PARTICLE REMOVAL RATES BY THE MUD SHRIMP UPOGEBIA PUGETTENSIS, ITS BURROW, AND A COMMENSAL CLAM: EFFECTS ON ESTUARINE PHYTOPLANKTON ABUNDANCE

• Main Authors: B Griffen, T DeWitt, C Langdon
• Format: Text
• Language: unknown
• Published: 2005
• Subjects: Pacific; Crassostrea gigas; Pacific oyster
• Online Access: http://oaspub.epa.gov/eims/eimsapi.dispdetail?deid=84591

The burrowing shrimp Upogebia pugettensis is an abundant intertidal inhabitant of Pacific Northwest bays and estuaries where it lives commensally with the bivalve Cryptomya californica. Suspension-feeding activities by the shrimp and by its commensal clam, as well as particle settlement within the burrow, represent three different components that could remove phytoplankton in shrimp habitats. These three components together comprise what we call the "shrimp-burrow complex". The goals of this study were 1) to determine the relative contributions of each of these three components of the shrimp-burrow complex to phytoplankton removal; 2) to determine whether shrimp-burrow complexes present in the lower Yaquina River estuary (Newport OR, USA) are capable of significantly reducing phytoplankton in overlying water; and 3) to examine the potential for food competition between Upogebia and other suspension feeders that are found in shrimp habitats, represented here by the Pacific oyster, Crassostrea gigas, an economically important species that is often grown commercially in shrimp habitats. We addressed these goals using feeding rate experiments conducted in the field and in the laboratory, and using a population filtration model that we developed for shrimp-burrow complexes in Yaquina River estuary. We compared particle retention efficiencies of Upogebia and oysters to determine potential food competition. Our results showed that Upogebia themselves are responsible for filtering the majority of phytoplankton removed by the shrimp-burrow complex at lower phytoplankton concentrations, with filtration by C. californica becoming more important at high phytoplankton concentrations. Particle settlement in the burrow and adhesion to the burrow wall may also be responsible for removal of significant amounts of phytoplankton. Our population filtration model, based on field measurements of filtration rates, predicted that shrimp-burrow complexes in the lower Yaquina River estuary are capable of filtering the entire body of overlying water between one and two times daily. Comparison of particle retention efficiencies for the shrimp-burrow complex and oysters indicated that Upogebia and oysters are capable of utilizing the same food resources and, therefore, may compete for food in regions where phytoplankton abundance is growth-limiting.