In the Mediterranean, Ostreopsis blooms induce skin and respiratory disorders when human beings are exposed to saltwater with a high concentration of algal cells. However, palytoxin dosages carried out on the food chain (urchins, mussels) indicate that this risk of toxins accumulation in seafood must be taken into account and that the surveillance network should be upgraded accordingly.

The accumulation of trace metals (Cd, Co, Cr, Hg, Ni and Pb) was measured in water, sediment, the mussel Mytilus galloprovincialis and the seagrass Posidonia oceanica. Samples were collected in three locations of the north-western Mediterranean (Canari, Livorno and Porto-Torres) which present different levels and sources of human impact. Analyses in the different compartments (water, sediment, M. galloprovincialis and P. oceanica) have allowed to identify Canari as the most Cd, Co, Cr and Ni contaminated site; Livorno as the most Hg contaminated and Porto-Torres as the most Pb contaminated. Furthermore, for the first time, metal concentrations found in P. oceanica have been compared with those found in the water column, in the sediment and in the recognized metal bio-indicator species M. galloprovincialis and the results obtained have led to the same conclusions. Thus, this study allows to validate the use of P. oceanica as metal biomonitor of coastal waters.

In coastal environments, plants are used for phytoremediation of contamination. Organic and inorganic contaminants may be due to natural and/or anthropogenic sources. The aim of this study is to compare inorganic (trace metal) and organic (PAH) contamination in Posidonia oceanica and to analyse the relationship between these types of pollutants indeed very few studies have been interested in their correlations and common sources. P. oceanica leaves were collected in two sites exhibiting different levels of human-induced pressure. Higher values were recorded in the more polluted site (Toulon) for trace metals (Ag, Hg, Pb) as well as for PAHs (Medium Molecular Weight and High Molecular Weight) due to the presence of the city and/or harbour in proximity. For the first time in a coastal environment, correlations were observed between metals and PAHs.

An atomic absorption‐hydride generation technique was devised with an air/hydrogen flame system for determination of the speciation of antimony(III) and antimony(V) in marine algae. Antimony(III) is determined selectively at pH 4, total antimony after low temperature ashing of the dry algae using electrically excited oxygen atoms. Detection limits are 0.05 ng ± 10%. For the three marine algae (Ulva sp., Enteromorpha sp., and Sargassum sp.) sampled in San Diego Bay (California) seawater, Sb(V) is dominant. However, Sargassum sp. can contain up to 30% of Sb(III), showing an ability to form reduced compounds and therefore a possible role in the cycling of antimony in coastal waters.