Apparent water permeability and hemolymph acid phosphatase activity as indices of stress in the estuarine grass shrimp, Palaemonetes pugio

Abstract

1. Apparent water permeability and hemolymph acid phosphatase activity were determined in shrimp exposed for 32 days to fluctuating temperatures and to food contaminated with the aromatic hydrocarbon, dimethylnaphthalene. Both indices were determined again following a 16-day recovery period in which uncontaminated food was provided to shrimp in a stable temperature environment. 2. Fluctuating temperatures induced diminished apparent water permeability after both the exposure and the recovery periods. This decrease was offset by the ingestion of contaminated food. Contaminated food alone had no effect on apparent water permeability. All shrimp exhibited a uniform increase in apparent water permeability following the recovery period. 3. Shrimp exposed to fluctuating temperatures had significantly elevated enzyme activities when subjected to hypoxic conditions, compared to shrimp held in stable temperatures. Ingestion of contaminated food had no detectable effect on enzyme activities. 4. After the recovery period, shrimp which had previously ingested contaminated food had lower enzyme activities when exposed to hypoxic conditions than shrimp which had ingested nothing but uncontaminated food. Fluctuating temperatures had no residual effect on enzyme activity in shrimp exposed to hypoxic conditions.