Estuarine habitat evaluation measured by growth of juvenile summer flounder Paralichthys dentatus in a North Carolina estuary

Abstract

Habitat quality and fish success, in terms of growth and mortality, are presumably correlated, and abiotic conditions are likely to be a major component in determining habitat quality. We assessed habitat quality in terms of fish growth and mortality using basic abiotic factors as the major variables. Juvenile summer flounder Paralichthys dentatus (42 to 59 mm total length) were caged at 5 sites in and around Masonboro Island, North Carolina, USA, during June and July 1999. Temperature, dissolved oxygen, salinity and pH were recorded every 30 min at each enclosure site during the experiment. Potential predators were excluded by cages and known quantities of food were provided to reduce potential impacts of food availability. Fish were individually tagged, and growth rates calculated for surviving fish. Abiotic conditions varied significantly among sites, although no differences in growth rates were detected among sites. Variability in growth rates both within and among sites was high, with 1 site experiencing total mortality. Results suggest that basic abiotic conditions, at the levels and durations that occur within a southeastern US estuary during summer, have little impact on juvenile summer flounder growth, but may influence survival.