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Bruce A. Menge - One of the best experts on this subject based on the ideXlab platform.
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regional processes are stronger determinants of rocky Intertidal Community dynamics than local biotic interactions
Ecology, 2019Co-Authors: Sally D Hacker, Bruce A. Menge, Karina J Nielsen, Francis Chan, Tarik C GouhierAbstract:Understanding the relative roles of species interactions and environmental factors in structuring communities has historically focused on local scales where manipulative experiments are possible. However, recent interest in predicting the effects of climate change and species invasions has spurred increasing attention to processes occurring at larger spatial and temporal scales. The “meta‐ecosystem” approach is an ideal framework for integrating processes operating at multiple scales as it explicitly considers the influence of local biotic interactions and regional flows of energy, materials, and organisms on Community structure. Using a comparative‐experimental design, we asked (1) what is the relative importance of local biotic interactions and oceanic processes in determining rocky Intertidal Community structure in the low zone within the Northern California Current System, and (2) what factors are most important in regulating this structure and why? We focused on functional group interactions between macrophytes and sessile invertebrates and their consumers (grazers, predators), how these varied across spatial scales, and with ocean‐driven conditions (upwelling, temperature) and ecological subsidies (nutrients, phytoplankton, sessile invertebrate recruits). Experiments were conducted at 13 sites divided across four capes in Oregon and northern California. Results showed that biotic interactions were variable in space and time but overall, sessile invertebrates had no effect on macrophytes while macrophytes had weakly negative effects on sessile invertebrates. Consumers, particularly predators, also had weakly negative effects on both functional groups. Overall, we found that 40–49% of the variance in Community structure at the local scale was explained by external factors (e.g., spatial scale, time, upwelling, temperature, ecological subsidies) vs. 19–39% explained by functional group interactions. When individual functional group interaction strengths were used, only 2–3% of the variation was explained by any one functional group while 28–54% of the variation was explained by external factors. We conclude that Community structure in the low Intertidal zone is driven primarily by external factors at the regional scale with local biotic interactions playing a secondary role.
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long term declines in an Intertidal foundation species parallel shifts in Community composition
Global Change Biology, 2017Co-Authors: Cascade J B Sorte, Jane Lubchenco, Victoria E Davidson, Marcus C Franklin, Kylla M Benes, Meredith M Doellman, Ron J Etter, Robyn Hannigan, Bruce A. MengeAbstract:The earth is in the midst of a biodiversity crisis, and projections indicate continuing and accelerating rates of global changes. Future alterations in communities and ecosystems may be precipitated by changes in the abundance of strongly interacting species, whose disappearance can lead to profound changes in abundance of other species, including an increase in extinction rate for some. Nearshore coastal communities are often dependent on the habitat and food resources provided by foundational plant (e.g., kelp) and animal (e.g., shellfish) species. We quantified changes in the abundance of the blue mussel (Mytilus edulis), a foundation species known to influence diversity and productivity of Intertidal habitats, over the past 40 years in the Gulf of Maine, USA, one of the fastest warming regions in the global ocean. Using consistent survey methods, we compared contemporary population sizes to historical data from sites spanning >400 km. The results of these comparisons showed that blue mussels have declined in the Gulf of Maine by >60% (range: 29–100%) at the site level since the earliest benchmarks in the 1970s. At the same time as mussels declined, Community composition shifted: at the four sites with historical Community data, the sessile Community became increasingly algal dominated. Contemporary (2013–2014) surveys across 20 sites showed that sessile species richness was positively correlated to mussel abundance in mid to high Intertidal zones. These results suggest that declines in a critical foundation species may have already impacted the Intertidal Community. To inform future conservation efforts, we provide a database of historical and contemporary baselines of mussel population abundance and dynamics in the Gulf of Maine. Our results underscore the importance of anticipating not only changes in diversity but also changes in the abundance and identity of component species, as strong interactors like foundation species have the potential to drive cascading Community shifts.
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supply side ecology barnacle recruitment and rocky Intertidal Community dynamics do settlement surface and limpet disturbance matter
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Bruce A. Menge, Melissa M. Foley, Jacque Pamplin, Gayle Murphy, Camryn PenningtonAbstract:Abstract The supply of new recruits can be a critical determinant of Community structure, but estimating recruitment density can be challenging due to variation in larval supply, settlement, substratum, species interactions and physical stresses. We evaluated the effect of surface type and limpet “bulldozing” on settlement and recruitment of barnacles, using replicated field experiments sampled monthly at each of four sites along the central Oregon coast in 2001, 2003, and 2008. A particular goal was to evaluate the efficacy of Saf-T-Walk, a widely used textured surface, in quantifying actual patterns and levels of recruitment. In 2001 and 2003 experiments, surfaces were bare rock (ROCK) and Saf-T-Walk (STW). In 2008 experiments, to further evaluate the influence of surface rugosity, we added two additional artificial substratum types — smooth PVC plates (no texture) and travertine plates (TRAV, low texture). Limpet activity was manipulated using barriers of anti-fouling paint. Results indicated the overwhelming importance of surface texture. Recruitment density was highest in 2001, lower in 2003, and lowest in 2008. Recruitment on STW, the most textured surface, ranged up to 87 times greater than on ROCK, and the rank order of surfaces for recruitment density was STW > ROCK > TRAV > PVC which matches that for texture. Settlement differences were even greater, with up to 1180-fold higher settlement on STW than ROCK. Limpets usually had a negative effect on recruitment of Balanus glandula on ROCK, likely due to bulldozing and direct consumption, but had a positive effect on STW. These impacts were reduced or negated when recruitment density was higher (e.g., 2001) or lower than average (e.g., 2008). Limpets had no consistent effect on Chthamalus dalli. Abundances of settlers and recruits on the different surfaces were positively correlated (explaining up to 71% of the variance), and correlations between STW and other surfaces generally were stronger in the absence of limpets. Although compared to bare rock, recruitment to STW overestimates absolute rates of recruitment, use of STW settlement plates provides an effective and relatively efficient means of determining spatial and temporal patterns of recruitment at local to geographic scales.
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Supply-side ecology, barnacle recruitment, and rocky Intertidal Community dynamics: Do settlement surface and limpet disturbance matter?
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Bruce A. Menge, Melissa M. Foley, Jacque Pamplin, Gayle Murphy, Camryn PenningtonAbstract:The supply of new recruits can be a critical determinant of Community structure, but estimating recruitment density can be challenging due to variation in larval supply, settlement, substratum, species interactions and physical stresses. We evaluated the effect of surface type and limpet "bulldozing" on settlement and recruitment of barnacles, using replicated field experiments sampled monthly at each of four sites along the central Oregon coast in 2001, 2003, and 2008. A particular goal was to evaluate the efficacy of Saf-T-Walk, a widely used textured surface, in quantifying actual patterns and levels of recruitment. In 2001 and 2003 experiments, surfaces were bare rock (ROCK) and Saf-T-Walk (STW). In 2008 experiments, to further evaluate the influence of surface rugosity, we added two additional artificial substratum types - smooth PVC plates (no texture) and travertine plates (TRAV, low texture). Limpet activity was manipulated using barriers of anti-fouling paint. Results indicated the overwhelming importance of surface texture. Recruitment density was highest in 2001, lower in 2003, and lowest in 2008. Recruitment on STW, the most textured surface, ranged up to 87 times greater than on ROCK, and the rank order of surfaces for recruitment density was STW > ROCK > TRAV > PVC which matches that for texture. Settlement differences were even greater, with up to 1180-fold higher settlement on STW than ROCK. Limpets usually had a negative effect on recruitment of Balanus glandula on ROCK, likely due to bulldozing and direct consumption, but had a positive effect on STW. These impacts were reduced or negated when recruitment density was higher (e.g., 2001) or lower than average (e.g., 2008). Limpets had no consistent effect on Chthamalus dalli. Abundances of settlers and recruits on the different surfaces were positively correlated (explaining up to 71% of the variance), and correlations between STW and other surfaces generally were stronger in the absence of limpets. Although compared to bare rock, recruitment to STW overestimates absolute rates of recruitment, use of STW settlement plates provides an effective and relatively efficient means of determining spatial and temporal patterns of recruitment at local to geographic scales. ?? 2010 Elsevier B.V.
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effects of consumers and enrichment on abundance and diversity of benthic algae in a rocky Intertidal Community
Journal of Experimental Marine Biology and Ecology, 2009Co-Authors: Anne D Guerry, Bruce A. Menge, Robyn A DunmoreAbstract:Human alteration of nutrient cycling and the densities of important consumers have intensified the importance of understanding how nutrients and consumers influence the structure of ecological systems. We examined the effects of both grazing and nutrient enrichment on algal abundance and diversity in a high-Intertidal limpet-macroalgal Community on the South Island of New Zealand, a relatively nutrient-poor environment. We used a fully factorial design with three levels each of grazing (manipulations of limpet and snail densities) and nutrients (nutrient-diffusers attached to the rock). Top-down control by grazers appears to be the driving organizing mechanism for algal communities in this system, with strong negative effects of grazing on algal diversity and abundance across all levels of nutrient enrichment. However, in contrast to the conclusions drawn from the analysis of the whole algal Community, there was an interactive effect of grazing and enrichment on foliose algae, an important component of the algal system. When herbivory was reduced to very low levels, enrichment generated increases in the abundance and biomass of foliose algae. As expected, top-down control was the primary determinant of algal Community structure in this system, controlling abundance and diversity of macrophytes on the upper shore. Contrary to expectations, however, increased nutrients had no Community-wide effects, although foliose algal abundance increases were greatest with high nutrients and reduced grazing. It seems likely that most of the corticated algal species have limited capacity to respond to nutrient pulses in this nutrient-poor environment.
10. Anderson Dj. Transiting The Intertropical Convergence Zone.; 2007:8. - One of the best experts on this subject based on the ideXlab platform.
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Introduced rats indirectly change marine rocky Intertidal communities from algae- to invertebrate-dominated.
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Gerould S. Estimates Of Soil Ingestion By Wildlife. Journal Of Wildlife Managment. 1994;58(2):375-38 1. Beyer Wn, Connor Ee, 2011]. 3. Mathot Kj, Lund Dr, Elner Rw. Sediment In Stoma, Georgia Compilers : 1994;(january). 4. Schroeder Ba, Witherington Be. Noaa Technical M, 5. Protect Pp. National Invasive Species Management Plan Prevent. Management. 2012;(august 2008):200 2012., Et Al. High-impact Conservation: Invasive Mammal Eradications From The Islands Of Western México. Am 6. Aguirre-muñoz A, Croll D A, Donlan Cj, Kew Stable Url : Http://www.jstor.org/stable/4117674. Distribution. 2010;7(1):87-97. 7. Gardens Rb. On The Distribution Of Pisonia Gran, Portugal. 2010:16-20. 8. Amaral J, Almeida S, Sequeira M, Et Al. Black R, New Zealand. October. 1994;(october 1993):429-439. 9. Lee Wg. Regeneration In Indigenous Forest After, 2. Reeder Wg. Stomach Analysis Of A Group Of Shorebirds. The Condor. 1951, 10. Anderson Dj. Transiting The Intertropical Convergence Zone.; 2007:8.Abstract:It is widely recognized that trophic interactions structure ecological communities, but their effects are usually only demonstrated on a small scale. As a result, landscape-level documentations of trophic cascades that alter entire communities are scarce. Islands invaded by animals provide natural experiment opportunities both to measure general trophic effects across large spatial scales and to determine the trophic roles of invasive species within native ecosystems. Studies addressing the trophic interactions of invasive species most often focus on their direct effects. To investigate both the presence of a landscape-level trophic cascade and the direct and indirect effects of an invasive species, we examined the impacts of Norway rats (Rattus norvegicus) introduced to the Aleutian Islands on marine bird densities and marine rocky Intertidal Community structures through surveys conducted on invaded and rat-free islands throughout the entire 1,900-km archipelago. Densities of birds that forage in the Intertidal were higher on islands without rats. Marine Intertidal invertebrates were more abundant on islands with rats, whereas fleshy algal cover was reduced. Our results demonstrate that invasive rats directly reduce bird densities through predation and significantly affect invertebrate and marine algal abundance in the rocky Intertidal indirectly via a cross-Community trophic cascade, unexpectedly changing the Intertidal Community structure from an algae- to an invertebrate-dominated system.
Gerould S. Estimates Of Soil Ingestion By Wildlife. Journal Of Wildlife Managment. 1994;58(2):375-38 1. Beyer Wn, Connor Ee - One of the best experts on this subject based on the ideXlab platform.
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Introduced rats indirectly change marine rocky Intertidal communities from algae- to invertebrate-dominated.
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Gerould S. Estimates Of Soil Ingestion By Wildlife. Journal Of Wildlife Managment. 1994;58(2):375-38 1. Beyer Wn, Connor Ee, 2011]. 3. Mathot Kj, Lund Dr, Elner Rw. Sediment In Stoma, Georgia Compilers : 1994;(january). 4. Schroeder Ba, Witherington Be. Noaa Technical M, 5. Protect Pp. National Invasive Species Management Plan Prevent. Management. 2012;(august 2008):200 2012., Et Al. High-impact Conservation: Invasive Mammal Eradications From The Islands Of Western México. Am 6. Aguirre-muñoz A, Croll D A, Donlan Cj, Kew Stable Url : Http://www.jstor.org/stable/4117674. Distribution. 2010;7(1):87-97. 7. Gardens Rb. On The Distribution Of Pisonia Gran, Portugal. 2010:16-20. 8. Amaral J, Almeida S, Sequeira M, Et Al. Black R, New Zealand. October. 1994;(october 1993):429-439. 9. Lee Wg. Regeneration In Indigenous Forest After, 2. Reeder Wg. Stomach Analysis Of A Group Of Shorebirds. The Condor. 1951, 10. Anderson Dj. Transiting The Intertropical Convergence Zone.; 2007:8.Abstract:It is widely recognized that trophic interactions structure ecological communities, but their effects are usually only demonstrated on a small scale. As a result, landscape-level documentations of trophic cascades that alter entire communities are scarce. Islands invaded by animals provide natural experiment opportunities both to measure general trophic effects across large spatial scales and to determine the trophic roles of invasive species within native ecosystems. Studies addressing the trophic interactions of invasive species most often focus on their direct effects. To investigate both the presence of a landscape-level trophic cascade and the direct and indirect effects of an invasive species, we examined the impacts of Norway rats (Rattus norvegicus) introduced to the Aleutian Islands on marine bird densities and marine rocky Intertidal Community structures through surveys conducted on invaded and rat-free islands throughout the entire 1,900-km archipelago. Densities of birds that forage in the Intertidal were higher on islands without rats. Marine Intertidal invertebrates were more abundant on islands with rats, whereas fleshy algal cover was reduced. Our results demonstrate that invasive rats directly reduce bird densities through predation and significantly affect invertebrate and marine algal abundance in the rocky Intertidal indirectly via a cross-Community trophic cascade, unexpectedly changing the Intertidal Community structure from an algae- to an invertebrate-dominated system.
Christopher D G Harley - One of the best experts on this subject based on the ideXlab platform.
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Intertidal Community responses to field based experimental warming
Oikos, 2015Co-Authors: Steve Dudgeon, Rebecca L Kordas, Stefan Storey, Christopher D G HarleyAbstract:As the climate warms, there is little doubt that ecosystems of the future will look diff erent from those we see today. However, Community responses to warming in the fi eld are poorly understood. We examined the eff ects of fi eld-based warming on Intertidal communities in the Salish Sea, which is a regional thermal ‘ hot spot ’ and therefore a model system for studying thermally stressed communities. We manipulated temperature at three tidal heights by deploying black- and white-bordered settlement plates. Black plates increased in situ substratum temperature by an average of 2.6 ° C (maximum temperature, 40.9 ° C). Barnacles fared poorly on black plates in all zones. When overall thermal stress was highest (summer in the high Intertidal zone) herbivores were absent. In lower tidal zones, herbivores were abundant on white plates but were scarce on black plates. Th e total percent cover of algae was unaff ected by the temperature treatment, despite the fact that macroalgae were expected to be the least thermally tolerant functional group. However, we did fi nd that ephemeral green algae exhibited a delay in phenology on black plates. We also found that species richness declined and invertebrate assemblage structure was altered due to warming. Results from this year long experiment suggest that communities in thermally stressful habitats respond to warming via the interplay between species-specifi c thermal responses and secondary adaptive strategies such as behavioral microhabitat selection. Declines in diversity and changes in the invertebrate assemblage were due to the decline of local thermally-stressed species and the lack of replacement by warm-adapted species. Given the low variation in the species pool along the northeast Pacifi c coastline, the arrival of warm-adapted species to the Salish Sea may not occur over relevant time scales, leaving local communities depauperate.
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the effects of temperature on producers consumers and plant herbivore interactions in an Intertidal Community
Journal of Experimental Marine Biology and Ecology, 2006Co-Authors: Bionda Morelissen, Christopher D G HarleyAbstract:Abstract Although global warming is acknowledged as a primary threat to populations and communities, the impact of rising temperature on Community structure remains poorly understood. In this study, we investigated the direct and indirect effects of temperature on epilithic primary producers (micro- and macroalgae) and an abundant consumer, the rough limpet Lottia scabra , in the rocky Intertidal zone in central and northern California, USA. We factorially manipulated temperature and limpet abundance in the field to determine the effects of temperature on herbivore growth and mortality, algal abundance, and the strength of plant–herbivore interactions. Microalgal growth was positively affected by shading at both locations, and negatively affected by limpet grazing at Pacific Grove but not at Bodega Bay. Macroalgae were only abundant at Bodega Bay, where changes in abundance were negatively related to grazing and independent of temperature. Despite temperature-related changes in microalgal food supply, there were no direct or indirect effects of temperature manipulation on L. scabra growth or mortality. Furthermore, temperature did not alter the importance of herbivory at either site. These results indicate that the influence of increasing temperature, as is predicted with climate change, will have differential effects on producers and consumers. However, thermal effects at one trophic level do not necessarily propagate through the food web to other trophic levels.
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effects of physical ecosystem engineering and herbivory on Intertidal Community structure
Marine Ecology Progress Series, 2006Co-Authors: Christopher D G HarleyAbstract:Physical ecosystem engineers play dominant roles in a wide variety of communities. While many of the direct, positive effects of ecosystem engineers are readily apparent, the roles of engineers are often mediated by indirect interactions stemming from the facilitation of one or a few key species. Although direct and indirect effects are both critical drivers of Community dynamics, they are rarely considered together with regards to ecosystem engineering. In the present study barnacle and herbivorous gastropod densities are experimentally manipulated to investigate the direct positive effects of habitat provision by barnacles as well as indirect effects mediated by mollus- can grazers. Molluscan grazers (Littorina spp.) and herbivorous arthropods were positively influ- enced by the presence of barnacles. Arthropod abundance and species richness were lower when Littorina spp. were present. This pattern was not influenced by barnacle cover, suggesting that competition among herbivore functional groups was strong but independent of biogenic habitat complexity. In addition, Littorina spp. had strong negative effects on the filamentous alga Urospora penicilliformis, but this effect was only seen in the absence of barnacles. Finally, Littorina spp. reduced the recruitment of the principal habitat-forming barnacle Balanus glandula, suggesting that Littorina spp. may mediate a negative feedback loop in B. glandula population dynamics. Given the ubiquity of ecosystem engineers, similar combinations of direct and indirect influences may have far-reaching consequences for Community dynamics and species richness in a wide range of systems.
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light availability indirectly limits herbivore growth and abundance in a high rocky Intertidal Community during the winter
Limnology and Oceanography, 2002Co-Authors: Christopher D G HarleyAbstract:Light availability and consumer pressure are fundamental factors that structure aquatic communities, but their integrated effects are rarely studied in marine benthic systems. Using a factorial experiment, I investigated the effects of light availability and grazing by limpets (Lottia digitalis) to determine the relative influence of each on the growth and abundance of producers and consumers in a rocky Intertidal Community during the winter. Light reduction via shading reduced the abundance of filamentous algae and reduced the abundance of the herbivorous periwinkle Littorina sitkana. The effects of limpet grazing reduced the abundance of filamentous algae, Porphyra spp., and diatom mats. Higher limpet densities were also associated with significantly lower densities of adult, but not juvenile, Littorina spp. Light and limpet density interacted to determine Lottia growth, which was high in unshaded, single-limpet enclosures but was negligible in plots with two limpets, shades, or both. Variation in bottom-up (resource-driven) and top-down (consumer-driven) forces are important determinants of abundance at both trophic levels, but the effects are complex, taxon-specific, and, for littorine snails, size-specific. Because the study species accomplish most of their growth and reproduction during the winter, the interplay of light and herbivory during this season will likely influence long-term Community dynamics.
C H Baxter - One of the best experts on this subject based on the ideXlab platform.
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CLIMATE‐RELATED CHANGE IN AN Intertidal Community OVER SHORT AND LONG TIME SCALES
Ecological Monographs, 1999Co-Authors: Raphael D Sagarin, James P Barry, Sarah E Gilman, C H BaxterAbstract:Changes in the abundance of macroinvertebrate species documented in a rocky Intertidal Community between surveys in 1931-1933 and 1993-1996 are consistent with the predicted effects of recent climate warming. We resampled 57 0.84-M2 plots of an Intertidal transect first surveyed by W. G. Hewatt at Hopkins Marine Station (HMS), Pacific Grove, California, between 1931 and 1933. Replicating precisely the location of the plots and methodology used by Hewatt, we documented changes in the abundances of 46 invertebrate species, indicating that this Intertidal Community changed significantly during the 60 yr between surveys. Changes in abundance were related to geographic ranges of species. Most southern species (10 of 11) increased in abundance, whereas most northern species (5 of 7) decreased. Cosmopolitan species showed no clear trend, with 12 increasing and 16 decreasing. Although Hewatt did not record algal species as thoroughly as inver- tebrates, we were able to document a massive decline in cover of Pelvetia compressa, a cosmopolitan fucoid alga that is typically more common in the southern part of its range. Shoreline ocean temperature, taken daily at HMS, warmed by 0.790C during this 60-yr period, with average summer temperatures up to 1.940C warmer in the 13 yr preceding our study than in the 13 yr preceding Hewatt's. The hypothesis that-climatic warming drove the observed range-related Community shifts is supported further by historical records and data from other investigators. Several alternative hypotheses to explain changes in the invertebrate Community at HMS, including habitat changes, anthropogenic effects, indirect biological interactions, El Nifio-Southern Oscillation (ENSO) events, and upwelling are considered to be less important than climate change. Changes in species' abundances over a short period (3 yr) were relatively small compared to large species shifts over 60 yr and were unrelated to geographic range of the species, indicating that short-term population fluctuations play a relatively minor role in the long-term Community changes that we observed.
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climate related change in an Intertidal Community over short and long time scales
Ecological Monographs, 1999Co-Authors: Raphael D Sagarin, James P Barry, Sarah E Gilman, C H BaxterAbstract:Changes in the abundance of macroinvertebrate species documented in a rocky Intertidal Community between surveys in 1931-1933 and 1993-1996 are consistent with the predicted effects of recent climate warming. We resampled 57 0.84-M2 plots of an Intertidal transect first surveyed by W. G. Hewatt at Hopkins Marine Station (HMS), Pacific Grove, California, between 1931 and 1933. Replicating precisely the location of the plots and methodology used by Hewatt, we documented changes in the abundances of 46 invertebrate species, indicating that this Intertidal Community changed significantly during the 60 yr between surveys. Changes in abundance were related to geographic ranges of species. Most southern species (10 of 11) increased in abundance, whereas most northern species (5 of 7) decreased. Cosmopolitan species showed no clear trend, with 12 increasing and 16 decreasing. Although Hewatt did not record algal species as thoroughly as inver- tebrates, we were able to document a massive decline in cover of Pelvetia compressa, a cosmopolitan fucoid alga that is typically more common in the southern part of its range. Shoreline ocean temperature, taken daily at HMS, warmed by 0.790C during this 60-yr period, with average summer temperatures up to 1.940C warmer in the 13 yr preceding our study than in the 13 yr preceding Hewatt's. The hypothesis that-climatic warming drove the observed range-related Community shifts is supported further by historical records and data from other investigators. Several alternative hypotheses to explain changes in the invertebrate Community at HMS, including habitat changes, anthropogenic effects, indirect biological interactions, El Nifio-Southern Oscillation (ENSO) events, and upwelling are considered to be less important than climate change. Changes in species' abundances over a short period (3 yr) were relatively small compared to large species shifts over 60 yr and were unrelated to geographic range of the species, indicating that short-term population fluctuations play a relatively minor role in the long-term Community changes that we observed.
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climate related long term faunal changes in a california rocky Intertidal Community
Science, 1995Co-Authors: James P Barry, C H Baxter, Raphael D Sagarin, Sarah E GilmanAbstract:Changes in the invertebrate fauna of a California rocky Intertidal Community between the period 1931 to 1933 and the period 1993 to 1994 indicate that species9 ranges shifted northward, consistent with predictions of change associated with climate warming. Of 45 invertebrate species, the abundances of eight of nine southern species increased and the abundances of five of eight northern species decreased. No trend was evident for cosmopolitan species. Annual mean shoreline ocean temperatures at the site increased by 0.75°C during the past 60 years, and mean summer maximum temperatures from 1983 to 1993 were 2.2°C warmer than for the period 1921 to 1931.
