Effects of turbidity, light level and prey concentration on feeding of juvenile weakfish Cynoscion regalis

摘要: Highly turbid and dimly lit mid-Atlantlc estuaries, such as Delaware Bay (USA), a r e important nursery areas of juvenile wreakfish Cynoscion regalis where mysid shrimp Neomysis americana dominate their diet. Laboratory experiments were conducted to determine the effect light, turbidity, prey concentration on feeding by juvenlle weakfish shrimp. Juveniles fed 48 mysids daily t turbidities ranging from 0.95 11 nephelometric turbidity units (NTU) light levels dark 0.70 X 10"' quanta S ! cm-' At all i i~s , they consumed virtually in low 0.01 101"uanta ' However, complete darkness (<0.01 lOI4 5 cm-') reduced regardless turhidit)l. Darkness foraging efficiency similar degree among concentrations 0.5 4 timcs typical field densities, suggesting that teedlng depends 1s likely depend less efficient, non-visual encounter rate. Therefore, under conditions adequate may occur only when is sufficiently high or adequately dense patches are encountered wlth sufficient frequency. Juvenile appoar well-adapted for feedlng highly frequently estuarine Patterns turbidityhght conjunction patterns density control lnys~d availability influence feeding, growth, survival.