Respiratory changes and stability of haemocyanin—O 2 binding capacity in the crab cancer irroratus exposed to Kuwait crude oil in sea water

Abstract

To determine one possible mechanism of hydrocarbon toxicity, studies were carried out to establish: (a) the availability of hydrocarbons from sea water to the crab haemolymph, (b) the effects on respiration and (c) the possible effects on haemocyanin—O 2 binding characteristics in oiled crabs. Crabs incubated in 14C-naphthalene labelled oiled sea water (Kuwait crude) readily accumulated the isotope into the haemolymph, in concentrations exceeding those in the surrounding sea water medium with one-hour bioconcentration factors from 2·53 to 23·51. Respiration, as measured by uptake of O 2 from the respirometer sea water, was 12·5% lower in crabs held in 11·0 ppm Kuwait crude/sea water than in the same animals when held in unoiled sea water. Respiration levels returned to preoiling levels when the oiled sea water was replaced with fresh non-oiled sea water. Despite the observed effects of oiled sea water on respiration, the haemocyanin—O 2 binding potential, as well as the structural integrity of haemocyanin (as determined by its UV absorption spectrum, sub-unit dissociation and serum-free Cu ++ levels), remained unaltered. The results suggest that disruption of blood-oxygen transport via disruption of haemocyanin—O 2 binding as one possible mechanism of hydrocarbon toxicity is unlikely and that other alternatives must be considered.