Large-scale assessment of Mediterranean marine protected areas effects on fish assemblages.

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.

Assessment of the use potential of edible sea urchins (Paracentrotus lividus) processing waste within the agricultural system: influence on soil chemical and biological properties and bean (Phaseolus vulgaris) and wheat (Triticum vulgare) growth in an amended acidic soil.

In this study we evaluated the influence of ground purple sea urchin (Paracentrotus lividus) endoskeletons, a processing waste common to all edible sea urchin plants, on the chemical, biochemical and microbiological features of an acidic (pH 5.65) sandy-loam soil. The purple sea urchin endoskeletons were characterized by a high content of total carbonates (∼94%), a moderately alkaline pH in water (pH 7.88) and electrical conductivity values (3.55 mS/cm) very similar to those of commercial lime. To evaluate the influence of the P. lividus endoskeletons on soil properties four different amendment rates were tested, notably 0.5, 1.0, 3.0 and 5.0% based on soil dry weight, and the effects compared with those recorded on unamended control soil. The addition of the purple sea urchin processing waste caused an immediate and significant pH increase which was positively related to the rate of the amendment addition. After a six months equilibration period, the differences in soil pH were still evident and significant increases of electrical conductivity and available phosphorus were also detected in soils with the higher amendment rates. The number of heterotrophic and cellulolytic bacteria and actinomycetes significantly increased after amendment addition while the number of culturable fungi steadily declined. The analysis of the Biolog Community Level Physiological Profile indicated a clear influence of the purple sea urchin processing waste on the structure of the native microbial community while a significant increase of microbial functionality (i.e. dehydrogenase activity) was recorded in soil treated with the higher amendment rates (i.e. 3.0 and 5.0%). The improvement of microbial abundance and functionality as well as the change of the microbial community structure were ascribed to the pH shift induced by the P. lividus processing waste. To investigate possible effects on soil fertility, dwarf bean (Phaseolus vulgaris) and wheat (Triticum vulgare) growth were also assessed in a pot experiment. Plant growth was unaffected (wheat) or stimulated (bean) by the amendment addition in the 0.5-3.0% range while the higher amendment rate (i.e. 5.0%) was detrimental for both plant species indicating a phytotoxic effect which could be due to different factors such as an excess of calcium in soil, a suppression of Mg uptake or the higher EC values detected at the highest amendment rate. It is concluded that ground P. lividus endoskeletons have potential as a soil amendment to ameliorate chemical and biological properties of acidic Mediterranean soils. This seems particularly relevant, especially at the lower amendment rates, since for the first time, a sustainable management system is proposed for P. lividus processing waste, which foresees economic value in the sea urchin by-product through its re-use within the agricultural production system.