Effect of zinc on osmoregulation ofGammarus duebeni(crustacea: amphipoda) from the estuary and the sewage treatment works at Looe, Cornwall

Abstract

The osmoregulatory capacity of Gammarus duebeni Liljeborg from the estuary and the sewage treatment works at Looe, Cornwall (South-west England) has been compared. In unpolluted media, certain inter-populational differences in osmoregulatory and cuticle water permeability responses were identified; however, these were not consistent. Estuarine and ‘sewage’ Gammarus showed no haemolymph change when exposed to a range of external zinc concentrations at high salinity (30‰). Impairment of osmoregulatory capacity, relative to non-polluted levels, occurred at low salinity (10‰), but only at zinc concentrations ≥ 500 μg Zn 1^-12. For each population, depression of haemolymph osmolality was apparently the result of reduced levels of blood sodium (and presumably chloride) rather than any zinc-induced changes in cuticle water permeability. These results are discussed with reference to previously identified evidence, from these populations, for enhanced zinc tolerance in sewage works gammarids as a result of long-term zinc exposure.