Established suite of biomarkers is being extensively used worldwide to assess the impact of toxic and highly recalcitrant hydrocarbon pollutants on the marine ecosystem. Various species of sentinel marine organisms (e.g., sea urchins, mussels, and fish) are used as early warning signals indicating the potential environmental pollutants and may help to forecast changes at higher levels of biological organizations. The use of sea urchin gametes (sperm) and fertilized eggs (embryos) in testing developmental, reproductive, and cytogenetic effects of chemicals and complex mixtures has been successfully developed by a number of laboratories worldwide, and it has been demonstrated that this kind of bioassay is sufficiently sensitive to a number of pollutants. In this assay we are describing the spermio- and embryotoxicity approaches performed on sea urchins Paracentrotus lividus and Strongylocentrotus nudus. Moreover, the petroleum toxicity assays with fishes and bioaccumulation tests on molluscs are also presented.