Meeting Abstract
P1.29 Jan. 4 Feeding rates of benthic suspension-feeding macroinvertebrates in Washington state on the toxin-producing phytoplankton Pseudo-nitzschia DUSEK, Eva*; SIMENSTAD, Charles; PUNT, Andre; PARKER, Micaela; DETHIER, Megan; Univ. of Washington; Univ. of Washington; Univ. of Washington ; Univ. of Washington; Univ. of Washington itseva@gmail.com
In Washington state, blooms of the toxin-producing phytoplankton genus Pseudo-nitzschia have been responsible for numerous beach closures for shellfish collection. Several species of Pseudo-nitzschia produce the potent neurotoxin domoic acid, which bio-accumulates in the soft tissues of suspension-feeding macroinvertebrates, and can cause death in vertebrates that consume contaminated shellfish. Since 1991, when elevated levels of domoic acid were first found in razor clams (Siliqua patula) collected along the Washington coast, beach closures for shellfish collection have occurred regularly along the coast. In Puget Sound, however, the presence of domoic acid in shellfish has only recently become prominent, with the first beach closure occurring in 2003. One hypothesized reason for the higher frequency of beach closures along the Washington coast relates to differences between suspension-feeding assemblages on sandy beaches in the two locations: specifically, Puget Sound has a more complex assemblage of suspension-feeding macroinvertebrates that consume Pseudo-nitzschia, whereas along the Washington coast, consumption of Pseudo-nitzschia is concentrated in fewer and more harvestable species. To test this hypothesis, feeding experiments were conducted on 13 species of benthic suspension-feeders found in Washington to determine their feeding capacity on Pseudo-nitzschia. Generally, asiphonate bivalves consumed Pseudo-nitzschia at higher rates than their siphonate counterparts, and bivalves found in Puget Sound consumed Pseudo-nitzschia faster than razor clams found on the Washington coast. These data will be presented with a generalized model to assess the capacity of Washington’s nearshore assemblages to filter Pseudo-nitzschia from the water column.
