 0 0 0 0 0 4.25

2014 3 211.37 0.38 0 0 0 0 0 0 4.66

2014 6 468.94 3.75 0.10 0 0 0 0 0 7.20

2014 7 455.95 3.40 0.55 0.02 0 0 0 0 7.35

2014 8 369.07 1.95 0.40 0.03 0 0 0 0 7.75

2014 9 285.56 3.97 0.86 0.13 0 0 0 0 10.62

2014 10 325.50 3.48 0.74 0.17 0.01 0 0 0 9.00

2014 11 383.81 0.65 0 0 0 0 0 0 5.49

2014 12 163.82 2.85 0.02 0 0 0 0 0 9.27

2014 13 90.30 1.84 0.16 0 0 0 0 0 10.19

2014 14 – – – – – –` – – –

2014 15 424.03 11.29 5.27 2.59 0.66 0.13 0.13 0 18.98

2014 16 545.92 79.09 17.18 6.54 2.59 0.51 0.07 0 17.95

spring temperatures of 4.9–5.1°C and 3.5°C in Glacier 

Bay (2005–2006) and Tracy Arm (2011), respectively. 

Matsumoto (2007), however, found red tree corals thriving in deepwater areas of the Sea of Japan with summer 

temperatures of 0.2–1.1°C; therefore, they obviously can 

tolerate very cold water.

Red tree corals at Site 5 in the East Arm of Glacier 

Bay were subjected to temperatures between 4.1°C 

(March 2006) and 7.8°C (August and September 2005) 

(Fig. 9A). The average annual temperature at that site 

was 6.4°C. Red tree corals at Site 15 in Tracy Arm 

were subjected to temperatures between 2.8°C (February 2011) and 6.5°C (late November 2011). The average annual temperature at that site was 4.4°C. Results 

from this study indicate that red tree corals can tolerate 

temperatures between 2.8°C and 7.8°C, although corals 

held in the laboratory quickly die when the water temperature consistently holds (i.e., one week or more) near 

8.0°C (senior author, unpubl. data). These observations 

agree with data recorded at deepwater thicket sites in 

the eastern GOA where water temperatures ranged from 

5.3°C to 7.7°C (200 m depth) during the period from 

August 2013 to June 2015 (senior author, unpubl. data). 

The average annual temperature at that site was 5.8°C. 

Conversely, water temperature recorded at non-glacial 

sites at the same depth in Southeast Alaska ranged from 

4.4°C to 10.7°C during the period from July 1999 to 

June 2004 (Stone et al., 2017) and average annual temperature ranged from 7.1°C to 7.4°C. 

Red tree corals are more tolerant of a wider salinity 

range than expected. Salinity from CTD casts made every 

3 months in 2010 and 2011 at 15 m depth at Site 15 in 

Tracy Arm (Waller et al., 2014) showed a high of 31.41 

in March 2011 and a low of 26.86 in September 2011. 

Salinity ranged from 32.97 to 33.76 at the deepwater 

thicket sites in the eastern GOA (Stone et al., 2014). 

Bare, exposed bedrock is an abundant resource in the 

path of retreating glaciers and a major requirement of 
23

Table 11

Turbidity measured in nephelometric turbidity units at stations in Holkham Bay, Southeast Alaska, during a survey conducted 

in 2014 (7–9 June). Depths are adjusted to mean lower low water. Station numbers refer to those in Figure 7 and Appendix 

Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2014 1 7.02 7.32 8.67 8.70 6.93 3.69 2.60 1.50 1.32 1.46 1.46 1.12 1.12 1.56

2014 2 9.86 8.56 6.53 6.84 4.35 2.53 2.07 1.69 1.36 1.30 1.11 1.06 1.60 1.08

2014 3 5.72 6.73 6.47 5.44 4.04 2.52 2.12 1.47 1.24 1.12 1.08 0.98 0.99 0.91

2014 6 4.17 4.85 3.80 4.03 2.74 2.32 1.98 1.34 0.92 0.82 0.87 0.87 0.70 0.68

2014 7 2.89 3.22 3.11 3.11 2.30 1.96 1.21 1.00 0.79 0.86 0.65 0.66 0.60 0.57

2014 8 2.67 2.40 2.16 2.13 1.62 1.15 0.80 0.70 0.55 0.57 0.51 0.52 0.57 0.49

2014 9 2.41 2.22 2.14 1.97 1.49 0.84 0.67 0.59 0.60 0.57 0.57 0.50 0.46 0.50

2014 10 1.07 1.00 0.79 0.72 0.57 0.48 0.50 0.45 0.41 0.40 0.40 0.41 0.44 0.41

2014 11 10.62 12.34 10.91 5.55 3.32 2.51 2.01 1.86 1.64 1.85 1.45 1.81 1.28 1.53

2014 12 5.25 5.56 5.39 4.97 2.36 1.96 1.34 1.03 0.78 0.82 0.83 0.94 1.03 1.09

2014 13 4.79 3.47 1.90 1.81 1.23 0.83 0.83 0.95 0.78 0.75 0.88 0.77 0.78 0.86

2014 14 .– .– 0.90 0.60 0.55 0.47 0.46 0.47 0.45 0.46 0.50 0.45 0.45 0.50

2014 15 2.01 0.92 0.60 0.56 0.48 0.47 0.47 0.49 0.45 0.44 0.47 0.45 0.47 0.46

2014 16 1.55 0.89 0.72 0.67 0.47 0.44 0.44 0.44 0.44 0.46 0.49 0.46 0.46 1.55

Table 12

Levels of pH measured at stations in Holkham Bay, Southeast Alaska, during a survey conducted in 2014 (7–9 June). Depths 

are adjusted to mean lower low water. Station numbers refer to those in Figure 7 and Appendix Table 2. En dashes (–) indicate no measurements. 

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2014 1 8.06 7.99 7.96 7.93 7.91 7.90 7.90 7.89 7.88 7.88 7.87 7.86 7.86 7.86

2014 2 7.97 7.93 7.92 7.91 7.90 7.95 7.90 7.89 7.88 7.87 7.86 7.86 7.86 7.86

2014 3 7.90 7.90 7.89 7.88 7.88 7.88 7.88 7.88 7.87 7.86 7.86 7.85 7.85 7.84

2014 6 8.00 7.96 7.95 7.94 7.92 7.92 7.91 7.92 7.91 7.90 7.89 7.88 7.87 7.86

2014 7 8.09 7.96 7.96 7.94 7.91 7.90 7.91 7.91 7.90 7.89 7.88 7.87 7.87 7.86

2014 8 8.12 8.03 7.99 7.97 7.94 7.94 7.93 7.92 7.91 7.90 7.89 7.88 7.87 7.86

2014 9 8.10 8.02 7.98 7.95 7.93 7.94 7.94 7.92 7.91 7.90 7.89 7.88 7.87 7.87

2014 10 8.34 8.27 8.17 8.09 8.01 7.98 7.98 7.96 7.93 7.91 7.90 7.89 7.88 7.87

2014 11 7.90 7.89 7.89 7.89 7.89 7.88 7.87 7.86 7.85 7.84 7.82 7.80 7.78 7.77

2014 12 7.91 7.90 7.89 7.89 7.90 7.89 7.88 7.85 7.84 7.84 7.83 7.81 7.79 7.78

2014 13 7.91 7.90 7.89 7.89 7.89 7.88 7.87 7.86 7.85 7.84 7.83 7.82 7.80 7.78

2014 14 – – 7.87 7.88 7.88 7.87 7.87 7.86 7.85 7.84 7.83 7.82 7.81 7.80

2014 15 7.94 7.95 7.94 7.92 7.91 7.90 7.88 7.87 7.86 7.84 7.83 7.82 7.81 7.80

2014 16 8.00 7.99 8.00 7.99 7.93 7.90 7.87 7.86 7.85 7.84 7.84 7.83 7.83 7.82

red tree corals and many other corals for initial settlement (Stone et al., 2014). The upper depth limit of red 

tree corals was often nearly coincident with the lower 

depth limit of coralline algae, and this pattern was often conspicuous (e.g., Fig. 8A). Algae may outcompete 

the corals for settling substrate and even use allelopathic 

agents (Rasher et al., 2011) to do so; however, we suspect that the sharp delineation in bathymetric distribution observed in this study is due to preferences for or 

tolerances to light conditions. 

Species of Lithothamnion have been reported to grow 

to depths of 30 m at other locations (Lamb and Hanby, 

2005), but the only sites where the algae were observed 

at similar depths in this study were at the sites farthest 

from the heads of the fjords where corals were absent. 

Coralline algae, like all primary producers, require 
24 Professional Paper NMFS 20 

sunlight for life processes. Red tree corals, unlike most 

of their tropical counterparts, are azooxanthellate; that 

is, they lack intracellular symbiotic dinoflagellates that 

fix carbon through photosynthesis and have no requirements for sunlight. To the contrary, our observations of 

laboratory held octocorals indicate that they are quickly 

killed when covered with brown filamentous algae, possibly as a result of tissue suffocation by mucilage produced by the algae (Mistri and Ceccherelli, 1993; Tsounis et al., 2012). Therefore, the demarcation between the 

depth distributions of the 2 groups may represent the 

critical light levels for the algae (i.e., not enough) and 

the coral (i.e., too much). We believe this observation 

implicates the important role of reduced ambient radiation, caused by high siltation rates and possibly shading 

by steep walls (sensu Blockley and Chapman, 2006) in 

the upper reaches of the fjords, in deep-sea emergence of 

red tree corals.

Glacial fjords are very dynamic environments with 

disturbances from above (e.g., rock and ice slides) and 

upstream (iceberg scour) that affect the persistence of 

red tree coral populations in some areas. At several sites, 

particularly at Sites 5 and 7 in the East Arm of Glacier 

Bay (Fig. 10A), the rock forming the steep cliffs above 

is heavily weathered and unstable. There is evidence of 

frequent slides in some areas, and we observed several 

colonies encapsulating captured small shot rock with 

coenenchyme. Red tree corals in shallow-water habitats 

of the fjords also are subjected to the seasonal onslaught 

of iceberg scour. Some areas, particularly at depths less 

than 30 m at Sites 14 and 15 in Tracy Arm (Fig. 10B), 

had extensive iceberg scour as evidenced by coral stumps 

and bleached calcified basal plates (Fig. 8F). We found 

evidence of iceberg scour to a depth of 67 m at these 2 

sites.

Our observation that red tree corals occur in areas of 

Glacier Bay that were deglaciated as recently as 26 years 

ago clearly indicates that it is a pioneer species in certain 

settings. On the basis of the reported growth rates of red 

tree corals (Andrews et al., 2002), this species may have 

colonized bedrock areas that had been exposed only 

for a few years. Gorgonians, species of Primnoella and 

Primnoisis (Primnoisis) antarctica, were also early colonizers following iceberg disturbance in Antarctic benthic 

habitats, but Primnoa resedaeformis (later confirmed as 

P. notialis; Cairns and Bayer, 2005), a closely related 

species to P. pacifica, was a later colonizer in disturbed 

habitats (Teixidó et al., 2004). 

Glacier Bay has a well-documented history of rapid 

glacial retreat during the past 2 centuries with subsequent emergence of an extensive fjord system and adjacent terrestrial uplands (Sharman et al., 1995). Consequently, Glacier Bay has been an important site for 

studies of primary succession in terrestrial, lake, stream, 

and marine intertidal habitats (Sharman et al., 1995). 

Primary succession in the subtidal marine habitat has not 

yet been studied, and although not the principal focus 

of this study, our observations do support some of the 

hypotheses set forth by Sharman et al. (1995) regarding succession in marine environments. The pattern of 

increased species richness at sites farther from the heads 

of the fjords illustrates classic successional processes of 

benthic communities as new oceanographic and physical habitats become available in the path of retreating 

glaciers.

The glacial fjords, particularly the upper reaches, do 

not support the diverse and abundant demersal resources 

found in the climax communities in deepwater areas of 

the continental shelf and upper slope of the eastern GOA 

(Stone et al., 2014). The fjords are, however, noteworthy for rich stocks of forage fishes and schooling species, 

such as capelin (Mallotus villosus, Fig. 8G) and walleye 

pollock (Gadus chalcogrammus), that use the fjords as 

important spawning and overwintering habitat (Arimitsu 

et al., 2007; Arimitsu et al., 2008).

Given the paucity of demersal fish species, particularly shelter-seeking species like rockfish, we were not 

surprised to find few species using the shallow-water 

thickets of red tree corals as habitat. However, we did 

document a few cases of the corals providing seasonally 

important habitat for some species. Young-of-the-year 

walleye pollock (~95 mm total length), up to 3–4 fish 

per colony, use the shallow-water corals as nursery habitat in Tracy Arm during some winter months (Fig. 8H). 

These fish were so strongly associated with the corals 

that divers could actually catch them by hand. Sculpins 

(Cottidae) also were observed using the corals as cover, 

and several great sculpin (Myoxocephalus polyacanthocephalus) were observed guarding egg masses attached 

to colony branches (Fig. 8I). This behavior may be similar to that in which the goldeneye snailfish (Allocareproctus unangas) deposits its adhesive eggs on Primnoa 

in the Aleutian Islands (Busby et al., 2006). We also 

observed blue king crabs (Paralithodes platypus) occasionally using red tree corals as cover (Fig. 8J) and a 

single blackspotted rockfish (Sebastes melanostictus) using a large red tree coral as cover at a depth of 25 m in 

Tracy Arm. This fish was the only rockfish observed in 

Holkham Bay during this study.

Some commercial fisheries have historically existed 

within Glacier and Holkham bays, principally longline fisheries for Pacific halibut (Hippoglossus stenolepis) and sablefish (Anoplopoma fimbria) and pot fishing for Dungeness (Cancer magister) and king crabs 

(Paralithodes spp. and Lithodes aequispinus) (Taylor 

and Perry, 1990; Taggart et al., 2003; Mondragon et 

al., 2007). These fisheries target species that seldom actively associate with red tree corals (Stone et al., 2014); 

therefore, fishing gear effects are of minimal concern 

for the coral habitat there. Shallow-water populations 
25

Figure 10

(A) Photograph of Sites 5 and 7 at East Arm (Muir Inlet), Glacier Bay, Southeast Alaska, showing the heavily weathered and relatively unstable steep cliffs of vertical walls, both above and below sea level, that consist of well-worn schist and areas of plutonics. (B) Photograph of Sites 14 and 15 at Tracy Arm, Holkham Bay, Southeast Alaska, showing the relatively stable, steep vertical 

walls, both above and below sea level, that consist principally of well-worn graywacke and granodiorite.
26 Professional Paper NMFS 20 

have provided researchers the opportunity to study important aspects of the ecology of this important keystone species. Ready access to populations through the 

use of relatively simple techniques has facilitated studies on reproductive ecology (Waller et al., 2014), population-level genetics studies (Morrison et al., 2015), and 

ongoing studies on the physiological effects of ocean 

acidification. These studies will provide important information for appropriate designation of protective 

measures for populations at risk to human activities in 

deepwater areas of the GOA.

Glacial retreat and the unique oceanographic conditions created by tidewater glaciers promote the emergence of red tree corals in shallow water. Further, their 

proximity to tidewater glaciers makes them prime candidates to monitor the potential effects of global climate 

change, particularly ocean warming and acidification. 

The results of our study indicate that continued glacial 

retreat will ultimately lead to the demise of red tree corals in shallow water when tidewater glaciers ground in 

the valleys they formed, forcing red tree corals to retreat 

to deeper water, awaiting the next glacial advance.

Acknowledgments

First and foremost we thank A. Andrews who along with 

author J. Mondragon first discovered the red tree corals 

in Glacier Bay. Along with A. Andrews, we thank K. 

Cieciel, E. Brown, J. Wendland, and P. Fischel for assistance with field operations, S. Cairns for identification 

of corals, H. Lehnert for identification of demosponges, 

H. Reiswig for identification of hexactinellid sponges, 

D. Csepp for leading ROV operations, and A. H. Andrews and 2 anonymous reviewers for helpful reviews of 

this manuscript. We thank the captains and crews of the 

NOAA Ship John N. Cobb and the Alaska Department 

of Fish and Game RV Medeia for their assistance and 

support. We also thank B. Commins and L. Sharman of 

the National Park Service for their support of this project. This project was funded by the Alaska Fisheries Science Center of the National Marine Fisheries Service and 

the U.S. Geological Survey (2004 and 2005). The Glacier Bay study was conducted under authority of the National Park Service (permits GLBA-2004-SCI-0012 and 

GLBA-2005-SCI-0004).

Literature cited

Andrews, A. H., E. E. Cordes, M. M. Mahoney, K. Munk, K. 

H. Coale, G. M. Cailliet, and J. Heifetz.

2002. Age, growth and radiometric age validation of a 

deep-sea, habitat-forming gorgonian (Primnoa resedaeformis) from the Gulf of Alaska. Hydrobiologia 

471:101–110. https://doi.org/10.1023/A:1016501320206

Arimitsu, M. L., J. F. Piatt, M. D. Romano, and D. C. Douglas.

2007. Distribution of forage fishes in relation to the oceanography of Glacier Bay National Park. In Proceedings 

of the Fourth Glacier Bay Science Symposium; Juneau, 

AK, 26–28 October 2004 (J. F. Piatt and S. M. Gende, 

eds.), p. 102–106. U.S. Geol. Surv. Sci. Invest. Report 

2007–5047.

Arimitsu, M. L., J. F. Piatt, M. A. Litzow, A. A. Abookire, M. 

D. Romano, and M. D. Robards.

2008. Distribution and spawning dynamics of capelin 

(Mallotus villosus) in Glacier Bay, Alaska: a cold water refugium. Fish. Oceanogr. 17:137–146. https://doi.

org/10.1111/j.1365-2419.2008.00470.x

Blockley, D. J., and M. G. Chapman.

2006. Recruitment determines differences between assemblages on shaded and unshaded seawalls. Mar. 

Ecol. Prog. Ser. 327:27–36. https://doi.org/10.3354/

meps327027

Busby, M. S., J. W. Orr, and D. M. Blood. 

2006. Eggs and late-stage embryos of Allocareproctus 

unangas (family Liparidae) from the Aleutian Islands. 

Ichthyol. Res. 53:428–426. https://doi.org/10.1007/

s10228-006-0361-3

Cairns, S. D.

2011. A revision of the Primnoidae (Octocorallia: Alcyonacea) from the Aleutian Islands and Bering Sea. Smithson. 

Contrib. Zool. 634, 55 p. 

Cairns, S. D., and F. M. Bayer.

2005. A review of the genus Primnoa (Octocorallia: Gorgonacea: Primnoidae), with the description of two new 

species. Bull. Mar. Sci. 77:225–256.

Carney, D., J. S. Oliver, and C. Armstrong.

1999. Sedimentation and composition of wall communities in Alaskan fjords. Polar Biol. 22:38–49. https://doi.

org/10.1007/s003000050388

Cimberg, R. L., T. Gerrodette, and K. Muzik.

1981. Habitat requirements and expected distribution of 

Alaska coral. Final Report, Research Unit 601, VTN Oregon, Inc. Report prepared for the Office of Marine Pollution Assessment, Alaska Office, U.S. Dep. Commer., 

NOAA, OCSEAP Final Rep. 54:207–308.

Etherington, L. L., P. N. Hooge, E. R. Hooge, and D. F. Hill.

2007. Oceanography of Glacier Bay, Alaska: implications 

for biological patterns in a glacial fjord estuary. Estuar. 

Coasts 30:927–944. https://doi.org/10.1007/BF02841386

Federal Register.

2017. Fisheries of the exclusive economic zone off Alaska, 

50 CFR, Ch. VI, Part 679 (10–1–17 edition):490-964. 

[Available from https://www.gpo.gov/fdsys/pkg/CFR2017-title50-vol13/pdf/CFR-2017-title50-vol13-part679.

pdf.]

Försterra, G., and V. Häussermann.

2003. First report on large scleractinian (Cnidaria: Anthozoa) accumulations in cold-temperate shallow water of 

south Chilean fjords. Zool. Verh. 345:117–128.

Grange, K. R.

1985. Distribution, standing crop, population structure, 

and growth rates of black coral in the southern fiords of 

New Zealand. N. Z. J. Mar. Freshw. Res. 19:467–475. 

https://doi.org/10.1080/00288330.1985.9516111

Grange, K. R., R. J. Singleton, J. R. Richardson, P. J. Hill, and 

W. del Main.

1981. Shallow rock-wall biological associations of some 

southern fiords of New Zealand. N. Z. J. Zool. 8:209–

227. https://doi.org/10.1080/03014223.1981.10427963
27

Heifetz, J.

2002. Coral in Alaska: distribution, abundance, and species associations. Hydrobiologia 471:19–28. https://doi.

org/10.1023/A:1016528631593

Hunter, L. E., and R. D. Powell. 

1995. Climatic controls on glacier mass balance in Glacier 

Bay National Park and Preserve, Alaska. In Proceedings 

of the Third Glacier Bay Science Symposium, 1993; Gustavus, AK, 15–18 October 1993 (D. R. Engstrom, ed.), p. 

46–54. National Park Service, Anchorage, AK.

Krieger, K. J.

2001. Coral (Primnoa) impacted by fishing gear in the 

Gulf of Alaska. In Proceedings of the First International 

Symposium on Deep-Sea Corals (J. H. M. Willison, J. 

Hall, S. E. Gass, E. L. R. Kenchington, M. Butler, and 

P. Doherty, eds.), p. 106–116. Ecol. Action Cent. Nova 

Scotia Mus., Halifax, NB, Canada.

Krieger, K. J., and B. L. Wing.

2002. Megafauna associations with deepwater corals 

(Primnoa spp.) in the Gulf of Alaska. Hydrobiologia 

471:84–90. https://doi.org/10.1023/A:1016597119297

Lamb, A., and B. P. Hanby.

2005. Marine life of the Pacific Northwest: a photographic encyclopedia of invertebrates, seaweeds and selected 

fishes, 398 p. Harbour Publishing, Madeira Park, BC, 

Canada.

Lehnert, H., and R. P. Stone.

2016. A comprehensive inventory of the Gulf of Alaska 

sponge fauna with the description of two new species 

and geographic range extensions. Zootaxa 4144:365–

382. https://doi.org/10.11646/zootaxa.4144.3.5

Masuda, M. M., and R. P. Stone.

2015. Bayesian logistic mixed-effects modelling of transect 

data: relating red tree coral presence to habitat characteristics. ICES J. Mar. Sci. 72:2674–2683. https://doi.

org/10.1093/icesjms/fsv163

Matsumoto, A. K.

2007. Effects of low water temperature on growth and 

magnesium carbonate concentrations in the cold-water 

gorgonian Primnoa pacifica. Bull. Mar. Sci. 81:423–435. 

Matthews, J. B., and A. V. Quinlan.

1975. Seasonal characteristics of water masses in Muir Inlet, a fjord with tidewater glaciers. J. Fish. Res. Board 

Can. 32:1693–1703. https://doi.org/10.1139/f75-203

McNabb, R. W.

2013. On the frontal ablation of Alaska tidewater glaciers. 

Ph.D. diss., 111 p. Univ. Alaska Fairbanks, Fairbanks, 

AK.

Mistri, M., and V. U. Ceccherelli.

1993. Growth of the Mediterranean gorgonian Lophogorgia ceratophyta (L., 1758). Mar. Ecol. 14:329–340. 

https://doi.org/10.1111/j.1439-0485.1993.tb00004.x

Molnia, B. F.

2008. Glaciers of North America—glaciers of Alaska. U.S. 

Geol. Surv. Prof. Pap. 1386-K, 505 p.

Mondragon, J., L. L. Etherington, S. J. Taggart, and P. N. 

Hooge.

2007. The distribution and abundance of Pacific halibut 

in a recently deglaciated fjord: implications for marine 

reserve design. In Proceedings of the Fourth Glacier Bay 

Science Symposium; Juneau, AK, 26–28 October 2004 (J. 

F. Piatt and S. M. Gende, eds.), p. 107–109. U.S. Geol. 

Surv. Sci. Invest. Rep. 2007–5047.

Morrison, C. L., M. J. Springmann, K. M. Shroades, and R. P. 

Stone.

2015. Development of twelve microsatellite loci in the 

red tree corals Primnoa resedaeformis and Primnoa pacifica. Conserv. Genet. Resour. 7:763–765. https://doi.

org/10.1007/s12686-015-0455-1

Pickard, G. L.

1967. Some oceanographic characteristics of the larger inlets of southeast Alaska. J. Fish. Res. Board Can. 

24:1475–1506. https://doi.org/10.1139/f67-123

Powell, R. D.

1990. Advance of glacial tidewater fronts in Glacier Bay. 

In Proceedings of the Second Glacier Bay Symposium; 

Gustavus, AK, 19–22 September 1988 (A. M. Milner and 

J. D. Wood Jr., eds.), p. 67–73. National Park Service, 

Anchorage, AK.

Rasher, D. B., E. P. Stout, S. Engel, J. Kubanek, and M. E. Hay.

2011. Macroalgal terpenes function as allelopathic agents against reef corals. Proc. Natl. Acad. Sci. 

U.S.A. 108:17726–17731. https://doi.org/10.1073/

pnas.1108628108

Reisdorph, S. C., and J. T. Mathis.

2014. The dynamic controls on carbonate mineral saturation states and ocean acidification in a glacially dominated estuary. Estuar. Coast. Shelf Sci. 144:8–18. https://

doi.org/10.1016/j.ecss.2014.03.018

Sharman, L. C., A. M. Milner, F. S. Chapin III, and D. R. 

Engstrom.

1995. Qualitative successional models in Glacier Bay: a 

comparison of terrestrial, marine, stream, and lake ecosystems. In Proceedings of the Third Glacier Bay Science 

Symposium, 1993; Gustavas, AK, 15–18 September 1993 

(D. R. Engstrom, ed.), p. 190–195. National Park Service, Anchorage, AK.

Strömgren, T.

1970. Emergence of Paramuricea placomus (L.) and Primosa resedaeformis (Gunn.) in the inner part of Trondheimsfjorden (west coast of Norway). Norwegian Res. 

Counc. Sci. Hum. 4, 6 p.

1971. Vertical and horizontal distribution of Lophelia pertusa (Linne) in Trondheimsfjorden on the west coast of 

Norway. Det. K. Nor. Vidensk. Selsk. Skr. 6:1–9.

Stone, R. P., and S. D. Cairns.

2017. Deep-sea coral taxa in the Alaska Region: depth and 

geographical distribution. In The state of deep-sea coral 

and sponge ecosystems of the United States: 2017 (T. F. 

Hourigan, P. J. Etnoyer, and S. D. Cairns, eds.). NOAA 

Tech. Memo. NMFS-OHC-4. [Online Annex 1, available 

from https://deepseacoraldata.noaa.gov/library/2015-

state-of-dsc-report-folder/NOAA_DSC-Species-List_Alaska_Stone-Cairns_2017.pdf.]

Stone, R. P., H. Lehnert, and H. Reiswig.

2011. A guide to the deep-water sponges of the Aleutian 

Island Archipelago. NOAA Prof. Pap. NMFS 12, 187 p.

Stone, R. P., M. M. Masuda, and J. F. Karinen.

2014. Assessing the ecological importance of red tree coral 

thickets in the eastern Gulf of Alaska. ICES J. Mar. Sci. 

72:900–915. https://doi.org/10.1093/icesjms/fsu190

Stone, R. P., P. W. Malecha, and M. M. Masuda.

2017. A five-year, in situ growth study on shallow-water 

populations of the gorgonian octocoral Calcigorgia spiculifera in the Gulf of Alaska. PLoS ONE 12(1):e0169470. 

https://doi.org/10.1371/journal.pone.0169470
28 Professional Paper NMFS 20 

Taggart, S. J., P. N. Hooge, J. Mondragon, E. R. Hooge, and 

A. G. Andrews.

2003. Living on the edge: distribution of Dungeness crab 

Cancer magister in a recently deglaciated fjord. Mar. 

Ecol. Prog. Ser. 246:241–252. https://doi.org/10.3354/

meps246241

Taylor, M. S., and A. Perry.

1990. Commercial fishing patterns in Glacier Bay National 

Park, Alaska. In Proceedings of the Second Glacier Bay 

Symposium; Gustavas, AK, 19–22 September 1988 (A. 

M. Milner and J. D. Wood Jr., eds), p. 78–82. National 

Park Service, Anchorage, AK.

Teixidó, N., J. Garrabou, J. Gutt, and W. E. Arntz.

2004. Recovery in Antarctic benthos after iceberg disturbance: trends in benthic composition, abundance and 

growth forms. Mar. Ecol. Prog. Ser. 278:1–16. https://

doi.org/10.3354/meps278001

Tsounis, G., L. Martinez, L. Bramanti, N. Viladrich, J.-M. Gili, 

Á. Martinez, and S. Rossi.

2012. Anthropogenic effects on reproductive effort and 

allocation of energy reserves in the Mediterranean octocoral Paramuricea clavata. Mar. Ecol. Prog. Ser. 

449:161–172. https://doi.org/10.3354/meps09521

Waller, R. G., R. P. Stone, J. Johnstone, and J. Mondragon. 

2014. Sexual reproduction and seasonality of the Alaskan 

red tree coral, Primnoa pacifica. PLoS ONE 9(4):e90893. 

https://doi.org/10.1371/journal.pone.0090893
29

Appendix Table 1

Location of sites where surveys were conducted by scuba divers and with a remotely operated 

vehicle at the 4 study areas in Southeast Alaska to examine the distribution of red tree corals 

(Primnoa pacifica). Note that the distance from the head of fjord for all sites in the West Arm, 

Glacier Bay, was measured to the head of Johns Hopkins Inlet except for Sites 15, 16, and 17, 

where the distance was measured to the head of Tarr Inlet. Also note that the distance from 

the head of fjord for all sites in Tracy Arm, Holkham Bay, was measured to the face of South 

Sawyer Glacier except for Sites 1, 2, and 3, where the distance was measured to the face of 

Sawyer Glacier. An asterisk (*) indicates sites surveyed with a remotely operated vehicle.

Distance from

head of fjord Red tree Latitude Longitude

Site (km) corals present (N) (W)

East Arm, Glacier Bay

1 1.32 Yes 59°05.0930′ 136°21.8142′

2 5.24 No 59°03.6000′ 136°19.1400′

3 11.40 Yes 59°03.4105′ 136°12.7715′

4 11.63 Yes 59°03.3505′ 136°12.4700′

5 15.98 Yes 59°01.4625′ 136°10.4025′

6 17.66 Yes 59°01.2600′ 136°08.4000′

7 17.67 Yes 59°00.7180′ 136°09.6160′

8 22.58 Yes 58°58.6190′ 136°08.6565′

9 24.41 No 58°57.5400′ 136°07.5600′

10 26.00 No 58°56.7215′ 136°08.0675′

11 27.21 No 58°56.1640′ 136°07.4180′

12 33.13 No 58°53.1555′ 136°04.1130′

13 35.71 No 58°51.8550′ 136°03.2660′

14 47.62 No 58°46.0490′ 136°02.4080′

West Arm, Glacier Bay

15 3.44 No 59°01.6800′ 137°03.0600′

16 5.44 No 59°01.0200′ 137°00.4200′

17 12.30 No 58°58.0200′ 136°56.3400′

18 16.76 No 58°55.6800′ 136°55.5300′

19 4.57 No 58°52.4635′ 137°04.7030′

20 7.00 No 58°53.3810′ 137°03.8510′

21 11.22 No 58°54.1800′ 136°59.4900′

22 15.45 No 58°54.0600′ 136°55.3200′

23 22.59 No 58°54.3600′ 136°47.7900′

24 23.15 No 58°52.6800′ 136°47.7900′

25 30.10 No 58°53.5800′ 136°40.0500′

26 36.91 No 58°55.2000′ 136°36.1500′

27 38.19 No 58°49.9800′ 136°33.7500′

28 41.69 No 58°50.1600′ 136°29.1000′

Tracy Arm, Holkham Bay 

1 1.07 No 57°54.5490′ 133°09.5470′

2 2.06 No 57°53.9950′ 133°10.3280′

3 3.28 Yes 57°53.5660′ 133°11.3830′

4 4.90 Yes 57°52.5000′ 133°09.9160′

5 5.33 Yes 57°52.2640′ 133°10.8590′

6 5.82 Yes 57°52.9320′ 133°10.3160′

7 6.06 Yes 57°53.0490′ 133°10.4390′

8* 6.23 Yes 57°52.7890′ 133°11.3050′

9* 6.43 Yes 57°52.6320′ 133°11.7700′

10 6.40 Yes 57°52.6260′ 133°11.7700′

11 9.38 Yes 57°53.2010′ 133°14.2790′

12 9.36 Yes 57°53.1740′ 133°14.2630′

13* 13.43 Yes 57°53.4600′ 133°17.9820′

14* 14.33 Yes 57°53.3460′ 133°18.9730′

15 14.51 Yes 57°53.2740′ 133°19.0850′

Table continued
30 Professional Paper NMFS 20 

Appendix Table 1 (continued)

Distance from

head of fjord Red tree Latitude Longitude

Site (km) corals present (N) (W)

16 15.96 Yes 57°53.6810′ 133°20.2610′

17 17.71 Yes 57°53.5620′ 133°22.1480′

18 19.68 Yes 57°54.3990′ 133°23.5870′

19* 21.94 Yes 57°54.6820′ 133°25.8240′

20* 24.03 Yes 57°54.5760′ 133°27.8190′

21* 24.40 Yes 57°55.1830′ 133°28.1510′

22 24.39 Yes 57°55.1700′ 133°28.1390′

23* 25.75 No 57°55.0800′ 133°29.5790′

24* 26.02 Yes 57°55.1960′ 133°29.7590′

25* 27.42 Yes 57°55.4580′ 133°32.6400′

26 27.67 No 57°54.9350′ 133°33.1800′

27 27.81 No 57°55.5920′ 133°33.3000′

28 32.14 No 57°54.5320′ 133°34.8020′

29 37.17 No 57°51.8860′ 133°36.0470′

30 48.45 No 57°46.1050′ 133°38.8320′

Endicott Arm, Holkham Bay 

31 3.70 No 57°29.9530′ 132°56.4960′

32* 6.80 Yes 57°30.9160′ 132°59.2810′

33 7.80 Yes 57°30.7520′ 133°00.4970′

34* 7.90 Yes 57°30.8000′ 133°00.5460′

35* 8.60 Yes 57°31.3750′ 133°00.7880′

36* 10.00 Yes 57°30.8180′ 133°02.3950′
31

Appendix Table 2

Location of sampling sites where conductivity, temperature, 

and depth (CTD) instruments were used to collect oceanographic data in Glacier and Holkham Bays, Southeast Alaska, 

in 2004, 2005, 2006, 2008, and 2014. Depth is the typical 

maximum depth of each CTD cast. Station numbers refer to 

those in Figures 6 and 7. 

Station Latitude (N) Longitude (W) Depth (m)

Glacier Bay

1 59°04.7700′ 136°21.2200′ 200

2 59°03.0000′ 136°11.0400′ 200

3 59°01.6000′ 136°09.8700′ 200

4 59°01.5170′ 136°10.4550′ 60

5 59°01.2480′ 136°08.3970′ 30

6 58°58.5100′ 136°08.1700′ 160

7 58°52.6600′ 136°05.3600 275

8 59°00.2000′ 136°59.1800 290

9 58°58.3050′ 136°55.0750′ 290

10 58°53.8350′ 137°02.8600′ 290

11 58°53.9300′ 136°50.4700′ 300

12 58°53.8150′ 136°44.1950′ 300

13 58°55.0750′ 136°36.6000′ 150

14 58°51.9800′ 136°35.5700′ 300

15 58°48.6850′ 136°28.3700′ 300

16 58°45.2400′ 136°19.6540′ 290

17 58°39.8100′ 136°07.6500′ 275

18 58°11.4100′ 135°01.5900′ 300

Holkham Bay 

1 57°52.8180′ 133°10.7760′ 150

2 57°53.1000′ 133°12.7080′ 180

3 57°54.0300′ 133°17.2560′ 200

4 57°53.3460′ 133°18.9480′ 100

5 57°53.2440′ 133°18.7500′ 100

6 57°53.8140′ 133°21.7320′ 200

7 57°54.9420′ 133°27.0660′ 200

8 57°55.3560′ 133°31.1460′ 200

9 57°55.2660′ 133°35.0040′ 200

10 57°49.0200′ 133°36.2460′ 200

11 57°30.0840′ 132°54.6300′ 150

12 57°30.8100′ 132°59.8980′ 150

13 57°31.1160′ 133°02.9220′ 200

14 57°36.4740′ 133°12.1620′ 200

15 57°38.3160′ 133°16.8000′ 200

16 57°43.6140′ 133°30.9540′ 200
32 Professional Paper NMFS 20 

Appendix Table 3

Dissolved oxygen (mL/L) measured at stations in Glacier Bay, Southeast Alaska, during research cruises in 2004 (24–27 April) 

and 2005 (17–22 April). Depths are adjusted to mean lower low water. Station numbers refer to those in Figure 6 and Appendix Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2004 1 9.93 8.36 7.48 6.90 6.69 6.83 6.89 6.94 6.97 7.00 7.01 7.03 7.03 7.04

2004 4 6.88 7.06 6.84 6.78 6.91 6.96 6.98 – – – – – – –

2004 5 7.29 6.93 6.81 6.68 – – – – – – – – – –

2004 7 8.47 7.33 6.92 6.78 6.78 6.73 6.77 6.81 6.86 6.89 6.91 6.92 6.92 6.91

2004 17 8.86 8.36 7.70 7.41 7.15 7.04 7.07 7.12 7.14 7.17 7.19 7.21 7.21 7.21

2004 18 8.05 7.69 7.31 7.14 6.92 6.69 6.25 5.87 5.52 5.21 4.82 4.69 4.61 4.52

2005 1 4.66 4.91 5.25 5.27 5.23 5.20 5.18 5.16 5.13 5.08 5.06 4.97 4.97 4.91

2005 2 4.90 4.97 5.00 5.11 4.79 4.74 4.72 4.75 4.75 4.75 4.75 4.78 4.81 4.83

2005 3 – – – – – – – – – – – – – –

2005 6 5.06 5.42 5.59 5.58 5.57 5.55 5.54 5.53 5.51 5.50 5.49 5.49 5.48 5.47

2005 7 5.45 5.58 5.60 5.60 5.58 5.52 5.50 5.47 5.45 5.44 5.44 5.43 5.43 5.42

2005 8 8.32 6.37 5.63 5.14 4.89 4.70 4.62 4.60 4.60 4.61 4.61 4.61 4.62 4.62

2005 9 8.05 6.33 5.40 4.88 4.59 4.48 4.43 4.42 4.42 4.43 4.43 4.43 4.44 4.44

2005 10 8.45 6.36 5.07 4.59 4.43 4.41 4.41 4.41 4.40 4.40 4.40 4.40 4.40 4.40

2005 11 10.75 7.30 5.60 4.96 4.60 4.48 4.47 4.47 4.47 4.47 4.47 4.47 4.47 4.47

2005 12 11.37 7.41 6.04 5.03 4.62 4.47 4.43 4.42 4.42 4.43 4.43 4.43 4.44 4.44

2005 13 13.09 7.59 6.11 4.88 4.56 4.49 4.45 4.44 4.44 4.44 4.45 4.45 4.46 4.46

2005 14 12.35 8.35 7.02 5.22 4.63 4.48 4.43 4.42 4.40 4.40 4.40 4.40 4.40 4.40

2005 15 9.82 7.82 6.31 5.42 4.89 4.73 4.62 4.59 4.59 4.59 4.59 4.59 4.60 4.63

2005 16 – – – – – – – – – – – – – –

2005 17 13.04 12.96 8.03 6.63 5.60 5.26 5.08 5.00 4.99 4.98 5.00 5.02 5.03 5.05

2005 18 – – – – – – – – – – – – – –
33

Appendix Table 4

Dissolved oxygen (mL/L) measured at stations in Holkham Bay, Southeast Alaska, during 3 research cruises in 2006 (22–27 

March), 2007 (26–28 March), and 2008 (1–3 May). Depths are adjusted to mean lower low water. Station numbers refer to 

those in Figure 7 and Appendix Table 2. En dashes (–) indicate no measurements.

Depth (m)

Year Station 5 10 15 20 30 40 50 60 70 80 90 100 110 120

2006 1 2.83 2.74 2.65 2.42 2.42 2.41 2.40 2.40 2.40 2.40 2.40 2.40 2.41 2.28

2006 2 4.02 3.83 3.68 3.65 3.66 3.67 3.68 3.78 3.71 3.66 3.67 3.66 3.72 3.75

2006 3 7.08 4.81 4.27 4.00 3.89 3.88 4.78 4.38 4.03 4.05 3.97 4.00 3.97 3.96

2006 6 6.87 5.82 5.01 4.66 4.49 4.21 4.02 4.34 3.78 3.75 3.74 3.73 3.72 3.71

2006 7 6.12 5.07 4.69 4.57 4.37 4.12 3.98 3.77 3.71 3.68 3.67 3.66 3.66 3.65

2006 8 6.57 4.71 4.45 4.36 4.62 4.33 4.07 3.93 3.89 3.87 3.90 3.85 3.85 3.84

2006 9 5.98 5.00 4.88 4.41 4.26 4.21 4.10 3.83 3.74 3.74 3.72 3.72 3.72 3.72

2006 10 6.86 5.69 4.84 4.57 4.46 4.37 4.41 4.11 3.99 3.93 3.90 3.87 3.82 3.80

2006 11 – – – – – – – – – – – – – –

2006 12 5.68 4.50 4.06 3.85 4.46 3.85 3.57 3.50 3.50 3.53 3.53 3.49 3.50 3.50

2006 13 6.24 4.78 4.42 4.10 4.07 3.89 3.73 3.59 3.57 3.54 3.53 3.52 3.47 3.46

2006 14 5.78 4.40 4.07 3.84 3.92 3.63 3.67 3.53 3.50 3.48 3.47 3.43 3.45 3.47

2006 15 5.73 4.49 4.10 3.88 3.86 3.67 3.68 3.47 3.43 3.44 3.45 3.46 3.42 3.42

2006 16 5.89 5.46 4.74 4.57 4.46 4.23 4.25 3.93 3.87 3.84 3.81 3.81 3.76 3.73

2007 1 7.75 7.62 7.56 7.51 7.47 7.42 7.42 7.42 7.43 7.43 7.43 7.43 7.44 7.44

2007 2 7.62 7.57 7.56 7.48 7.44 7.42 7.42 7.42 7.43 7.43 7.43 7.43 7.43 7.44

2007 3 7.60 7.56 7.49 7.48 7.45 7.42 7.42 7.43 7.43 7.43 7.43 7.43 7.43 7.44

2007 6 7.64 7.54 7.48 7.45 7.41 7.43 7.43 7.43 7.43 7.43 7.43 7.44 7.44 7.44

2007 7 7.60 7.54 7.44 7.43 7.42 7.42 7.42 7.43 7.43 7.44 7.44 7.44 7.44 7.45

2007 8 7.59 7.53 7.47 7.44 7.41 7.42 7.42 7.43 7.43 7.44 7.44 7.44 7.45 7.45

2007 9 7.65 7.52 7.46 7.45 7.45 7.43 7.44 7.45 7.45 7.46 7.46 7.46 7.46 7.47

2007 10 7.51 7.50 7.48 7.45 7.45 7.45 7.46 7.46 7.47 7.47 7.47 7.47 7.47 7.46

2007 11 – – – – – – – – – – – – – –

2007 12 7.39 7.34 7.31 7.32 7.33 7.33 7.34 7.35 7.35 7.35 7.35 7.37 7.37 7.38

2007 13 7.38 7.35 7.33 7.31 7.33 7.33 7.34 7.35 7.37 7.38 7.39 7.39 7.40 7.40

2007 14 7.37 7.33 7.32 7.36 7.39 7.40 7.40 7.40 7.41 7.41 7.41 7.41 7.42 7.42

2007 15 7.36 7.35 7.33 7.33 7.34 7.35 7.36 7.37 7.38 7.39 7.40 7.41 7.41 7.41

2007 16 7.37 7.35 7.39 7.40 7.41 7.42 7.43 7.43 7.43 7.43 7.43 7.43 7.43 7.43

2008 1 7.80 7.65 7.63 7.60 7.54 7.51 7.47 7.45 7.45 7.44 7.44 7.44 7.43 7.43

2008 2 7.72 7.64 7.61 7.58 7.52 7.48 7.46 7.45 7.44 7.44 7.44 7.43 7.43 7.43

2008 3 7.74 7.64 7.60 7.57 7.52 7.47 7.45 7.44 7.44 7.44 7.44 7.43 7.43 7.43

2008 6 7.65 7.60 7.57 7.54 7.49 7.47 7.44 7.44 7.44 7.44 7.44 7.43 7.43 7.43

2008 7 7.63 7.60 7.57 7.52 7.48 7.45 7.44 7.44 7.44 7.44 7.43 7.43 7.43 7.43

2008 8 7.65 7.61 7.57 7.54 7.49 7.47 7.45 7.44 7.44 7.44 7.43 7.43 7.43 7.43

2008 9 7.38 7.42 7.45 7.44 7.44 7.44 7.44 7.44 7.44 7.44 7.43 7.43 7.42 7.42

2008 10 7.37 7.41 7.42 7.41 7.43 7.42 7.42 7.42 7.41 7.40 7.38 7.38 7.37 7.37

2008 11 – – – – – – – – – – – – – –

2008 12 7.53 7.52 7.50 7.46 7.44 7.42 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.40

2008 13 7.49 7.51 7.49 7.45 7.43 7.41 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.40

2008 14 7.39 7.40 7.41 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.40

2008 15 7.33 7.40 7.41 7.41 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.40 7.39 7.39

2008 16 7.29 7.30 7.33 7.34 7.35 7.35 7.36 7.36 7.36 7.37 7.38 7.38 7.38 7.38