Sedimentation rates and metal content of sediments in a Venezuelan coral reef

The sedimentation rate and metal content in trapped sediments were determined at four localities at the Parque Nacional Morrocoy and for a sampling period of 1 year. The sedimentation rate was inversely related to the distance from the main terrestrial sources of sediment and ranged from 44±7 to 281±46 g m−2 d−1 (mean±SE) for the farthest two localities (11 km apart). February through May showed the highest sedimentation rate considering all localities. Except for Ca and Hg, metals in sediments also varied inversely to the distance from terrestrial sources and ranged as follows: Al 1.01–2.57, Fe 0.70–2.08, Ca 22.3–34.8 in %; and Zn 44.6–77.9, V 19.9–41.8, Pb 18.1–35.6, Cr 18.1–31.9, Cu 6.8–40.3, Hg 0.269–0.325 in μg g−1 based on dry weight. A common source of metal pollution is suggested from the positive and significant correlation found between the concentrations of most metals. Only Hg was not correlated with any other metal and its concentration was relatively constant for all localities. Based on our results we speculate that reef environments of P.N. Morrocoy are being affected by long-term continuous load of sediment moderately contaminated, brought about by drainage of the neighboring rivers.