Trophic relationships and transference of cadmium, copper, lead and zinc in a subtropical coastal lagoon food web from SE Gulf of California.

Trophic relationships and heavy metal transference in a coastal subtropical lagoon marine food web were investigated through the use of stable isotopes in food sources and biota. A selective extraction scheme was applied to the surface sediments as an indirect way to evaluate the potential of toxicity of metals. Results showed that cadmium, copper, lead and zinc concentrations were within sediment quality guidelines criteria. Concentrations of these metals in organisms varied widely among functional groups and within the same and closely related taxa. delta(13)C values varied significantly among organisms from different functional groups, while the delta(15)N values varied according with their feeding habits. Cd, Cu, Pb, and Zn were not positively transferred (biomagnification factor <1) through entire food web. However, a partial positive transference was observed for Cu and Zn involving three trophic levels (from the phytoplankton to crab as secondary consumer).