Growing Trial of Gilthead Sea Bream (Sparus aurata) Juveniles Fed on Chironomid Meal as a Partial Substitution for Fish Meal.

Insect meal derived from chironomid larvae and collected from aquatic environments was included in the feed of gilthead sea bream juveniles (75 ± 1.1 g) in a growth trial of 90 days. Three feeds, which were namely one control (L1) and two experimental diets (L2, L3), were analyzed and formulated as isonitrogenous (45%) and isolipidic (13%). In L1, the protein source was mainly soybean meal (32%), followed by fish meal (20%), wheat meal (20%), gluten corn (17%), and hemoglobin (11%). In L2, the proportion of soybean meal was increased (33.5%), followed by gluten corn (21%), wheat meal (14%), and hemoglobin (11%), whereas the fish meal source was reduced (15%) due to the inclusion of chironomids (5%). In L3, the proportion of fish meal was further reduced (8%) and that of chironomid meal was increased to 10% of the protein source. The L2 and L3 groups showed similar growth performances with respect to the L1 group. The feed conversion rate was favorable in all the groups, ranging from 1.18 (L1) to 1.22 (L3). Survival rates varied from 93.62% (L3) to 94.31% (L1). Feed palatability showed similar results for all diets. Although the inclusion of chironomid meal was used in small quantities, our results suggest a significant advantage in replacing 50% of the fish meal with the chironomid meal for growing gilthead sea bream fishes.

Metals in Mediterranean aquatic species.

Metals such as arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), vanadium (V), have been determined in species of Mediterranean marine organisms collected from areas supposed to be at background contamination levels. The Inductively Coupled Plasma Mass Spectrometry (ICP-MS) approach was adopted for the determination of all the metals. Arsenic, Cd and Pb determined in the 42 samples, do not exceed the pertinent maximum level except a sample of hake. In wild fish, the concentration range for Cr, Ni, V and Cu was, respectively: 0.07-0.09, 87.6-124, 0.022-0.075 and 0.79-1.74 µg/g fresh weight (fw). The farmed fish samples show concentration levels below the wild fish ones, except for Cr which range at the same levels. Cadmium and Pb show a high sample number under the quantification limit. The elements do not bio-magnify among the species considered and appear to show low variations in relation to organisms' position in the food chain and at sampling sites.

Persistent toxic substances in Mediterranean aquatic species.

Fish and fishery products may represent one of the main sources of dietary exposure to persistent toxic substances (PTSs) such as polychlorinated dibenzodioxins, dibenzofurans, and biphenyls; polybromodiphenyl ethers; organochlorine pesticides; perfluorooctanoic acid and perfluorooctane sulfonate; and inorganic mercury and methyl mercury. In this study, PTS contamination of Mediterranean fish and crustaceans caught in Italian coastal waters was investigated in order to increase the representativeness of the occurrence database for wild species. The objectives were to verify the suitability of regulatory limits for PTSs, identify background concentrations values, if any, and examine the possible sources of variability when assessing the chemical body burdens of aquatic species. Twelve wild species of commercial interest and two farmed fish species were chosen. Excluding methyl mercury, chemical concentrations found in wild species fell generally towards the low ends of the concentration ranges found in Europe according to EFSA database and were quite lower than the tolerable maximum levels established in the European Union; farmed fish always showed contamination levels quite lower than those detected in wild species. The data obtained for wild species seemed to confirm the absence of local sources of contamination in the chosen sampling areas; however, species contamination could exceed regulatory levels even in the absence of specific local sources of contamination as a result of the position in the food web and natural variability in species' lifestyle. A species-specific approach to the management of contamination in aquatic organisms is therefore suggested as an alternative to a general approach based only on contaminant body burden. A chemical-specific analysis performed according to organism position in the food chain strengthened the need to develop this approach.