Alterations in prey capture and induction of metallothioneins in grass shrimp fed cadmium-contaminated prey

The aquatic oligochaete Limnodrilus hoffmeisteri from a Cd-contaminated cove on the Hudson River, Foundry Cove, New York, USA, has evolved Cd resistance. Past studies have focused on how the mode of detoxification of Cd by these Cd resistant worms influences Cd trophic transfer to the grass shrimp Palaemonetes pugio. In the present study, we investigate reductions in prey capture in grass shrimp fed Cd-contaminated prey. We also investigate the induction of metal-binding proteins, metallothioneins, in these Cd-exposed shrimp. Grass shrimp were fed held-exposed Cd-contaminated Foundry Cove oligochaetes (for 1 week) or laboratory-exposed Cd-contaminated Artemia salina (for 1 or 2 weeks). Following these exposures, the ability of Cd-dosed and control shrimp to capture live A. salina was compared. Results show that shrimp fed laboratory-exposed Cd-contaminated A. salina for 2 weeks exhibit significant reductions in their ability to successfully capture prey (live A. salina). Reductions in prey capture were also apparent, though not as dramatic in shrimp fed for 1 week on field-exposed Cd-contaminated Foundry Cove oligochaetes. Shrimp were further investigated for their subcellular distribution of Cd to examine if alterations in prey capture could be linked to saturation of Cd-metallothionein. Cd-dosed shrimp produced a low molecular weight (similar to 10,000 daltons) Cd-binding metallothionein protein in a dose- and time-dependent manner. Most importantly, successful prey capture decreased with increased Cd body burdens and increased Cd concentration bound to high molecular weight proteins (i.e., enzymes).