Some effects of cadmium on Ulva laetevirens Areschoug collected in Lagoon of Venice.

Although water bodies are a major vehicle for contamination by cadmium (Cd), works on the morpho-physiological effects of this heavy metal on macroalgae are still very scarce. The aim of this research was to study the damaging effects of 9 day-experimental exposure to 1, 5, 10 and 100 μM of Cd on thalli of Ulva laetevirens Areschoug, a macroalga which grows abundantly in the Lagoon of Venice where heavy metals are found. Cd-treated thalli, compared with control thalli, were less thick and less pigmented, due to reduced chlorophyll contents. These symptoms became more evident as the Cd concentration in the seawater growth medium increased. In proportion to that concentration, thalli accumulated great quantities of the metal, most of which remained outside the cells, bound to anionic polysaccharides in cell walls. In particular, 10 and 100 μM Cd disturbed cell wall organization, affecting the fibrous component, and impaired the thylakoid system of chloroplasts.