2014 Intertidal Ecology Survey
Monterey Bay National Marine Sanctuary, Pacific Grove CA
Field Survey Report
James Landers, April 4, 2014 (Rev. November 26, 2014)
Abstract. Like the previous survey in this series, at the Cambria CA White Rock SMCA, a survey plot in the Monterey Bay National Marine Sanctuary at Pacific Grove CA also exhibits less diversity than might be expected of the rocky intertidal along the Pacific coast, however the middle and lower intertidal zones are less dominated by tar spot algae (Petrocelis), stunted Turkish towel (Mastocarpus papillatus) and black turban snails (Tegula funebralis). The circumstances at this location of barnacles, and Endocladia, raise questions about how settlement is accomplished in high, dry conditions, and on top of broad patches of Endocladia that deplete open space.
Introduction. This document is the second of several that will report the findings of a 2014 study of the ecology of intertidal invertebrate and marine plant communities between Point Conception and Point Arena on the central California coast. The primary objective of the study is to record detail of environmental conditions and catalogue invertebrate species at selected survey sites. Secondarily, further evaluation will be made of one species, the owl limpet Lottia gigantea, previously observed in 2001 at Fitzgerald Marine Reserve in Moss Beach CA. Finally, related topics of previous research on the intertidal ecology of the California coast will also be considered as opportunity permits.
The data underlying this report is in the accompanying MBNMS, Field Observation Data Sheet (see under Category “Field Data”). That document contains detail observations of conditions and specimens in each of the four intertidal zones, as well as photographs of the specimens cited here.
Survey Site. The site surveyed for this report is in the Monterey Bay National Marine Sanctuary, at Pacific Grove CA, latitude 36°38’07.28″ N, longitude 121°55’35.99″ W. The location is protected coast on south end of the Monterey Bay bight, on the east side of Point Pinos. The site is a sandy beach with low, rocky bluffs along the west side of Ocean View Blvd. On the east side of street are suburban residences and B&Bs. The shoreline is open to the public and is frequented by dog-walkers, joggers, and tourists.
The survey date was April 4, 2014. Early morning overcast and drizzle changed to light overcast toward midday. The wind generally was from the west (260°) at 5-10mph. The sea was calm and flat and the tide came throughout the morning “on little cat’s paws.” Water quality was clear. Three or four harbor seals hauled out on rocks 100 feet north of the site. The tides for this date were:
|8:06:00 AM||-0.1||2:55:00 PM||3.4|
Maximum tidal ranges for this year at this location are:
|Highest level||Lowest level|
The following environmental conditions at the start of the survey period, between 7:00am and 2:00pm, were recorded.
Air temperature: 59° Fahrenheit (15° centigrade).
Water temperature: 59° Fahrenheit (15° centigrade).
Temperature stratification: not taken.
Salinity: 38.5 ppt.
Specific gravity: 1.030.
Methods. Mapping of the site was confirmed by reference to California Geological Survey, and National Oceanic and Atmospheric Administration (NOAA), maps. On-site survey methods utilized four transects and fourteen quadrats to quantify organisms in the selected site, which encompassed an area of roughly 225 square meters of exposed rocky intertidal below sand beach, and 10 square meters of ten-foot high coarse-grained granitics cross-cut by dykes of finer-grained igneous material, surrounded on three sides by sand beach. In Zone 4, a less rigorous approach of visual observation and scaled estimation of species abundance was employed in an environment where specimens occurred in patches and clumps rather than evenly distributed over a level substrate [Murray, et. al., “Methods for Performing Monitoring….”].
Data for each Zone was recorded separately.
Zone 1. The splash zone here was divided into two levels because of an abrupt change in Zone 1 population between the lower three feet and upper seven feet. Higher up, common periwinkles (Littorina planaxis) were numerous, checkered periwinkle (Littorina scutulata) occasional, and rough limpets (Acmaea scabra) and barnacles rare.
Vertical rock surfaces of the lower area of the splash zone were covered profusely with tiny acorn barnacles (Balanus spp.), numerous rough limpets and fewer ribbed limpets (Lottia, or Acmaea, digitalis), and abundant Brillo Pad algae (Endocladia muricata).
Zone 2-3 #1. Animals and plants that elsewhere reside in distinct zones occur at this survey site in such close proximity that that they are discussed together. Two transects were completed in the areas combined for Zones 2-3; Transect A, of fifteen meters, is labeled Zone 2-3 #1.
The rocks in this transect are almost completely covered with Endocladia, turfweed, in which plentiful stunted Turkish towel (Mastocarpus papillatus) occurs, with occasional encrustations of tar spot algae (Petrocelis middendorffii), and some sea lettuce (Ulva). Acorn barnacles (Balanus spp.) were numerous on bare rock faces that were perhaps one-quarter of the available surface. An occasional turban snail (Tegula funebralis) or limpet (Lottia, or Acmaea) can be found underneath the Endocladia, however turfweed seems to have taken possession of most of the rock surface. In the few places free of it, turban snails predominate, mostly bunched together in crevices, and rarely with a small black limpet (Collisella asmi) attached to a turban shell. Other rare specimens were ribbed limpets, pink acorn barnacles (Tetraclita rubescens), an aggregating anemone (Anthopleura elegantissima), and a volcano limpet (Fissurella volcano).
Zone 2-3 #2. The second transect completed in the areas combined for Zones 2-3 is Transect C, about six meters in length, which is labeled Zone 2-3 #2 (a Transect B was started but finished as a single quadrat included in Transect C). In this transect, there were several bare patches of rock, and vertical rock faces about three feet high.
Brillo Pad algae covered half the surface of this transect, with frequent Turkish towel, occasional sea lettuce, green pincushion (Cladophora columbiana), dwarf rockweed (Pelvetiopsis limitata), and small patches of tar spot algae. Sections of bare rock had rare rough and ribbed limpets, and numerous Tegula in crevices. The vertical rock surfaces were covered with thick colonies of aggregating anemone, each individual about an inch in diameter.
A highlight of this survey was the remarkable instance of communal feeding activity by about fifteen Pagurus in turban snail shells (and one dog whelk shell) ranging in size from about 1 to 2.5cm, scrambling about together inside the upturned 5-inch wide carapace of what appeared to be a red rock crab, Cancer productus.
One giant green anemone, and a bat star, were also among the specimens in this transect, as well as one clump of a dirty white algae that could not be identified, but which had the leaf pattern of Coralline and might have been an example of bleached Coralline. Strangely, it was by itself high in the zone, nestled among Mastocarpus and Endocladia.
As with the first survey site in the White Rock reserve, mussels, sea stars other than a rare bat star, shore crabs, and sea urchins were conspicuous by their absence in Zone 2-3.
Zone 4. As seen in the White Rock survey (q.v. this website), large patches of surf grass (Phyllospadix) grew in the bottom of pools. Red algae (Corallina) grew in a skirt along the bottom of the rocks lining the pools. Black turban snails were occasional residents of crevices, colonies of aggregating anemones were common, and giant green anemones frequented the foot of rock walls.
Another remarkable specimen was a sea hare (Aplysia californica) about eight inches long by five inches wide, light greenish in color with dark purplish spots each a quarter inch in diameter, occurring roughly eight spots per square inch. When touched, the specimen ejected a small amount of dark purple ink that curled through the water.
Discussion. The small scale of observation for this survey is understood to be inadequate to support any substantial conclusions. Larger samples studied over time will always yield more useful data. Therefore, discussion here is intended more as a point of departure for further inquiry.
Species Diversity. As with the first survey site in Cambria CA, the plot surveyed in Pacific Grove was characterized by the absence of a number of animals that might otherwise be expected in the rocky intertidal of the Pacific coast: mussels, sea stars (other than a rare bat star), shore crabs, and sea urchins. Barnacles were abundant on bare rock faces in Zone 1, and Zone 2-3. An abundance of Endocladia covered much of the rock surface in the middle and lower intertidal, leaving little room for sessile attachment by other animals. Petrocelis, Macrocarpus and Tegula were not so evident as at White Rock.
Barnacles. The high density of non-motile barnacles in Zone 1 seems noteworthy. In this zone at this location, barnacles are not often submerged in water, so the sparse conditions of these dry rocks may have some influence on their consistently very small size. Bell (2010) found the size of Semibalanus balanoides is constrained by increased durations of aerial exposure. Also, it is difficult to imagine how settlement could be achieved where there is little water to transport spawned larvae.
However, barnacles are hermaphroditic and some species of barnacle have been proven to self-fertilize. Thomas Carefoot, at his website A Snail’s Odyssey, cites Barnes & Barnes (1958) saying that a strategy of self-fertilization “would be of survival value particularly to Chthamalus spp., where isolated individuals commonly occur high up the shore.” Both Chthamalus fissus and C. dalli on the west coast were confirmed to self-fertilize “for the former species in Santa Monica and Malibu Beach, California, and for the latter species in Coos Bay, Oregon, and Anacortes and San Juan Islands, Washington.”
Moreover, individuals separated from other barnacles by more than five centimeters “lag behind their contiguous conspecifics [members of the same species] in terms of stage of development, suggesting that they wait for cross-fertilization, and only self-fertilize as a last-ditch strategy.” Carefoot states that “it is not known whether this occurs in west-coast forms other than Chthamalus.”
This calls for closer attention to the splash zone barnacles photographed for this survey. Unfortunately, in this survey the barnacles were not examined closely enough to determine species (just assumed to be B. glandula). Pearlstein (2004) describes C. fissus as “smaller, [up to] 8 mm in diameter, and has a smooth, oval operculum, whereas B. glandula is larger and has deeply ridged plates on the operculum,” however my photographs do not have sufficient resolution to show an operculum clearly. Neither do the barnacles at this location have the dramatic variance in size shown in photographs of C. fissus together with B. glandula (see http://www.eeb.ucsc.edu/pacificrockyintertidal/target/target-species-chthamalus-balanus.html); those in this survey all appear the same size, about one to three millimeters.
Endocladia. The predominance of Endocladia muricata in the intertidal of the sites surveyed to date is unexpected for someone returning to the shoreline after thirty years away (the author’s earliest interest in the California intertidal dates from the early 1960s). There is little mention of Brillo Pad algae in early references such as Between Pacific Tides. So, we take special note of a dissertation by Hunt (2006), who states “Over the last 104 years, the climate has changed more or less gradually, with the most noteworthy change being a 24 cm increase in the sea level at HMS [Hopkins Marine Station, Pacific Grove CA]. The upper limit of Endocladia rose in conjunction with the rising sea level. However, most of Endocladia’s range increase happened during the 7 years between 1963 and 1970. Thus, the history of the range edge consists of three periods: the range was relatively stable between 1897 and 1963; then between 1963 and 1970, the range extended upward dramatically; and since 1970, the range has again remained constant.” This being the case, it is less surprising that the intertidal looks so much different today than it did in 1962.
The consequences for recruitment and settlement of intertidal animals on rock surfaces, and species diversity in general, would seem to be impacted by the quantity of Endocladia covering substrates. Thus far we have seen at our survey sites very few instances of other species together with Endocladia ̶ an occasional Tegula, limpet, or Ulva is all. Elsewhere, it is reported that the larvae of Mytilus often settle in Endocladia (O’Clair and Lindstrom, 2000), however no occurrence of Mytilus was found associated with Endocladia in this survey, nor was Petrocelis seen together with Endocladia. Browsing online literature does not locate any studies indicating that Endocladia can prevent settlement of sessile animals and, as in the previous reference, does find some suggestions that mussels sometimes prefer settlement in Endocladia. So, as the survey continues, we will watch more closely for other plants and animals residing together with Endocladia.
Zonation. The concept of zonation may deserve further consideration in light of how at this location so many species occurred in close proximity that there seemed little distinction between a Zone 2 and a Zone 3, neither from the standpoint of spacial differences, nor that of species distinctions. As early as 1949, T. A. and Anne Stevenson proposed three zones for the intertidal: the supralittoral zone, the midlittoral zone, and the sublittoral zone. Fringe areas above and below these three zones, the supralittoral fringe and the sublittoral fringe, covered infrequent exceptions. Other schemes have been proposed. It may be that because zonation varies between locations, more than one model may be needed, and applied according to circumstances.
Barnes, H. and Maraget, Further Observations on Self-Fertilization in Chthamalus Sp.,Ecology Vol. 39, No. 3 (Jul., 1958), p. 550.
Bell, Katie, Effects of aerial exposure on size of the common barnacle (Semibalanus balanoides), an inhabitant of the intertidal zone in St. Andrews, New Brunswick, Studies by Undergraduate Researchers at Guelph (SURG), Volume 3, Number 2, 2010,
Carefoot, Thomas H., A Snail’s Odyssey website, “Acorn Barnacle, Chthamalus spp., Research study 1,”
Carefoot, Thomas H., Pacific Seashores: A Guide to Intertidal Ecology, University of Washington Press, Seattle, 1977.
Friday Harbor Laboratories (FHL), University of Washington, “Endocladia muricata, The Brillo Pad Algae,”
Hunt, Luke John Hoot, The Rise Of Endocladia Muricata: Punctuated Change At An Abrupt Range Edge, PhD Dissertation, Stanford University, 2006.
Littler, M. M. and D. S. Littler, 1985, Nondestructive Sampling, Pages 161-175 in M. M. Littler, and D. S. Littler, editors. Handbook of Phycological Methods, Cambridge University Press, Cambridge, UK, http://littlersworks.net/reprints/Littler1985d.pdf
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Murray, S.N. 1997. Effectiveness of marine life refuges on southern California shores. California and the World Ocean 1997. 1453-1465.
Murray, Steven N.et. al., Methods for Performing Monitoring, Impact, and Ecological Studies on Rocky Shores, U.S. Department of the Interior, Minerals Management Service, Pacific OCS Region, Camarillo CA, and Southern California Educational Initiative, Marine Science Institute University of California, Santa Barbara, CA, March 2002,
O’Clair, Rita M. and Sandra C. Lindstrom. North Pacific Seaweeds, Alaska: Plant Press. 2000, referenced at https://depts.washington.edu/fhl/mb/Endocladia_Laura/ecology.html.
Pacific Rocky Intertidal Monitoring: Trends and Synthesis, “Chthamalus/Balanus (Acorn Barnacles),” University of California at Santa Cruz, Ecology and Evolutionary Biology website, http://www.eeb.ucsc.edu/pacificrockyintertidal/target/target-species-chthamalus-balanus.html
Perlstein, Susanna, Balanus glandula, Great Acorn Barnacle (2004), http://academic.evergreen.edu/curricular/invertebratezoology/webpage/balanus/balanus.htm
Ricketts, Edward F. and Jack Calvin, Between Pacific Tides, Stanford University Press, Stanford, CA, 1981.