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Bivalve grazing can shape phytoplankton communities

Frontiers in Marine Science

By:
, , , , and
https://doi.org/10.3389/fmars.2016.00014

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Abstract

The ability of bivalve filter feeders to limit phytoplankton biomass in shallow waters is well-documented, but the role of bivalves in shaping phytoplankton communities is not. The coupled effect of bivalve grazing at the sediment-water interface and sinking of phytoplankton cells to that bottom filtration zone could influence the relative biomass of sinking (diatoms) and non-sinking phytoplankton. Simulations with a pseudo-2D numerical model showed that benthic filter feeding can interact with sinking to alter diatom:non-diatom ratios. Cases with the smallest proportion of diatom biomass were those with the fastest sinking speeds and strongest bivalve grazing rates. Hydrodynamics modulated the coupled sinking-grazing influence on phytoplankton communities. For example, in simulations with persistent stratification, the non-sinking forms accumulated in the surface layer away from bottom grazers while the sinking forms dropped out of the surface layer toward bottom grazers. Tidal-scale stratification also influenced vertical gradients of the two groups in opposite ways. The model was applied to Suisun Bay, a low-salinity habitat of the San Francisco Bay system that was transformed by the introduction of the exotic clam Potamocorbula amurensis. Simulation results for this Bay were similar to (but more muted than) those for generic habitats, indicating that P. amurensis grazing could have caused a disproportionate loss of diatoms after its introduction. Our model simulations suggest bivalve grazing affects both phytoplankton biomass and community composition in shallow waters. We view these results as hypotheses to be tested with experiments and more complex modeling approaches.

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Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Bivalve grazing can shape phytoplankton communities
Series title:
Frontiers in Marine Science
DOI:
10.3389/fmars.2016.00014
Volume:
3
Issue:
Article 14
Year Published:
2016
Language:
English
Publisher:
Frontiers Research Foundation
Publisher location:
Lausanne, Switzerland
Contributing office(s):
National Research Program - Western Branch
Description:
17 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Frontiers in Marine Science
Country:
United States
State:
California
Other Geospatial:
Suisun Bay
Online Only (Y/N):
Y
Additional Online Files (Y/N):
N