Thanos Dailianis

The biodiversity of the Mediterranean Sea: estimates, patterns, and threats.

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well. This abstract has been translated to other languages (File S1).

Population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) in the northern Aegean Sea (NE Mediterranean)

The population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) were studied in the northern Aegean Sea in samples collected annually (1997–2000) in summer, through experimental trawl, at depths down to 600 m. Females were larger than males in Plesionika martia and Plesionika heterocarpus; no significant differences in size of males and females were found in Chlorotocus crassicornis and Plesionika antigai. A trend of increasing size with depth was observed, as well as a linear increase in the proportion of females with increasing size. Sex ratio was skewed towards females at all depths in P. antigai, while in P. heterocarpus and C. crassicornis males dominated the intermediate depths. Negative allometries were apparent in the carapace length–weight relationships in males of all species. Isometric relationships were found in females apart from in P. heterocarpus. The population patterns conform to relevant Mediterranean reports. However, some population differences exist that may reflect the distinct environmental conditions prevailing in the study area.

Assembling ecological pieces to reconstruct the conservation puzzle of the aegean sea

The effective conservation of marine biodiversity through an integrated ecosystem-based management approach requires a sound knowledge of the spatial distribution of habitats and species. Although costly in terms of time and resources, acquiring such information is essential for the development of rigorous management plans and the meaningful prioritization of conservation actions. Located in the northeastern part of the Mediterranean, the Aegean Sea represents a stronghold for marine biodiversity. However, conservation efforts are hampered by the apparent lack of spatial information regarding marine habitats and species. This work is the first to address this knowledge gap by assembling, updating, and mapping information on the distribution of key ecological components. A range of data sources and methodological approaches was utilized to compile and complement the available data on 68 ecological features of conservation interest (58 animal species, six habitat categories, and four other vulnerable ecological features). A standardized data evaluation procedure was applied, based on five semi-quantitative data quality indicators in the form of a pedigree matrix. This approach assessed the sufficiency of the datasets and allowed the identification of the main sources of uncertainty, highlighting aspects that require further investigation. The overall dataset was found to be sufficient in terms of reliability and spatiotemporal relevance. However, it lacked in completeness, showing that there are still large areas of the Aegean that remain understudied, while further research is needed to elucidate the distribution patterns and conservation status of several ecological features; especially the less charismatic ones and those found in waters deeper than 40 m. Moreover, existing conservation measures appear to be inadequate to safeguard biodiversity. Only 2.3% of the study area corresponds to designated areas for conservation, while 41 of the ecological features are underrepresented in these areas. Considering the high geomorphological complexity and transnational character of the Aegean Sea, this study does not offer a complete account of the multifaceted diversity of this ecoregion. Instead, it represents a significant starting point and a solid basis for the development of systematic conservation plans that will allow the effective protection of biodiversity within an adaptive management framework.

Spatio-temporal benthic biodiversity patterns and pollution pressure in three Mediterranean touristic ports

The Mediterranean Sea is one of the busiest areas worldwide in terms of maritime activity, facing considerable anthropogenic disturbance, such as pollution by hydrocarbons and heavy metals. The present study has evaluated the environmental and benthic biodiversity characteristics of three touristic ports, Cagliari (Sardinia, Italy), Heraklion (Crete, Greece) and El Kantaoui (Tunisia), based on the combined assessment of physical parameters, chemical variables (i.e. nutrients, pigments), sediment pollution and macrobenthic biodiversity. Different port sectors (leisure, fishing, passenger, cargo, shipyard) and different seasons (winter, before touristic period, after touristic period) were compared. Salinity and sediment concentration of copper and antimony were the three environmental parameters most highly correlated with benthic species composition and diversity. Both the environmental variables and the benthic biodiversity patterns were significantly different between the three ports (i.e. different geographical locations). Heraklion port was heavily polluted by AHs in surface and anoxic sediments and had the highest percentage of opportunistic species, while Cagliari had the highest levels of PAHs and UCM and low species richness. El Kantaoui port was less polluted and characterised by a richer biodiversity. The shipyard sector in Heraklion port was significantly different from all other sectors in terms of abiotic and biotic parameters. Physico-chemical and pollution variables recorded during the period after tourism (late summer) were significantly different from the ones recorded in winter. Seasonal differences were not significant between benthic species diversity patterns, but were revealed when the patterns derived from the aggregation of higher taxonomic levels were compared. The present study indicates that a regular-basis monitoring plan including evaluation of environmental health based on benthic biodiversity, can provide a basis for perceiving changes and reveal the degree of anthropogenic disturbance in port environments.

Testing the robustness of Citizen Science projects: Evaluating the results of pilot project COMBER

Abstract Background Citizen Science (CS) as a term implies a great deal of approaches and scopes involving many different fields of science. The number of the relevant projects globally has been increased significantly in the recent years. Large scale ecological questions can be answered only through extended observation networks and CS projects can support this effort. Although the need of such projects is apparent, an important part of scientific community cast doubt on the reliability of CS data sets. New information The pilot CS project COMBER has been created in order to provide evidence to answer the aforementioned question in the coastal marine biodiversity monitoring. The results of the current analysis show that a carefully designed CS project with clear hypotheses, wide participation and data sets validation, can be a valuable tool for the large scale and long term changes in marine biodiversity pattern change and therefore for relevant management and conservation issues.