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Document Type

Article

DOI

10.25778/nxk3-4246

Abstract

Sporadic, high mortality in test populations of wedge clams (Rangia cuneata) has limited the potential for using this otherwise desirable test organism in biomonitoring studies. To determine whether high mortality was due to ontogenic or experimental variables, a two-phased study was conducted. In phase I, mortality of collected and re-deployed wedge clams, subjected to varying transport conditions, was determined at 7, 14, 21 and 60 days re-deployment. The use of three transport times (1, 2, 3 hr.), two vehicle conditions (open, closed) and three transport treatments (open, closed, iced containers) yielded 18 test groups. Individual test group mortalities were below 10% through the 21 day re-deployment period and peaked at 13% at the 60 day re-deployment point. The low rates of mortality observed in phase I of this study indicate that reasonable collection and transport of wedge clams does not significantly increase natural mortality and suggests other parameters are more strongly correlated to test population mortality. In phase II of this study, percent survival of collected and "acutely" redeployed and "acclimated" redeployed wedge clams was determined. Acclimated re-deployment is the transfer of R. cuneata from saline to freshwater in decrements of 3-4 ppt/day in accord with recommendations in Bedford and Anderson (1972). Acute re-deployment is the placement of R. cuneata in lower salinity waters or freshwater without acclimation. Although percent survival of clams acutely deployed to the freshwater test site was significantly (p

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