The fishery biology of the invasive Atlantic blue crab Callinectes sapidus in the Mediterranean Sea outside the eastern sectors of the basin has been only recently investigated. Here we studied the population of C. sapidus in the Lesina Lagoon (Adriatic Sea, SE Italy). In total, 838 crabs were captured monthly between February 2021 and January 2022 using fyke nets. Abundances varied seasonally with catches per unit effort ranging between 0 and 1.76 crabs fyke nets⁻¹ d⁻¹ in winter and summer. Spatial abundances estimated in summer by a Carle–Strub procedure ranged between 0.06 and 0.64 crabs m⁻². The sex ratio (♂/♀) was close to 1:1; males prevailed only in August and September; ovigerous females occurred from April to August. The males’ size at morphological maturity was smaller than females (110.6–112.3 mm vs. 122.1–123.1 mm). Seasonal von Bertalanffy growth parameters indicated that, compared with males, females showed a shorter maximum lifespan (5 vs. 8 years), a higher growth coefficient K (0.6 vs. 0.4 y⁻¹) and growth performance index Ф’ (4.6 vs. 4.3), while maximum sizes CW∞ (237.8 vs. 232.6 mm) and seasonality indices C (0.62 vs. 0.57) were similar. Furthermore, females showed higher natural and fishing mortalities and exploitation rate. We discussed the results of the present study in the context of the available literature to provide a valuable basis for the implementation of standardized Mediterranean-scale management plans, matching exploitation of C. sapidus with sustainable conservation of coastal ecosystems.

The fishery biology of the invasive Atlantic blue crab Callinectes sapidus in the Mediterranean Sea outside the eastern sectors of the basin has been only recently investigated. Here we studied the population of C. sapidus in the Lesina Lagoon (Adriatic Sea, SE Italy). In total, 838 crabs were captured monthly between February 2021 and January 2022 using fyke nets. Abundances varied seasonally with catches per unit effort ranging between 0 and 1.76 crabs fyke nets-1 d-1 in winter and summer. Spatial abundances estimated in summer by a Carle-Strub procedure ranged between 0.06 and 0.64 crabs m-2. Sex ratio (♂/♀) was close to 1:1; males prevailed only in August and September; ovigerous females occurred from April to August. Males’ size at morphological maturity was smaller than females (110.6-112.3 mm vs. 122.1-123.1 mm). Seasonal von Bertalanffy growth parameters indicated that, compared with males, females showed a shorter maximum lifespan (5 vs. 8 years), a higher growth coefficient K (0.6 vs. 0.4 y-1) and growth performance index ' (4.6 vs. 4.3), while maximum sizes CW∞ (237.8 vs. 232.6 mm) and seasonality indices C (0.62 vs. 0.57) were similar. Furthermore, females showed higher natural and fishing mortalities and exploitation rate. We discussed the results of the present study in the context of the available literature to provide a valuable basis for the implementation of standardised Mediterranean-scale management plans, matching exploitation of C. sapidus with sustainable conservation of coastal ecosystems.

Integrated Multi-Trophic Aquaculture (IMTA) has been demonstrated to be a very useful tool to minimize the waste product production of fish monocultures whilst promoting biomass that can be used for different purposes. The stable isotope analysis (δ¹³C, δ¹⁵N, and C:N ratio) of bioremediating organisms present in an IMTA facility is critical to understanding the nutrient flow between farm food waste and filter-feeding organisms, and hence the bioremediation capability of the IMTA system. Here, we report the isotopic signature of the sediment below the fish cages, the fish artificial food and sixteen different suspension feeding species present in the IMTA system in the Mar Grande of Taranto (Italy). A comparison of the stable isotopes results of the bioremediating organisms with those of the same species collected from a control (Cnt) site, unaffected by the plant discharges, was thus conducted looking for trophic level patterns. This assessment aimed to evaluate the possible influence of aquaculture waste on the diet of the organisms, revealing these findings for the first time. Similar δ¹⁵N values (below 2–3‰ between areas) were found between the IMTA and Cnt sites, while differences in δ¹³C values were found among multiple organisms between the two sites, suggesting a possible different primary source of the organic matter that supports the trophic web. Almost all analyzed species in the IMTA site reported δ¹³C values lower than Cnt site, being more similar to the isotopic signature of the aquaculture finfish food. However, the wide IMTA isotopic range for both δ¹⁵N and δ¹³C suggested a broad spectrum of diets for bioremediating organisms that can actively mitigate the impacts of mariculture by capturing different particles and using various food sources, leading to more sustainable mariculture activities.

Biofouling communities are usually managed as pests in aquaculture, yet their natural proliferation in fish farms makes them also promising IMTA extractive components. The growth and biomass production of four dominant macrofoulers, Mytilus galloprovincialis (mussels), Sabella spallanzanii (polychaete worms), Phallusia mammillata and Styela plicata (ascidians), were evaluated under a novel IMTA system in the Ionian Sea (southern Italy). Coconut-fiber ropes (10 m) were deployed around fish cages in October 2022 and monitored over a 1-year cycle. Monthly density, length-frequency and cohort analyses combined with species-specific length-weight relationships were used to estimate target species’ growth and biomass. Mytilus and Sabella showed single-cohort dynamics, with densities steadily declining over time, whereas ascidians displayed continuous recruitment allowing for additional rope-deployment windows. Specific growth rates in length were significantly higher in Phallusia and Sabella (≈25% month⁻¹) than in Mytilus and Styela (≈17 and 22% month⁻¹). Total macrofouling biomass (live weight) increased from ≈350 kg in May to a peak of ≈2500 kg in August, remaining as high in October. Mytilus and Sabella accounted for 60–80% of total biomass while ascidians contributed 20–40%. Beyond environmental restoration, this multispecies biomass offers several potential commercial opportunities and could be further valorized through biorefinery-based cascading extraction, including final conversion into bioenergy. Overall, IMTA could leverage traditionally undesired fouling organisms as multifunctional crops, enhancing bioremediation while supporting circular blue-bioeconomy principles. Future research should focus on optimizing rope deployment timing, harvesting strategies, and biomass valorization pathways to fully exploit the emerging potential of integrating multispecies fouling biomass within IMTA systems.

The analysis of crustaceans’ diet by direct inspection of stomach contents is often unsuccessful as prey are often crushed, partially ingested, or incompletely digested, ultimately hampering their taxonomic identification. In the present paper, the usefulness of molecular methods to identify the species present in the stomach contents of the Atlantic blue crab Callinectes sapidus was tested in several specimens captured in the Ugento ponds (SE Italy). Metabarcoding analysis identified a wide spectrum of food items at species/genus level, providing a highly resolved taxonomic resolution of the blue crab diet. Molluscs, crustaceans, bryozoans, polychaetes, fishes and plants, already known as part of the C. sapidus diet, were identified at a species level and for the first time cnidarians and ctenophores were suggested to be included in the Mediterranean diet of C. sapidus. The omnivorous trophic habits of the species were also confirmed, since a substantial aliquot of the identified food items was represented by benthic microalgae. Some general considerations on the trophic pressure of C. sapidus on recipient communities in Mediterranean transitional habitats are provided and the resulting impacts on the environment are discussed.

The Mediterranean Sea represents a hotspot of non-indigenous fish species introductions. Here, we provide a comprehensive bibliographic synthesis on five Lessepsian fish invaders—Fistularia commersonii, Lagocephalus sceleratus, Pterois miles, Siganus luridus, and S. rivulatus—verifying whether international bibliographic databases (IBDs) and online biodiversity information facilities (BIFs) provide adequate information on their occurrence, biology, ecology, and potential or extant commercial use. To this end, we extended to non-indexed bibliographic (NIB) sources available on Google Scholar and compared the results on spatial expansion dynamics and bibliographic trends. We demonstrate that the information provided on occurrence records exclusively by IBD and BIF sources underestimated the total expansion area of invaders by up to 14.8% and determined artifactual temporal voids. Remarkable knowledge gaps were identified in the literature on the reproductive biology and commercial use of all the species, independent of the literature sources, while a relatively larger breadth of information was available on their morphometrics and trophic ecology. Noticeably, NIB sources provided more complete bio-ecological information, particularly for L. sceleratus. In addition, the majority of the studies on commercial uses were published in NIB sources, to the point that for some species, IBD sources provided negligible or null information on the topic. This study indicates that disregarding non-indexed literature sources might exacerbate knowledge voids exclusively related to linguistic barriers or geographic biases, weakening the scientific support necessary for identifying appropriate strategies of control and mitigation of bioinvasions in the Mediterranean Sea.