Trace Metals Co-Toxicity in Hard Body Structures of Liza Klunzingeri (Mugilidae: Perciformes) Mullet Fish (Technical Report‪)‬

INTRODUCTION The factors that cause stress in the Kuwaiti marine environment may be multidimensional in their origin. Sources include industrial and domestic effluent discharges, oil spills, accumulation of organic and inorganic pollutants in Kuwait Bay and in the coastal region due to industrialization and rapid human activities were identified after the Gulf War-I in 1991. Discharges from the power, thermal, desalination and water treatment plants and leakage from oil wells that contained high metal levels were observed in Kuwait marine environment (1-2). Most metals are essential for the physiological function processes in fish (3). However, above tolerable limits, these metals were found to be one among the factors that caused 'fish kill' in the year 1999 and 2000 especially to L. klunzingeri in Kuwait while, sub-lethal concentrations of metals showed behavioural, biochemical and histological changes in fish (4). Observation showed the main routes of accumulation of trace metals over time by fish are through the gills, skin, muscles and food (3), (5). Likewise, hard body parts of fish such as otolith, scales and dorsal spines showed significant accumulation of trace metals in the marine environment (6-10). Studies also observed co-toxic effect of metals in mixture on sensitive fish (11-13). Besides the direct effect of trace metals, their interaction to seawater variables such as temperature, pH, D.O., salinity, nutrients and biological factors may attribute to enhance the co-toxicity effect on fish (14-15). Previous publications showed no evidences of co-toxicity of trace metals in L. klunzingeri in Kuwait's marine environment. Hence, this study aims to determine the acute toxicity ([LC.sub.50]) and bioaccumulation of trace metals, individually and in mixture (co-toxicity) in L. klunzingeri.