A critical review on the evaluation of toxicity and ecological risk assessment of plastics in the marine environment.

The increasing production of plastics together with the insufficient waste management has led to massive pollution by plastic debris in the marine environment. Contrary to other known pollutants, plastic has the potential to induce three types of toxic effects: physical (e.g intestinal injuries), chemical (e.g leaching of toxic additives) and biological (e.g transfer of pathogenic microorganisms). This critical review questions our capability to give an effective ecological risk assessment, based on an ever-growing number of scientific articles in the last two decades acknowledging toxic effects at all levels of biological integration, from the molecular to the population level. Numerous biases in terms of concentration, size, shape, composition and microbial colonization revealed how toxicity and ecotoxicity tests are still not adapted to this peculiar pollutant. Suggestions to improve the relevance of plastic toxicity studies and standards are disclosed with a view to support future appropriate legislation.

Parrotfishes (Teleostei: Labridae: Scarini) of the Socotra Archipelago: Diversity and distributional biogeography, including a range extension of Scarus zufar Randall & Hoover, 1995.

An updated account of the diversity of parrotfishes from the Socotra Archipelago is provided. Fourteen species are positively recorded based on underwater observations, photography and collections, including confirmations of three species which were previously only tentatively recorded: Scarus falcipinnis(Playfair, 1868), Scarus scaber Valenciennes, 1840 and Scarus tricolorBleeker, 1847. The distribution of Scarus zufar Randall & Hoover, 1995, previously known only from coastal waters of southern Oman, Pakistan and Bangladesh, is extended to the Archipelago, with Abd al-Kuri Island representing the westernmost edge of its known range. Visual records of three additional species are yet to be documented. With 1417species the Archipelago approximates the modal richness range of 1518 species for Arabian ecoregions. A species account, accompanied by photographs, provides distinctive characters, distribution details in the Arabian region, and general remarks for each species. The distributional biogeography of the family pertinent to the Socotra Archipelago and the Arabian region is analysed in the context of the Western Indian Ocean. Three main Arabian units are identified: A Red Sea unit spans the combined Red Sea ecoregions and the western Gulf of Aden; a Socotra unit covers south-eastern Arabia including the Archipelago, the eastern Gulf of Aden and southern Oman; and a Gulf unit combines the Arabian/Persian Gulf, the Gulf of Oman, and putatively central Oman. These units form a discrete pan-Arabian cluster within the wider Western Indian Ocean. The Socotra unit resembles more strongly the Gulf unit than the Red Sea unit. Parrotfishes thus contrast overall distributional patterns of reef fishes in Arabia.

Biogeography of the coastal fishes of the Socotra Archipelago: Challenging current ecoregional concepts.

The Socotra Archipelago, located in the eastern Gulf of Aden, has a unique marine environment, which combines tropical and 'pseudo-temperate' elements. An updated species inventory recently considered its coastal fish diversity the highest among Arabian ecoregions, necessitating to re-assess the ichthyogeographic position of the island group. The main aim of this study is to describe the distributional biogeography of its coastal fish fauna in relation to contemporary ichthyogeographic and ecoregional concepts. Inferences are drawn with regard to the marine biogeographic arrangement and ecoregional partitioning of the Arabian region. The main datasets comprise eight and twenty selected families including 404 and 898 species, respectively, from Arabian ecoregions. The Socotra Archipelago has close affinities to a putative ecoregion in the eastern Gulf of Aden that extends to southern Oman. It is more closely related to the Arabian Sea coast of Oman than to ecoregions in the Red Sea and a putative ecoregion in the western Gulf of Aden. The Gulf of Aden does not represent a consistent ecoregion in ichthyogeographic terms, because its eastern and western parts are less closely related to one another than to other ecoregions. The Socotra Archipelago and the eastern Gulf of Aden should therefore not be assigned to a joined province with Red Sea ecoregions. The coastal fish faunas of the southern Red Sea have close affinities with those of the western Gulf of Aden. The Arabian/Persian Gulf is least related to the other Arabian ecoregions. The authors posit the Socotra Archipelago as a distinct ecoregion, either on its own or in combination with affiliated mainland areas. This best reflects the ichthyogeographic data and the exceptionally high levels of fish and overall marine diversity. Two alternative ecoregional delineations are proposed, serving as working hypotheses for onward research.

Impacts of chemical stress, season, and climate change on the flounder population of the highly anthropised Seine estuary (France).

The main objective of this study was to improve our knowledge on the responses of fish populations to multistress (diffuse pollution and warming waters) in estuaries. Adult flounders were caught in two estuaries in the Eastern English Channel: the heavily polluted Seine estuary vs the moderately contaminated Canche estuary. Fish samplings were conducted in January just before the reproduction period, and in July when gonads were at rest. The overall rise in coastal winter water temperatures detected over the Channel impairs the flounder's phenology of reproduction in the two estuaries, inducing a delay of maturation process and probably also spawning. The higher liver histopathology index in Seine vs Canche could be the consequence of the fish exposition to a complex cocktail of contaminants in a strongly industrialized estuary. Higher levels of neurotoxicity, gill lipid peroxidation, and liver EROD activity were observed in Seine vs Canche. Furthermore, a possible impairment in mitochondrial metabolism was suggested in the Seine flounder population. We confirmed in this study the potential role of two membrane lipids (sphingomyelin and phosphatidylserine) in the resistance towards oxidative stress in Seine and Canche. Finally, we suggest that the Seine flounder population (and possibly the connected Eastern English Channel flounder populations over the French Coast) could be seriously impacted in the future by multistress: higher winter temperatures and chemical contamination.

Effects of forest cover on richness of threatened fish species in Japan.

Estuaries--one of the most vulnerable ecosystems globally--face anthropogenic threats, including biodiversity loss and the collapse of sustainable fisheries. Determining the factors contributing to the maintenance of estuarine biodiversity, especially that of fish, is vital for promoting estuarine conservation and sustainability. We used environmental DNA metabarcoding analysis to determine fish species composition in 22 estuaries around Japan and measured watershed-scale land-use factors (e.g., population size, urban area percentage, and forest area percentage). We sought to test the hypothesis that the richness of the most vulnerable estuarine fish species (i.e., registered by the Japanese Ministry of the Environment in the national species red-list) is determined by watershed-scale land-use factors. The richness of such species was greater, where forest cover was highest; thus, forest cover contributes to their conservation. The proportion of agriculture cover was associated with low species richness of red-listed fishes (redundancy analysis, adjusted R2 = 43.9% of total variance, df = 5, F = 5.3843, p = 0.0001). The number of red-listed species increased from 3 to 11 along a watershed land-use gradient ranging from a high proportion of agriculture cover to a large proportion of forest cover. Furthermore, the results showed that throughout Japan all the examined watersheds that were covered by >74.8% forest had more than the average (6.7 species per site) richness of red-listed fish species. This result can be attributed to the already high average forest cover in Japan of 67.2%. Our results demonstrate how the land use of watersheds can affect the coastal sea environment and its biodiversity and suggest that proper forest management in conjunction with land-use management may be of prime importance for threatened fish species and coastal ecosystems in general.

Efectos de la Cobertura Forestal sobre la Riqueza de Especies Amenazadas de Peces en Japón Resumen Los estuarios-uno de los ecosistemas más vulnerables a nivel mundial-enfrentan amenazas causadas por el hombre, incluyendo la pérdida de biodiversidad y el colapso de las pesquerías sustentables. La determinación de los factores que contribuyen al mantenimiento de la biodiversidad estuarina, especialmente la de los peces, es vital para fomentar la conservación y sustentabilidad estuarinas. Usamos un análisis de metasecuenciación de ADN ambiental para determinar la composición de especies de peces en 22 estuarios de Japón y medimos los factores del uso de suelo a nivel de cuenca (p. ej.: tamaño poblacional, porcentaje de área urbana y porcentaje de área forestal). Buscamos probar la hipótesis de que la riqueza de las especies de peces más vulnerables (es decir, aquellas registradas por el Ministerio Japonés del Ambiente en la lista roja de especies a nivel nacional) está determinada por los factores de uso de suelo a nivel de cuenca. La riqueza de dichas especies fue mayor en donde la cobertura forestal era la más alta; por lo tanto, la cobertura forestal contribuye a la conservación de estas especies. La proporción de la cobertura agrícola estuvo asociada con una baja riqueza de especies de peces en la lista roja (análisis de redundancia, R2 ajustada = 43.9% de la varianza total, gl = 5, F = 5.3843, p = 0.0001). El número de especies en la lista roja incrementó de 3 a 11 a lo largo del gradiente de uso de suelo de la cuenca, yendo desde una proporción alta de cobertura agrícola a una proporción alta de cobertura forestal. Además, los resultados mostraron que, en Japón, todas las cuencas analizadas que contaban con una cobertura forestal >74.8% tenían mayor riqueza de especies de peces en la lista roja que el promedio (6.7 especies por sitio). Este resultado puede atribuirse a la ya de por sí elevada cobertura forestal de Japón (67.2%). Nuestros resultados demuestran cómo el uso de las cuencas puede afectar al ambiente costero marino y a su biodiversidad y sugiere que la gestión adecuada de los bosques en conjunto con el manejo del uso de suelo puede ser de suma importancia para las especies amenazadas de peces y los ecosistemas costeros en general.

Coastal fish diversity of the Socotra Archipelago, Yemen.

The Socotra Archipelago, located in the eastern Gulf of Aden, has a unique marine environment which combines tropical and 'pseudo-temperate' elements. Studies on the fish biogeography of the archipelago, partially framed in regional studies, have substantially outpaced critical elementary research on the archipelago's fish diversity. The present study seeks to close this gap and identifies the Socotra Archipelago as a major hotspot of coastal fish diversity in the Indian Ocean.       The archipelago supports unique coastal fish assemblages which are predominantly composed of coral-associated ("reef") species, in spite of the limited biogenic reef frameworks. A Preliminary Checklist comprises 682 species with confirmed records and a "Working List" includes an additional 51 records, totalling 733 faunal records in 108 families. The family Labridae is the most speciose, followed by Gobiidae, Pomacentridae, Serranidae and Chaetodontidae. The species richness of the archipelago is the highest when compared to adjacent Arabian ecoregions. The richness of the Acanthuridae, Chaetodontidae, Labridae, Pomacentridae and Pseudochromidae stand out as particularily high, and the richness of several families is as high as or higher than in the entire Red Sea. The total archipelagic richness is extrapolated at up to 875 species based on incidence-based richness models and expert opinion. Inshore fish inventories, covering 497 species, found between 14 and 132 species per site (x̄ = 66). Site diversity decreased across the archipelago from west to east and from north to south. Total fish diversity was highest around Socotra Island, followed by Abd al-Kuri Kal Farun and Darsa Samha. Occurrence frequencies were very unevenly distributed and dominated by Pomacentrus caeruleus and Thalassoma lunare, whilst many species were infrequent. The fish assemblages are dominated by species from the Indo-West Pacific and the north-western Indian Ocean. The assemblages are rich in rare species and hybrids, and include a low number of endemics (4-5), and a high number of species with far-reaching and Western Indian Ocean ranges.

The coastal fishes and fisheries of the Socotra Archipelago, Yemen.

The Socotra Archipelago is situated in the Gulf of Aden where tropical and "pseudo-temperate" conditions combine to create a unique marine ecosystem. The diversity, ecology, productivity and fisheries of the coastal fish assemblages are still relatively understudied and no update of the scientific knowledge existed. The islands support unique coastal and coral-associated fish assemblages in spite of the limited biogenic reef frameworks. Fish diversity is the highest among comparable Arabian eco-regions, and fish biomass productivity high too by Indian Ocean standards. The production of the once traditionally-managed small-scale fishery is severely declining and whether it is sustainable nowadays is extremely doubtful. At a time when Yemen is torn apart by a severe political and humanitarian crisis it is timely to review and update the current state of knowledge for scientists and managers, and thereby ease access to existing information, facilitating follow-on studies and evidence-based conservation and fisheries management.

Does the chronic chemical contamination of a European flounder population decrease its thermal tolerance?

Juvenile flounders (Platichthys flesus), collected in two estuaries with similar temperature regimes (the heavily polluted Seine and the moderately contaminated Vilaine), were submitted to a common garden experiment. After an acclimation period, both populations were challenged by a thermal stress (9-24°C for 15days, then maintenance at 24°C for 19days). The condition factor of the Vilaine fish increased in both conditions, while it decreased for the heated Seine flounders after 34days. The expression of genes related to the energetic metabolism was measured in the liver. The expression levels for ATP-F0 and COII were significantly reduced for heated vs. standard fish from both estuaries, while a decrease of the 12S expression was detected only in heated vs. standard fish from the Seine estuary. Thus, it is suggested that highly contaminated fish from Seine could display a lower tolerance to thermal stress, compared to moderately contaminated fish from Vilaine.