Abstract
Abstract Osmo- and ionoregulatory abilities were examined in the intertidal grapsid crab, Gaetice depressus, transferred from normal seawater (30 ppt) to low (10 ppt) or high (50 ppt) salinities for 2 and 10 days, in addition to animals kept out of water for 2 days. The results of the hemolymph osmotic and ionic status indicate that G. depressus is able to adapt for more than 10 days in these salinities and for 2 days under terrestrial conditions. Especially, the free Ca2+ concentration was relatively maintained compared with concentrations of monovalent ions and osmolality values in 10 and 50 ppt, partly using the complexed calcium (total minus free calcium) as an internal reserve in the hemolymph. In 10 ppt, complexed calcium disappeared from the hemolymph after 10 days, indicating that all the hemolymph calcium was ionized. In 50 ppt, free Ca2+ was regulated to lower levels than concentrations in the medium, while total calcium increased to higher levels after 2 days. Examination of Na+/K+-ATPase activity, which has been implicated in ion transport in many crustaceans, revealed that induction of high Na+/K+-ATPase activity varies among the posterior gills in response to salinities. Ten-ppt salinity induces activity in two of the posterior gills (gill numbers 6 and 7, eight in total), albeit with differing degrees of response. In contrast, 50-ppt salinity stimulates the activity primarily in gill number 8, suggesting that this gill may be associated specifically with ion excretion in G. depressus. As a euryhaline amphibious crab, this abundant species around Japan will serve as a model to study the osmotic/ionic regulatory mechanisms which operate in crustaceans.
Highlights
The metal pollution of the marine ecosystem has always been admitted as a serious environmental issue (Blakas et al 1982; Tariq et al 1991)
The concentration of ten metals elements measured in liver and muscle tissues are reported for each species in Tables 2 and 3
The investigation of trace metal contamination levels in fish from the southern Atlantic Moroccan coast showed the presence of differences of contamination between species and considered organs, as well as Concentrations μg.g-1d.w
Summary
The metal pollution of the marine ecosystem has always been admitted as a serious environmental issue (Blakas et al 1982; Tariq et al 1991). Four pelagic fish species including (Engraulis encrasicolus (anchovy), Sardina pilchardus (sardine), trachurus trachurus (horse mackerel) and Scomber japonicus (mackerel)) were selected These fish species are of particular importance due to their intermediate position in the food web and for their abundance. Mackerel has a cosmopolitan distribution including warm and temperate waters of the Atlantic, Indian and Pacific Oceans and adjacent seas It is essentially a near coastal species, with a vertical distribution ranging between 0 and 300 m of depths. The purpose of this work (involved in the framework of EPURE project research program) is to determine and compare the concentrations of Zn, Fe, Cu, Pb, Cd, Cr, Co and Hg in the liver and muscle of four small pelagic fish species from the south Atlantic Moroccan coast during two periods of upwelling phenomena, in July season of strong upwelling and December season of weak upwelling. The objective is to describe the differences of the concentrations of trace metals between species, between upwelling seasons and to compare the results with guidelines set down by the European Commission Regulation (European Commission Regulation (EC) 2008, 2014, 2015) for the safe consumption limits of fish and the other studies
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