Research Product

Dry weight (W), carbon (C), nitrogen (N) and energy (E) (calculated) accumulation were measured in the estuarine grass shrimp, Palaemonetes pugio, throughout larval development and during the first 2 weeks as postlarvae in seawater over sediment containing the pyrethroid insecticide fenvalerate (SCF; nominal concentrations of 1, 10, and 100 µg fenvalerate kg-1 sediment). The influence of fenvalerate-laden sediment on shrimp growth and utilization patterns of C,N, and E was dependent on fenvalerate concentration, age of shrimp, and whether shrimp were premetamorphic or postmetamorphic in development. The fenvalerate concentration in the sediment, which ultimately inhibited larval metamorphosis (100 µg fenvalerate kg-1 sediment), significantly reduced W accumulation in developing larvae and in postlarvae growing on the sediment for an equivalent time. Accumulation of C,N, and E varied not only with concentration of SCF, but differed between pelagic larvae developing in water above SCF and newly settled postlarvae growing in direct contact with SCF. Larvae developing above >=10 µg kg-1 SCF contained significantly less N, while postlarval shrimp settling onto >=10 µg kg-1 SCF accumulated significantly less C and E. Measurable variations in growth and energy reserves of toxicant-sensitive life stages in response to environmentally realistic insecticide exposures have a direct link to ecological consequences of toxic stress and may be useful as biomarkers to diagnose early damage in estuarine populations.