Search results | Digital Commons of Moss Landing Marine Laboratories

Title: Detecting long-term change in-complex communities: A case study from the rocky intertidal zone,
Description: Despite the recognition of the usefulness of BACI designs for assessing environmental impacts, there are few examples because of the need for repetitive sampling over long time periods. Our examination of the application of a BACI design to detect the impacts of elevated seawater temperature from the Diablo Canyon Power Plant in central California on rocky intertidal communities showed statistically significant changes in a large percentage of the species analyzed. The statistical power of the analysis resulted from both the large numbers of surveys before and during plant operation and from other design features that made the study resilient to the effects of two "100-year" storms, several ENSO warming events, and the highly variable nature of the impacts. The large data set from the study required the development of decision rules for determining the appropriate surveys, stations, and species to analyze. BACI analyses were used to test the effects of the thermal plume on 47 algal and 50 invertebrate data sets. There were statistically significant effects for 79% of the algal and 60% of the invertebrate data sets. At the impact sites, there was a loss of cover by foliose algae and increases in crustose forms. Many invertebrates, particularly grazing gastropods, increased in abundance. Multivariate analysis of the community showed that there was continual change in impact sites that lasted throughout the study. The nature, magnitude, and spatial extent of the effects identified from the study are being used to determine appropriate plant modifications or mitigation for the effects of discharge. This study illustrates many of the problems in analyzing environmental effects and clearly demonstrates the need for long-term monitoring. This was especially true for this study, where storms and ENSO events affected our ability to analyze data from some of the stations, and points out the importance of having redundancies built into monitoring programs. The complex interactions among the direct effects of the discharge, indirect community-level effects, and variation due to oceanographic conditions provide useful insights for planning impact assessments and other ecological studies, and help contribute toward science-based regulation and management., Cited By (since 1996):9, CODEN: ECAPE, ,
Author: Steinbeck, Schiel, Foster
Date: 2005-01-01T00:00:00Z

Title: The structure of subtidal algal stands in temperate waters,
Description: , , ,
Author: Schiel, Foster
Date: 1986-01-01T00:00:00Z

Title: The population biology of large brown seaweeds: Ecological consequences of multiphase life histories in dynamic coastal environments,
Description: Seaweed population biology has received far less attention than trophic dynamics, yet is critically important in establishing and maintaining algal communities. Complex life histories of habitat-forming kelps and fucoids, including spores, gametophytes, gametes, and microscopic and macroscopic benthic stages, must be considered within the context of their highly dynamic nearshore environments. We evaluate differences within and between kelps and fucoids in life histories as they affect population biology; dispersal and potential limitations in population establishment; macroscopic stages and variations in survival and longevity affecting stand structure; and microscopic stage responses to disturbance and variation in the physical environment. We suggest that the commonly made comparisons of seaweeds with terrestrial seed plants are misleading because of large differences in morphology, environments, and the ephemeral nature of propagule banks in the sea. We conclude that progress in understanding algal populations depends on better knowledge of microscopic stages and on feedback through density-dependent reproductive processes, dispersal, and settlement. Copyright © 2006 by Annual Reviews. All rights reserved., http://www.annualreviews.org/doi/abs/10.1146/annurev.ecolsys.37.091305.110251, , , ,
Author: Schiel, Foster
Date: 2006-01-01T00:00:00Z

Title: Kelp communities and sea otters,
Description: Observations at sites in the NE Pacific have led to 2 generalizations: 1) kelp communities on nearshore, subtidal reefs exist in one of 2 stable states, forested with few large sea urchins or deforested with abundant large sea urchins, and 2) changes of state are controlled by a keystone predator, Enhydra lutris. Sea urchin grazing effects can be highly variable in the absence of sea otters; deforestation by sea urchins is the exception (<10% of the sites surveyed). Also, the communities do not exist in 2 states controlled by otters, but rather exhibit a dynamic range of composition where the above "states' are the uncommon extremes. The keystone species hypothesis is rejected as a geographic generality for the control of kelp community structure in California and perhaps elsewhere., Cited By (since 1996):31, ,
Author: Foster, Schiel
Date: 1988-01-01T00:00:00Z

Title: Loss of predators and the collapse of southern California kelp forests (?): Alternatives, explanations and generalizations,
Description: It is increasingly argued that human-induced alterations to food webs have resulted in the degradation of coastal ecosystems and even their "collapse." We examined the evidence for this argument for Macrocystis pyrifera (giant kelp) forests in southern California. Others have concluded that forests in this region collapsed between 1950 and 1970 as a result of sea urchin grazing driven by overfishing of sea urchin predators (sheephead wrasse and spiny lobsters) and competitors (abalone), and that the kelp forests recovered but are currently sustained as a result of a commercial sea urchin fishery that began in the early 1970s. Our examination of the historical record, primary publications, and previously unpublished data showed that there was no widespread decline in the region between 1950 and 1970, but there were localised declines in mainland kelp forests near the rapidly growing cities of Los Angeles and San Diego. The preponderance of evidence indicates that kelp losses were caused primarily by large increases in contaminated sewage discharged into coastal waters, sedimentation from coastal development, and the 1957-1959 El Niño. Increases in active sea urchin foraging were most likely a secondary effect following dwindling food resources. The forests recovered when sewage treatment improved and sewage outfalls were relocated. The effects of fisheries were explored by correlation analysis between kelp canopy cover and commercial sea urchin landings, and among fisheries landings for sea urchins, abalone, sheephead and lobster. These correlations were generally insignificant, but were often confounded by differences in the spatial scale over which the data were collected as well as factors other than simple abundance that affect the fisheries. However, where area-specific data were available, the landings of sea urchins generally tracked kelp abundance, most likely because roe (gonad) development is directly related to food availability. A literature review showed that although sheephead and lobsters may control sea urchin abundance at small spatial scales within some sites, there is little evidence they do so over large areas. That abalone and sea urchins compete, such that sea urchins increased as a result of abalone harvesting, is largely conjecture based on their similar habitat and food utilization. This study shows that kelp forests in southern California did not collapse, and that declines in some coastal sites were caused primarily by degradation of water quality, increased sedimentation and contamination, and unfavorable oceanographic conditions. We conclude that management by species' protection or reserves will not be effective if poor habitat quality impacts the ability of giant kelp to survive and thrive. © 2010 Elsevier B.V., Cited By (since 1996):20, Seaweeds, CODEN: JEMBA, ,
Author: Foster, Schiel
Date: 2010-01-01T00:00:00Z

Title: Ten years of-induced ocean warming causes comprehensive changes in marine benthic communities,
Description: One of the most commonly predicted effects of global ocean warming on marine communities is a poleward shift in the distributional boundaries of species with an associated replacement of cold-water species by warm-water species. However, these types of predictions are imprecise and based largely on broad correlations in uncontrolled studies that examine changes in the distribution or abundances of species in relation to seawater temperature. Our study used an 18-year sampling program in intertidal and subtidal habitats and before-after, control-impact analyses. We show that a 3.5°C rise in seawater temperature, induced by the thermal outfall of a power-generating station, over 10 years along 2 km of rocky coastline in California resulted in significant community-wide changes in 150 species of algae and invertebrates relative to adjacent control areas experiencing natural temperatures. Contrary to predictions based on current biogeographic models, there was no trend toward warmer-water species with southern geographic affinities replacing colder-water species with northern affinities. Instead, the communities were greatly altered in apparently cascading responses to changes in abundance of several key taxa, particularly habitat-forming subtidal kelps and intertidal foliose red algae. Many temperature-sensitive algae decreased greatly in abundance, whereas many invertebrate grazers increased. The responses of these benthic communities to ocean warming were mostly unpredicted and strongly coupled to direct effects of temperature on key taxa and indirect effects operating through ecological interactions., Cited By (since 1996):91, Seaweeds, CODEN: ECOLA, ,
Author: Schiel, Steinbeck, Foster
Date: 2004-01-01T00:00:00Z

Title: Top-down vs. bottom-up effects in kelp forests,
Description: Cited By (since 1996):6, Seaweeds, CODEN: SCIEA, , ,
Author: Foster, Edwards, Reed, Schiel, Zimmerman
Date: 2006-01-01T00:00:00Z

Title: The structure of subtidal algal and invertebrate assemblages at the Chatham Islands, New Zealand,
Description: , , , We examined the distribution and abundance of organisms on subtidal rocky reefs at nine sites around the Chatham Islands, a remote group 780 km east of southern New Zealand. We sampled five depth strata ranging from 1 to<16 m to identify spatial patterns in the abundance of algae and invertebrates and to assess their variation within and among sites. This information is used to discuss hypotheses concerning community structure at this remote locality. Several patterns were apparent. The immediate subtidal was occupied by the southern bull kelp Durvillaea spp. A suite of 11 fucalean species were dominant to a depth of 10 m with an average abundance of 28 m-2, while one species, Carpophyllum flexuosum, occurred mostly in deeper water. Only two laminarian species of algae were present at the islands. The indigenous Lessonia tholiformis was abundant at 2.5 to 15 m and was not found in deeper water, while the giant kelp Macrocystis pyrifera was abundant at two sites in 12 to 18 m. The commercially valuable abalone Haliotis iris was extremely abundant in shallow water, with an overall mean of 6 m-2 at 5 m. The sea urchin Evechinus chloroticus was common, but reached high densities only in small (<25 m2) patches. The characteristic urchin-dominated zones reported in kelp beds world-wide were not seen. There was considerable site-to-site variation in the occurrence and abundance of individual species. Some differences between sites were associated with shelter from swell (e.g. M. pyrifera was found only in sheltered sites) and physical habitat (e.g. juvenile H. iris were found only beneath boulders inshore), but much of the variation could not be explained by physical or depth-related factors alone. We hypothesize that the differences in these kelp bed assemblages compared to mainland New Zealand are partially due to the high degree of endemism at the Chatham Islands. Local variation cannot be explained by herbivory, and is most likely the result of the various life-history characteristics of the major habitat-forming species, the large brown algae., ,
Author: Schiel, Andrew, Foster
Date: 1995-01-01T00:00:00Z

Title: The ecology of kelp communities,
Description: , , ,
Author: Foster, Carter, Schiel, Bascom
Date: 1983-01-01T00:00:00Z

Title: The ecology of giant kelp forests in California: A community profile,
Description: Giant kelp forests are marine communities dominated by the large brown alga Macrocystis pyrifera. Stands of this species occur along the outer coast of the E Pacific from near Santa Cruz in central California to the central coast of Baja California, Mexico. Plants are usually attached to rocky substrata at depths of 5-20m. These submarine forests are probably the most species-rich, structural complex and productive communities in temperate waters., Cited By (since 1996):51, Seaweeds, ,
Author: Foster, Schiel
Date: 1985-01-01T00:00:00Z