Toxicity and bioaccumulation of heavy metals to some marine biota from the Egyptian coastal waters

Abstract

Exposure of Isopoda (Idotea baltica) to different concentration levels of metals has enabled the identification of the mode of metal accumulation adopted by this species. The toxicity of inorganic tin was studied at different concentration levels between 1–135 ppm. The acute lethality of tin to the species was examined and found to be 24 hLC_M = 96 ppm and 17 hLC₅₀ = 115 ppm. The maximum allowable concentration of tin being 125 mg/m³ and threshold level was 1891 mg/m³. Tin was also found to hamper the growth of the animals.

The toxicity and bioaccumulation of Cr, Co and Ni were studied individually and in paired and triad combinations in the animals. They showed net accumulation of dissolved metals at different concentration levels, between 1 and 150 ppm. Their toxicity increased with increasing metal concentration and exposure time, until an asymptotic was reached. Some indications of metal regulation were also observed, Laboratory results were confirmed to field conditions, and it was realized that, Idotea baltica are able to obtain sufficient metabolic metals from solution, and the use of such isopods in metal biomonitoring is of great interest. The observed results have confirmed that the metals regulation might be achieved by balancing the rate of metal excretion to match the rate of their uptake, which is more effective at low levels due to uptake and depuration.

The rate of bioaccumulation of a mixture of Cr, Co and Ni was also studied in brown & green algae, (Jania rubens and Ulva lactuca), bivalves (Modiolus adtriaticus), isopoda (Sphaeroma serratum) and gastropoda (Ocinebra edwarsi). Ulva lactuca showed the least comparable BCF values for all metals studied (Cr, Co & Ni), which may increase their economic importance.