OCS Study MMS 2006-015 

Final Report 

Role of Grazers on the Recolonization of Hard-Bottom 

Communities in the Alaska Beaufort Sea 

Principal Investigator: Brenda Konar 

School of Fisheries and Ocean Sciences 

University of Alaska Fairbanks 

bkonar@guru.uaf.edu 

May 2006 
Contact information 

e-mail: carter@sfos.uaf.edu 

 phone: 907.474.1811 

 fax: 907.474.1188 

 postal: Coastal Marine Institute 

 School of Fisheries and Ocean Sciences 

 P.O. Box 757220 

 University of Alaska Fairbanks 

 Fairbanks, AK 99775-7220 

ii 
Table of Contents 

Table of Contents...........................................................................................................................iii 

List of Figures................................................................................................................................ iv 

List of Tables................................................................................................................................. iv 

Abstract........................................................................................................................................... 1 

Introduction..................................................................................................................................... 2 

Methods........................................................................................................................................... 4 

Cages........................................................................................................................................... 4 

Community surveys..................................................................................................................... 4 

Results............................................................................................................................................. 6 

Cages........................................................................................................................................... 6 

Community surveys..................................................................................................................... 6 

Discussion................................................................................................................................... 6

Acknowledgements....................................................................................................................... 14 

Study Products.............................................................................................................................. 14 

Refereed Publications............................................................................................................... 14 

Technical Reports..................................................................................................................... 14 

Presentations and Interviews.................................................................................................... 14 

References..................................................................................................................................... 15 

Appendix 1.................................................................................................................................... 19 

iii 
List of Figures 

Figure 1: Chart of Stefansson Sound within the Beaufort Sea showing the location of DS11 

within the Boulder Patch. Hatched polygons are areas with high boulder/cobble 

density. Figure from Dunton and Schonberg (2000). ............................................................. 3 

Figure 2: Mean percent cover (±1 s.e.) of bare rock, encrusting coralline algae, total foliose 

algae, and total invertebrates on uncleared control boulders in 2002 through 2005. 

n=18, 18, 15, and 12 for 2002, 2003, 2004, and 2005, respectively....................................... 9 

Figure 3: Mean percent cover (±1 s.e.) of encrusting coralline algae, bryozoans, hydroids, 

spirorbids, and barnacles on each of the treatment boulders in 2005. n=14, 13, and 15 

for cages, cage controls, and cleared rocks, respectively. ...................................................... 9 

Figure 4: Mean percent light attenuation (±1 s.e.) under cages, in cage controls, and adjacent 

to cages. Measurements were taken on three separate days in 2002. ................................... 10 

Figure 5: Mean density (±1 s.e.) of grazers at DS11 in 2004. Estimates are from searches done 

on fifteen randomly placed 0.25m2 quadrats........................................................................ 10 

Figure 6: Percent cover (±1 s.e.) of sessile organisms and bare rock at DS11 in 2004. 

Estimates are from five random point contacts placed along eight randomly placed 

transects................................................................................................................................. 11 

Figure 7: Biomass (±1 s.e.) in grams of macroalgae at DS11 in 2004. Estimates are from five 

0.25m2 randomly placed quadrats. ....................................................................................... 12 

List of Tables 

Table 1: Fisher’s PLSD for percent cover of sessile organisms and bare rock at DS11 in 2004. 

S=Significance level of 5%................................................................................................... 11 

Table 2: Fisher’s PLSD for macroalgal biomass at DS11 in 2004. S=Significance level of 5%. .... 13 

iv 
v 
0 
Abstract

Recovery and recolonization of hard-bottom 

macroalgal communities vary temporally and 

spatially because of multiple biotic and abiotic 

factors. This study examined the relative 

importance of grazing on recolonization rates of 

sessile organisms in a high latitude environment, 

the Boulder Patch in the Beaufort Sea. A simple 

manipulative experiment using cleared boulders 

and cages was used to test the hypothesis that 

grazing causes slow recovery of sessile 

macrophytic and macrofaunal communities. 

Monitoring cleared boulders (caged and 

uncaged) for three years resulted in no growth of 

any sessile organism for the first two years. In 

the third year, new invertebrate and coralline 

growth was seen on 79% of the cleared boulders, 

with significantly more growth on caged 

boulders. Uncleared control rocks showed no 

significant temporal variation. Concurrent 

surveys and observations suggested that in this 

arctic community 1) there were two conspicuous 

types of macrograzers on rocks, chitons and 

seastars, 2) space was limiting, 3) the dominant 

alga, Laminaria solidungula was reproductive 

during the study period. This study strongly 

suggests that any perturbations causing scouring 

of hard substrate in the Beaufort Sea will result 

in very slow community recovery. 

1 
Introduction 

Alaska’s Beaufort Sea shelf is typically 

characterized by silty sands and mud and as 

having an absence of macroalgal beds and 

associated organisms (Barnes and Reimnitz 

1974). In 1971, a diverse kelp and invertebrate 

community was discovered near Prudhoe Bay in 

Stefansson Sound, Alaska (Figure 1). This area 

was named the Boulder Patch by the U.S. Board 

of Geographic Names. Since its discovery, the 

Boulder Patch has been subject to much 

biological and geological research (Dunton et al. 

1982, Dunton and Schell 1987, Dunton and 

Jodwalis 1988, Dunton 1990, Martin and 

Gallaway 1994, MMS 1996, 1998, Dunton and 

Schonberg 2000, Konar and Iken 2005, and 

others). 

The Boulder Patch contains numerous 

cobbles and boulders that provide substrate for 

attachment for many invertebrates, several 

species of red and brown algae, and one green 

alga. These algae and epilithic invertebrates 

cover nearly all exposed substrate, except 

recently upturned rocks. The invertebrate 

assemblage that inhabits the rocks and 

associated kelp beds has representatives from 

every major phylum (Dunton 1985). The 

dominant brown alga is Laminaria solidungula, 

which constitutes 90% of the brown algal 

biomass (Dunton et al. 1982). This alga is an 

important food source to many benthic and 

epibenthic organisms (Dunton and Schell 1987). 

Differences in infaunal abundance and biomass 

between the Boulder Patch and peripheral 

sediment areas demonstrate the importance of 

this unique habitat (Dunton and Schonberg 

2000). 

Boulder fields are very dynamic systems 

because of physical disturbance (Sousa 1979, 

1980, vanTamelen 1987). In the high arctic, ice 

gouging can overturn large boulders and cobbles 

and hence expose new substrate (Dunton et al. 

1982, Conlan et al. 1998). In many areas, 

currents can overturn smaller rocks that have 

epilithic organisms attached to them (Dunton et 

al. 1982). These organisms cause resistance to 

the currents, which results in rocks moving and 

turning. The existence of dead (white) corallines 

on the underside of many small rocks suggests 

that these processes are common in the Boulder 

Patch (Dunton et al. 1982). When a boulder is 

overturned, algae and sessile invertebrates can 

be killed in whole or part by a combination of 

grazing, anoxia, low light levels, or mechanical 

damage caused by crushing or abrasion (Sousa 

1980). Algal and some invertebrate populations 

recolonize cleared surfaces through either 

vegetative regrowth of surviving individuals or 

by recruitment from spores or larvae (Sousa 

1979, Airoldi 2000). 

Recolonization experiments in the Boulder 

Patch have shown that recovery of denuded 

areas is slow (Dunton et al. 1982). In temperate 

systems, algal communities can recover to 

previous densities within one year of denuding 

(Foster 1975, Konar and Estes 2003). Many 

studies on coralline algal recruitment have 

shown that although their growth is remarkably 

slow, they will settle to a visible size in a few 

months (Johanson and Austin 1970, Colthart and 

Johanson 1973, Adey and Vasser 1975, Matsuda 

1989, Konar and Foster 1992, Konar 1993, 

Dethier and Steneck 2001). In contrast to 

temperate systems, 50% of the substrate in the 

Boulder Patch was still bare three years after an 

initial disturbance (Dunton et al. 1982). One 

reason suggested for this slow recolonization is 

invertebrate grazing. Motile herbivorous, 

omnivorous, and carnivorous invertebrates such 

as chitons, snails, seastars, and polychaetes have 

been frequently observed in the Boulder Patch 

(Dunton et al. 1982). Many studies have shown 

that grazers can be very important in structuring 

communities (Johnson et al. 1997, Worm and 

Chapman 1998, Jenkins et al. 1999, Ojeda and 

Munoz 1999, Morton 1999, Wilson et al. 1999, 

Konar 2000, and others). 

The reason that grazing has been suggested 

to cause the slow recovery in the Boulder Patch 

is that polystyrene floats (suspended 1 m above 

the bottom) that were used to mark sites in a 

study by Dunton (1985) recolonized much more 

quickly than denuded substrates. When the floats 

were first examined by Dunton 12 months after 

initial deployment, all were covered with 

hydroids, bryozoans, red algae, and polychaete 

worm tubes. This is the same suite of species 

2 
that eventually recruited onto the denuded 

experimental boulders; however, recruitment 

onto the boulders was much slower. Since the 

floats were not intended to be experimental 

substrates, no quantitative comparison was made 

to non-floating experimental substrates. Dunton 

(1985) did suggest that these floats may have 

recovered faster than the experimental substrates 

because the floats were not subject to grazing or 

predation pressures by benthic animals. 

Recruitment onto the floats may have been due 

to larvae and spores exhibiting a substrate 

preference for polystyrene; however, Dunton 

concluded that this was unlikely because 

probably not all epilithic species possess the 

same selectivity for this artificial substrate. 

To determine if grazing is associated with the 

slow recruitment in the Boulder Patch, various 

comparisons using exclusion cages, cage 

controls, and natural rock were employed. The 

specific hypothesis tested was that there would 

be no significant difference between recruitment 

of sessile organisms on cleared boulders with 

and without cages, which were employed to 

exclude macrograzers. Concurrent with this 

recruitment study, community observations and 

surveys were performed to determine which 

macrograzers were the most conspicuous on the 

rocks, if space was limiting (which would be 

suggested by a paucity of bare space on rocks), 

and if the dominant brown alga, Laminaria 

solidungula, was reproductive during the study 

period.

 

Figure 1: Chart of Stefansson Sound within the Beaufort Sea showing the location of DS11 within the 

Boulder Patch. Hatched polygons are areas with high boulder/cobble density. Figure from Dunton and 

Schonberg (2000).

3 
Methods 

Cages 

To address the hypothesis that there is no 

significant difference between recruitment of 

sessile organisms on cleared boulders with and 

without cages, cage and non-cage treatments 

were deployed at each of the three sites within 

DS11 at the Boulder Patch in August 2002 

(Figure 1). Cages are commonly used for 

inclusion and exclusion manipulative 

experiments (see Vadas 1985, Coyer et al. 1999 

for overviews). The boulders used in this study 

were collected from DS11. Because of the 

difficulty in removing living material from 

rocky substrata underwater, all boulders were 

brought to the surface to be cleared. Care was 

given not to chip boulders so as to expose new 

surface because this leaching and weathering of 

newly exposed surfaces may affect recruitment 

(Dayton 1971, Reed and Foster 1984). After five 

days, denuded rocks (with and without cages 

and cage controls) were placed back into the 

field. 

Six cages were deployed to exclude large 

macrograzers at each of three locations within 

DS11, totaling 18 cages. The cages were 25 cm 

on a side, 10 cm tall, with a 1 cm mesh size and 

constructed of stainless steel mesh (Figure 2). 

All cages were coated with a non-toxic 

antifouling compound to inhibit sessile 

invertebrate and algal growth (Coyer et al. 

1999). Eighteen cage controls also were 

deployed to control for any artifacts caused by 

the cages, such as decreased light levels or 

increased sedimentation. These cage controls, 

which were cages with holes cut into the sides so 

that grazers could easily pass through them, are 

commonly used (Russ 1980, Breitberg 1985, 

Stocker 1986, and others). For comparison, 18 

cleared rocks were deployed with no cages to 

determine natural recruitment. As a control for 

natural community changes, 18 non-cleared 

boulders also were monitored. 

Visual estimates were used to determine 

percent cover of sessile organisms on all 

boulders. All algae (except for corallines) were 

identified to genus while all other organisms 

(corallines, sponges, bryozoans, hydroids and 

tunicates) were combined into larger taxonomic 

groups. Care was taken not to disturb boulders 

while sampling so as not to affect mobile 

organisms under and around the boulders 

(Chapman and Underwood 1996). 

To determine if there was significant light 

reduction due to cage shading, light 

measurements were taken under and adjacent to 

cages and cage controls with a Li-Cor Model LI185A Quantum Light Meter on three different 

days in 2002 (Foster et al. 1985, Ramus 1985). 

Light has been shown to influence algal 

recruitment (Reed and Foster 1984, Graham 

1996, 1997, Edwards 1998, Dayton et al. 1999, 

Huovinen et al. 2000, Clark et al. 2004, and 

others) and to a limited extent invertebrate 

settlement (Duggins et al. 1990). 

Some rocks that were cleared of sessile 

organisms were also surveyed for overlapping 

borders between organisms. These surveys were 

supplemented by other random rocks that were 

surveyed in the field to increase the sample size 

of organisms observed. This was done to 

determine the dominant competitors in the 

system (overgrowth at an overlapping border 

demonstrated a dominant competitor). The data 

obtained by these observations are presented in 

the appendix as a note as published by Polar 

Biology (Appendix 1). 

Community surveys 

Surveys were conducted in 2004 to 

determine community composition (grazers, 

sessile organisms, macroalgae, and bare rock), 

and reproductive status of the dominant alga, 

Laminaria solidungula at DS11. To determine 

potential grazers, random boulders were 

collected from fifteen 0.25m2

 quadrats from 

which grazer densities were calculated. Percent 

cover estimates of sessile organisms 

(invertebrates and macroalgae) and of bare rock 

were used to assess substrate cover and available 

open space along eight randomly placed 

transects. Along each transect, five one-meter 

long random point contact bars (similar to that 

described by Foster 1975, Coyer et al. 1999) 

were randomly placed. These bars had a string 

attached at each end, with five knots along their 

length. Knots randomly placed on the line were 

4 
pulled tight away from the bar and placed on the 

substrate, and the identity of the alga or 

invertebrate was recorded. If no organism was 

present at the knot, the type of substratum was 

noted. By moving the string from one side of the 

bar to the other, 10 points were sampled per 

area. Macroalgal biomass estimates were 

completed by collecting boulders from five 

randomly placed 0.25m2

 quadrats. Boulders 

were brought back to the lab where all 

macroalgae were removed, identified, and 

weighed for damp biomass. To determine if the 

dominant alga, Laminaria solidungula was 

reproductive at DS11, one random 10m2

 area 

was surveyed along eleven randomly placed 

30m transects. All L. solidungula in each area 

were enumerated and the state of reproduction 

was recorded.

 

5 
Results 

Cages 

Community composition on the uncleared 

control boulders did not significantly vary over 

time (ANOVA, F3,59=0.626, p=0.6, Figure 2). 

The majority of these uncleared boulders were 

covered with encrusting coralline algae and 

foliose algae, while very little (a mean of 2% or 

less) was bare. Foliose algae were primarily 

Phycodrys rubens, averaging 21% over the three 

year period. Other foliose algae included 

Phyllophora truncata (synonym Coccotylus 

truncates), Dilsea socialis, and Odonthalia

dentata

In the first two years of this study, no growth 

was observed on any experimentally cleared 

rock. In the third year, 79% of the cleared rocks 

showed some growth. While growth was limited 

on all cleared rocks (never exceeding 10% and 

averaging less than 2%), the rocks in full cages 

had significantly more growth than the other two 

treatments (cage control and uncaged; ANOVA, 

F2,39=10.599, p=0.0002). All growth seen in the 

third year was relatively small in size (typically 

less than 0.5cm) and included bryozoans, 

hydroids, spirorbids, barnacles, sponges, and 

encrusting corallines (Figure 3). No growth of 

brown or red foliose algae was seen on any 

cleared boulder in any year. 

Cages and boulders were examined for light 

effects. While boulders in open areas did receive 

significantly more light than boulders in cages 

and in cage controls (ANOVA, F2,6=12.924, 

p=0.0067), there was no significant light 

difference between cages and cage controls 

(Figure 4). This suggests that differences found 

between recruitment occurring within caged 

boulders and cage control boulders were not due 

to a lighting effect. 

Community surveys

Grazers that were found in the DS11 surveys 

consisted of two chitons, Amicula vistita and 

Ischnochiton albus, and seastars of various 

genera (Figure 5). There were significantly more 

I. albus than there were seastars (ANOVA, 

F2,24=3.264, p=0.01) but no differences were 

seen between A. vistita densities and densities of 

the other two grazers during this survey. 

In general, substrate (as measured by percent 

cover) at DS11 was dominated by encrusting 

corallines (Figure 6). Red holdfasts were also 

fairly abundant, covering approximately 25% of 

the substrate. Bare rock was found during these 

surveys, however it was in very small amounts 

(typically less than 5%). Overall, significant 

differences were found in the percent cover of 

various sessile organisms (ANOVA, 

F5,234=103.893, p<0.0001). In particular, 

macroalgae were always significantly more 

abundant than any invertebrate group, with 

encrusting corallines also being more abundant 

than red holdfasts (Table 1). 

Macroalgal biomass at DS11 in 2004 was 

dominated by foliose red algae, particularly 

Phycodrys rubens, Phyllophora truncata, and 

Dilsea socialis (Figure 7). Other reds found in 

these surveys included Odonthalia dentata, 

Rhodomela confervoides, and Ahnfeltia sp. 

Brown macroalgal biomass was dominated by 

Laminaria solidungula. Laminaria saccharina

also was found, but in very small amounts. 

Another brown macroalga, Alaria esculenta, was 

not found during these surveys but was seen 

adjacent to some transects. Overall, some 

significant differences were found among the 

macroalgae for biomass (ANOVA, F7,32=2.013, 

p=0.0841, Table 2). These differences typically 

involved Phycodrys and Phyllophora being 

significantly more abundant than other 

macroalgae. 

Laminaria solidungula were reproductive 

during this study. Divers noticed this alga in a 

reproductive state during all years, and a 

quantitative survey was completed in 2004. 

From this survey, 115 plants out of 178 

observed were reproductive, approximately 70% 

of the population. 

Discussion 

Grazing does have significant impacts on 

community structure and recruitment in many 

temperate systems. In some areas, grazers, such 

as urchins, can completely eliminate all foliose 

6 
macroalgae and sessile invertebrates leaving a 

“barren ground”, or encrusting coralline 

monoculture (Harrold and Reed 1985, 

Scheibling 1986, Konar and Estes 2003, and 

many others). In these situations, typically some 

event causes grazer densities to increase 

dramatically, such as the elimination of their top 

predator (see Estes et al. 1998 for example). In 

this study of a high latitude macroalgal 

community, cages that excluded macrograzers 

were found to have statistically significant 

effects on the recovery and recruitment of 

epilithic organisms (Figure 3). It should be noted 

that overall recruitment was extremely low (less 

than 10% on all rocks) but corallines, hydroids, 

and barnacles had a higher degree of presence 

on caged rocks than uncaged or cage control 

rocks. 

Light effects caused by cages are probably 

not the reason for the differences seen on the 

cleared rocks. While cages placed in hard 

bottom communities can have artifacts such as 

the reduction of light and water motion affecting 

larval settlement of barnacles and ascidians 

(Schmidt and Warner 1984) and the attraction of 

small fish (Stocker 1986), many intertidal and 

subtidal studies have successfully used cages 

(Menge 1978, Andrew and Choat 1982, Petraitis 

1983, Zeller 1988, Kennelly 1991, Williams 

1993, Bartol et al. 1999, Bertness et al. 1999, 

Fernandes et al. 1999, Leonard 1999, and 

others). In this study, light reduction was noted 

in cages (Figure 4), however, no differences in 

light were found between cages and cage 

controls. This suggests that differences seen in 

the results between cages and cage controls were 

not due to light. 

Three noteworthy results from this study 

were: First, from the community surveys of 

sessile organisms (percent cover–Figure 6 and 

biomass estimates–Figure 7) and surveys of 

control rocks (Figure 2), the dominant organisms 

in this high latitude community are the 

encrusting corallines (by percent cover) and the 

red and brown macroalgae (by biomass). In fact, 

the monitoring surveys of the uncleared control 

rocks demonstrated that the composition of this 

community is very stable as no significant 

temporal variation was noted. Interestingly, no 

foliose red or brown macroalgal individuals 

recruited to any cleared rock in three years of 

monitoring. Typically, exclusion of grazers 

causes an increase in foliose macroalgae 

(Belliveau and Paul 2002). Along with the lack 

of foliose macroalgal recruitment, encrusting 

coralline recruitment also was very limited, 

found only on one caged boulder. In other 

studies, these algal organisms, particularly 

corallines, have been amongst the first to 

colonize and do so relatively quickly (Konar and 

Foster 1992, Airoldi 2000). While the 

reproductive status of the corallines was not 

assessed during this study, the dominant brown 

macroalga, Laminaria solidungula, was 

observed to be reproductive during all years. 

Reproductive status of this alga was quantified 

in 2004 and these surveys showed that 

approximately 70% of the plants were 

reproductive. Reproductive maturity of one red 

alga, Phyllophora truncata, was observed in 

multiple years as many of these plants contained 

cystocarpic material (pers. obs.). The reasons 

why these reproductive macroalgae were not 

recruiting onto the cleared areas are unknown 

and can only be speculated. Macroalgae are 

known to have recruitment “windows” where 

specific conditions are needed for sexual 

propagules to establish, whereas vegetative 

propagation is much more constant and 

predictable (Deysher and Dean 1986, Airoldi 

2000). In this study, rocks were completely 

cleared so vegetative regrowth was not possible. 

Perhaps much of the recovery that occurs in this 

system is accomplished through regrowth and 

not recruitment. Boulder Patch sessile organisms 

do compete for space through vegetative growth 

as seen by overlapping borders of existing 

organisms (Konar and Iken 2005). The rate of 

growth and subsequent recovery from 

disturbances are unknown and require further 

investigation. 

The second noteworthy result was that 

barnacles were among the dominant space 

occupiers on cleared boulders (especially in the 

cages). This is contrary to another study that 

found that barnacles recruited less inside cages 

than outside, which was speculated to have been 

caused by reduced light and water motion 

(Schmidt and Warner 1984). In the Boulder 

Patch, community surveys based on percent 

7 
cover and surveys of uncleared control rocks 

never resulted in barnacle presence. In fact, 

sessile invertebrates actually appear to play a 

minor role (typically less than 10%) as far as 

space occupation (based on percent cover as 

biomass was not recorded for invertebrates in 

this study). One potential reason for the presence 

of barnacles on the cleared rocks but not in the 

community surveys is that the barnacles that 

were found were extremely small, typically less 

that 2mm. Organisms this small would be 

missed in community surveys because of the 

overwhelming dominance of other organisms. 

Perhaps multiple very small (but reproductive) 

barnacles inhabit the community, but they rarely 

grow to significant size. 

The third and most noteworthy result of this 

study is the extremely slow recolonization rate. 

As in many other macroalgal systems, surveys in 

this study suggest that available substrate is a 

limiting resource in the Boulder Patch. Very 

little bare rock was found during the community 

surveys (Figure 6). Observations of these rocks 

showed that most had no bare space and that 

only a few had a bit more (but never exceeding 

about 10%). Ecological theory asserts that if 

space becomes available in a space limiting 

system, recruitment onto these bare areas should 

be rapid (Castro and Huber 2005). In a clearing 

experiment at a subtidal site in California, it took 

only a few weeks for coralline recruits to be 

visible to the naked eye (Foster 1975, Konar and 

Foster 1992). In Kachemak Bay Alaska, subtidal 

recruits began to settle on cleared rocks after just 

a couple months (Harman and Konar, 

unpublished data). Typically, one to two years 

after clearing, bare areas can not be 

distinguished from control areas (Foster 1975, 

Konar and Foster 1992, Konar and Estes 2003). 

At the current recruitment rate in the Boulder 

Patch, it might take 10+ years for full recovery if 

rocks are completely damaged and vegetative 

regrowth is not possible. The reasons for this 

incredibly slow recruitment in the Boulder Patch 

are unknown. Also, the actual time that would 

be needed for a full recovery is unknown. Both 

the reason for the slow recovery and the time 

needed for a full recovery require more study 

and are imperative knowledge that should be 

obtained if the Boulder Patch is to be preserved. 

This study strongly suggests that any 

perturbations causing scouring of hard substrate 

in the Beaufort Sea will result in very slow 

community recovery. 

8 
Figure 2: Mean percent cover (±1 s.e.) of bare rock, encrusting coralline algae, total foliose algae, and 

total invertebrates on uncleared control boulders in 2002 through 2005. n=18, 18, 15, and 12 for 2002, 

2003, 2004, and 2005, respectively. 

Figure 3: Mean percent cover (±1 s.e.) of encrusting coralline algae, bryozoans, hydroids, spirorbids, and 

barnacles on each of the treatment boulders in 2005. n=14, 13, and 15 for cages, cage controls, and 

cleared rocks, respectively.

9 
Figure 4: Mean percent light attenuation (±1 s.e.) under cages, in cage controls, and adjacent to cages. 

Measurements were taken on three separate days in 2002. 

Figure 5: Mean density (±1 s.e.) of grazers at DS11 in 2004. Estimates are from searches done on fifteen 

randomly placed 0.25m2 quadrats.

10 
Figure 6: Percent cover (±1 s.e.) of sessile organisms and bare rock at DS11 in 2004. Estimates are from 

five random point contacts placed along eight randomly placed transects. 

Table 1: Fisher’s PLSD for percent cover of sessile organisms and bare rock at DS11 in 2004. 

S=Significance level of 5%.

11 
 

Figure 7: Biomass (±1 s.e.) in grams of macroalgae at DS11 in 2004. Estimates are from five 0.25m2

randomly placed quadrats. 

12 
Table 2: Fisher’s PLSD for macroalgal biomass at DS11 in 2004. S=Significance level of 5%.

13 
Acknowledgements 

This project could not have been completed 

without the logistical support offered by the 

Dunton Brothers and by BP (particularly 

everyone at Endicott Production Island). I also 

would like to thank my field assistants: Katrin 

Iken, Casey Debenham, Nicholas Harman, and 

Chris Wyatt. Ken Dunton guided many 

stimulating discussions on Boulder Patch 

biology. Katrin Iken provided insightful advice 

during this study and on the manuscript. This 

project was partially funded by the Coastal 

Marine Institute. Match support was provided by 

BP. 

Study Products 

Refereed Publications 

Konar, B and K Iken. 2005. Competitive 

dominance among sessile marine organisms 

in a high Arctic boulder community. Polar 

Biology. (see Appendix 1) 

Technical Reports 

Role of grazers in the recolonization of hardbottom communities in the Alaska Beaufort 

Sea. Annual Reports for 2003 and 2004. 

Presentations and Interviews 

March 8, 2005: Presentation at Coastal Marine 

Institute Annual Meeting 

February 16, 2004: Presentation at Coastal 

Marine Institute Annual Meeting 

November 7–10, 2003: Symposium Speaker: 

Western Society of Naturalists, 84th Annual 

Meeting in Long Beach, CA 

August 22, 2003: Interviewed for KUAC on 

Boulder Patch project 

August 10, 2003: Presentation for Endicott 

Island BP workers 

August 5, 2003: Interviewed for series on 

Boulder Patch project for KUAC 

February 19, 2003: Presentation at Coastal 

Marine Institute Annual Meeting 

November 8–11, 2002: Poster presented at the 

Western Society of Naturalists 83rd Annual 

Meeting in Monterey, CA 

October 2002: Interviewed by Arctic Science 

Journeys radio program 

August 1 and 8, 2002: Presentation for Endicott 

Island BP workers 

November 18–20, 2005, Western Society of 

Naturalists 86th Annual Meeting in Monterey, 

CA, Symposium Speaker 

 

14 
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