Reprint Series No. 8
Reprinted October 1990

EFFECTS OF HABITAT CHARACTERISTICS ON MUSSEL GROWTH IN PADILLA BAY, WASHINGTON

Mary H. Ruckelshaus

1988

Bibliographic Citation
Ruckelshaus, Mary H. 1981. Effects of habitat characteristics on mussel growth in Padilla Bay, Washington. M.S. Thesis, University ofWashington. 53 pp. Seattle, Washington. Padilla Bay National Estuarine Research Reserve Reprint Series No. 8.

Abstract
Growth rates of estuarine suspension feeders represent a response to physical and biological characteristics of their habitat. In order to be able to use consumer growth rates as indicators of overall habitat quality, the effects of habitat characteristics; such as origins, quantity and quality of food, on growth must be better understood. This study addresses the question of how biological and physical habitat characteristics affect mussel growth in the Padilla Bay estuary in northern Puget Sound. Mussels (Mytilus edulis) were placed in cages in habitats dominated by different primary producers and physical characteristics. Growth rates of caged mussels were highest at the mouth of the estuary and lowest in a fresh water slough. However, concentrations of food sources (chlorophyll a and particulate organic carbon and nitrogen) showed an inverse relationship with growth rates. Physical stresses associated with the habitats appeared to depress growth rates despite high food concentrations. Decreases in growth rates showed a strong positive correlation with decreases in salinity, concentration of inorganic matter in the seston and submergence time. Additionally, natural abundances of stable carbon isotopes suggested that different primary food sources for mussels in different habitats may have been partly responsible for variable growth rates. If food sources and physical conditions critical to consumer performance can be determined, prioritization of estuarine habitat management goals may be facilitated.