Worldwide anthropogenic activities result in the production and release of poten-tially damaging toxic pollutants into ecosystems, thereby jeopardizing their health and continuity. Research studies and biomonitoring programs attend to this emerging problematic by applying and developing statistically relevant indexes that integrate complex biomarker response data to provide an holistic approach reflecting toxically induced alterations at the organism’s or population level. Ultimately, indexes allow simple result communication, enhancing policy makers understanding, so contributing for better resource and environmental managing policies. In this study three indexes , the Integrated Biomarker Response index (IBR), the Bioeffects Assessment Index (BAI) and the Principal Components Analysis (PCA), were evaluated for their sensitivity in revealing toxically induced stress patterns in cells of the diatom Phaeodactylum tricornutum under contaminant exposure. The set of biomarkers selected for index construction comprise the anti-oxidant enzymes APX, CAT and SOD, and the lipid peroxidation marker TBARS. Several significant inverse correlations with the concentration gradients applied, , was noticed for all indexes, though, the IBR excels for its reliability in delivering statistically significant dose-response patterns for four out of the five compounds tested.

The marine red algae Asparagopsis armata is an invasive species which competitive advantage arises from the production and release of large amounts of toxic compounds to the surrounding invaded area, reducing the abundance of native species. The main objective of this study was to evaluate the effects of this invasive seaweed on marine invertebrates by exposing the common prawn Palaemon elegans and the marine snail Gibbula umbilicalis to the exudate of this macroalgae. The seaweed was collected and placed in tanks, for 12 hours, in the dark in a 1:10 ratio. Afterwards the media containing its secondary metabolites was collected for further testing. Lethal and sublethal effects of A. armata were investigated. Biochemical biomarkers responses associated with energy metabolism (lactate dehydrogenase, LDH; electron transport system activity, ETS; content in lipids, proteins and carbohydrates) were analysed. The biomarker responses showed invertebrates’ physiological status impairment after exposure to low concentrations of this algae exudate. Highest concentrations of exudate significantly increased lipid content in both organisms. In the shrimp, protein content, ETS, and LDH were also significantly increased. On the contrary, these parameters were significantly decreased in G. umbilicalis. A behavioural impairment was also observed in G. umbilicalis exposed to A. armata exudate, with reduction in feeding consumption. These results represent an important step in the research of natural toxic exudates released to the environment and prospective effects of this seaweed in invaded communities under increasing global change scenarios.