Predicting the outcome of future climate change requires an understanding of how alterations in multiple environmental factors manifest in natural communities and affect ecosystem functioning. We ...conducted an in situ, fully factorial field manipulation of CO.sub.2 and temperature on a rocky shoreline in southeastern Alaska, USA. Warming strongly impacted functioning of tide pool systems within one month, with the rate of net community production (NCP) more than doubling in warmed pools under ambient CO.sub.2 levels relative to initial NCP values. However, in pools with added CO.sub.2, NCP was unaffected by warming. Productivity responses paralleled changes in the carbon-to-nitrogen ratio of a red alga, the most abundant primary producer species in the system, highlighting the direct link between physiology and ecosystem functioning. These observed changes in algal physiology and community productivity in response to our manipulations indicate the potential for natural systems to shift rapidly in response to changing climatic conditions and for multiple environmental factors to act antagonistically.
Accelerating rates of climate change and a paucity of whole-community studies of climate impacts limit our ability to forecast shifts in ecosystem structure and dynamics, particularly because climate ...change can lead to idiosyncratic responses via both demographic effects and altered species interactions. We used a multispecies model to predict which processes and species' responses are likely to drive shifts in the composition of a space-limited benthic marine community. Our model was parametrized from experimental manipulations of the community. Model simulations indicated shifts in species dominance patterns as temperatures increase, with projected shifts in composition primarily owing to the temperature dependence of growth, mortality and competition for three critical species. By contrast, warming impacts on two other species (rendering them weaker competitors for space) and recruitment rates of all species were of lesser importance in determining projected community changes. Our analysis reveals the importance of temperature-dependent competitive interactions for predicting effects of changing climate on such communities. Furthermore, by identifying processes and species that could disproportionately leverage shifts in community composition, our results contribute to a mechanistic understanding of climate change impacts, thereby allowing more insightful predictions of future biodiversity patterns.
Predicting the impacts of ocean acidification in coastal habitats is complicated by bio-physical feedbacks between organisms and carbonate chemistry. Daily changes in pH and other carbonate ...parameters in coastal ecosystems, associated with processes such as photosynthesis and respiration, often greatly exceed global mean predicted changes over the next century. We assessed the strength of these feedbacks under projected elevated CO
levels by conducting a field experiment in 10 macrophyte-dominated tide pools on the coast of California, USA. We evaluated changes in carbonate parameters over time and found that under ambient conditions, daytime changes in pH,
CO
, net ecosystem calcification (
), and O
concentrations were strongly related to rates of net community production (
). CO
was added to pools during daytime low tides, which should have reduced pH and enhanced
CO
. However, photosynthesis rapidly reduced
CO
and increased pH, so effects of CO
addition were not apparent unless we accounted for seaweed and surfgrass abundances. In the absence of macrophytes, CO
addition caused pH to decline by ∼0.6 units and
CO
to increase by ∼487 µatm over 6 hr during the daytime low tide. As macrophyte abundances increased, the impacts of CO
addition declined because more CO
was absorbed due to photosynthesis. Effects of CO
addition were, therefore, modified by feedbacks between
, pH,
CO
, and
. Our results underscore the potential importance of coastal macrophytes in ameliorating impacts of ocean acidification.
Species with broader geographical ranges are expected to be ecological generalists, while species with higher heat tolerances may be relatively competitive at more extreme and increasing ...temperatures. Thus, both traits are expected to relate to increased survival during transport to new regions of the globe, and once there, establishment and spread. Here, we explore these expectations using datasets of latitudinal range breadth and heat tolerance in freshwater and marine invertebrates and fishes. After accounting for the latitude and hemisphere of each species’ native range, we find that species introduced to freshwater systems have broader geographical ranges in comparison to native species. Moreover, introduced species are more heat tolerant than related native species collected from the same habitats. We further test for differences in range breadth and heat tolerance in relation to invasion success by comparing species that have established geographically restricted versus extensive introduced distributions. We find that geographical range size is positively related to invasion success in freshwater species only. However, heat tolerance is implicated as a trait correlated to widespread occurrence of introduced populations in both freshwater and marine systems. Our results emphasize the importance of formal risk assessments before moving heat tolerant species to novel locations.
Predicting the outcome of future climate change requires an understanding of how alterations in multiple environmental factors manifest in natural communities and affect ecosystem functioning. We ...conducted an in situ, fully factorial field manipulation of CO2 and temperature on a rocky shoreline in southeastern Alaska, USA. Warming strongly impacted functioning of tide pool systems within one month, with the rate of net community production (NCP) more than doubling in warmed pools under ambient CO2 levels relative to initial NCP values. However, in pools with added CO2, NCP was unaffected by warming. Productivity responses paralleled changes in the carbon-to-nitrogen ratio of a red alga, the most abundant primary producer species in the system, highlighting the direct link between physiology and ecosystem functioning. These observed changes in algal physiology and community productivity in response to our manipulations indicate the potential for natural systems to shift rapidly in response to changing climatic conditions and for multiple environmental factors to act antagonistically.
REVIEWS AND SYNTHESES Harley, Christopher D G; Hughes, A Randall; Hultgren, Kristin M ...
Ecology letters,
02/2006, Letnik:
9, Številka:
2
Journal Article
Recenzirano
Anthropogenically induced global climate change has profound implications for marine ecosystems and the economic and social systems that depend upon them. The relationship between temperature and ...individual performance is reasonably well understood, and much climate-related research has focused on potential shifts in distribution and abundance driven directly by temperature. However, recent work has revealed that both abiotic changes and biological responses in the ocean will be substantially more complex. For example, changes in ocean chemistry may be more important than changes in temperature for the performance and survival of many organisms. Ocean circulation, which drives larval transport, will also change, with important consequences for population dynamics. Furthermore, climatic impacts on one or a few 'leverage species' may result in sweeping community-level changes. Finally, synergistic effects between climate and other anthropogenic variables, particularly fishing pressure, will likely exacerbate climate-induced changes. Efforts to manage and conserve living marine systems in the face of climate change will require improvements to the existing predictive framework. Key directions for future research include identifying key demographic transitions that influence population dynamics, predicting changes in the community-level impacts of ecologically dominant species, incorporating populations' ability to evolve (adapt), and understanding the scales over which climate will change and living systems will respond.PUBLICATION ABSTRACT
As the climate warms, species that cannot tolerate changing conditions will only persist if they undergo range shifts. Redistribution ability may be particularly variable for benthic marine species ...that disperse as pelagic larvae in ocean currents. The blue mussel, Mytilus edulis, has recently experienced a warming-related range contraction in the southeastern USA and may face limitations to northward range shifts within the Gulf of Maine where dominant coastal currents flow southward. Thus, blue mussels might be especially vulnerable to warming, and understanding dispersal patterns is crucial given the species' relatively long planktonic larval period (>1 month). To determine whether trace elemental "fingerprints" incorporated in mussel shells could be used to identify population sources (i.e. collection locations), we assessed the geographic variation in shell chemistry of blue mussels collected from seven populations between Cape Cod, Massachusetts and northern Maine. Across this 500 km of coastline, we were able to successfully predict population sources for over two-thirds of juvenile individuals, with almost 80% of juveniles classified within one site of their collection location and 97% correctly classified to region. These results indicate that significant differences in elemental signatures of mussel shells exist between open-coast sites separated by 50 km throughout the Gulf of Maine. Our findings suggest that elemental "fingerprinting" is a promising approach for predicting redistribution potential of the blue mussel, an ecologically and economically important species in the region.
An important step in connecting the organismal response to thermal stress to patterns of community structure is determining at what scale discernable levels of variation are manifested. The ...temperature signal to which organisms may potentially respond varies at many spatial scales including microhabitat, tidal height, site and latitude. A number of studies have taken physiological assessment of the heat shock response (HSR) into the intertidal both as a tool for examining the HSR in nature and for examining the utility of HSR molecules as population or community level indicators. Most commonly, immunodetection of the total pool of the Hsp70 family of isoforms is used. Here we present data on levels of Hsp70 in intertidal organisms from microhabitat to the mesoscale. Our data and previously published work show that Hsp70 levels vary at all scales examined, similar to other physical and biological variables of interest. This demonstrates both the potential utility of Hsp70 detection as a molecular tool for field biologists and to the care that must be taken in assessing scale of variation when looking for potential bioindicator molecules.
Filter-feeding invertebrates consume phytoplankton and detritus and therefore serve as important mediators of the exchange of materials from nearshore pelagic to intertidal benthic ecosystems. Here, ...we evaluated the linkages between nearshore and intertidal systems on temperate rocky reefs on the coasts of Oregon, USA, and New Zealand’s South Island. We used differences in the concentrations of both nearshore particulate organic carbon and chlorophyll a (chl a), a proxy for phytoplankton availability, at different sites in Oregon and New Zealand to evaluate the influences of suspended particulate organic material (POM) quality and quantity on the rates of carbon inputs associated with intertidal mussels (Mytilus californianus in Oregon and Mytilus galloprovincialis in New Zealand). We also analyzed the carbon stable isotope ratios (δ¹³C) of intertidal mussels and nearshore POM to examine changes in mussel growth in carbon relative to changes in their potential food sources along gradients of POM quality (i.e. carbon-to-chlorophyll ratios, C:chl a). In both Oregon and New Zealand, the δ¹³C in mussel tissues did not change along a gradient of food quality, whereas the δ¹³C of the POM declined as food quality declined (i.e. C:chl a increased), suggesting that mussels were selectively consuming high-quality food. We also found that the availability of phytoplankton, a high-quality component of the POM, was a better predictor of mussel growth in carbon (mg C g⁻¹ d⁻¹) than the total concentration of particulate organic carbon, which includes both higher-quality phytoplankton and lower-quality detrital material. Our results highlight the necessity of considering POM quality while evaluating the role of filter-feeders as mediators of carbon inputs into intertidal systems.
This is the publisher’s final pdf. The published article is copyrighted by Inter-Research and can be found at: http://www.int-res.com/journals/meps/meps-home/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.
Fundingwas provided by the National Science Foundation (grantsOCE-0351778 to J. Stachowicz and OCE-0549944 to S. Williams and M.E.S.B.), Bodega Marine Laboratory institutionalfunds (to M.E.S.B.), the Andrew W. Mellon Foundation(to J.L., B.A.M., and D.R.S.), the Partnership for InterdisciplinaryStudies of Coastal Oceans (PISCO; to J.L. andB.A.M.), and the New Zealand Foundation for Research, Scienceand Technology (to D.R.S.). This is contribution number417 from PISCO, a long-term, large-scale ecologicalconsortium funded by the David and Lucile Packard and theGordon and Betty Moore Foundations, contribution number283 from the Marine Science Center, Northeastern University,and a contribution from the Bodega Marine Laboratory,University of California, Davis.
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