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Despite emerging and increasing concerns related to marine micro and macroplastics, no systematic surveys have been undertaken yet in the Lebanese marine area. To understand the spatio-temporal variation of plastic litter (macro and microplastics) in the Lebanese marine environment and to determine the sources of pollution, this study investigated the characteristics of plastic pollution in sea surface waters during wet and dry seasons in 22 sites of Beirut and Tyre regions. A total of 23,023 items were identified and assessed according to the shape, color, and concentration; moreover, the risk of microplastics (MPs) contamination was explored based on a risk assessment model. The obtained results demonstrated that the average macroplastics concentration was 0.45 ± 0.6 items/m3. The average microplastics concentration was found to be 20.1 ± 21.8 and 3.78 ± 5.2 items/m3 in spring and fall respectively. During fall, MPs fragments were dominant in Beirut (97%) and Tyre (91%), and no pellets were observed. During spring, filaments were most encountered in Beirut (76.5%). The most dominant marine litter color was blue followed by black and white. The Pollution Load Index (PLI) values showed a moderate contamination of the Lebanese coast with MPs (PLI: 5.79 ± 3.93) except for several sites in Beirut that showed high values of PLI, highlighting the local influence of cities and rivers on MPs concentration. This study serves as an important baseline for understanding the characteristics of the seasonal variation of MPs along the Lebanese marine environment; it will help stakeholders and countries to take proactive and reactive actions to face plastic litter pollution in the Lebanese coastal area.

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International audienceWe present a new and fast method for blending altimetry and surface drifters data in the Eastern Levantine Mediterranean. The method is based on a vari-ational assimilation approach for which the velocity is corrected by matching real drifters positions with those predicted by a simple advection model, while taking into account the wind effect. The velocity correction is done in a time-continuous fashion by assimilating at once a whole trajectory of drifters using a sliding time window. Except for the wind component, the velocity is constrained to be divergence free. We show that with few drifters, our method improves the the estimation of velocity in two typical situations: an eddy between the Lebanese coast and Cyprus, and velocities along the Lebanese coast

Pufferfishes are among the best-known marine organisms that accumulate marine biotoxins such as Tetrodotoxin (TTX). In the Mediterranean Sea, the silver-cheeked toadfish Lagocephalus sceleratus is the most reported TTX-bearer, causing many fatal and non-fatal cases. In Lebanon, no previous studies have measured TTX levels although the possibility of TTX-poisoning is high since L. sceleratus is caught in different sizes and can be mistaken with other small fishes. Hence, this study reports TTX and its analogue 4,9-anhydro TTX in L. sceleratus collected from Lebanese waters in the Eastern Mediterranean Sea. The results show that TTX concentrations in fish tissues varied between 0.10 and 252.97 µg/g, while those of 4,9-anhydro TTX oscillated between 0.01 and 43.01 µg/g. Internal organs of L. sceleratus were the most toxic parts of its body, with the highest TTX levels found in gonads (mainly ovaries) and liver, followed by the muscles and skin with concentrations always exceeding the safety level. Toxicity fluctuations of L. sceleratus, its expansion, ecological and economic effects were also elucidated. Based on the present findings, it has been confirmed that L. sceleratus constitutes a health, ecological and economic risks, and therefore its trade in seafood markets should be banned to avoid any potential intoxication.