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The preliminary survey of the marine debris on the coasts of Kornati and Elaphiti islands (Adriatic Sea, Croatia)

Marine litter (or marine debris) is an artificial object that reaches the marine environment after use. The most frequent material in marine litter is plastics (categorized from micro- to megaplastics) due to their widespread use and long decomposition time (approx. 450 years for a plastic bottle). In recent times, the pollution of marine environments with microplastics has been widely addressed in scientific studies, which led to increasing scientific interest in the study of marine litter in general. The prerequisite for any marine litter management project is a detailed survey of the coasts to determine which parts are the most vulnerable and what are the driving mechanisms for accumulations of litter on those coasts. As a relatively long, narrow and semi-enclosed basin, the Adriatic Sea is considered a preferential area for marine litter accumulation in the whole Mediterranean due to prevailing winds and sea currents. Since the Adriatic coast is a European tourism hotspot, pollution with marine litter could potentially cause environmental and economic challenges. Adriatic islands are susceptible to marine litter pollution due to the exposition of their coasts and the fact that local communities depend almost exclusively on tourism. In this paper, we present the results of the preliminary survey of marine litter on the coasts of two archipelagos in the Croatian Adriatic: Elafiti islands in the south and the Kornati islands in the central part of the Adriatic Sea. The study sites were chosen because of their exposure to the open sea and their tourist appeal. Moreover, both locations have a high seasonal population while sparsely populated in the off season, so the locally produced waste can be excluded as the leading contributor to the marine litter. The survey was conducted visually and does not include any form of micro waste (microplastics, microorganisms, or the like) or marine and beach sediment pollution. We have approached the subject from an environmental geography point of view to determine some islands’ features regarding the coastal pollution state-of-the-art.The preliminary research was carried out on the Kornati islands in 2018. We have used that survey mainly to test the research methodology as we prepared the list of indicators, which were used to determine the features of marine litter, its type and possible origin. That methodology was later used in a similar study on the Elafiti islands. The methodology was established as a geographical concept from the physical and social point of view concerning wind and sea currents and other environmental settings. The list of environmental indicators included: 1) coast orientation, 2) exposure of the bay/cove to the open sea, 3) coastal vegetation presence and state, 4) distance between marine litter and the shoreline, and 5) landscape exposure of the waste area. To show the socio-geographical features of the marine litter locations, we have chosen: 6) the amount of litter (in m3), 7) origin of litter (information obtained from the packaging), 8) type and percentage of the litter type, 9) share of plastic litter (in %) and 10) type of litter distribution. During the survey, we registered 43.8 m3 of marine litter on the Elafiti islands and 52.8 m3 on the Kornati archipelago. The average share of plastic waste was higher in the Kornati region, 65.4 %, compared to 51.54 % on Elafiti islands.The origin of the litter remains uncertain. Determining the origin of the “made in” labels can be misleading as it indicates the country of production and not necessarily the country from which the litter entered the Adriatic Sea. Nevertheless, using the “made in” labels, we have identified 19 countries regarding litter in Elafiti and 12 countries for the Kornati islands. Perhaps a better indicator of the litter’s origin would be massive litter pollution after the strong SE wind (sirocco), particularly on the Elafiti islands, which indicates that most non-Croatian litter originates from the southern Adriatic basin and the coasts of Albania, Montenegro, and south-eastern Italy. However, further investigation is needed to corroborate these findings. However, even the preliminary results show that the problem of marine litter can only be solved through a joint effort of all Adriatic countries.

marine litter, coast pollution, Kornati islands, Elafiti islands, Croatia

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