In this study, we analyzed and compared feces of free-living and cultivated fish species, Epinephelus fuscoguttatus under different environmental conditions in Indonesian waters. Metagenome analysis was performed using Illumina MiSeq sequencing of the whole metagenomic DNA isolated from fish feces samples. The analysis covered both prokaryotic and eukaryotic DNA. Feces samples from mariculture fish revealed a highly stable distribution of several orders of bacteria when compared to samples from free-living fish, which were highly diverse and dominated by Vibrionales, Pseudomonales, Rhizobiales and non-classifiable Alphaproteobacteria. The eukaryotic content of the samples was dominated by residues of the host and nine additional fish species that formed a portion of the diet. Investigations on functional annotations for predominant bacterial taxa, using Gene Ontology enrichment, revealed a number of functions related to DNA metabolic processes, especially DNA repair, as well as antibiotic response in the free-living fish species.

Every step of microplastic analysis (collection, extraction and characterization) is time-consuming, representing an obstacle to the implementation of large scale monitoring. This study proposes a semi-automated Raman micro-spectroscopy method coupled to static image analysis that allows the screening of a large quantity of microplastic in a time-effective way with minimal machine operator intervention. The method was validated using 103 particles collected at the sea surface spiked with 7 standard plastics: morphological and chemical characterization of particles was performed in <3h. The method was then applied to a larger environmental sample (n=962 particles). The identification rate was 75% and significantly decreased as a function of particle size. Microplastics represented 71% of the identified particles and significant size differences were observed: polystyrene was mainly found in the 2–5mm range (59%), polyethylene in the 1–2mm range (40%) and polypropylene in the 0.335–1mm range (42%).

Ocean acidification (OA), induced by rapid anthropogenic CO2 rise and its dissolution in seawater, is known to have consequences for marine organisms. However, knowledge on the evolutionary responses of phytoplankton to OA has been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations ~700 to ~1550), it reduced it in the later selection period up to 2000 generations. Similarly, stimulated production of particulate organic carbon and nitrogen reduced with increasing selection period and decreased under OA up to 2000 generations. The specific adaptation of growth to OA disappeared in generations 1700 to 2000 when compared with that at 1000 generations. Both phenotypic plasticity and fitness decreased within selection time, suggesting that the species' resilience to OA decreased after 2000 generations under high CO2 selection.

Plastic debris and other floating materials endanger severely marine ecosystems. When they carry attached biota they can be a cause of biological invasions whose extent and intensity is not known yet. This article focuses on knowledge gaps and research priorities needed for, first, understanding and then preventing dispersal of alien invasive species attached to marine litter.

Microplastics are firmly recognized as a ubiquitous and growing threat to marine biota and their associated marine habitats worldwide. The evidence of the prevalence of microplastics was documented for the first time in the marine waters of Qatar's Exclusive Economic Zone (EEZ). An optimized and validated protocol was developed for the extraction of microplastics from plankton-rich seawater samples without loss of microplastic debris present and characterized using Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy. In total 30 microplastic polymers have been identified with an average concentration of 0.71particlesm−3 (range 0–3particlesm−3). Polypropylene, low density polyethylene, polyethylene, polystyrene, polyamide, polymethyl methacrylate, cellophane, and acrylonitrile butadiene styrene polymers were characterized with majority of the microplastics either granular shape, sizes ranging from 125μm to 1.82mm or fibrous with sizes from 150μm to 15.98mm. The microplastics are evident in areas where nearby anthropogenic activities, including oil-rig installations and shipping operations are present.

Approximately 9.5billiontonnes of goods is transported over the world oceans annually with dry bulk representing the largest cargo group. This paper aims to analyse whether the transport and associated inputs of dry bulks into the sea create a risk for the marine environment. For this purpose, we analyse the international regulatory background concerning environmental protection (MARPOL), estimate quantities and identify inputs of such cargoes into the oceans (accidental and operational), and use available information for hazard assessment. Annually, more than 2.15milliontonnes of dry bulk cargoes are likely to enter the oceans, of which 100,000tonnes are potentially harmful to the marine environment according to the definition included in draft maritime regulation. The assessment of the threat to the marine environment is hampered by a lack of available information on chemical composition, bioavailability and toxicity. Perspectives for amendments of the unsatisfying pollution prevention regulations are discussed.

The bioavailable fraction of metals (Zn, Cu, Cd, Mn, Pb, Ni, Fe, and Cr) in sediments of the Huelva estuary and its littoral of influence has been estimated carrying out the most popular methods of sequential extraction (BCR and Tessier) and a biomimetic approach (protease K extraction). Results were compared to enrichment factors found in Arenicola marina. The linear correlation coefficients (R2) obtained between the fraction mobilized by the first step of the BCR sequential extraction, by the sum of the first and second steps of the Tessier sequential extraction, and by protease K, and enrichment factors in A. marina, are at their highest for protease K extraction (0.709), followed by BCR first step (0.507) and the sum of the first and second steps of Tessier (0.465). This observation suggests that protease K represents the bioavailable fraction more reliably than traditional methods (BCR and Tessier), which have a similar ability.

Plastic ingestion by marine biota has been reported for a variety of different taxa. In this study, we investigated 290 gastrointestinal tracts of demersal (cod, dab and flounder) and pelagic fish species (herring and mackerel) from the North and Baltic Sea for the occurrence of plastic ingestion. In 5.5% of all investigated fishes, plastic particles were detected, with 74% of all particles being in the microplastic (<5mm) size range. The polymer types of all found particles were analysed by means of Fourier transform infrared (FT-IR) spectroscopy. Almost 40% of the particles consisted of polyethylene (PE). In 3.4% of the demersal and 10.7% of the pelagic individuals, plastic ingestion was recorded, showing a significantly higher ingestion frequency in the pelagic feeders. The condition factor K was calculated to test differences in the fitness status between individuals with and without ingested plastic, but no direct effect was detected.

National audience | présentation invitée au colloque annuel de l'ARET Synthèse des travaux du Leesu sur les microplastiques en milieu urbain