Spatio-temporal distributions of zoobenthos in Mersin Bay (Levantine Sea, eastern Mediterranean) and the importance of alien species in benthic communities

<div><p></p><p>Spatio-temporal variations of soft-bottom zoobenthic communites in Mersin Bay were examined at seven stations between February and October 2009. A total of 337 species were encountered, of which Polychaeta had the highest number of species (136 species), and Mollusca possessed the highest number of individuals (65% of total specimens) and biomass (59% of total biomass). The highest benthos density (max. 9760 ind. m⁻²) and biomass (max. 133 g m⁻²) were found at shallow-water stations, whereas the highest diversity index values were calculated at the deepest station. The molluscs <i>Cerithidium diplax</i>, <i>Corbula gibba</i> and <i>Bittium reticulatum</i> dominated the area. Changes of zoobenthic communities were spatial rather than temporal and were strongly correlated with depth and the sediment structures. A total of 40 alien species were found in the area, of which 15 species were possibly transported to the area by ships and the others were Lessepsian migrants. The most domiant alien species in the area were <i>C. diplax</i>, <i>Finella pupoides</i>, <i>Notomastus mossambicus</i> and <i>Amphiodia obtecta</i>. Alien species formed dense populations at shallow water stations, and accounted for 12% of total number of species and 31% of total number of individuals in the area. The community parameters estimated for alien species significantly differed among stations but not among sampling periods. The main factors negatively affecting the number of alien species and individuals were depth, the clay percentage and total organic carbon concentration in sediment. The number of native species and individuals in the area show moderate positive correlations with those of aliens.</p> </div

Distribution of marine caves in the Mediterranean Sea.

<p>Different colours indicate the variation in cave number per planning unit, warmer colours illustrating planning units with higher number of caves. Information on the spatial distribution of marine caves was extracted from various sources which are provided as a supplementary material.</p

Distribution of coralligenous formations in the Mediterranean Sea.

<p>Red cells indicate planning units with the presence of coralligenous formations. Information on the spatial distribution of coralligenous formations was extracted from various sources which are provided as a supplementary material.</p

Distribution of opportunity cost for commercial fishing, non-commercial fishing and aquaculture across the Mediterranean Sea.

<p>Darker shades indicate areas with higher opportunity cost (in Euros).</p

Spatial overlap between the identified priority conservation areas and existing MPAs in each ecoregion.

<p>Different colours have been used to illustrate the percentage of planning units for the A. Alboran Sea, B. Algero-Provencal Basin, C. Tunisian Plateau, D. Levantine Sea, E. Tyrrhenian Sea, F. Adriatic Sea, G. Ionian Sea, and H. Aegean Sea, that a) did not contain an MPA but was identified as priority area (red), b) contained an MPA and was identified as priority area (orange), c) did not contain an MPA and was not identified as a priority area (green) and d) contained an MPA but was not identified as priority area (blue).</p

Percentage of area cover and opportunity cost when planning at different spatial scales.

<p>Percentage area cover and percentage opportunity cost of planning units required in each ecoregion of the Mediterranean Sea for scenarios a and b (scenario a: selection of priority areas across the whole Mediterranean Sea, and b: selection of priority areas for each ecoregion separately).</p

Map of the study area divided into 8 ecoregions, <i>sensu</i> Notarbartolo di Sciara and Agardy (2010).

<p>The study area comprises the entire Mediterranean Sea, excluding areas deeper than 1000</p

Distribution of <i>Posidonia oceanica</i> meadows in the Mediterranean Sea.

<p>Green cells indicate planning units with the presence of <i>P. oceanica</i>. Information on the spatial distribution of <i>P. oceanica</i> was extracted from various sources which are provided as a supplementary material.</p

Distribution of habitats across ecoregions of the Mediterranean Sea.

<p>We calculated (i) the number of planning units in each ecoregion (N); (ii) the number of planning units with presence of each habitat in each ecoregion (<i>P. oceanica</i>: Ns, coralligenous: Nc, marine caves: Nmc), (iii) the percentage of Ns, Nc, Nmc across the Mediterranean Sea (N %), (iv) the percentage of Ns, Nc, Nmc across each ecoregion (Nr %); (v) the number of caves in each ecoregion (Nc) and (vi) the percentage of marine caves of each ecoregion across the Mediterranean Sea (Nc %).</p