Effects of Zooplankton Spatial Variation on Growth of Larval Striped Bass: An Experimental Approach

We quantified growth and mortality rates of larval striped bass Morone saxatilis in laboratory experiments simulating variability of prey abundance and composition along the riverine to lentic gradient in Lake Marion, South Carolina. Larvae were reared from 4 to14 d posthatch in three treatments: (1) low‐prey, which simulated average prey abundance and composition in riverine and transitional habitats; (2) medium‐prey, which simulated average abundance and composition in lentic habitats; and (3) high‐prey, which simulated peak (patch) abundance and composition in lentic habitats. Larvae did not grow (weight‐specific growth, G = −0.80 to −0.062/d; −0.02 to −0.01 mm/d) in the low‐prey treatment but grew in the medium‐ and high‐prey treatments (G = −0.035 to 0.105/d; 0.02–0.17 mm/d). Additionally, mortality also varied significantly among prey treatments. Larvae in the medium‐ and high‐prey treatments experienced minimal mortality (Z = 0.041–0.085/d), whereas mortality was greater in the low‐prey treatment (Z = 0.072–0.238/d). These results suggest that large‐scale (km) spatial variability of zooplankton and other prey in Lake Marion may affect growth and survival of larval striped bass. Cohorts of striped bass transported to lentic habitats in the upper portion of Lake Marion should experience better growth and survival than cohorts in riverine or transitional habitats.