Biodiversity plays a crucial role in maintaining ecosystem functioning and ensuring the provision of ecosystem services that support human well-being, since the potential ecosystem functions in an ecosystem are a function of the diversity within it. In the marine environment, diverse species in different measure contribute to essential processes such as primary production, nutrient cycling, carbon sequestration and others, due their traits and main ecological attributes. However, biodiversity is increasingly threatened by anthropogenic stressors and climate change, leading to significant alterations in species composition and ecosystem dynamics. Seagrass meadows play a crucial role in coastal ecosystems, they enhance biodiversity in the areas where they are present by influencing the productivity, carbon cycling, filtration, food webs and other functions that make them great source of ecosystem services. The capacity of the seagrass to provide shelter and food is related to its architecture, which apart from being a direct measure of the state of the meadow, drives the secondary production, affecting the consumption and predation of organisms associated and, therefore, shaping its associated biodiversity. Seagrass structural complexity is then strictly connected with most of the ecological interactions, the structure of the community and the number of functions expressed by the underlying community. Here we present the results of our research where biodiversity is studied in a gradient of habitat structural complexity (shoot density; based on the hypothesis in which: higher complexity = higher biodiversity) to investigate its relationship to some indicators of ecosystem functions such as habitat provision, sediment stabilization and carbon sequestration. These results represent an important step in understanding the underlying mechanisms that drive ecosystem functioning, which then can be used to inform decisionmakers about the relevance of biodiversity when prioritizing conservation actions.

Besides providing important ecosystem functions, seagrasses are highly productive habitat-forming species essential in supporting fish diversity. In the Mediterranean Sea, seagrasses represent the main component of the sublittoral marine environment hosting a huge number of fish species that use this habitat for reproduction, foraging and/or refuge from predation. Despite these key roles, a complete synthesis of fish species observed in different seagrass habitats at Mediterranean basin scale is still lacking, potentially limiting the understanding of the main mechanisms involved in determining fish diversity patterns.

We performed a systematic review by implementing a semi-automated, threshold-based filtering pipeline that allowed building up one of the most up-to-date databases covering all fish species reported in native Mediterranean seagrasses, including specific functional traits known to be involved with the potential use of seagrasses by fish. From a total of 62,881 papers covering decades of literature, the filtering pipeline allowed selecting 165 papers reporting original and unduplicated data about the presence of fish species on seagrasses, alongside spatial information, sampling methods, habitat composition, substrates and the life stage at which species have been reported. The database is composed of more than 9,000 records, for a total number of 248 species belonging to 75 families recorded from 101 localities and 10 different habitats.

Multivariate analysis allowed illustrating the potential of the database, providing support to several assumptions repeatedly stated in literature but so far sustained mainly by local and fragmented data, ultimately suggesting the onset of a general pattern in the occurrence of species, mostly based on life history and driven by body size and feeding habits. Although we evidenced unexpected knowledge gaps, our dataset could provide a sound basis for scientists and managers across many fields, from fisheries to biodiversity assessment and conservation.

Understanding the determinants of range extent and distribution of species is an important goal in community ecology. Based on the mid-domain effect (MDE) hypothesis, species range extent and their distribution are random within the limits of a spatial domain (e.g., an elevational or latitudinal gradient). On the other hand, Rapoport’s rule postulates that species range extent and distribution vary according to the climatic fluctuations experienced along a climatic variability gradient. As climatic variability usually increases with elevation, species are expected to sort based on their climatic niche. Climatic specialists should only occur in climatically stable regions and therefore should present narrow range extents. Climatic generalists, conversely, are expected to inhabit both climatically stable and unstable areas and therefore present wide range extents. As a result, average range extents should increase from lower to higher elevations. We explored whether the hyperdiverse myrmecofauna of the Santa Catalina Mountains in the Madrean Sky Island Region conforms to the MDE hypothesis or Rapoport’s rule. Ants were collected using pitfall traps. Elevational range extent was calculated for each species. Then, we divided the elevational range into bands of 50 m (from 1000 to 2800 m) and calculated for each band the mean species range extent. Finally, we regressed mean range extents against elevation. Since, according to Rapoport’s rule, the variability of range extent should decline with increasing elevation (i.e., climatic variability), we also regressed the coefficient of variation of range extent against elevation. Mean range extent weakly increased with increasing elevation, while the coefficient of variation did not decline with increasing elevation. These findings suggest that, in general, the ants of the study area do not follow Rapoport’s rule but conform to the MDE hypothesis.

Anaerobic fungi (AF) thrive in the rumen ecosystem, where they are recognised as the microbial component with the greatest capacity to hydrolyse plant biomass. Due to their ability to also degrade lignin and the strictly anaerobic conditions of the rumen, AFs have recently been taken into consideration for promising biotechnological applications. These include the energy valorization of waste biomass and in particular anaerobic digestion (AD) applied for the production of methane-rich biogas. However, the incomplete knowledge about AFs role in the AD trophic chain as well as the difficulty in detecting fungal structures metabolically active during the process limit the studies of their application at industrial scale. To gain new insights into the ecological role of AFs during AD, a bioaugmentation experiment was conducted in batch configuration using wheat straw as substrate and digestate from an industrial AD plant as inoculum. Moreover, a protocol was defined for the detection of metabolically active fungal structures. The results suggest that the role of AFs in the AD trophic web is at least twofold. They are both at its base, before the hydrolytic bacteria with which they cooperate, and at its apex, directly related with methanogenic Archaea. The latter connection seems to prevail in case of AD metabolic imbalance, in response to the need to consolidate the trophic web. In terms of bioprocess, bioaugmentation made AD more efficient, with an increase in CH₄ production of up to 80% when using AF and up to 120% in case of combined bioaugmentation with a pool of fermenting bacteria. These findings are of particular interest for future applications of AF aimed at producing sustainable and renewable energy also contributing to ecological waste disposal.

The geometrid moths (Lepidoptera Geometridae), whose larvae have a quite restricted food niche and establish strong links with their host plants and habitats, are good candidates as bio-indicators of environmental quality. We analyzed the diversity pattern of geometrid moths and plant communities on dune landscapes in the Central Adriatic coast in a N2K site (SIC IT7228221 Foce Trigno - Marina di Petacciato), included in the LTER Network LTER_EU_IT_081). Moth and plant communities were sampled along three strips perpendicularly to the seashore. Within each strip, we sampled vegetation and moths on two dune sectors: (a) shifting dunes (EU Habitats 2120 and 2230), and (b) fixed dunes (EU Habitat 2260). Moths were collected using light traps with UV LEDs every 15 days for one year (December 2021 - November 2022). Vegetation was sampled by randomly placing 5 (4 m × 4 m) plots per sector in each strip (30 plots). For both moths and vascular plants, we compared the community structure of shifting dunes and fixed dunes. We also used multivariate analyses to explore the relation between moths and vegetation. We recorded 37 moth and 71 plant species. Moth alpha-diversity showed similar values in shifting and fixed dunes, while species composition varied substantially (high beta-diversity) between the two zones. Fixed dunes hosted a greater number of moth species with larvae feeding on woody plants. Shifting dunes were home to generalist moths associated with herbaceous vegetation. The most abundant species on the fixed dunes were Cyclophora puppillaria and Peribatodes rhomboidaria (both associated with woody species - phanerophytes and chamaephytes). The most abundant species on the shifting dunes was Eucrostes indigenata (associated with Euphorbia paralias). Geometrid communities are tightly associated with the different zones of the dune vegetation and preserving dunes requires attention to both habitat types and their moths.

Marine Animal Forests (MAFs) encompass a set of the most important marine benthic habitats into which diversified sessile suspension feeders like anthozoans, sponges, bryozoans, corals, sea pens, ascidians, tube worms, and bivalves occur. Such a mix of sessile species raises unique structures and supports important ecosystem functions, providing three-dimensional environments suitable for a number of additional associated species, and ultimately resulting in biodiversity hotspots. In the last decades, some MAFs have been the object of international conventions, EU directives, and national policies to address human-induced disturbances. Effective conservation, monitoring, and restoration actions require summarizing the available information to include MAFs in conservation plans. In the present research, the main international policies for the protection of coastal and marine fauna were screened in order to provide a list of protected species occurring in the Mediterranean basin. These international normative documents include the Washington Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Convention on the Conservation of European Wildlife and Habitats (Bern Convention), the European Habitat Directive, and the Protocol concerning Specially Protected Areas and Biological Diversity in the Mediterranean (SPA/BD Protocol) of the Barcelona Convention. A wider view such as the one proposed by the International Union for Conservation of Nature (IUCN) is accompanying effective conservation measures. The obtained findings revealed that several MAF species are protected by some normative tools, nevertheless only a few species are reported by the EU Habitat Directive, which is the main legal instrument in the European nature conservation policy. This database represents a starting point to handle the dramatic loss of MAF biomass and biodiversity in the Mediterranean Sea, supporting the effective implementation of appropriate conservation and management measures in the Mediterranean basin.

Investigating the mechanisms underlying the organization and maintenance of phytoplankton communities is crucial, particularly in the context of climate change. Since Hutchinson's plankton paradox in 1961, numerous theories have explored phytoplankton species coexistence mechanisms in highly diverse local guilds, linking individual-based processes to broader ecosystem and global dynamics. However, despite significant advancements, these mechanisms remain not fully understood. Here, we present a conceptual niche-based approach to decode the mechanisms organizing phytoplankton biodiversity using phytoplankton occurrence and abundance data. The study is based on an integrated dataset of 127311 individual phytoplankton records, belonging to 306 taxa, collected across 24 transitional water ecosystems distributed among five biogeographical regions: the Northern Atlantic Ocean, South-Western Atlantic Ocean, South-Western Pacific Ocean, Indo-Pacific Ocean and the Mediterranean Sea. We investigated size-abundance and species-area relationships and biodiversity patterns in terms of richness, diversity and similarity at different levels of data aggregation and scale. Our findings revealed a high taxonomic diversity both at regional and intra-regional level, with the Northern Atlantic Ocean area showing the highest taxonomic diversity and the Indo Pacific Ocean area showing the highest morpho-functional diversity. Negative trends in species-area relationships have been observed in all ecoregions except for South-Western Atlantic Ocean. Overall, tropical ecoregions (South-Western Atlantic Ocean, South-Western Pacific Ocean, Indo-Pacific Ocean) exhibited high intraregional similarity (between 42 and 70%) while, mid-latitude regions (Northern Atlantic Ocean and Mediterranean Sea) showed low intraregional similarity (less than 20%). The achieved results suggest neutral and lottery competition theories as the most likely to explain biodiversity organizations in the phytoplankton guilts of the studied biogeographical areas. These results seem to indicate the potential use of commonly collected data on phytoplankton community to address the community organization when integrated with the proposed conceptual niche-based approach.

The Antarctic marine food web supports high biodiversity and ecosystem services, including carbon sequestration, fisheries and tourism. Climate change is altering sea ice dynamics, modifying resource availability with cascading effects throughout the food web. Fish fauna, a dominant component of Antarctic marine communities, reach high biomass densities even with limited resources. However, mechanisms underlying Antarctic fish coexistence are poorly understood. Understanding trophic niche partitioning among fish populations and their dependence on sea-ice resources is thus essential for predicting climate change effects on food webs and associated services.

This study investigated the trophic niche of six Antarctic fish species in Terra Nova Bay (Ross Sea) under conditions of low (winter) and high (late spring) resource availability to evaluate coexistence mechanisms. It is hypothesized that strong trophic niche partitioning occurs both within and between species, particularly during the less productive season. Individual stable isotope analysis of carbon and nitrogen was performed on muscles and livers, which provided information on the winter and the late spring diet, respectively. ITUs (Isotopic Trophic Units, Rossi et al., 2019) were used to quantify trophic-functional redundancy (as the number of species per ITU) and potential vulnerability to species invasion (as proportion of empy ITUs in total). In winter, species had narrow niches with differences between populations yet a very low differentiation in resource use among conspecifics. In late spring, trophic niches were broader, with conspecifics specialising on different resources while maintaining a low overlap with other species. While supporting coexistence, such marked trophic niche differentiations produced a low functional redundancy among the studied populations and hence a high potential vulnerability to species invasion. Our results highlight the importance of resource diversity, including sea-ice resources, for fish coexistence in Antarctic ecosystems. Consequently, changes in resource availability due to variations in sea ice coverage could impact biodiversity persistence.