Marine protected areas (MPAs) were acknowledged globally as effective tools to mitigate the threats to oceans caused by fishing. Several studies assessed the effectiveness of individual MPAs in protecting fish assemblages, but regional assessments of multiple MPAs are scarce. Moreover, empirical evidence on the role of MPAs in contrasting the propagation of non-indigenous-species (NIS) and thermophilic species (ThS) is missing. We simultaneously investigated here the role of MPAs in reversing the effects of overfishing and in limiting the spread of NIS and ThS. The Mediterranean Sea was selected as study area as it is a region where 1) MPAs are numerous, 2) fishing has affected species and ecosystems, and 3) the arrival of NIS and the northward expansion of ThS took place. Fish surveys were done in well-enforced no-take MPAs (HP), partially-protected MPAs (IP) and fished areas (F) at 30 locations across the Mediterranean. Significantly higher fish biomass was found in HP compared to IP MPAs and F. Along a recovery trajectory from F to HP MPAs, IP were similar to F, showing that just well enforced MPAs triggers an effective recovery. Within HP MPAs, trophic structure of fish assemblages resembled a top-heavy biomass pyramid. Although the functional structure of fish assemblages was consistent among HP MPAs, species driving the recovery in HP MPAs differed among locations: this suggests that the recovery trajectories in HP MPAs are likely to be functionally similar (i.e., represented by predictable changes in trophic groups, especially fish predators), but the specific composition of the resulting assemblages may depend on local conditions. Our study did not show any effect of MPAs on NIS and ThS. These results may help provide more robust expectations, at proper regional scale, about the effects of new MPAs that may be established in the Mediterranean Sea and other ecoregions worldwide.

The effects of diving activity in different Mediterranean subtidal habitats are scarcely known. This study evaluates diver behaviour (for example time spent in each habitat), use (contacts made with the substrate) and immediate effects of diver contact on benthic species in a marine protected area (MPA) in\ud Sicily. Over a two-year period, intentions of 105 divers were observed within seven subtidal habitats: algae on horizontal substrate, algae on vertical substrate, Posidonia oceanica, encrusted walls, caves, sand and pebbles. Divers selected a habitat in proportion to its availability along the scuba trail. On average, each diver made 2.52 contacts every seven minutes, and no differences were detected among the levels of\ud diver scuba certification. The highest rates of total and unintentional contacts were recorded on caves and encrusted walls, and the slow growing species Eunicella singularis and Astroides calycularis were the most frequently injured by divers. Most of the contacts were concentrated in the first minutes of the dives. The identification of diving effects in different habitats will\ud enable management strategies to specifically control this impact at a habitat scale, for example restricting the start of the dive to low vulnerability habitats would reduce damage to benthic organisms, allowing sustainable use of MPAs

Mediterranean trawl fisheries are characterized by a critical combination of high fishing effort and low size at first capture for most commercial species. In this study we tested the use of sorting grids installed on bottom trawl nets to minimize the catch of undersized deep-water rose shrimp (Parapenaeus longirostris, DPS) and European hake (Merluccius merluccius, HKE). The catch of a traditional trawl net was compared with that obtained with the same net equipped with ad hoc designed juveniles and trash excluder devices (JTEDs) during an experimental survey. Three different JTEDs were tested: the first (G1-SM40) was built with a net of 40-mm square mesh; the second (G2-ST20) and third (G3-ST25) with vertical steel bars spaced 20 and 25 mm, respectively. The probability of retaining DPS and HKE by length class in trawl nets with and without JTED was analysed using generalized additive mixed models. With G1-SM40, the reduction of undersized individuals in the cod-end was about 60% and 44% for DPS and HKE, respectively. With G2-ST20, a 34% catch decrease of HKE individuals smaller than 20 cm total length was observed. A loss of marketable fractions of DPS was recorded with G1-SM40 (–25%) and G2-ST20 (30%). Finally, JTD G3-ST25 was efficient at reducing the catch of undersized specimens of DPS and HKE, but showed a higher loss of marketable fractions than the other JTEDs. Although further fishing trials would be required to maximize the sorting efficiency of the grids, the results obtained clearly indicated that grids can substantially reduce unwanted catches of undersized DPS and HKE in Mediterranean bottom trawl fisheries.

Scuba diving is now one of the major form of commercial use of marine protected areas (MPAs) around the world and the control of its potential impacts on the marine environment represents a fundamental key to manage this recreational activity in highly dived areas. A potential tool to tackle such issues has been thought to be the definition of a value of recreational carrying capacity of an area, but this approach has been rarely considered management-effective. Therefore, the first step for effectively managing\ud scuba-diving should be ‘bottom-up’: characterizing the benthic communities potentially affected by diving and evaluating their vulnerability. Aim of this paper is to propose a tool to define an index of vulnerability for dive trails (STVI: scuba trail vulnerability index).\ud This has taken into consideration both physical and biological features of each trail. All the considered features are represented by non-quantitative variables, because either they are purely qualitative or their quantitative measurement is impractical. The management of such qualitative information and its translation into a formal methodology was performed by means of fuzzy logic, which has been repeatedly proposed as a powerful technique to develop indices of environmental quality. The approach adopted in this study provided a\ud useful tool for the preliminary assessment of the potential vulnerability of benthic assemblages to scuba-diving and may represent an alternative method to the assessment of\ud carrying capacity. The application of this index will enable management strategies for\ud potentially reducing the degradation of benthic organisms/assemblages, and allowing a\ud sustainable use of MPAs

Di Franco, A., Ferruzza, G., Baiata, P., Chemello, R., and Milazzo, M. 2010. Can recreational scuba divers alter natural gross sedimentation rate? A case study from a Mediterranean deep cave. – ICES Journal of Marine Science, 67: 871–874. Submarine caves are environments with features distinguishing them from other littoral habitats but, despite their ecological importance, their response to anthropogenic disturbance has been seldom verified. One potential threat affecting natural communities within caves is represented by recreational scuba diving. Divers' disturbance within marine caves is mainly related to physical contacts and increased sediment resuspension potentially affecting sessile organisms. The aim was to assess the potential effect of recreational divers' frequentation on the natural gross sedimentation rate (GSR) in a Mediterranean deep-water cave. To achieve this, sediment traps were deployed along a scuba trail before, during, and after the peak season for tourist-related diving. No effects of divers' frequentation were evident in terms of alteration of natural GSR, but findings will need to be validated for other caves to asses whether potential disturbance depends on frequentation levels and/or cave characteristics, i.e. sediment grain size or cave depth.