Contamination of planktonic food webs in the Mediterranean Sea: Setting the frame for the MERITE-HIPPOCAMPE oceanographic cruise (spring 2019).

This paper looks at experiential feedback and the technical and scientific challenges tied to the MERITE-HIPPOCAMPE cruise that took place in the Mediterranean Sea in spring 2019. This cruise proposes an innovative approach to investigate the accumulation and transfer of inorganic and organic contaminants within the planktonic food webs. We present detailed information on how the cruise worked, including 1) the cruise track and sampling stations, 2) the overall strategy, based mainly on the collection of plankton, suspended particles and water at the deep chlorophyll maximum, and the separation of these particles and planktonic organisms into various size fractions, as well as the collection of atmospheric deposition, 3) the operations performed and material used at each station, and 4) the sequence of operations and main parameters analysed. The paper also provides the main environmental conditions that were prevailing during the campaign. Lastly, we present the types of articles produced based on work completed by the cruise that are part of this special issue.

Chemical contamination baseline in the Western basin of the Mediterranean Sea based on transplanted mussels.

The MYTILOS project aimed at drawing up a preliminary report on coastal chemical contamination at the scale of the Western Mediterranean (continental coasts of the Balearic Islands, Sicily, Sardinia, Corsica and Maghreb) based on a transplanted mussels methodology validated along the French coasts since 1996 by Ifremer and the Rhône Méditerranée & Corsica water board. MYTILOS is backed up by the INTERREG III B/MEDOC programme, the PNUE/PAM-MEDPOL and Rhône Méditerranée & Corsica water board. Three cruises (2004, 2005, 2006) have taken place to assess the first state of chemical contamination along the Western Mediterranean shores with the same methodology. Approximately 120 days were spent at sea deploying and retrieving 123 mussel bags. The results obtained for all studied contaminants were equivalent to those obtained along the French coast according the RINBIO network. These similarities relate to both the highest measured levels and background levels throughout the 123 stations. The areas of greatest impact were mainly urban and industrial centers and the outlets of major rivers, with a far higher midsea impact on the dilution of organic compounds than on metals. Metal levels measured in midsea zones were found to be similar to those in natural shellfish populations living along the coast. On a global scale we can observe that the contaminants levels in the Mediterranean Sea are in the same range as in other areas worldwide. Overall, the research demonstrates the reliability of this methodology for marine pollution monitoring, especially in the Mediterranean sea.

Western Mediterranean coastal waters--monitoring PCBs and pesticides accumulation in Mytilus galloprovincialis by active mussel watching: the Mytilos project.

In order to evaluate the contamination levels in the Western Mediterranean basin, the active mussel watch methodology has been applied. This methodology consists of mussel transplantation (Mytilus galloprovincialis) from non impacted areas to selected coastal areas, characterised by potential impact from the continent due to contaminating sources. The areas of interest were selected along the entire coastal development of the Western Mediterranean sea, 122 sites in total. The time of mussel caging exposure was 12 weeks. The project was co-financed in the frame of the Interreg IIIB Meddoc Programme, aimed at determining the overall chemical quality of the Mediterranean sea, consistent with the Water Framework Directive 2000/60. Several partners representative of the coastal Mediterranean Countries were involved in the Project, with the purpose of building up a common surveillance network, adopting shared methodologies. In this paper we present the results of three yearly monitoring campaigns (2004, 2005, 2006) carried out along the coasts of Italy, France, Spain, Morocco, Algeria and Tunisia, including the coastal environment of Baleares, Sicily, Sardinia and Corsica. The contamination levels of Pesticides (DDT and its metabolites, Hexachlorocyclohexane isomers alpha and gamma) and Polychlorinated biphenyls, are reported and discussed. Statistical elaborations performed on the original data set were mainly aimed at validating the raw sample distributions, by means of the Johnson method. Both DD and PCB species frequency distributions have been approximated to appropriate theoretical distributions, belonging to the Log-normal and Bounded families. By integrating the related Probability Density Functions (p.d.f.), different accumulation values for DDT, DDD and DDE and PCB species have been estimated, corresponding to fixed percentage points of the area under the respective curves. By choosing appropriate probability level boundaries (33rd and 66th percentile), different regional zones have been ranked in terms of low, medium and high accumulation for Pesticides and PCBs.

The use of a predictive habitat model and a fuzzy logic approach for marine management and planning.

Bottom trawl survey data are commonly used as a sampling technique to assess the spatial distribution of commercial species. However, this sampling technique does not always correctly detect a species even when it is present, and this can create significant limitations when fitting species distribution models. In this study, we aim to test the relevance of a mixed methodological approach that combines presence-only and presence-absence distribution models. We illustrate this approach using bottom trawl survey data to model the spatial distributions of 27 commercially targeted marine species. We use an environmentally- and geographically-weighted method to simulate pseudo-absence data. The species distributions are modelled using regression kriging, a technique that explicitly incorporates spatial dependence into predictions. Model outputs are then used to identify areas that met the conservation targets for the deployment of artificial anti-trawling reefs. To achieve this, we propose the use of a fuzzy logic framework that accounts for the uncertainty associated with different model predictions. For each species, the predictive accuracy of the model is classified as 'high'. A better result is observed when a large number of occurrences are used to develop the model. The map resulting from the fuzzy overlay shows that three main areas have a high level of agreement with the conservation criteria. These results align with expert opinion, confirming the relevance of the proposed methodology in this study.