Sediment trace metal levels in the Ojo de Liebre Lagoonal Complex (Baja California, Mexico), a marine wildlife protected area.

Abstract

Surficial sediment quality in the Ojo de Liebre Lagoon (OLL), Mexico, was evaluated via five geochemical indices. Results indicate that concentrations of the elements Ag, As, Cu, Fe, Mn, Mo, Ni, Sb, U, V and Zn do not exert adverse biological effects in this ecosystem. However, minor enrichment was observed for Ba (mean\xa0±\xa0SD: 1.09\xa0±\xa00.17) and Co (1.57\xa0±\xa00.22) and was moderately severe for Cd (9.3\xa0±\xa02.0), possibly due to natural processes. The adverse effect index was >1 only for Hg, suggesting that concentrations of this element are sufficiently high (0.40 to 1.13\xa0nmol\xa0g-1) to potentially elicit adverse effects on local organisms in contact with sediments. This result is particularly important for grey whales (Eschrichtius robustus), given that they ingest large quantities of benthic organisms during their seasonal stay in the OLL.