1

Marine Sanctuaries Conservation Series ONMS-15-10

Long-term Monitoring of Surfgrass Meadows in 

the Monterey Bay National Marine Sanctuary: 

Recovery followed by Stability after the 

Termination of a Domestic Sewage Discharge.

U.S. Department of Commerce

National Oceanic and Atmospheric Administration

National Ocean Service

Office of National Marine Sanctuaries December 2015
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About the Marine Sanctuaries Conservation Series

The Office of National Marine Sanctuaries, part of the National Oceanic and

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are available on the Office of National Marine Sanctuaries Web site

(http://www.sanctuary.noaa.gov). 
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Long-term Monitoring of Surfgrass Meadows in the Monterey 

Bay National Marine Sanctuary: Recovery followed by 

Stability after the Termination of a Domestic Sewage 

Discharge.

John S. Pearse, William T. Doyle, Vicki B. Pearse, Marcia M. Gowing,

J. Timothy Pennington, Eric Danner, Ann Wasser

John S. Pearse, William T. Doyle, Vicki B. Pearse, and Marcia M. Gowing: Institute of 

Marine Science, University of California, Santa Cruz, CA 95064; J. Timothy Pennington, 

Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039; Eric Danner, 

Southwest Fisheries Science Center, Santa Cruz, CA 95060; Ann Wasser, Pacific Grove 

Museum of Natural History, Pacific Grove, CA, 93950

U.S. Department of Commerce

Penny Pritzker, Acting Secretary

National Oceanic and Atmospheric Administration

Kathryn Sullivan, Ph.D.

Acting Under Secretary of Commerce for Oceans and Atmosphere

National Ocean Service

Russell Callender, Ph.D., Acting Assistant Administrator

Silver Spring, Maryland Office of National Marine Sanctuaries

December 2015 John Armor, Acting Director
4

Disclaimer

Report content does not necessarily reflect the views and policies of the Office of

National Marine Sanctuaries or the National Oceanic and Atmospheric Administration,

nor does the mention of trade names or commercial products constitute endorsement or

recommendation for use.

Report Availability

Electronic copies of this report may be downloaded from the Office of National Marine

Sanctuaries web site at http://sanctuaries.noaa.gov.

Cover

California Naturalists from the Pacific Grove Museum of Natural History sampling the

plot monitored by LiMPETS at Opal Cliffs, California. June 16, 2014. Soquel Point 

where the second plot is monitored is on the horizon, ~1 km away. 

Suggested Citation

Pearse, J.S., W.T. Doyle, V.B. Pearse, M.M. Gowing, J. T. Pennington, E. Danner, A.

Wasser. 2015. Long-term monitoring of surfgrass meadows in the Monterey Bay

National Marine Sanctuary: Recovery followed by stability after the termination of a 

domestic sewage discharge. Marine Sanctuaries Conservation Series ONMS-15-10. U.S. 

Department of Commerce, National Oceanic and Atmospheric Administration, Office of 

National Marine Sanctuaries, Silver Spring, MD. 42pp.

Contacts

John S. Pearse, pearsester@gmail.com

William T. Doyle, billdoyle@surfnetusa.com/

Vicki B. Pearse, vpearse@gmail.com

Marcia M. Gowing, marcia_gowing@hotmail.com/

J. Timothy Pennington, peti@mbari.org

Eric Danner, eric.danner@noaa.gov

Ann Wasser, wasser@pgmuseum.org
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Abstract 

Surfgrass meadows are major habitats along the coast of the North Pacific Ocean, 

providing complex biotic communities and nurseries for fishes and crustaceans. They 

have been little studied in most areas, including central California. We present here the 

results of monitoring two 450m2plots over a period of 42 years within the Monterey Bay 

National Marine Sanctuary by citizen scientists (trained students and naturalists). One, 

the Soquel Point plot, was near a small (~3 million gallons per day) domestic sewage 

outfall that was discontinued in 1976, and the other, the Opal Cliffs plot, was in a 

comparison site ~1 km away. Monitoring was done nearly annually between 1973 and 

2003, then in 2006, 2012, 2014, and 2015. The abundance of common seaweeds and 

invertebrates was recorded each year from counts of individuals, or their presence in 25 

10x10 cm squares, in randomly placed 50x50 cm quadrats (mean number of counts, 24.3; 

range 10-41). 

Surfgrasses (Phyllospadix spp., mainly P. torreyi) were absent in the Soquel Point plot 

when the sewage was being discharged and were first seen in the plot in 1978, two years 

after the sewage discharge was terminated. Surfgrass abundance increased slowly and 

was comparable to that in the Opal Cliffs plot only in the late 1990s, over 20 years after 

the termination of the sewage discharge. In contrast, species in one genus of coralline 

algae (Corallina) were abundant when the sewage was being discharged and declined 

slowly for 30 years following discharge termination, never reaching levels comparable to 

those in the Opal Cliffs plot. Frilly red algae (Cryptopleura spp.) were nearly absent from 

the Soquel Point plot when the sewage was discharged and rose just before the discharge 

was terminated, reaching levels comparable to those of Corallina spp. Levels of 

Cryptopleura spp. and Corallina spp. slowly decreased in parallel while those of 

Phyllospadix spp. rose, suggesting both facilitation (Corallina spp. facilitating both 

Cryptopleura spp. and Phyllospadix spp.) and competition (Phyllospadix spp. eventually 

dominating). 

The abundance of species of a second genus of coralline algae, Bossiella, was low in the 

Soquel Point plot when the sewage was discharged, increased just before termination of 

the discharge, and remained similar to or slightly higher than that at Opal Cliffs during 

the rest of the monitoring period. Abundances of sea lettuces (Ulva spp.), turban snails

(Tegula spp.), and hermit crabs (Pagurus spp.), which were low when the sewage was 

discharged, also increased just before the discharge was terminated. The increase in the 

abundance of these taxa corresponded to a steady decrease in grease content in the 

sewage. Within a few years after the sewage discharge was terminated, the abundances of 

all these taxa stabilized; they remained low and similar to those in the Opal Cliffs plot for 

the remainder of the monitoring period.

In the Opal Cliffs plot, ~1 km downstream from the discharge, the sewage discharge 

apparently enhanced the abundance of coralline algae (both Corallina and Bossiella), 

frilly red algae, sea lettuces, and honeycomb tube worms. Abundance of all these taxa 

decreased after the discharge was terminated, indicating that they had benefited from the 

nutrients in the sewage. 
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Sunburst anemones (Anthopleura sola) were more abundant in the Soquel Point plot than 

the Opal Cliffs plot throughout most of the monitoring period. They were likely 

established in the Soquel Point plot when the sewage had denuded the area, exposing 

bare rock suitable for attachment, then were able to persist for decades following the 

termination of the sewage discharge and the re-establishment of the surfgrass meadow.

Overall taxon richness of both seaweeds and invertebrates was lowest in the Soquel Point 

plot and highest in the Opal Cliffs plot when the sewage was discharged, converged to 

moderate levels in both plots within a few years after the discharge was terminated, and 

then remained steady and indistinguishable throughout the rest of the monitoring period. 

This overall stability in taxon richness was similar to the abundances seen for most 

specific taxa monitored. The surfgrasses, Corallina spp., and frilly red algae in the 

Soquel Point plot took longer to stabilize, 20 to 30 years after the termination of the 

sewage discharge.

This long-term monitoring program demonstrates that citizen science programs using 

trained students and naturalists can provide robust information about the condition of 

intertidal communities within National Marine Sanctuaries. It found that surfgrass 

communities are remarkably resilient, even after chronic disturbance (in this case by 

domestic sewage) removes the foundation species (surfgrasses). Although recovery of the 

surfgrasses took decades, most taxa in the community returned to abundances similar to 

those recorded in the comparison plot within a few years, and the overall community 

structure displayed persistent stability. Similar resilience can be expected with other 

disturbances such as major storms, chemical spills, or ship groundings that could damage 

surfgrass meadows. The consequences of disruption from global warming are uncertain, 

and these data provide a baseline for future evaluation.

Key Words

Monterey Bay National Marine Sanctuary, citizen science, LiMPETS, surfgrasses, 

Phyllospadix, coralline algae, Cryptopleura, domestic sewage impact and recovery, longterm monitoring 

Acknowledgements

This monitoring program was begun in 1971 with a grant to William T. Doyle, “Marine 

Algal Resources of Santa Cruz and San Mateo Counties,” from the California Sea Grant 

Program (#s R/CA-8 and R/CA-10) through NOAA’s National Sea Grant College 

Program, U.S. Department of Commerce, and a contract to William T. Doyle and John S. 

Pearse from the Association of Monterey Bay Area Governments (Doyle and Pearse, 

1972). Dane Hardin set up the original database, and graduate students Judith Hansen 

(Johnson), and Kathy Truscott (Frost) coordinated the initial data collection by UCSC 

undergraduate students in Doyle and Pearse’s classes. Students and colleagues of Pearse 

continued to collect data through 2006. J. Timothy Pennington assembled the data on the 
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sewage discharge from the Santa Cruz County Sanitation District, and Lynn Scally 

confirmed that the District no longer retains those data. Eric Danner assembled and 

archived the remaining data from the annual counts before they were archived by the 

LiMPETS program (limpets.org). Ann Wasser organized the data collection after 2006 by 

volunteers with the California Naturalists at the Pacific Grove Museum of Natural 

History as part of the LiMPETS program. We could not have done this monitoring 

without the hundreds of hours put in by students and other volunteers who joined us on 

very early morning low tides to do counts. We thank Andrew DeVogelaere for suggesting 

we publish our findings in the Marine Sanctuaries Conservation Series and for his 

comments on the manuscript, Jessie Alstatt for useful comments, Mariah Salisbury for

completing the line drawings, and three reviewers for their constructive comments.
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Table of Contents

Topic Page

Abstract ..............................................................................................................................5

Key Words...........................................................................................................................6

Acknowledgements............................................................................................................6

Table of Contents...............................................................................................................8

List of Figures...................................................................................................................9

Introduction.....................................................................................................................10

Study Site..........................................................................................................................11

Monitoring Protocols.......................................................................................................14

Taxa monitored................................................................................................................14

Monitoring Schedule........................................................................................................16

Data Analysis and Archive...............................................................................................16

General Observations......................................................................................................17

Monitoring Results...........................................................................................................21

 Surfgrasses (Phyllospadix spp.)................................................................................21

 Upright coralline algae (Bossiella spp. and Corallina spp.)....................................22

 Frilly red algae (Cryptopleura spp.).........................................................................24

 Sea lettuces (Ulva spp.).............................................................................................24

 Honeycomb tubeworms (Phragmatopoma californica)........................................26

 Sunburst anemones (Anthopleura sola)..................................................................26

 Turban snails (Tegula spp.)......................................................................................27

 Hermit crabs (Pagurus spp.)....................................................................................27

 Taxon richness..........................................................................................................29

Discussion........................................................................................................................30

Literature Cited...............................................................................................................36

Appendix..........................................................................................................................42
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List of Figures 

Figure Number and Title Page

Figure 1. Photos showing intertidal platform from the cliff top...............................11

Figure 2. Map of study area in northern Monterey Bay........................................12

Figure 3. Google views of the Soquel Point and Opal Cliffs plots............................12

Figure 4. Photo of the block at the end of the sewage discharge pipe in 1974..............13

Figure 5. Characteristics of the sewage discharged at Soquel Point..........................13

Figure 6. Map showing expansion of area without surfgrass blades.........................17

Figure 7. Photos of surfgrasses returning to the Soquel Point plot...........................18

Figure 8. Photos of people sampling the Soquel Point and Opal Cliffs plots...............19

Figure 9. Photos of the same 1-m

2 quadrat within the Soquel Point plot....................20

Figure 10. Photo of honeycomb tubeworm mounds at Soquel Point.........................21

Figure 11. Changes in the abundance of surfgrasses...........................................22

Figure 12. Changes in the abundance of upright coralline algae..............................23

Figure 13. Changes in the abundance of frilly red algae and sea lettuces....................25

Figure 14. Changes in the abundance of honeycomb tubeworms............................26

Figure 15. Changes in the abundance of sunburst anemones.................................27

Figure 16. Changes in the abundance of turban snails and hermit crabs....................28

Figure 17. Changes in the abundance of macrophyte and macroinvertebrate taxa.........29

Figure 18. Abundances of surfgrasses (Phyllospadix), coralline algae (Corallina), and

 frilly red algae (Cryptopleura) in the Soquel Point plot..........................33
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Introduction

Seagrasses are flowering plants that form extensive, productive meadows in shallow 

marine habitats around the world (Green and Short 2003). They are particularly important 

on soft muddy or sandy substrates in bays and estuaries where they support diverse 

communities and serve as nurseries for fishes and invertebrates (Boström et al. 2008, 

Cullen-Unsworth et al. 2014), as well as important carbon sinks in a world of 

dangerously increasing CO2 (Fourqurean et al. 2012). While most inhabit soft bottoms, 

species in the genus Phyllospadix W.J.Hooker live on rocky, surf-swept shores of the 

North Pacific (Short et al. 2007). Known as surfgrasses, they are indicators of the low 

zone in the rocky intertidal (Ricketts et al. 1985, Foster et al. 1988). They attach firmly to 

the bedrock, trapping sand among their rhizomes, and form a specialized habitat that 

supports a wide variety of species while excluding others (Stewart and Myers 1980, 

Turner 1985, Duncan et al. 2014). They are a “foundation” species (Dayton 1972, 

Shelton 2010, Moulton and Hacker 2011), effectively serving as an “ecosystem engineer” 

(Jones et al. 1994). 

Three species of surfgrasses, Phyllospadix serrulatus Ruprecht ex Ascherson, P. scouleri 

W.J.Hooker, and P. torreyi S.Watson, co-occur on the west coast of North America from 

Alaska to Mexico (den Hartog and Kuo 2006), and the latter two are prominent shoreline 

features in California. The largest surfgrass meadow in the Monterey Bay National 

Marine Sanctuary occurs on the northern shores of Monterey Bay between Soquel Point 

and the mouth of Soquel Creek. In 1952, Santa Cruz County began discharging primarytreated, domestic sewage off Soquel Point into the southern portion of this surfgrass 

meadow. By the early 1970s surfgrass was all but gone in a large area down current from 

the discharge and replaced by a stunted cover of upright coralline algae and diatomcoated mudstone.

Undergraduate students in classes at the University of California, Santa Cruz began 

documenting the impact of the sewage discharge in the fall of 1971. They determined the 

extent of the area affected and the number and abundance of species present in 

comparison with other areas away from the discharge (Doyle and Pearse 1972). In 1973 

two 450 m

2

plots were established, one within the affected area and a second within an

apparently unaffected area ~1 km away. These were monitoring annually until 2003, then 

again in 2006, 2012, 2014, and 2015. A preliminary note reported the apparent recovery 

of the surfgrass meadow in the Soquel Point plot in the mid 1990s, ~20 years after the 

sewage discharge was terminated in 1976 (Pearse et al. 1998). 

We now more fully document changes in the Soquel Point plot after the sewage discharge 

was terminated, as well as the near-stability of the surfgrass community in the Opal Cliffs 

plot over the same 42-year period. Documentation of the impact of domestic sewage on 

surfgrass communities is scanty, as is documentation of their recovery once discharge is

terminated. In addition, other major disruptions − including those following ongoing 

shifts in global climate (increases in sea temperature, decreases in pH, sea level rise, 

disease) − are likely to impact surfgrass communities and other major intertidal 

ecosystems around the world (Duncan et al. 2014). Our findings provide insight into the 
11

various ways taxa within this complex intertidal community respond over a long time 

period. 

Study Site

Cliffs on the northern shore of Monterey Bay overlook the wave-cut, nearly flat but 

channeled intertidal platform of fine-grained Purisima mudstone. The intertidal platform 

extends from the base of the cliffs at a near zero tide level out 40 to 50 m to a depth of 

about -1.5’ MLLW, and supports a large surfgrass meadow (Cover photo, Figs. 1, 2, 3). 

Santa Cruz County’s East Cliff-Capitola sewage treatment plant, designed to handle 4 

million gallons of primary-treated domestic sewage, went into operation in 1952. It 

discharged liquid waste into the intertidal of Monterey Bay off Soquel Point on the outer 

edge of the surfgrass meadow. Incoming waves swept in from the southwest carrying the 

sewage northeast back across the intertidal platform (Figs. 1, 2, 3, 4). In the fall of 1971, 

surfgrass was all but absent in an area of ~5,000 m

2 extending ~120 m northeast of the 

sewer outfall.

A 15x30 m plot was established on the outer edge of the platform in the center of the 

affected area (36.9550333, -121.972). This plot was designated the Soquel Point plot. A 

second 15x30 m plot, the Opal Cliffs plot, was established ~1 km to the northeast of the 

outfall on what appeared to be an unaffected surfgrass meadow (36.959917,

-121.963817) (Figs. 1, 2, 3). 

Figure 1. Photos showing the intertidal platform from the cliff top: (left) Soquel Point, 

1977, with arrows pointing to the sewer block (right arrow) and the Soquel Point plot 

(left arrow); (right) Opal Cliffs, 1974, with arrow pointing to the Opal Cliffs plot. 

Between 1968 and 1971, dry-weather flow of the sewage discharge increased from 

slightly less than 2 million gallons per day to 2.9 million gallons per day (U.S. 

Environmental Protection Agency, 1973), and it was between 2.5 and 3.5 mgd from 1971 

to 1976 (Fig. 4), after which the discharge was terminated. Cases of hepatitis among local 

surfers prompted an increase in chlorination in the early 1970s (Talley 1973) with 

average levels of 10 to 14 ppm of chlorine gas (Cl2). While the daily load of suspended 

solids decreased from about 110 ppm to 80 ppm during that time, the level of grease in 
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the sewage dropped from about 85mg/l to about 20mg/l in 1976, just before discharge 

was terminated on June 9, 1976.

Figure 2. Map of study area in northern Monterey Bay showing the location of the sewer 

outfall and the two 450m2plots that were monitored from 1973 to 2015. 

Figure 3. Google views of the Soquel Point plot (left) and Opal Cliffs plot (right). White 

arrows point to locations of the plots; yellow arrow points to sewer outflow.
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Figure 4. Photo of the block at the end of the sewage discharge pipe in 1974. The Soquel 

Point plot is in the background directly behind the person on the right (arrow). Note the 

surfgrass in the foreground on the seaward side of the pipe. Waves swept across the pipe 

carrying the sewage landward across the intertidal platform in the background. 

Figure 5. Characteristics of the sewage discharged at Soquel Point from 1971 until it was 

terminated in June 1976. (Data from the Santa Cruz County Sanitation District obtained 

in 1976.)

0

2

4

6

8

10

12

14

16

1971 1972 1973 1974 1975 1976

Average units per year

Flow (mgd)

Chlorine (ppm)

Solids (ppmx10)

Grease (mg/lx10)
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Monitoring Protocols 

Classes of undergraduate students in quarter-long field courses were trained in field 

identification and monitoring protocols, beginning in 1972. In the spring of 1973 the 

classes established two 450m

2

plots, one in the affected area at Soquel Point (“Pleasure 

Point”) and one in a comparison site ~1 km away off Opal Cliffs (“The Hook”). Both 

plots were located along single transect lines that were perpendicular to the shore and

marked with stainless steel rods cemented into the substrate. The rods in the soft 

mudstone remained in place for various lengths of time before they needed to be 

replaced; by 2003 they were abandoned and the position of the plots was determined by 

cracks in the platform (see: limpets.org) and GPS. The GPS locations of the 0 and 15m 

ends of the transect tape are, respectively, N36° 57.302' W121° 58.260', N36° 57.299' 

W121° 58.254', and N36° 57.294' W121° 58.253' for the Soquel Point plot and N36° 

57.595' W121° 57.829' and N36° 57.612' W121° 57.808' for the Opal Cliffs plot. 

The abundances of the common organisms were estimated in both plots with a random 

sampling protocol (Murray et al. 2006). These two plots were monitored at the end of 

successive undergraduate classes nearly annually until 1998. This schedule provided time 

to train the students and also meant that monitoring could be done in late spring or early 

summer when there are suitable low tides. Some of the students remaining in the Santa 

Cruz area volunteered to continue the annual late spring to early summer monitoring to 

2003, then again in 2006. Beginning in 2012, adults trained in the California Naturalists 

program of the Pacific Grove Museum of Natural History began monitoring the two sites.

The two 450 m

2

plots, each 15x30 m, were monitored using 50x50 cm quadrats divided 

into 25 10x10 cm squares. A random number table that provided positions for X-Y 

coordinates along and perpendicular to the transect line, respectively, was used to place 

the quadrats in the plots. Abundance was estimated using protocols adopted by LiMPETS 

(Long-term Monitoring Program and Experiential Training for Students, see: 

limpets.org). To quantify abundance, we used either total number of individuals within 

the quadrat (discrete organisms) or number of squares within which an organism was 

attached (cloning or aggregated organisms such as algae and surfgrasses) (Foster et al. 

1988). 

Teams of two to four people estimated the abundance of selected organisms within the 

quadrats, each team usually doing counts for 2-5 randomly placed quadrats. With 3 to 10 

teams, we were able to obtain 10 or more replicate counts to obtain estimates of the mean 

abundance (mean and range of number of counts for each date: Soquel Point, 24.0, 10-41; 

Opal Cliffs, 24.5, 11-40; see Appendix).

In addition to the 50x50 cm quadrats used to estimate the abundance of organisms, 1x1 m 

quadrats were placed over stainless steel rods embedded in the rock as reference points. 

These were photographed to record changes in fixed quadrats over time (see Fig. 8).

Taxa Monitored
15

During the first several years of monitoring, an attempt was made to identify and monitor 

most macrophytes (=macroalgae and plants) and macroinvertebrates that were present in 

the quadrats. Specimens of species found in the area around Soquel Point, both within 

and outside the surfgrass-free area, also were collected, identified, and maintained as 

vouchers. Representative vouchers of invertebrates were deposited with the California 

Academy of Sciences, while algal vouchers were maintained in the collections of the 

University of California, Santa Cruz. Comprehensive lists were compiled, archived, and

combined with species lists generated in similar surveys in the mid-1990s to compare

intertidal biota in central California and Hawaii (Zabin et al. 2012; the number of 

invertebrate species recorded at Soquel Point more than doubled between 1972-3 and 

1996-7).

However, it soon became evident that most species were too sparse to sample adequately 

with 50x50 cm quadrats. Moreover, many very similar species were difficult to 

distinguish in the field. Consequently, similar species were grouped and the list reduced 

mainly to genera that could both be reliably recognized and expected to be present in 

most quadrats. Recent analyses found very little difference for evaluating ecological 

conditions in littoral marine environments when genera are used rather than species (Díez 

et al. 2010, Xu et al. 2013). Nine of these taxa are treated in this report. Following Zabin 

et al. (2012), updated from the Worldwide Register of Marine Species, the common and 

scientific names of these taxa are: 

1. Surfgrasses: Phyllospadix spp. (P. scouleri and P. torreyi; almost all P. torreyi).

The epiphytic alga Smithora naiadum (C.L.Anderson) Hollenberg was usually very 

abundant on the blades of Phyllospadix spp. but was not quantified. 

2. Coralline algae (part): Bossiella spp. (B. californica (Decaisne) P.C. Silva, B. 

chiloensis (Decaisne) H.W.Johansen, B. dichotoma (Manza) P.C. Silva, and B. plumosa 

(Manza) P.C.Silva).

3. Coralline algae (part): Corallina spp. (C. chilensis Decaisne, and C. vancouveriensis 

Yendo).

[For the 2006, 2012, and 2014 counts, Bossiella spp. and Corallina spp. were combined 

as “upright coralline algae”; these counts are not considered in this report.]

4. Frilly red algae: Cryptopleura spp. (C. lobulifera (J.Agardh) Kylin, C. ruprechtiana 

(J.Agardh) Kylin, and C. violacea (J.Agardh) Kylin). 

5. Sea lettuces: Ulva spp. (including species in the formerly recognized genus

Enteromorpha Link, which are notoriously difficult to distinguish from those in Ulva L.). 

6. Sunburst sea anemones: Anthopleura sola Pearse and Francis, 2000 (before 2000 

counted as the solitary form of Anthopleura elegantissima (Brandt, 1835), which was the 

only form found in these plots). 
16

7. Honeycomb tubeworms: Phragmatopoma californica (Fewkes, 1889).

8. Turban snails: Tegula spp. (T. brunnea (Philippi, 1848) and T. funebralis (A.Adams, 

1855)). 

9. Hermit crabs: Pagurus spp. (P. granosimanus (Stimpson, 1859), P. hirsutiusculus

(Dana, 1851) and/or P. venturensis Coffin, 1957). 

In addition to enumerating the abundance of the above-named taxa, from 1973 to 1993

teams were asked to list other taxa found in the quadrats to estimate species richness. In 

most cases, species were not identified and only listed as distinct items, often with 

descriptive common names (e.g., filamentous alga, red sponge, colonial hydroid, small 

snail, channeled whelk, kelp crab, isopod, white tunicate.) Although underestimating the 

species richness, the lists can be used to compare the two plots and how the sewage 

discharge affected species richness. 

Monitoring Schedule

Monitoring was possible only on extreme low tides, near or below -1.0’ MLLW. Such 

low tides occur only in the early mornings of April to July and late afternoons of October 

to January. In 1976 monitoring was done in May, before the sewage discharge was 

terminated on June 9, and again in October. Otherwise, monitoring was in spring-summer

every year until 2003, except for 1982 for the Opal Cliffs plot and 1989 for both plots. 

After 2003 both plots were monitored in 2006, 2012, 2014, and 2015. Monitoring 

required two days, one day at each site. Dates for the monitoring are given in the 

Appendix. 

Data Analysis and Archive

John Pearse retained the collected data, including notes of the conditions during 

the monitoring and photographs. Summaries (means, standard deviations, sample sizes) 

were tabulated and graphed to track changes. Over the years, some of the original data 

sheets were lost. However, the means, sample sizes, and standard deviations remained 

available in tables and graphs, and they could be plotted with the more complete data to 

reveal major trends over the 42 years of monitoring. The numerical data used in this 

report are listed in the Appendix and posted on the LiMPETS website (limpets.org), and 

they can be used to compare with data collected in the future. 

General observations
17

When the study began in 1971, the area around the Soquel Point plot was devoid of 

surfgrass and instead consisted of mostly sand-free bare mudstone covered with lowgrowing clumps of coralline algae (mainly C. chilensis) and diatoms, with a scattering of 

Cryptopleura lobulifera and stunted and deformed specimens of Egregia menziesii (var. 

laevigata), Laminaria setchellii, Stephanocystis osmundacea, Chondracanthus 

corymbiferus, Mazzaella volans, M. flaccida, and M. splendens (Doyle and Pearse 1972).

Sponges and tunicates were conspicuously absent, as were their nudibranch predators, 

and decapod crustaceans and sculpins were scarce (Zabin et al. 2012). The general aspect 

of the Soquel Point plot was in stark contrast with the Opal Cliffs plot, which was

dominated by surfgrass that held a thick layer of sand over the mudstone. Over the 

following five years, the affected area landward of the Soquel Point plot expanded as the

long blades of the surfgrass died back, leaving twisted rhizomes attached to the bedrock

(Fig. 6). 

Figure 6. Map showing expansion of area without surfgrass blades between 1972 and 

1975, and recovery in June 1977. Each surfgrass boundary was determined by walking 

along the edge and sketching it in on the original map drawn in 1972. 

Within a month after the 9 June 1976 termination of the sewage discharge, the affected 

Soquel Point area was covered with a carpet of broad-bladed sea lettuces (Ulva spp.). 

Small areas manually scraped clean on 15 May 1976 were filled mainly with long, 

narrow-bladed U. taeniata, while similar scraped areas at Opal Cliffs were still bare, 
18

perhaps because of scour from surrounding surfgrass. Moreover, the branches of 

Corallina spp. had conspicuous, growing tips; the small, stunted vegetative clumps of 

Stephanocystis osmundacea were covered with new fronds; and there were many small 

recruits of the kelps Egregia menziesii and Laminaria sp. Small hermit crabs (Pagurus 

spp.) were conspicuously abundant within the first year of the termination, but after two 

years they declined as the lush new cover of coralline algae trapped sand, covering the 

previously near-bare mudstone. 

The rhizomes of Phyllospadix (all, or nearly all, P. torreyi) remaining attached to rock 

around the edge of the affected area, beyond the study plot, sprouted new blades; an 

expanding surfgrass meadow was apparent within a year (Fig. 6). However, the area

within the study plot remained nearly free of surfgrass for the following four years. The 

first appearance of a few seedlings was in 1978, and only small patches of surfgrass were 

present in 1980 (Fig. 7). Establishment of a dense cover of surfgrass proceeded very

slowly, with large areas still lacking surfgrass in 1988 and not visually matching the Opal 

Cliffs area until about 20 years after the sewage discharge was terminated (Fig. 8, 9).

Figure 7. Photos of surfgrass (Phyllospadix torreyi) returning to the Soquel Point plot; 

Seedling found attached to coralline algae in 1978 among lush cover of Corallina spp., 

Cryptopleura spp., and Ulva spp. (left), and small patches of surfgrass (arrows) among 

the dense cover of Corallina spp. in 1980 (right).
19

Figure 8. Photos of people sampling the Soquel Point plot in 1975 (upper left), 1980 

(upper right), 1993 (middle left), and 2015 (middle right); and the Opal Cliffs plot in 

1974 (lower left) and 2015 (lower right). 

The most noticeable macroinvertebrates in the affected area were large, solitary sea 

anemones, later determined to be Anthopleura sola (considered at the time to be the 

“solitary form” of Anthopleura elegantissima). These are shown in a 1-m

2

quadrat 

photographed over time (Fig. 9). Three were in the same location within the quadrat in 

1975 and 1980, then at least 2 in 1988, and 1 in 1993, although it was difficult to be sure 

if the others were not buried in the sand. The one noted in 1993 was present in 

subsequent years until 1997 when the stainless steel pin marking the position of the 

quadrat was lost. 
20

Figure 9. Photos of the same 1-m

2 quadrat within the Soquel Point plot. Upper left: 1975,

no surfgrass. Upper right: 1980, no surfgrass. Lower left: 1988, partially filled with 

surfgrass. Lower right: 1993, surfgrass abundant. Note the specimens of sunburst 

anemones, Anthopleura sola, located in the same positions (arrows). The stainless steel 

rod in the lower, left-hand corner of the quadrat was used to locate and position the 

quadrat.

One other conspicuous macroinvertebrate at Soquel Point, the honeycomb tube 

polychaete Phragmatopoma californica, was present in low abundance in the monitored 

plot. However, it formed aggregations of sandy mounds shoreward of where the surfgrass 

cover was reduced when the sewage was discharged (Fig. 10). The mounds all but 

disappeared after the sewage discharge ceased. 
21

Figure 10. Photo of honeycomb tubeworm (Phragmatopoma californica) mounds 

shoreward of the Soquel Point plot in 1975 when sewage was discharged. Students in the 

center of the photograph were monitoring quadrats shoreward of the Soquel Point plot;

their data are not included in this paper. Arrow points to area of the Soquel Point plot.

Monitoring Results

Surfgrasses (Phyllospadix spp., nearly all P. torreyi)

As noted in the general observations above, surfgrass appeared as scattered clumps in the 

Soquel Point plot about four years after the sewage discharge was terminated: its

abundance increased slowly after that (Fig. 11). In contrast, surfgrass abundance 

remained nearly constant throughout the 42-year monitoring period in the Opal Cliffs

plot. The abundance of surfgrass in the Soquel Point plot did not reach that in the Opal 

Cliffs plot until the late 1990s, more than 20 years after the sewage discharge was 

terminated. The relatively low abundance of surfgrass in the 2015 count corresponded to 

an unusually low amount of sand cover, exposing bare rock covered with a bloom of 

opportunistic sea lettuces (Ulva spp.)(see Fig. 14). 
22

Figure 11. Changes in the abundance of surfgrasses (Phyllospadix spp., nearly all P. 

torreyi) within 50x50 cm quadrats in the Soquel Point and Opal Cliffs plots. Triangle 

symbols are for the years when the sewage was discharged. Dotted vertical line indicates 

when sewage discharge terminated. 

Upright coralline algae (Bossiella spp. and Corallina spp.)

The two main genera of upright coralline algae revealed very different patterns in 

response to the sewage discharge and its termination. 

Although stunted in appearance, Corallina spp. were found in nearly every 10x10 cm 

square of the quadrats before sewage discharge ended. Despite showing vigorous 

growing tips after the sewage discharge stopped, they started to decrease in abundance 

starting about three years after termination of the sewage discharge (Fig. 12). They had

not reached the low level of abundance found in the Opal Cliffs plot by 2015, nearly 40 

years later. At Opal Cliffs the abundance of Corallina spp. increased to relatively 

moderate levels over the four years prior to the termination of the discharge, then fell to 

low levels throughout the remainder of the monitoring period. 

0

5

10

15

20

25

1970 1980 1990 2000 2010 2020

Number of Squares (mean 

± standard error)

Phyllospadix spp.

Soquel Point Opal Cliffs
23

Figure 12. Changes in the abundance of upright coralline algae Corallina spp. (above) 

and Bossiella spp. (below) within 50x50 cm quadrats in the Soquel Point and Opal Cliffs 

plots. Triangle symbols are for the years when the sewage was discharged. Dotted 

vertical line indicates when sewage discharge terminated. 

0

5

10

15

20

25

1970 1980 1990 2000 2010 2020

Number of Squares (mean 

± standard error)

Corallina spp.

Soquel Point Opal Cliffs

0

5

10

15

20

25

1970 1980 1990 2000 2010 2020

Bossiella spp.

Soquel Point Opal Cliffs

Number of Squares (mean 

± standard error)
24

In contrast to Corallina spp., the abundance of Bossiella spp. was very low at Soquel 

Point when the sewage was discharged; it rose immediately to moderate levels just before

the discharge’s termination, and then decreased very slowly over the following 

monitoring period (Fig. 12). In the Opal Cliffs plot the abundance of Bossiella spp. was 

relatively high during the sewage discharge and immediately after its termination, then

slowly declined. Three years after the discharge ended, the abundance of Bossiella spp. 

was similar between the two sites, although mean values were always higher in the 

Soquel Point plot.

Frilly red algae (Cryptopleura spp.)

The abundance of frilly red algae was near zero in the Soquel Point plot when the sewage 

was discharged, but increased in the year before the sewage discharge was terminated. 

These species were present in nearly every 10x10 cm square of the quadrats for several 

years afterwards (Fig. 13 above). In the Opal Cliffs plot, abundance was moderately high 

when the sewage was discharged and increased after the discharge ended. At both sites 

the abundance of frilly red algae generally declined over the succeeding years, stabilizing

at relatively low levels, but was consistently higher in the Soquel Point than in the Opal 

Cliffs plot.

Sea lettuces (Ulva spp.)

Although relatively high in 1973, sea lettuce abundance dropped to near zero in the 

Soquel Point plot in 1974 and 1975, when the sewage was being discharged. Abundance 

rose in 1976 before the sewage discharge was terminated, and reached high levels in 

1977 and 1978 followed by a drop to near zero in 1979 (Fig. 13 below). In contrast, in the 

Opal Cliffs plot, sea lettuce abundance dropped steadily from moderately high in 1973 to 

near zero in 1979. After 1979, mean abundance of sea lettuce in both plots fluctuated 

from very low to moderate levels with no apparent pattern. The relatively high abundance 

in the Soquel Point plot in 2015 corresponded to an unusually low cover of sand on the 

rocks and a drop in the abundance of surfgrass.

Honeycomb tubeworms (Phragmatopoma californica)

As noted above, large mounds of honeycomb tubeworms occurred shoreward of the 

Soquel Point plot when the sewage was discharged (see Fig. 10). These animals were 

always relatively scarce in both the Soquel Point and Opal Cliffs plots (Fig. 14). 

However, they were more abundant in the Opal Cliffs plot when the sewage was 

discharged and just after; then they fluctuated at low levels with no apparent pattern. 
25

Figure 13. Changes in the abundance of frilly red algae (Cryptopleura spp.) and sea 

lettuces (Ulva spp.) within the Soquel Point and Opal Cliffs plots. Triangle symbols are 

for the years when the sewage was discharged. Dotted vertical line indicates when 

sewage discharge terminated. 

0

5

10

15

20

25

1970 1980 1990 2000 2010 2020

Number of Squares (mean 

± standard 

error)

Cryptopleura spp. 

Soquel Point Opal Cliffs

0

5

10

15

20

25

1970 1980 1990 2000 2010 2020

Number of Squares (mean 

± standard error)

Ulva spp. 

Soquel Point Opal Cliffs
26

Figure 14. Changes in the abundance of honeycomb tubeworms (Phragmatopoma 

californica) within 50x50 cm quadrats in the Soquel Point and Opal Cliffs plots. Triangle 

symbols are for the period when the sewage was discharged. Dotted vertical line indicates 

when sewage discharge terminated. Two symbols each are given for 1976, a triangle for 

before (May) and a circle or square for after (October) the discharge was terminated in 

June. Note that the Y-axis only goes to 4 squares and the “high” value in 1973 is actually 

relatively low.

Sunburst anemones (Anthopleura sola) 

Large specimens of sunburst anemones were conspicuous on the sand-free rocks at 

Soquel Point before the termination of the sewage outfall (see Fig. 9), and they continued 

to be present in similar numbers through the following monitoring period (Fig. 15). 

While their numbers varied considerably among the years, probably due to variation in 

sand burial, the mean number was always higher in the Soquel Point plot than the Opal 

Cliffs plot until 2002, after which mean numbers were nearly identical in both plots. In 

2014 for the first time the mean number of sunburst anemones was substantially higher in 

the Opal Cliffs plot than in the Soquel Point plot. 

0

1

2

3

4

Number of Squares (mean 

1970 1980 1990 2000 2010 2020

± standard error)

Phragmatopoma californica

Soquel Point Opal Cliffs
27

Figure 15. Changes in the abundance of sunburst anemones (Anthopleura sola) within

50x50 cm quadrats in the Soquel Point and Opal Cliffs plots. Triangle symbols are for the 

period when the sewage was discharged. Dotted vertical line indicates when sewage 

discharge terminated. Two symbols each are given for 1976, a triangle for before (May) 

and a circle or square for after (October) the discharge was terminated in June.

Turban snails (Tegula spp.)

Turban snails were more numerous in the Soquel Point plot than in the Opal Cliffs plot 

when the sewage was discharged and for a few years afterwards (Fig. 16, above). 

Particularly striking was the increase in mean number three weeks before the sewage

discharge was terminated in June 1976. These were mostly very small snails. By 1979 

turban snail abundance was very low and, except for 2006, nearly identical between the 

two sites. 

Hermit crabs (Pagurus spp.)

Hermit crabs were rare in the Soquel Point plot when the sewage was discharged in 1973-

74, but a few were counted in the 1975-76 samples before the sewage discharge was 

terminated (Fig. 16, below). Abundance increased by October 1976 only four months 

after the discharge was stopped, peaked in 1978, exceeding the abundance in the Opal 

Cliffs plot, then dropped to levels that were consistently lower than in the Opal Cliffs 

plot. The high number of hermit crabs in 1976-78, with many very small animals, 

probably reflected new recruits from the plankton and an abundance of empty snail 

shells. 

0

0.5

1

1.5

2

2.5

3

3.5

4

1970 1980 1990 2000 2010 2020

Anthopleura sola

Soquel Point Opal Cliffs

Number of Individuals (mean 

± standard error)
28

Figure 16. Changes in the abundance of turban snails (Tegula spp.) (above) and hermit 

crabs (Pagurus spp.) (below) within 50x50 cm quadrats in the Soquel Point and Opal 

Cliffs plots. Triangle symbols are for the period when the sewage was discharged. Dotted 

vertical line indicates when sewage discharge terminated. Two symbols each are given 

for 1976, a triangle for before (May) and a circle or square for after (October) the 

discharge was terminated in June. 

0

1

2

3

4

5

6

1970 1980 1990 2000 2010 2020

Tegula spp. 

Soquel Point Opal Cliffs

Number of Individuals (mean 

± standard error)

0

5

10

15

20

25

1970 1980 1990 2000 2010 2020

Pagurus spp.

Soquel Point Opal Cliffs

Number of Individuals (mean 

± standard error)
29

Taxon richness

When monitoring began in 1973, about one-third as many taxa of both macrophytes and 

macroinvertebrates were noted in the quadrats in the Soquel Point plot as in the Opal 

Cliffs plot (Fig. 17). These proportions narrowed before the sewage discharge was 

terminated, both because of increased numbers in the Soquel Point plot and in the case of 

macroinvertebrates, decreased numbers in the Opal Cliffs plot. From 1978 to 1992 the 

number of taxa in the two plots was indistinguishable, and collection of these data was 

discontinued. 

Figure 17. Changes in the abundance of macrophyte and macroinvertebrate taxa within

50x50 cm quadrats in the Soquel Point and Opal Cliffs plots. Triangle symbols are for the 

years when the sewage was discharged. Dotted vertical line indicates when sewage 

discharge terminated.

0

2

4

6

8

10

12

14

1970 1975 1980 1985 1990 1995

Total Macrophytes

 Soquel Pt Opal Cliffs

Number of Taxa ± standard error)

0

2

4

6

8

10

12

14

16

1970 1975 1980 1985 1990 1995

Total Macroinvertebrates

 Soquel Pt Opal Cliffs

Number of Taxa (mean ± standard error)
30

Discussion

Seagrass meadows are known to be sensitive to a wide variety of natural and 

anthropogenic disturbances (Short and Wyllie-Echeverria 1996, Orth et al. 2006, Hughes 

et al. 2009, Waycott et al. 2009, Hogarth 2015). However, little documentation has been 

published on the impacts of domestic sewage pollution on seagrass meadows in the 

intertidal (reviewed for California by Foster et al. 1988) and even less for surfgrass 

meadows (e.g., North 1964, Littler and Murray 1975, Pearse et al. 1998). As sewage 

treatment has improved on the west coast of North America and sewage disposal has 

moved offshore, documentation of the impact of sewage on surfgrass meadows in the 

future is unlikely (but see, for e.g., Archambault et al. 2001, Cabral-Oliveira et al. 2014 

for recent studies on the impact of sewage disposal in the rocky intertidal on other 

assemblages.) Nevertheless, the present monitoring program demonstrates how a large 

disturbed area within a surfgrass meadow recovered after the termination of long-term 

stress from domestic sewage. Moreover, although the comparison area, ~1 km distant,

was also affected by the sewage discharge, it showed remarkable stability in the 

abundance of the species monitored over the entire 42-year period. Of course, as 

Underwood (1994) points out, replicate sites, if such had been available, are needed to 

conclusively show the impact of sewage on this seagrass meadow, but the available data 

in this study, including the photographs, are compelling.

How the domestic sewage negatively impacted the surfgrass community near the sewage 

discharge outfall is unknown. Between 1972, when our observations began, and 1976,

when the discharge was stopped, the area that was devoid of surfgrass cover more than 

doubled, suggesting that whatever was impacting the surfgrass was an ongoing and 

perhaps increasing stress. Chlorine, used as a disinfectant, is a known toxin, and it 

produces a large variety of organo-halogenated by-products known to be toxic when 

mixed with organic material (Abarnou and Miossec 1992). Between 1973 and 1976 the 

level of chlorine in the sewage remained nearly unchanged (see Fig. 5). However, with 

increasing concern about health issues, the level of chlorination had increased in the early 

1970s (Talley 1973), which may have led to the expanded die-off of surfgrass recorded 

between 1972 and 1975 (see Fig. 6).

After the sewage discharge was stopped, surfgrass foliage (mainly or all, P. torreyi) 

appeared relatively quickly shoreward of the monitored plot at Soquel Point. This rapid 

recovery was almost certainly due to regrowth of blades from surviving rhizomes that 

were defoliated during the previous few years. Similar rapid recovery was observed after 

a fuel spill from a grounded ship on the Monterey Peninsula; the blades of Phyllospadix 

scouleri were bleached and lost while the rhizomes remained intact (Walder and Foster 

2000). However, there were no rhizomes surviving within the monitored Soquel Point 

plot, and new plants were established there only from seedlings that recruited into the 

plot. No recruitment of seedlings was noted until 1978, two years after the sewage 

discharge was terminated. Moreover, accumulation of seedlings and their subsequent

growth by rhizome expansion was very slow. Substantial increase did not begin until 

1982, and it took over 20 years for surfgrass abundance to reach that recorded in the 

comparison plot at Opal Cliffs. Similarly, Dethier (1984), Turner and Lucas (1985),
31

McConnico and Foster (2005), and Shelton (2010) followed the recovery of P. scouleri 

populations after storm or artificial removal, and they likewise found that when the plants 

were completely removed, re-establishment and recovery were very slow, in part because 

of barriers to seed attachment and seedling mortality. 

Seeds of Phyllospadix attach to branching, low-growing algae, including upright coralline 

algae such as Bossiella and Corallina (Gibbs 1902, Turner 1983, Dethier 1984, Turner 

and Lucas 1985, Blanchette et al. 1999, Menge et al. 2005, Shelton 2010). Reed et al. 

(2009) found that seedling recruitment into meadows of P. torreyi depended on both seed 

production and dispersal. Although a large surfgrass meadow that could have provided 

numerous seeds surrounded our Soquel Point plot, we have no measure of seed 

production. If seed production was moderate to high in the surrounding meadow, seed 

availability should not have been limiting. Blanchette et al. (1999) found that species of 

Bossiella and Corallina were only moderately effective at snaring seeds of P. torreyi, and 

this may be a factor in the slow expansion of the surfgrass meadow in the Soquel Point 

plot. Nevertheless, seedlings with only a few blades were noted in 1978 attached to 

coralline algae, without being attached to underlying rock (see Fig. 7). It seems likely that 

as the blades grew, they produced drag on the seedling and the host coralline alga, and 

wave surge broke most seedlings free, washing them away before they had a chance to 

become securely attached to the underlying rocks. The seedlings that became successfully 

attached to the rocks were the ones that spread by rhizome growth to eventually reestablish the meadow. Such rhizome growth would likely be very slow as found by 

Turner (1983) and Turner and Lucas (1985) for rhizome growth of P. scouleri in Oregon.

Turning to coralline algae, Dawson (1959: p. 182, 1965: p. 225) noted that “... several 

species of Bossiella and Corallina are markedly tolerant of high levels of foreign 

substances in intertidal waters of southern California, and ... their abundance in some 

areas is the result of their ability to compete more favorably in such an environment than 

a majority of other algal species.” His examples were in areas around three domestic 

sewage outfalls and, with respect to Corallina spp., are similar to our observations at 

Soquel Point, as well as two other intertidal sites in the Monterey Bay area that had small 

outfalls of domestic sewage disinfected with chlorine in the mid-20th century (Point Pinos 

and Carmel Bay, JSP, pers. obs.). Species of Corallina also have been found to be more 

abundant in the intertidal around other sewage outfalls around the world (e.g., Littler and 

Murray 1975, Archambault et al. 2001, Cabral-Oliveira et al. 2014), although not always 

(e.g., Bellgrove et al. 1997, Díez et al. 2009). On the other hand, we documented a 

striking difference between the abundance of Corallina and Bossiella in the Soquel Point 

plot when sewage was discharged; Corallina was abundant and dominated in the plot 

while Bossiella was nearly absent (Fig. 12). Clearly, different genera and probably 

species of coralline algae respond differently to various forms of chemical toxins. 

The abundances of Bossiella spp., Cryptopleura spp., and Ulva spp. were higher in the 

Opal Cliffs plot than the Soquel Point plot when the sewage was discharged, and their 

abundances dropped over the years after the sewage discharge was terminated. In 

addition, the abundance of Corallina spp. in the Opal Cliffs plot was highest just before 

the sewage discharge was terminated, after which it slowly dropped to lower levels. All 
32

of these algae probably benefited from the nutrient enrichment due to the sewage as 

reported for Ulva spp. and other algae by North et al. (1970) in southern California, as 

well as in Australia (Bellgrove et al. 1997, Archambault et al. 2001, Bishop et al. 2002,

Bellgrove et al. 2010). In addition, the suspension feeding, sabellariid tubeworms 

Phragmatopoma californica formed large mounds at Soquel Point near the Soquel Point 

plot, but not within it, when the sewage was discharged. This tubeworm was more 

abundant in the Opal Cliffs plot when the sewage was discharged than at any time 

afterwards. Another species of sabellariid, Sabellaria alveolata L., was also reported to 

be much more abundant near a sewage outfall than at two reference sites on the coast of 

Portugal (Cabral-Oliveira et al. 2014). Whether these animals benefited from increased 

food particles (e.g., bacteria) or dissolved organic material in the water remains 

unresolved. Regardless, at least some of the species in the healthy-appearing surfgrass 

community in the Opal Cliffs plots, more than one kilometer distant from the sewage 

discharge pipe, appeared to be enhanced by the nutrients in the sewage. On the other 

hand, surfgrass itself at Opal Cliffs showed little difference between when the sewage 

was discharged and afterwards, indicating that it was not nutrient limited. 

Cryptopleura, in particular, increased from near absence in the Soquel Point plot in 1973-

75 to very high abundance just before and immediately after the sewage discharge was 

terminated in 1976. This increase corresponded to a decrease in suspended solids and 

grease content in the sewage. Subsequently, its abundance decreased very slowly over 

about 20 years before reaching levels seen in the Opal Cliffs plot. The slow decrease in 

the abundance of Cryptopleura spp. closely followed that of Corallina spp., both in 

contrast to the increase in abundance of Phyllospadix spp. (Fig. 18). These correlations in 

abundance suggest both facilitation and competition among the three taxa (Connell and 

Slayter 1977). 

The abrupt increase in Cryptopleura in the Soquel Point plot had no effect on the 

abundance of Corallina, and there is no evidence that the two taxa compete for space,

with one displacing the other. Indeed, it seems more likely that Corallina facilitates 

Cryptopleura by providing substrate for attachment when sand held by the luxuriant

growth of Corallina and Phyllospadix covers the rocks. On the other hand, the slow 

increase in Phyllospadix corresponds to a slow decrease in both Cryptopleura and 

Corallina (Fig. 20), suggesting competitive interactions. McConnico and Foster (2005) 

suggested that Cryptopleura and upright coralline algae that recruited in a low intertidal 

area cleared by a ship grounding inhibited the re-establishment of Phyllospadix.

Similarly, Bellgrove et al. (2010) found that turfs of Corallina officinalis became 

established after sewage disposal in the intertidal in Australia removed a canopy-forming 

fucoid alga, and such turfs could prevent the fucoid’s re-establishment. They proposed 

that alternative stable states might occur between those dominated by fucoids and those 

dominated by coralline turf. However, with respect to surfgrass meadows, our findings 

support the conclusion of Menge et al. (2005) that surfgrass is the competitive dominant, 

and although Corallina might inhibit the recruitment of surfgrass by snaring seeds then 

breaking off, it does snare seeds and given enough time after a major disturbance, 

surfgrass will eventually become established and displace other space holders by trapping 

sand that covers the rocky substrate needed by other species for attachment. But the time 
33

required for restoration is in the order of decades. Díez et al. (2014) were concerned that 

canopy-forming algae in northern Spain that were replaced by coralline algae after longterm exposure to sewage showed no evidence of recovery 11 years after sewage upgrade, 

and they suggested that global climate change was involved. 

Figure 18. Abundances of surfgrasses (Phyllospadix spp.), coralline algae (Corallina 

spp.), and frilly red algae (Cryptopleura spp.) in the Soquel Point plot. Dotted vertical 

line indicates when sewage discharge was discontinued. 

The increase in abundance of Cryptopleura spp. in the Soquel Point plot just before the 

sewage discharge was terminated in 1976 also was noted with Bossiella spp., Ulva spp., 

Tegula spp., Pagurus spp., and the richness of both macrophytes and macroinvertebrates. 

Indeed, turban snails (Tegula spp.) were more abundant in the Soquel Point plot when the 

sewage was still being discharged than at any other time during out monitoring. While 

the amount of suspended solids decreased somewhat between 1971 and 1976, the most 

notable change in the sewage treatment was the decrease in grease content (see Fig. 5). 

Among other effects, grease could inhibit algal (including diatom) attachment and growth 

on the rocks. Thus the decrease in grease could explain the increase in abundance of 

organisms when sewage was still being discharged into the intertidal. In addition, after 

the sewage discharge was stopped, the new luxuriant growth of coralline algae trapped

sand that obliterated most of the rock surfaces on which turban snails graze. These 

observations indicate that the affected area at Soquel Point could have undergone 

considerable restoration if the treatment had been improved further, as has been found 

around sewage-affected areas in northern Spain (Bustamante et al. 2012, Díez et al. 

2013). 

0

5

10

15

20

25

Mean Number of Squares

Phyllospadix spp. Corallina spp Cryptopleura spp.
34

The abundance of hermit crabs (Pagurus spp.) was lower in the Soquel Point plot than 

the Opal Cliffs plot throughout nearly the whole period of this survey, suggesting subtle 

differences between the two plots beyond their exposure to sewage. For example, Opal 

Cliffs is less exposed to incoming waves that Soquel Point. The exception was the first 

two years (1977-78) after the sewage discharge was terminated when many small hermit 

crabs were found in the Soquel Point plot. These small hermit crabs probably reflected 

the renewed occupation of empty snail shells that had accumulated earlier when the 

hermit crabs were absent. 

The one species that was found to be unchanging in abundance throughout most of this 

42-year monitoring period was the sunburst anemone, Anthopleura sola. These animals 

were consistently more abundant in the Soquel Point plot than the Opal Cliffs plot, both 

when the sewage was discharged and after until 2006. Anthopleura sola is a southern 

species that appears to have increased in the Monterey Bay area within the past several 

decades (Pearse and Francis 2000). With the decline in surfgrass cover, the relatively 

sand-free rocks in the sewage-affected area at Soquel Point may have been particularly 

favorable for recruitment of these anemones. Once established, they could survive

attached to the rocks even after the sand accumulated among the luxuriant growth of 

coralline algae and later, surfgrass. The lifespan of anemones, including sunburst 

anemones, is unknown, but they apparently lack senescence (Shick 1991) so are 

potentially immortal. Our photographs of the same 1 m

2

plot between 1975 and 1993

showed individual sunburst anemones in nearly the same locations, and the one 

remaining in 1993 was seen until 1997, suggesting lifespans of at least 22 years. 

Johnson and Roberts (2009) reviewed 216 studies on the effects of contaminants upon the 

diversity of marine communities and concluded that species richness tended to be the 

most sensitive index. Although our attempt at following species richness was not 

thorough (we did not specifically identify most species), it did show patterns seen in 

other studies (e.g., Bustamante et al. 2012, Díez et al. 2013), with the taxon richness 

values converging in the Soquel Point and Opal Cliffs plots two years after the sewage 

discharge was terminated. Afterwards, taxon richness remained remarkably stable and 

indistinguishable between the two plots. The same stability was seen in most of the other 

taxa monitored, the exceptions being Phyllospadix spp., Corallina, spp., and 

Cryptopleura spp., all of which took decades or more to reach comparable levels in the 

two plots. Such stability was seen despite considerable climatic and oceanographic 

variability that occurred during this time period (Pennington et al. 2007). There is little 

evidence, for example, of any impact from the major El Niño events of 1982 and 1997-

98, except perhaps on the abundance of Cryptopleura, which was noticeably low in the 

Soquel Point plot in both 1982 and 1997 (see Fig. 20). 

Our monitoring protocol is commonly used to monitor rocky intertidal shores (Murray et 

al. 2006); it averages multiple random samples taken within a defined area to detect 

changes in a relatively large area (in our case 450m2plots). It is what Menge et al. (2005) 

called the “mean field approach.” However, it ignores changes that might be occurring 

within patches in the area. For example, many taxa were recorded in our surveys for the 

taxon richness data, most being different and in low abundance within the two plots and 
35

among years. Most of the species recorded for Soquel Point and other locations on the 

Santa Cruz-San Mateo coast in the early 1970s and mid 1990s were rare (Zabin et al. 

2012). Consequently, even though taxon richness appeared to be very stable in our 

monitoring, we have little evidence that the same taxa were present year after year or in 

the two monitored plots. Consequently, our monitoring provides little information about 

the dynamic changes that may have gone on within or among patches in our plots. 

Menge et al. (2005) examined community structure, disturbance by storms, and species 

interactions within a surfgrass meadow in Oregon using a “spatially explicit approach” 

that followed small individual quadrats over 15 years at 5 sites differing in wave 

exposure. They found, as we did, that average patterns of species abundance were 

relatively constant through time. In contrast, there was considerable change in the 

“mosaic elements” of their communities that were mainly related to wave exposure. As 

documented for other intertidal landscapes (Paine and Levin 1981, Sousa 1984), most 

changes noted by Menge et al. (2005) involved patches of competitive dominants 

(surfgrasses in their case) that were torn out by storms and then recovered, displacing 

other species that were more transitory. Our monitoring protocols would not detect such 

change within our plots if they occurred. Still, while documenting surfgrass slowly 

recolonizing space, the photos we took of the same 1m2quadrats showed considerable 

differences in species distribution and abundance within them (see Fig. 9). Clearly, 

interactions among species in our plots were likely very dynamic on a small scale, both 

spatially and temporally, even though our monitoring protocol, which addressed large 

scale disturbance and recovery, could not detect them

While surfgrass meadows appear to remain healthy in the northeastern Pacific, they can 

experience damage from human coastal activities, as has been seen in Korea where 

surfgrass meadows have been severely degraded by on-shore development (Park and Lee 

2009). Pollution from oil spills, such as occurred when a tanker went aground on the 

Monterey Peninsula, also can destroy large areas of surfgrass (Walder and Foster 2000, 

McConnico and Foster 2005). In addition, surfgrass meadows will likely be susceptible to 

severe storms and rising sea level that are expected to result from global warming. And 

global warming could make surfgrass meadows susceptible to pathogens. For example, 

wasting diseases, caused by the heterokont Labyrinthula, which have devastated eelgrass 

(Zostera marina L.) meadows around the Northern Hemisphere, are now being found in 

other species of seagrasses (Sullivan et al. 2013).

The potential of large-scale losses of surfgrass meadows has led to several efforts to 

develop methods to restore them (Wyllie-Echeverria et al. 2007). Working with 

Phyllospadix torreyi in southern California, for example, Bull et al. (2004) found that 

transplanting short lengths of rhizomes was much more effective for establishing 

meadows than transplanting laboratory-reared seedlings. Park and Lee (2009) also used 

short pieces of shoots (with blades) to successfully establish meadows of P. japonicus in 

Korea. Success with pieces of transplanted surfgrasses rather than seeds or seedlings is in 

line with our finding of very slow recovery in the Soquel Point plot from field-recruited 

seedlings. Recently, attempts to establish surfgrass meadows using seeded artificial reefs 

have been promising (Park et al. 2014). 
36

Our long-term monitoring program can be useful for resource managers of the National 

Marine Sanctuaries when they consider the status of surfgrass meadows in their areas of 

concern. Both natural and anthropogenic causes can lead to the degradation of surfgrass 

meadows that serve as carbon sinks and habitats for many other species, including those 

important for fisheries. Baselines such as those provided here can be used to detect and 

evaluate declines, as well as provide predictions about how these habitats might recover. 

As found by Turner (1983) and Turner and Lucas (1985) for P. scouleri in Oregon, we 

found that recovery of surfgrass meadows composed mainly of P. torreyi in central 

California takes decades. In contrast, many other species in the system recover much 

more quickly. How the whole system functions without the underlying foundation species

remains unknown and should be better understood before efforts are made at restoration. 

The Soquel Point and Opal Cliffs plots are now part of a citizen-science program, Longterm Monitoring Program and Experiential Training for Students (LiMPETS), which

monitors the shores of California in an integrated effort to follow changes in habitatforming organisms as recommended by Duncan et al. (2014). Data summarized here are 

on the LiMPETS website (limpets.org), and more data will be added as they are

collected. These data can be used to assess the health of surfgrass meadows in northern 

Monterey Bay and provide a baseline in the event of future disturbance of this rich and 

diverse ecosystem. 

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42

Appendix

Data used in this report: dates, means, standard deviations, and number of quadrats 

counted on each monitoring day in the Soquel Point and Opal Cliffs plots. Data compiled 

from the LiMPETS website, Access files archived by E.M. Danner, and summary tables 

and graphs archived by J.S. Pearse. Most of the original data taken before 2000 have been 

lost, and in some cases only means and sample sizes remain. 

Phyllospadix spp.

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 0.1 0.4 22 4-Jun-73 9 6.9 21

25-Apr-74 0 0.0 19 26-Apr-74 12.3 8.4 25

27-Apr-75 0 0.0 30 29-Apr-75 15.1 5.8 23

15-May-76 0 0.0 35 16-May-76 11.7 7.6 24

25-Oct-76 0 0.0 15

4-Jul-77 0 0.0 17 3-Jul-77 13.1 6.3 21

23-May-78 0.1 0.2 19 25-May-78 12.1 6.9 16

11-Jun-79 0 0.0 29 13-Jun-79 13.6 5.9 29

15-May-80 0.1 0.3 30 17-May-80 15.9 8.1 40

3-Jun-81 0.1 0.3 16 4-Jun-81 14.5 8.6 16

22-Jun-82 0.6 2.5 36

12-Jun-83 2 5.2 28 13-Jun-83 8.5 8.1 32

15-Jun-84 2.2 6.2 32 16-Jun-84 18.4 9.4 28

4-Jun-85 2.4 6.2 36 5-Jun-85 13 7.6 32

23-Jun-86 5.2 8.7 24 24-Jun-86 14.3 7.8 20

13-Jun-87 0.8 2.0 24 14-Jun-87 11.5 6.8 16

4-Jun-88 3.4 6.4 32 5-Jun-88 12.8 7.3 28

23-Jun-90 8.6 10.1 28 24-Jun-90 17.8 10.2 28

13-Jun-91 2.7 5.6 20 14-Jun-91 12.1 7.3 24

5-May-92 10 7.2 30 1-May-92 15.6 7.9 35

21-Jun-93 5.4 7.5 24 22-Jun-93 13.7 7.2 28

24-Jun-94 4.4 6.0 36 25-Jun-94 11.8 7.6 32

13-Jul-95 7.5 6.7 26 14-Jul-95 14.5 24

4-Jun-96 7.7 26 5-Jun-96 14.5 6.2 24

21-Jun-97 12.3 11.5 40 22-Jun-97 22 24

26-Jun-98 12.2 9.9 23 25-Jun-98 16.6 8.6 31

15-Jun-99 14.4 8.4 24 16-Jun-99 17.8 7.1 27

3-Jul-00 9.1 9.0 30 2-Jul-00 14.9 7.1 27

26-May-01 9.4 8.8 15 27-May-01 16.8 6.7 29

27-May-02 12.9 9.9 17 26-May-02 14.2 8.9 21

18-May-03 9.5 8.6 23 17-May-03 16.4 7.2 26
43

12-Jun-06 11.2 7.6 29 13-Jun-06 12.9 5.6 23

4-Jul-12 14.8 8.1 10 8-May-12 14.3 8.3 16

14-Jun-14 16.1 8.1 12 16-Jun-14 15.6 5.7 11

17-Jun-15 8.3 4.3 14 2-Jul-15 13.1 5.6 15

Mean 5.5 14.3

Corallina spp.

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 25 0.0 22 4-Jun-73 8.3 6.4 21

25-Apr-74 24.8 1.0 19 26-Apr-74 10.2 5.8 25

27-Apr-75 25 0.0 30 29-Apr-75 12.4 6.7 23

15-May-76 25 0.0 35 16-May-76 12.5 6.8 24

25-Oct-76 25 0.0 21

4-Jul-77 25 0.0 17 3-Jul-77 8.8 5.8 21

23-May-78 25 0.0 19 25-May-78 7.2 5.5 16

11-Jun-79 23.9 3.0 29 13-Jun-79 3.4 3 29

15-May-80 19.6 6.6 30 17-May-80 2.7 3.2 37

3-Jun-81 23.8 1.9 16 4-Jun-81 2.9 3.3 16

22-Jun-82 14.1 10.7 36

12-Jun-83 22.1 4.1 28 13-Jun-83 3.2 4.1 32

15-Jun-84 19.5 7.6 32 16-Jun-84 1.7 2.3 28

4-Jun-85 18.9 7.8 36 5-Jun-85 2.5 4.9 32

23-Jun-86 19.5 7.7 20 24-Jun-86 5.9 5.8 20

13-Jun-87 21.2 5.8 24 14-Jun-87 2.3 2.9 16

4-Jun-88 14.6 8.9 32 5-Jun-88 2.8 3.5 28

23-Jun-90 15.4 7.7 24 24-Jun-90 2.2 3.8 28

13-Jun-91 16.2 7.6 20 14-Jun-91 4.3 5.1 24

5-May-92 14.5 6.7 30 1-May-92 4.6 3.5 35

21-Jun-93 12.4 8.5 24 22-Jun-93 2 2.7 28

24-Jun-94 14.9 8.9 28 25-Jun-94 1.7 2.9 32

13-Jul-95 13.8 8.4 28 14-Jul-95 2.2 2.6 24

4-Jun-96 17.5 24 5-Jun-96 2 26

21-Jun-97 12.5 32 22-Jun-97 2 24

26-Jun-98 14.8 8.4 24 25-Jun-98 0.9 2 36

15-Jun-99 9.3 6.6 24 16-Jun-99 1.1 2 28

3-Jul-00 15.2 7.3 30 2-Jul-00 4.7 7.4 28

26-May-01 14.4 6.2 22 27-May-01 0.9 1.9 29

27-May-02 10.5 5.6 17 26-May-02 2.4 2.7 21

18-May-03 6.7 4.6 23 17-May-03 0.7 1.4 26

17-Jun-15 7.7 5.2 14 13-Jun-06 0.9 1.1 15

Mean 17.7 4.0
44

Bossiella spp.

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 2.3 3.5 22 4-Jun-73 17.4 4.2 21

25-Apr-74 1.1 2.3 19 26-Apr-74 17.6 5.9 25

27-Apr-75 1.5 1.8 30 29-Apr-75 10 6.6 23

15-May-76 11.4 5.7 35 16-May-76 17.8 6.5 24

4-Jul-77 7.1 4.8 17 3-Jul-77 15.8 5.1 21

23-May-78 11.7 4.1 19 25-May-78 10.2 4.3 16

11-Jun-79 8.2 6.6 29 13-Jun-79 10.8 5.9 29

15-May-80 11.2 6.6 30 17-May-80 11.8 4.2 37

3-Jun-81 6.4 4 16 4-Jun-81 10.3 4.4 15

22-Jun-82 8.4 9.6 36

12-Jun-83 7.1 5 28 13-Jun-83 5 5.3 32

15-Jun-84 8.6 5 32 16-Jun-84 2.3 3.1 28

4-Jun-85 7.8 4.8 36 5-Jun-85 4.1 4.9 32

23-Jun-86 5.5 3.5 20 24-Jun-86 4.7 5.2 20

13-Jun-87 7.5 4.8 24 14-Jun-87 4.3 4.6 16

4-Jun-88 8.9 6.6 32 5-Jun-88 4.2 4.2 28

23-Jun-90 6.3 5 24 24-Jun-90 3.9 6.3 28

13-Jun-91 8.5 5.2 20 14-Jun-91 5.2 4.2 24

5-May-92 3.2 3.5 30 1-May-92 2.8 4.6 40

21-Jun-93 1.8 2.1 24 22-Jun-93 1.9 2.6 28

24-Jun-94 5 4.4 28 25-Jun-94 1.6 2.7 32

13-Jul-95 2.2 3.2 28 14-Jul-95 0.8 1.2 24

26-Jun-98 4.8 5.7 24 25-Jun-98 4.8 5.7 24

15-Jun-99 8.1 7.4 24 16-Jun-99 2.8 3.6 28

3-Jul-00 11.1 7.7 30 2-Jul-00 3.5 5.6 28

26-May-01 7.1 6.7 22 27-May-01 2 2.7 29

27-May-02 8.2 4.3 17 26-May-02 1.8 2.4 21

18-May-03 10 6.7 23 17-May-03 2.2 2.7 26

17-Jun-15 2.4 3.5 14 13-Jun-06 1.4 1.5 15

Mean 6.7 6.5

Cryptopleura spp

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 0.5 0.9 22 4-Jun-73 12.8 5.5 21

25-Apr-74 0.2 0.4 19 26-Apr-74 12.2 7.6 25

27-Apr-75 0.03 0.2 30 29-Apr-75 11.5 6.7 23
45

15-May-76 20.3 3.4 35 16-May-76 11.7 6.4 24

4-Jul-77 22.8 2.7 17 3-Jul-77 18.1 5.8 21

23-May-78 23.8 2.8 19 25-May-78 16.6 7.1 16

11-Jun-79 23.9 1.4 29 13-Jun-79 10 8.3 29

15-May-80 16.0 8.2 32 17-May-80 5.8 5.7 38

3-Jun-81 18.6 4.9 16 4-Jun-81 6.9 6.9 16

22-Jun-82 7.6 9.0 34

12-Jun-83 15.6 8.5 28 13-Jun-83 5.2 6.2 32

15-Jun-84 16.3 8.0 30 16-Jun-84 3 3.3 26

4-Jun-85 13.8 7.2 35 5-Jun-85 3.6 3.8 31

23-Jun-86 19.3 6.7 20 24-Jun-86 6.2 5 20

13-Jun-87 21.1 5.7 24 14-Jun-87 5.7 5.5 17

4-Jun-88 16.1 8.4 32 5-Jun-88 5.9 6.5 28

23-Jun-90 13.7 7.7 24 24-Jun-90 2.9 5.2 28

13-Jun-91 16.6 8 20 14-Jun-91 8.5 7.1 24

5-May-92 14.9 5.8 30 1-May-92 8.4 6.2 40

21-Jun-93 7.5 6.1 24 22-Jun-93 3.5 3.3 28

24-Jun-94 13.5 7.7 28 25-Jun-94 2.8 3.1 32

13-Jul-95 8.2 7.2 28 14-Jul-95 1.9 2.8 24

4-Jun-96 12 24 5-Jun-96 2.3 26

21-Jun-97 5.5 32 22-Jun-97 3 24

26-Jun-98 11.4 8.4 23 25-Jun-98 2.8 3.8 31

15-Jun-99 12.2 7.3 24 16-Jun-99 3.9 4.2 27

3-Jul-00 12.1 7.0 30 2-Jul-00 1.6 2.9 27

26-May-01 8.1 5.2 15 27-May-01 3.3 3.4 29

27-May-02 10.5 7.5 17 26-May-02 2.7 3.4 21

18-May-03 14 6.7 23 17-May-03 6.6 3.6 26

12-Jun-06 9.4 6.6 28 13-Jun-06 6.8 6.1 23

4-Jul-12 7.3 7.7 10 8-May-12 7.6 6.6 16

14-Jun-14 9 8.2 12 16-Jun-14 7 6 11

17-Jun-15 10.8 6.5 14 2-Jul-15 10.4 5.3 15

Mean 12.7 6.7

Ulva spp. Ulva

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 17.4 6.8 22 4-Jun-73 19.5 4.7 21

25-Apr-74 0.3 1.4 19 26-Apr-74 14.6 7.3 25

27-Apr-75 0.5 1 30 29-Apr-75 9.4 8.4 23

15-May-76 4.9 2.8 35 16-May-76 8.8 5.9 24

4-Jul-77 22.2 4.7 17 3-Jul-77 7.2 5.3 21

23-May-78 21.9 2.9 19 25-May-78 2.4 3.2 16
46

11-Jun-79 1.3 1.6 29 13-Jun-79 0.5 1.8 29

15-May-80 7 5.6 30 17-May-80 7.2 8.2 37

3-Jun-81 1.6 1.5 16 4-Jun-81 3.9 5.9 15

22-Jun-82 6.7 7.6 36

12-Jun-83 3.9 5 28 13-Jun-83 6.6 7.91 32

15-Jun-84 3.5 4.8 32 16-Jun-84 0.9 1.64 28

4-Jun-85 8.3 8 36 5-Jun-85 2.5 3.42 32

23-Jun-86 6.9 6.2 20 24-Jun-86 10.9 8.28 20

13-Jun-87 5.3 4.4 24 14-Jun-87 3.9 3.79 16

4-Jun-88 9.8 7.7 32 5-Jun-88 10.4 7.54 28

23-Jun-90 8 6.6 24 24-Jun-90 7.4 8.12 32

13-Jun-91 5.4 4.5 20 14-Jun-91 6.8 5.73 24

5-May-92 0.8 2.2 30 1-May-92 0.8 1.59 40

21-Jun-93 0.2 0.6 24 22-Jun-93 1.11 1.79 28

24-Jun-94 2 3 28 25-Jun-94 5.5 5.42 32

13-Jul-95 0.2 0.8 28 14-Jul-95 4.2 6.8 24

5-Jun-96 0.2 26

22-Jun-97 3.1 24

26-Jun-98 1.8 4.3 23 25-Jun-98 10.5 7.6 31

15-Jun-99 5.3 4 24 16-Jun-99 6.1 6.8 27

3-Jul-00 5.4 4.1 30 2-Jul-00 7.4 7.4 27

26-May-01 9.6 8.2 15 27-May-01 9.1 6.4 29

27-May-02 2.5 3.2 17 26-May-02 7.2 7.7 21

18-May-03 2.6 2.6 23 17-May-03 4.9 4.4 26

12-Jun-06 3.3 4.4 29 13-Jun-06 8.5 5 23

4-Jul-12 1.6 3.5 10 8-May-12 0.1 0.5 16

14-Jun-14 0.5 0.9 12 16-Jun-14 4.7 7 11

17-Jun-15 15.2 7.6 14 2-Jul-15 4.9 4 15

Mean 5.9 6.1

Anthopleura sola

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 2.1 1.2 15 4-Jun-73 0.9 1.6 14

25-Apr-74 1.5 17 26-Apr-74 0.9 14

27-Apr-75 2 24 29-Apr-75 0.9 23

15-May-76 3.1 1.9 15 16-May-76 0.6 15

25-Oct-76 1.9 1.6 21 23-Oct-76 1.5 1.8 24

4-Jul-77 1.9 1.8 23 3-Jul-77 1.3 1.7 20

23-May-78 1.4 1.5 22 25-May-78 0.3 0.6 24

11-Jun-79 1.4 1 28 13-Jun-79 0.8 0.8 24

15-May-80 1.8 1.7 36 17-May-80 0.8 1.1 39
47

3-Jun-81 1.5 2.1 20 4-Jun-81 0.4 0.7 16

22-Jun-82 2.5 1.9 41 

12-Jun-83 1.4 1.1 28 13-Jun-83 0.8 1.2 32

15-Jun-84 2.3 2.1 32 16-Jun-84 0.6 0.8 26

4-Jun-85 1.8 1.9 35 5-Jun-85 0.8 1.1 31

23-Jun-86 1.4 1.6 20 24-Jun-86 0.7 0.9 20

13-Jun-87 1.2 1.2 24 14-Jun-87 0.7 1.0 16

4-Jun-88 1.6 1.3 30 5-Jun-88 0.7 0.9 27

23-Jun-90 1.7 1.6 22 24-Jun-90 0.9 1.0 27

13-Jun-91 1.3 1.5 18 14-Jun-91 0.7 0.8 22

5-May-92 0.9 1.1 30 1-May-92 0.6 0.9 35

21-Jun-93 1.3 1.4 17 22-Jun-93 0.9 1.1 28

24-Jun-94 1.8 1.7 25 25-Jun-94 0.8 1.1 30

13-Jul-95 1.5 1.6 25 14-Jul-95 0.6 0.7 23

4-Jun-96 2.2 1.7 26 5-Jun-96 1.2 1.2 26

22-Jun-97 0.7 1.2 23

26-Jun-98 1.6 1.3 23 25-Jun-98 1.1 1.3 29

15-Jun-99 2 1.4 24 16-Jun-99 1.0 1.1 27

3-Jun-00 2.2 1.5 31 2-Jul-00 1.2 1.5 27

26-May-01 2.1 1.6 15 27-May-01 1.2 1.1 29

27-May-02 1.4 1.7 17 26-May-02 1.2 1.7 21

18-May-03 1.2 1.1 23 17-May-03 1.3 1.6 26

12-Jun-06 0.9 1 29 13-Jun-06 1 1.3 23

4-Jul-12 0.3 0.5 10 8-May-12 0.6 1.2 16

14-Jun-14 0.8 1 12 16-Jun-14 1.6 1.8 11

17-Jun-15 0.9 1.4 14 2-Jul-15 0.7 1 15

Mean 1.6 0.6

Phragmatopoma californica

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 0.1 0.3 16 4-Jun-73 3.1 5.5 14

25-Apr-74 0.3 0.6 20 26-Apr-74 2.8 5.8 16

27-Apr-75 0.5 1.2 24 29-Apr-75 1.9 2.5 24

15-May-76 0.3 0.8 15 16-May-76 2.3 2.9 15

25-Oct-76 0.6 1.4 21 23-Oct-76 2.7 2.9 24

4-Jul-77 0.1 0.3 23 3-Jul-77 1.7 3.1 20

23-May-78 0 0 22 25-May-78 0.04 0.2 24

11-Jun-79 0.1 0.4 28 13-Jun-79 0.3 1 24

15-May-80 0.03 0.2 36 17-May-80 0.2 0.5 39

3-Jun-81 0.1 0.5 20 4-Jun-81 0.4 1.1 16

22-Jun-82 0.3 1.6 41
48

12-Jun-83 0 0 28 13-Jun-83

 

0 0

 

32

15-Jun-84 1.2 2.8 32 16-Jun-84 0.04 0.2 26

4-Jun-85 0.8 2.2 34 5-Jun-85 0.9 2.2 31

23-Jun-86 0.1 0.2 20 24-Jun-86 0.7 1.8 20

13-Jun-87 0 0 24 14-Jun-87 0 0 16

4-Jun-88 0 0 32 5-Jun-88 0 0 10

23-Jun-90 0.04 0.2 24 24-Jun-90 0.04 0.2 24

13-Jun-91 0.4 1.2 20 14-Jun-91 0 0 24

5-May-92 0.2 30 1-May-92 0.6 2.1 40

21-Jun-93 0.2 0.4 24 22-Jun-93 0.3 0.8 28

24-Jun-94 0 0 30 25-Jun-94 0 0 32

13-Jul-95 0 0 24 14-Jul-95 0 0 28

23 5-Jun-96 0.2 24

24 22-Jun-97 0.1 23

26-Jun-98 0.04 0.2 23 25-Jun-98 0.03 0.2 29

15-Jun-99 0.04 0.2 24 16-Jun-99 0.3 1.4 27

3-Jul-00 1.8 4.3 30 2-Jul-00 1.1 2.3 27

26-May-01 0.7 2 15 27-May-01 0.1 0.7 29

27-May-02 0.3 1 17 26-May-02 1.1 3.7 21

18-May-03 0.4 0.9 23 17-May-03 0.2 0.8 26

12-Jun-06 0 0 29 13-Jun-06 0.04 0.2 23

4-Jul-12 0.1 0.3 10 8-May-12 0.1 0.3 16

14-Jun-14 0 0 12 16-Jun-14 0 0 11

17-Jun-15 0.7 1.7 14 2-Jul-15 0 0 15

Mean 0.3 0.9

Tegula spp. 

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 1.9 2.1 16 4-Jun-73 0.4 0.5 14

25-Apr-74 1.4 2.8 20 26-Apr-74 0.7 1 16

27-Apr-75 2.3 4.3 24 29-Apr-75 0.5 0.8 24

15-May-76 4.6 4.2 15 16-May-76 0.1 0.4 15

25-Oct-76 2.1 3.6 21 23-Oct-76 0.04 0.2 24

4-Jul-77 0.9 17 3-Jul-77 0.2 0.4 20

23-May-78 0.3 0.5 12 25-May-78 0.1 0.3 24

11-Jun-79 0.1 25 13-Jun-79 0.1 0.3 24

15-May-80 0.2 30 17-May-80 0.1 0.6 39

3-Jun-81 0.3 15 4-Jun-81 0.1 0.3 16

22-Jun-82 0.3 0.5 24

12-Jun-83 0.3 28 13-Jun-83 0.2 0.5 32
49

15-Jun-84 0.3 0.5 24 16-Jun-84 0.04 0.2 26

4-Jun-85 0.4 0.5 26 5-Jun-85 0.1 0.3 31

23-Jun-86 0.1 19 24-Jun-86 0.1 0.3 20

13-Jun-87 0.2 22 14-Jun-87 0 0 16

4-Jun-88 0.1 30 5-Jun-88 0.1 0.3 10

23-Jun-90 0 22 24-Jun-90 0.0 0.0 27

13-Jun-91 0.4 0.5 16 14-Jun-91 0.2 0.4 22

5-May-92 0.1 30 1-May-92 0.03 0.2 35

21-Jun-93 0.2 17 22-Jun-93 0.04 0.2 28

24-Jun-94 0 30 25-Jun-94 0.03 0.2 30

13-Jul-95 0 25 14-Jul-95 0.1 0.5 23

4-Jun-96 0.3 24 5-Jun-96 0.0 0.0 28

21-Jun-97 0 0 28 22-Jun-97 0.0 0.0 23

26-Jun-98 0 0 23 25-Jun-98 0.1 0.3 29

15-Jun-99 0.1 0.4 24 16-Jun-99 0.2 0.6 27

3-Jul-00 0.1 0.4 30 2-Jul-00 0 0 27

26-May-01 0 0 15 27-May-01 0.1 0.3 29

27-May-02 0.1 0.5 17 26-May-02 0 0 21

18-May-03 0.3 0.5 23 17-May-03 0.4 1.1 26

12-Jun-06 0.1 0.3 29 13-Jun-06 0.9 2 23

4-Jul-12 0 0 10 8-May-12 0.1 0.3 16

14-Jun-14 0.2 0.6 12 16-Jun-14 0.1 0.3 11

17-Jun-15 0.2 0.3 14 2-Jul-15 0.1 0.3 15

Mean 0.5 0.2

Pagurus spp.

Soquel Point Opal Cliffs

Date

 

Mean sd # Date

 

Mean sd #

1-Jun-73 0.1 0.3 16 4-Jun-73 4.9 6.1 14

25-Apr-74 0 0 20 26-Apr-74 3.1 3.5 16

27-Apr-75 0.7 1.4 24 29-Apr-75 2.1 2.9 24

15-May-76 1.3 0.3 15 16-May-76 3.2 1.8 15

25-Oct-76 9.1 13.4 21 23-Oct-76 2.1 2.5 24

4-Jul-77 8.4 7.9 23 3-Jul-77 3.5 2.8 20

23-May-78 19.1 30.6 22 25-May-78 4.8 5.3 24

11-Jun-79 0.5 1.4 28 13-Jun-79 2.8 4.3 24

15-May-80 2.8 6.5 36 17-May-80 5.8 6.3 39

3-Jun-81 2.8 4.2 20 4-Jun-81 4.9 6.6 16

22-Jun-82 1.7 3.1 41

12-Jun-83 1.2 2.9 28 13-Jun-83 2.2 3.5 32

15-Jun-84 2.8 3.7 32 16-Jun-84 3.6 4.8 26

4-Jun-85 2.4 4.2 34 5-Jun-85 3.6 4.2 31
50

23-Jun-86 6.1 7.5 20 24-Jun-86 7.9 12.6 20

13-Jun-87 0.8 0.9 24 14-Jun-87 5.3 8.9 16

4-Jun-88 0.3 0.5 30 5-Jun-88 3.0 6.4 27

23-Jun-90 1.1 1.3 22 24-Jun-90 2.5 3.3 27

13-Jun-91 1.1 1.4 18 14-Jun-91 3.7 3.7 22

5-May-92 0.4 0.9 30 1-May-92 2.3 3.3 35

21-Jun-93 1.1 1.8 17 22-Jun-93 3.6 5.1 28

24-Jun-94 1.4 1.7 25 25-Jun-94 2.0 1.8 30

13-Jul-95 1 1.2 25 14-Jul-95 2.1 2.6 23

4-Jun-96 1.2 1.3 26 5-Jun-96 5.3 4.9 28

21-Jun-97 0.3 0.7 28 22-Jun-97 2.8 3.0 40

26-Jun-98 1 1.8 23 25-Jun-98 4.7 4.5 29

15-Jun-99 1.5 1.8 24 16-Jun-99 4.6 4.4 27

3-Jul-00 1.9 1.8 30 2-Jul-00 9.5 13.3 27

26-May-01 1.1 1.2 15 27-May-01 8.7 6.3 29

27-May-02 3.4 5 17 26-May-02 6.3 6.6 21

18-May-03 1.7 3.1 23 17-May-03 8.2 7.5 26

12-Jun-06 0.4 0.7 28 13-Jun-06 5 4.9 23

4-Jul-12 1 1.5 10 8-May-12 3.6 3.8 16

14-Jun-14 1.1 2.9 12 16-Jun-14 8.8 8.1 11

17-Jun-15 0.5 1 14 2-Jul-15 2.9 3.6 15

Mean 2.3 4.4

Total Macrophytes

Soquel Point Opal Cliffs

Date 

Mean sd # Date Mean sd #

1-Jun-73 3.8 1.5 22 4-Jun-73 10.8 2.1 21

25-Apr-74 2 1.3 19 26-Apr-74 8.2 1.6 25

27-Apr-75 2 0.7 30 29-Apr-75 8 2.3 23

15-May-76 5.8 0.5 15 16-May-76 8 2.2 24

4-Jul-77 5.8 0.2 17 3-Jul-77 8 1.8 21

23-May-78 8.5 2 19 25-May-78 7.3 1.4 16

11-Jun-79 6 1 29 13-Jun-79 6 1.3 29

15-May-80 7 0.7 30 17-May-80 7.5 1.4 37

3-Jun-81 7.8 1.2 20 4-Jun-81 6.2 1.3 15

22-Jun-82 6.2 1.7 34 0

12-Jun-83 6.3 1.4 28 13-Jun-83 5.8 1.7 28

15-Jun-84 5.6 2 26 16-Jun-84 5.8 1.3 30

4-Jun-85 6 2 30 5-Jun-85 7 1.4 33

23-Jun-86 8 2.2 19 24-Jun-86 10 2.2 20

13-Jun-87 7.8 1.8 23 14-Jun-87 7.8 2 15

4-Jun-88 8 1.2 31 5-Jun-88 7.7 0.8 26
51

23-Jun-90 8.1 1.5 22 24-Jun-90 8.1 1.1 23

13-Jun-91 8 1.7 18 14-Jun-91 8 1.7 22

5-May-92 6.8 0.8 30 1-May-92 6.5 1.3 22

Total Macroinvertebrates

Soquel Point Opal Cliffs

Date 

Mean sd # Date Mean sd #

1-Jun-73 5.2 1.1 22 4-Jun-73 13.2 3.3 21

25-Apr-74 2.8 0.8 19 26-Apr-74 11.5 4 25

27-Apr-75 5.8 2 30 29-Apr-75 9.6 2.3 23

15-May-76 7 1.3 15 16-May-76 9.8 2.1 24

4-Jul-77 9 1.6 17 3-Jul-77 13 4.6 21

23-May-78 7.8 1.8 19 25-May-78 7.6 1.7 16

11-Jun-79 3 1.2 29 13-Jun-79 7.7 3 29

15-May-80 5.2 1.7 30 17-May-80 7.8 2.3 37

3-Jun-81 5 3.7 20 4-Jun-81 5.8 2.3 15

22-Jun-82 5.8 1.8 34 0

12-Jun-83 3.8 1.3 28 13-Jun-83 5.7 2 28

15-Jun-84 7.8 1.6 26 16-Jun-84 5.8 2.3 30

4-Jun-85 5 2 30 5-Jun-85 7.5 2.4 33

23-Jun-86 6.2 2 19 24-Jun-86 7.8 2.3 20

13-Jun-87 6 2.3 23 14-Jun-87 7.5 2.6 15

4-Jun-88 5.5 1.1 31 5-Jun-88 6 1.8 26

23-Jun-90 5.8 2 22 24-Jun-90 6.2 2.2 23

13-Jun-91 5.4 2.2 18 14-Jun-91 5.8 2.1 22

5-May-92 4.2 1.8 30 1-May-92 4 2.1 22