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Abstract In the Mediterranean Sea (Med Sea), Dissolved Organic Matter (DOM) dynamics shows some peculiarities that can be investigated by using its optical properties. Despite being a marginal sea, the Med Sea behaves as a miniature ocean for DOM concentrations and distribution. Its surface waters are "greener" than it would normally result from their generally low phytoplankton content and in the deep waters DOC is ~1000 years older and more degraded than in the Atlantic Ocean. These observations suggest a greater contribution of allocthonous substances to the DOM pool in this basin. With this work we aim at presenting new data on optical properties of chromophoric DOM (CDOM) and fluorescent DOM (FDOM) in open sea waters of the Med Sea, in order to investigate the main drivers of CDOM and FDOM dynamics in both surface and deep waters and to get insights into their origin. Our data confirm the occurrence of DOM with a different composition with respect to the oceans and suggest some differences with respect to other marginal basins, opening intriguing questions about the source and cycle of allocthonous molecules in the open sea waters of the Med Sea. CDOM absorption in the western Med Sea and Ionian Sea is generally lower than that observed in the other marginal seas, but higher than in the oceans. The parallel factor analysis unveiled the presence of one PAH-like and one terrestrial humic-like component that were found in the other marginal basins but that were not found in the open oceans. In contrast to the oceans and most of the marginal seas, only one protein-like component was found. Net production of humic-like FDOM as function of mineralization was not observed in the intermediate and deep waters of the Med Sea, supporting that in this basin CDOM/FDOM dynamics is different than in the oceans. In the surface layer, photobleaching plays a relevant role in the removal of humic-like fluorescence, and the release of both protein-like and humic-like substances occurs in proximity of the deep chlorophyll maximum. Highlights • Humic acids are a major component of DOM pool in the Med Sea. • No production of humic-like FDOM as function of mineralization rates. • a 254 can be a good proxy for DOC in the Med Sea. • Protein-like and humic-like substances are released in the surface layer. • External sources plays a crucial role in DOM dynamics in the Med Sea. [ABSTRACT FROM AUTHOR]

The Mediterranean Lessepsian migrations excite the interest of biologists who are devoted to inferring the effects of selection on the genetic structure of immigrants. The bluespotted cornetfishFistularia commersoniiis an Indo-Pacific species that was first recorded in the Levantine cost of Mediterranean, and within a few years, it rapidly expanded throughout the entire basin. Studies on its genetic variability, performed via mitochondrial sequencing of the Mediterranean specimens, suggest that a limited number of mitochondrial lineages passed through the Suez Canal. However, nuclear markers provide a scenario, with a high genetic variability among the MediterraneanF. commersoniimigrants, along with the occurrence of haplotype sharing between the Mediterranean and the Red Sea. The aim of this study was to enlarge the number of Mediterranean sites in order to evaluate if the rapid expansion and different patterns of spread ofF. commersoniiin the basin could have led to a genetic structuring. The analysis was carried out by sequencing mitochondrial D-loop I in individuals from Sardinia, Sicily, Tunisia, Lampedusa, Libya and Lebanon. Sequences available from previous studies were included in the data set, allowing us to obtain a data set that likely represents the entire distribution range of the species. Results suggest the possible occurrence of two mitochondrial lineages involved in the Mediterranean invasion ofF. commersonii, a bottleneck may have caused a loss in the genetic variation, leading to the fixation of specific lineages as an adaptive response to the new environmental conditions. [ABSTRACT FROM AUTHOR]

Pinna nobilis is the largest endemic Mediterranean marine bivalve. During past centuries, various human activities have promoted the regression of its populations. As a consequence of stringent standards of protection, demographic expansions are currently reported in many sites. The aim of this study was to provide the first large broad-scale insight into the genetic variability of P. nobilis in the area that encompasses the western Mediterranean, Ionian Sea, and Adriatic Sea marine ecoregions. To accomplish this objective twenty-five populations from this area were surveyed using two mitochondrial DNA markers (COI and 16S). Our dataset was then merged with those obtained in other studies for the Aegean and Tunisian populations (eastern Mediterranean), and statistical analyses (Bayesian model-based clustering, median-joining network, AMOVA, mismatch distribution, Tajima’s and Fu’s neutrality tests and Bayesian skyline plots) were performed. The results revealed genetic divergence among three distinguishable areas: (1) western Mediterranean and Ionian Sea; (2) Adriatic Sea; and (3) Aegean Sea and Tunisian coastal areas. From a conservational point of view, populations from the three genetically divergent groups found may be considered as different management units. [ABSTRACT FROM AUTHOR]

A new species of mesopsammic polyclad, Theama mediterranea sp. nov., from lower intertidal habitats of the Mediterranean Sea, is described. The species differs from congeneres found in the tropical Pacific and the Atlantic coast of South America, in terms of size, structure of the male copulatory organ and number of eyes. T. mediterranea sp. nov. has a short pelagic juvenile phase, while adults are strictly interstitial; the life cycle is annual. Based on observation of the type material of Theama evelinae Marcus, 1949, the genus Eutheama Faubel, 1983 is synonymized with Theama Marcus, 1949. [ABSTRACT FROM AUTHOR]

Abstract: The effect of human trampling on the abundance of small invertebrates inhabiting rocky shallow bottoms was studied at Asinara Island MPA. To this aim we have conducted two experiments. The first was a quantitative study and tested the hypothesis that small invertebrates are more abundant at no-entry locations than at the location visited by tourists through time (before, during and after tourist season). The second was a manipulative experiment and tested the hypothesis that the abundance of small invertebrates is indirectly related to experimental trampling intensities. The effect due to tourist visitation was not highlighted on overall assemblages, suggesting that present seasonal tourist load at the MPA does not cause a significantly negative effect on the zoobenthic community studied. Although tourists exhibited trampling activity at the visited location, none of taxa examined showed a significant lower abundance during and strictly after the end of seasonal tourism peak in the visited location, rather than at control locations. However, results obtained with the second experiment suggested that the effects of different experimental trampling intensities on small invertebrates were variable among taxa. The experimental trampling caused immediate declines in the density of tanaids, nematodes, acari, bivalves, gammarids, echinoderms, isopods, and harpacticoids. For some of these taxa a recovery in abundance was observed within one month. This kind of data may offer important information to estimate the number of visitors compatible with the sensitivity of zoobenthic assemblages, and may substantially contribute to appropriate MPA management. [Copyright &y& Elsevier]

In the Mediterranean Sea, Cystoseira species are the most important canopy-forming algae in shallow rocky bottoms, hosting high biodiverse sessile and mobile communities. A large-scale study has been carried out to investigate the structure of the Cystoseira -dominated assemblages at different spatial scales and to test the hypotheses that alpha and beta diversity of the assemblages, the abundance and the structure of epiphytic macroalgae, epilithic macroalgae, sessile macroinvertebrates and mobile macroinvertebrates associated to Cystoseira beds changed among scales. A hierarchical sampling design in a total of five sites across the Mediterranean Sea (Croatia, Montenegro, Sardinia, Tuscany and Balearic Islands) was used. A total of 597 taxa associated to Cystoseira beds were identified with a mean number per sample ranging between 141.1 ± 6.6 (Tuscany) and 173.9 ± 8.5(Sardinia). A high variability at small (among samples) and large (among sites) scale was generally highlighted, but the studied assemblages showed different patterns of spatial variability. The relative importance of the different scales of spatial variability should be considered to optimize sampling designs and propose monitoring plans of this habitat. [ABSTRACT FROM AUTHOR]