| Summary: | Despite the increasing number of hypersaline discharges associated with desalination and, more recently, solute mining activities, there is little existing information relating to the effects such environmental disruptions may have on populations of commercially-important crustacean species. The present studies aim to redress this information-gap with novel investigations which have addressed some hypersalinity-induced behavioural and physiological responses of three crustacean species, the European lobster, Homarus gammarus (L), and two crab species, the brown crab, Cancer pagurus (L) and the velvet crab, Necora puber (L). All three species feature prominently in the East Yorkshire fisheries, and are found typically in full salinity seawater environments that show little salinity variability. The development of extensive gas storage caverns underground in East Yorkshire, UK, has led to the commencement of the discharge offshore of large volumes of hypersaline brine effluent into the local, normally salinity-stable habitat of the three test species The combined volume and concentration of this discharge has the potential to raise the salinity in the local environment and these studies have focused on the possible ecological and commercial implications of such changes. Each species was found to have a threshold value of hypersalinity above which halotaxic, preference behaviour was evoked (salinity 50 for H. gammarus and N. puber and salinity 45 for C. pagurus). The relationship between cardioventilatory activity and hypersalinity of H. gammarus and N. puber was examined under conditions when escape from the test salinity was prevented. Both showed a significantly decreased mean scaphognathite beat rate beyond a critical salinity value (salinity of 50 and 45 for H. gammarus and N. puber respectively). These salinities are consistent with the onset of the preference behaviour of these species. The heart rate of H. gammarus is also negatively related to increased salinity. These significant reductions in ...
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