Effects of diluted salinity on the survival, righting reflex and respiration of a marine intertidal isopod, Cirolana harfordi

Umme Salma (1), Murray Thomson (1)

(1)The School of Biological Sciences, University of Sydney, NSW 2006 Australia usal2541@uni.sydney.edu.au

The marine intertidal isopod C. harfodi is abundantly found in Pacific coastal areas. This species can be a dangerous pest for the fishery industry. It is not known whether C. harfordi is a euryhaline animal and can survive in brackish waters. In order to begin to understand the physiological and behavioral response of this important marine crustacean to brackish water, specimens of the animal were exposed to undiluted artificial sea water and  four different dilutions of artificial sea water, 50%, 25%, 10% and 0% for six hours and the survival rate, oxygen consumption and righting reflex behavior were measured. In these conditions the animals were tolerant to 50% salinity, displayed limited tolerance to 10% salinity but were completely intolerant to freshwater where 100% mortality occurred within 4 hours of exposure. The righting behavior and respiration rate was significantly affected by the exposure to 25%, 10% and 0% sea water salinity but not significantly affected by a reduction in sea water salinity of 50%. The findings of this study indicate that C. harfordi can survive for at least 6 hours with little or no physiological effects in water that is 50% the salinity of sea water, but the animal risks pathophysiology if it ventures into waters of lower salt content. More work is needed on the effects   of   longer-term   exposure   to   brackish   water   and   whether   this   affects   the reproduction cycle of the animal. This type of future research will indicate how far inland these animals can travel via an estuary.


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