This work reports the comparative study of heavy metal water concentrations from two coastal ecosystems of Cadiz Gulf (SWSpain): Bay of Cadiz and Ria ofHuelva estuary in samples taken on years 1999-2000. Sampling zones showed different heavymetal levels. Statistical analysis of dissolved trace metal concentrations (Cu, Zn, Cd and Pb) showed significant differences between Huelva and Cadiz zones based on the Cu level, with a marked seasonal factor and different metal sources (Industrial, geological, urban,...), observing a higher Cu concentration in Ria de Huelva respect to Bay of Cadiz. On the other hand, to evaluate the pollutant effects on aquatic biota, a histopathological analysis have been conducted in specimens of flat fish, Solea senegalensis from both zones. Lesions weremore severe in fish fromRia ofHuelva, being themost significant alterations: gill hyperplasia, fusion of secondary lamellae, disorganization of the hepatic parenchyma, cellular hypertrophy and vascular congestion in liver and tubular occlusion, loss of interstitial tissue and lipid-like vacuoles in kidney. Obtained results are useful as reference data for future environmental monitoring studies in these zones where to establish a heavy metal concentration temporal trend would be necessary
