Spread of alien species (AS) is a serious threat to marine habitats and analysis of principal descriptors of their occurrence is pivotal to set reliable conservation strategies. In order to assess the susceptibility of marine habitats to biological invasions, a dataset was gathered of the occurrence of 3899 species from 29 phyla, taken from 93 marine sites located along the Italian coast in the period 2000-2012. In total, 61 AS belonging to 11 phyla have been recorded. Invertebrates were the most represented (63%). Alien species were found in all the habitats examined (EUNIS, level 2), although they showed highest abundance in benthic habitats. Most of the AS were associated with a single EUNIS habitat, while some of them were present in more than one habitat. Trans-habitat occurrence suggests the potential invasiveness of AS. According to statistical analysis, AS recorded could have been more numerous, since some of the marine habitats seemed to be still unsaturated. The model that best describes the spread of AS takes account of both native species richness (Rn) and EUNIS habitat type as explanatory variables. The number of observed AS was directly related to Rn and it was highest in rocky circalittoral and infralittoral habitats. The results of this macro-ecological study focus on the importance of performing large-scale studies, since adopting ecosystem approaches to marine invasion management seems especially fruitful. The results, moreover, highlight the importance of AS monitoring of different habitats, from those subjected to anthropogenic pressure, historically considered to be hubs of introduction of AS, to the most biologically rich and diverse marine habitats. Indeed, it is necessary to set monitoring strategies to detect the introduction, the distribution and persistence of AS over time. These recommendations are especially significant in the light of the strategic plans currently under formulation in Mediterranean countries with regard to AS monitorin

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CO2 leakage alters benthic carbon cycling and leads to shifts in the food web and ecological functioning of local communities.

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Knowledge on ecosystem functioning can largely contribute to promote ecosystem-based management and its application. The Mar Piccolo of Taranto is a densely populated area at a high risk of environmental crisis. Here, planktonic primary production (PP) and heterotrophic prokaryotic production (HPP) were measured as proxies of functioning in three sampling sites located in two inlets at different levels of industrial contamination, during three sampling surveys (June 2013, February and April 2014). To have a better overall view and provide some insights into the benthic-pelagic coupling, we integrated PP and HPP in the water column with those in the sediments and then discussed this with the origin of the organic matter pools based on analysis of stable isotopes. Heavy metals and polychlorobiphenyls (PCBs) were also analysed in the surface (1 cm) sediment layer and related to the overall ecosystem functioning. Multidimensional scaling (MDS) analysis, based on the main data, clearly separated the second inlet from the first one, more severely impacted by anthropogenic activities. The stable isotope mixing model suggested the prevalent terrestrial/riverine origin of the particulate organic matter pools (mean 45.5 %) in all sampling periods, whereas phytoplankton contributed up to 29 % in February. Planktonic PP and HPP rates followed the same pattern over the entire study period and seemed to respond to phytoplankton dynamics confirming this community as the main driver for the C cycling in the water column. On the contrary, benthic PP rates were almost negligible while HPP rates were lower or comparable to those in the water column indicating that although the Mar Piccolo is very shallow, the water column is much more productive than the surface sediments. The sediment resuspension is likely responsible for a pulsed input of contaminants into the water column. However, their interference with the proper functioning of the pelagic ecosystem seems to be limited to the bottom layers.

Sediment samples were collected in 4 sites along a salinity gradient (between 0.2 and 27.3) of the Aussa River (Marano Lagoon, northern Adriatic Sea, Italy) and a decreasing gradient of industrial contamination downstream (from Stn A1 to Stn A4) to assess how a riverine-lagoonal system responds to chemical contamination by applying an integrative measure of its benthic ecological properties. Benthic biodiversity (primary producers, meiofauna, macrofauna) along with other structural and functional parameters were related to contamination. Meiofaunal abundance varied between 176 ± 65 and ~4000 ind. 10 cm −2 downstream. The macrofaunal composition shifted from one composed exclusively of chironomid larvae to a typically lagoonal one. At Stn A1, the benthic microalgal abundance exceeded 500 000 cells cm −3 and seemed unaffected by contamination. In the freshwater-impacted site, primary production was one order of magnitude higher than in the more saline one (7.20 and 0.60 µg C cm −3 h −1, respectively). High organic carbon enrichment (65 mg C g dry −1) at Stn A2 probably caused the highest community respiration, estimated by O 2 microprofiles, along with the highest exoenzymatic activities (β-glucosidase, leucine aminopeptidase and lipase). The 4 investigated sites were well separated by principal component analysis along a decreasing gradient of organic load. An extremely active microbial community in the contaminated site ensured high production and degradation rates. Correct assessment of the benthic ecosystem functioning in polluted areas may represent a useful tool for transitional system management in order to plan environmental interventions in a rational way.