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Effects of Bottom-up and Top-down Controls and Climate Change on Estuarine Macrophyte Communities and the Ecosystem Services they Provide
Citation:
FOX, S. E., Y. S. OLSEN, AND A. SPIVAK. Effects of Bottom-up and Top-down Controls and Climate Change on Estuarine Macrophyte Communities and the Ecosystem Services they Provide. In Proceedings, Eco-DAS VIII, HONOLULU, HI, October 11 - 16, 2010. American Society of Limnology and Oceanography, Lawrence, KS, 129-145, (2010).
Impact/Purpose:
Estuaries are highly productive coastal habitats, typically shallow in depth and with light penetration reaching the benthos. The flora and fauna of estuaries worldwide vary considerably, but primary producer communities generally include phytoplankton, benthic microalgae, macroalgae, seagrasses, and epiphytes growing on the surfaces of macrophytes. The biomass and composition of these producer communities depend on a range of factors, including depth, light availability (or turbidity), nutrient supply, water residence time, grazing, and predation. In this chapter, we begin with a brief review of the bottom-up and top-down literature, since there are numerous recent articles that have thoroughly analyzed the relative influence of these controlling mechanisms for seagrasses, macroalgae, and estuaries in general. We highlight (1) how the relative influence of bottom-up and top-down controls in estuarine benthic communities are altered by anthropogenic disturbances, including increased nutrient inputs, water quality degradation, and fishing pressure; (2) how climate change might affect carbon flow through these ecosystems; and (3) how these altered pathways might affect some important ecosystem services provided by estuaries.
Description:
Macrophytes provide important estuarine benthic habitats and support a significant portion of estuarine productivity. The composition and characteristics of these benthic communities are regulated bottom-up by resource availability and from the top-down by herbivory and predation. Human activities in coastal zones have dramatically altered the relative strengths of these controls by delivering nutrients to coastal waters and over-exploiting fishery resources. Here, we review bottom-up and top-down controls and how these may interact to structure estuarine macrophyte communities and the ecosystem services they provide. We further discuss the impacts of climate change on macrophyte communities, and highlight the interactions that are likely to occur with our current knowledge of bottom-up and top-down forcings. . Future research on the interactive effects of bottom-up and top-down controls and climate change on estuarine ecosystem properties (e.g. diversity, community structure, biogeochemistry, etc.) and the services they provide (e.g. food production, nutrient filtration, etc.) will supply important information for the preservation and management of these critical coastal habitats.
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Effects of Bottom-up and Top-down Controls and Climate Change on Estuarine Macrophyte Communities and the Ecosystem Services they Provide