HR: 13:30h
AN: NB43C-01 INVITED     [Abstracts]
TI: Context-Dependent Species Effects in Freshwater Mussel Communities
AU: * Vaughn, C C
EM: cvaughn@ou.edu
AF: Oklahoma Biological Survey and Department of Zoology, University of Oklahoma, Norman, OK 73019 United States
AU: Spooner, D E
EM: dspooner@ou.edu
AF: Oklahoma Biological Survey and Department of Zoology, University of Oklahoma, Norman, OK 73019 United States
AU: Galbraith, H S
EM: cvaughn@ou.edu
AF: Oklahoma Biological Survey and Department of Zoology, University of Oklahoma, Norman, OK 73019 United States
AB: Riverine unionids typically occur as multi-species assemblages and are considered a `filter-feeding' guild. Through a series of field-enclosure and laboratory stream-mesocosm experiments we are addressing three fundamental questions concerning this guild: (1) What is the overall importance of the mussel guild to stream ecosystem function? (2) Do species perform different ecological roles or are they functionally redundant? and (3) Do species roles vary with environmental context? Results to date demonstrate strong effects of a potentially keystone species, Actinonaias ligamentina, but comparatively weak diversity effects. In summer field experiments, A. ligamentina increased periphyton biomass, and A. ligamentina biomass was correlated with biomass changes in other mussel species. These patterns were not observed in fall field experiments when water temperatures were lower and average discharge higher. Most of the samples from the mesocosm experiments are still being processed, but data we have analyzed also indicate strong effects of A. ligamentina on both whole community respiration rates and biodeposition of organic matter. Our results indicate that some mussel species are performing differently in streams and are thus not redundant, but that performance and potential redundancy are context dependent.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly