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AbstractMarine biota is redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. We further found that single surveys do not cover the full range of the main commercial demersal fish species and that an average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with vector autoregressive spatio-temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate-driven ocean changes.

The replacement of fish meal and fish oil by insect-based ingredients in the formulation of marine aquafeeds can be an important step towards sustainability. To pursue this goal, the modulation of the lipid profile of black soldier fly larvae (Hermetia illucens) has received great attention. While its nutritional profile can shift with diet, the ability to modulate its lipidome is yet to be understood. The present work provides an overview of the lipid modulation of H. illucens larvae through its diet, aiming to produce a more suitable ingredient for marine aquafeeds. Marine-based substrates significantly improve the lipid profile of H. illucens larvae, namely its omega-3 fatty acids profile. An improvement of approximately 40% can be achieved using fish discards. Substantial levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two essential fatty acids for marine fish and shrimp species, were recorded in H. illucens larvae fed on fish discards and coffee silverskin with Schyzochytrium sp. Unfortunately, these improvements are still deeply connected to marine-based bioresources, some still being too costly for use at an industrial scale (e.g., microalgae). New approaches using solutions from the biotechnology toolbox will be decisive to make H. illucens larvae a feasible alternative ingredient for marine aquafeeds without having to rely on marine bioresources.

The global decline in amphibian populations is a major environmental issue. Chytridiomycosis, Ranaviruses and the red-leg syndrome have been identified in unusual mortality events. However, these infections do not account for all causes of declining amphibian populations. Moreover, several cases of amphibian mortality are difficult to solve without resorting to an interdisciplinary approach. Two cases of unusual mortality in Rana temporaria occurred at two high-mountain ponds (northwest Italy) in April and May 2021. Water and frog samples were analysed to understand the possible causes responsible for the unusual mortalities. Results of the main physicochemical (pH, conductivity, dissolved oxygen, chemical and biochemical oxygen demand) and nutrient (ammonia/ammonium, nitrite, nitrate, total phosphorus) parameters revealed a good condition of the water quality, with the absence of the main cyanotoxins (microcystins/nodularins). However, unseasonably high spring water temperatures were recorded in both ponds (12.73 °C and 14.21 °C for Frog Pond and Selleries Pond, respectively). Frogs (n = 50; snout-vent length: 7.0-9.8 cm; body mass: 85-123 g) collected from Frog Pond mainly presented bumps on the ventral cavity and dermal ulceration associated with the isolation of Carnobacterium maltaromaticum. On the other hand, frogs (n = 5; snout-vent length: 8.0-9.1 cm; body mass: 87-92 g) from Selleries Pond presented petechiae and dermal ulcerations on the rear limbs associated with the isolation of Aeromonas salmonicida and A. sobria. In both mortality events, the interdisciplinary approach revealed an association between frog mortalities and the isolation of bacteria. Isolated bacteria are considered opportunistic pathogens, and the high values of the water temperature has certainly led a stress on the frogs, favouring the spread of bacteria and the death of the frogs. Further studies are needed to assess the pathophysiological effects of the opportunistic bacteria here isolated, clarifying the interactions between emerging pathogens and climate change.

In the present study we used the high-throughput sequencing technology Illumina MiSeq to develop 26 polymorphic microsatellite loci for the marine snailGibbula divaricata. Four to 32 alleles were detected per locus across 30 samples analyzed. Observed and expected heterozygosities ranged from 0.130 to 0.933 and from 0.294 to 0.956, respectively. No significant linkage disequilibrium existed. Seven loci deviated from Hardy-Weinberg equilibrium that could not totally be explained by the presence of null alleles. Sympatric distribution with other species of the genusGibbula, asG. rarilineataandG. varia, lead us to test the cross utility of the developed markers in these two species, which could be useful to test common biogeographic patterns or potential hybridization phenomena, since morphological intermediate specimens were found.

Global environmental changes are challenging the structure and functioning of ecosystems. However, a mechanistic understanding of how global environmental changes will affect ecosystems is still lacking. The complex and interacting biological and physical processes spanning vast temporal and spatial scales that constitute an ecosystem make this a formidable problem. A unifying framework based on ecological theory, that considers fundamental and realized niches, combined with metabolic, evolutionary, and climate change studies, is needed to provide the mechanistic understanding required to evaluate and forecast the future of marine communities, ecosystems, and their services.