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The accumulation of plastic litter in coastal environments has become an issue of high priority for policymakers around the globe, due to their potential hazardous effects to biota and human health, and their impact on ecosystem services and local economies. To develop effective mitigation measures, it is critical to acquire knowledge on the distribution and levels of plastic litter. However, in many world regions, such as in West Africa or Southeast Asia, the concentration of plastics reaching coastal areas is still poorly documented. To address the data gaps in marine plastic litter distribution worldwide, citizen science programs are instrumental in complementing shoreline assessments, and are effective in increasing public awareness of plastic pollution. The Citizen Observation of Local Litter in coastal ECosysTems (COLLECT) project is a citizen science initiative which aims to acquire distribution and abundance data of coastal plastic debris in seven countries, in Africa (Benin, Cabo Verde, Côte d'Ivoire, Ghana, Morocco, Nigeria) and Asia (Malaysia). The project consists of training local students (15-18 years old) from secondary cycle institutions on sampling and analysing macro-, meso- and microplastic in beach sediments, using scientific procedures. The project will also measure the impact of the citizen science intervention by assessing shifts in ocean literacy and pro-environmental behaviour in the students. The results from COLLECT will contribute to establishing baseline information on coastal plastic debris, with citizen science being an enabler of open science, allowing data to be freely available to the public, academics and policymakers. Results will further contribute to the identification of hotspots of plastic coastal litter, and bring awareness to local communities on the potential consequences of plastic pollution. Also see: https://micro2022.sciencesconf.org/427338/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

This study investigated the main water-level (WL) variability modes of Nokoué Lagoon in Benin (West-Africa). The average WL ranges between 1.3 and 2.3 m between the low-and high-water seasons. Seasonal as well as weak interannual variations between 2018 and 2019 are driven by rainfall regime over the catchment and associated river inflow. At sub-monthly scales, the lagoon is tidally choked: ocean tides can reach 90 cm, whereas in the lagoon semi-diurnal and diurnal tides hardly reach few centimeters. Choking conditions vary with river inflow and ocean tide amplitude, correctly represented by a simple tidal choking model. Diurnal modulation and asymmetry of the tide are stronger (weaker) during high (low) water period. We also observed WL variations of ±5-10 cm at a fortnightly frequency, stronger during wet (high-water) season. Superimposed on the seasonal, fortnightly and tidal WL variations, we further observed short-term high-frequency seiche events. Mostly observed during dry (low-water) conditions, they are characterized by typical standing-wave oscillations of 5-10 cm amplitudes and 3 h periods. They are forced by the passage of fast-moving squall-lines that induce strong wind variations, heavy rainfalls and rapid drop-off of the air temperature. Results obtained in this study provide useful metrics for the validation of flood forecasting models to be implemented in Benin, and elsewhere on the West African coastline.

The global objectives of this study are to assess biodiversity composition in the tested trawling areas during the survey period. This study cannot take in account all species that can occur in the fishing areas because of the shortness of the work. To have a most complete list of species it will be better to carry out the survey covering four hydrologic periods (2 hot and 2 cold hydrologic periods) to have a chance to meet most of the species. However, the work was done during the most important period for the study. This study was conducted in terms of the demersal fish stock assessment survey initiated by the West African Economic and Monetary Union in the continental shelves of states members and neighboring countries (Côte d'Ivoire, Ghana, Togo and Benin) for the south part of Africa in order to determine fish population and abundance. In the waters of Benin, there have been listed 100 fish species including 76 demersal species (69 bony and 7 cartilaginous fish) and 13 pelagic species consisting entirely of bony specimens. Species richness, according to the reports of trawling stations, varies between 28 and 7 species. Fish abundance is the largest at the depth of 25-50 m. According to the data of station 10, species number makes 7.76% of the total, followed by station 19 with 26 taxa at the depth of 50-100 m. The lowest taxon number is registered in station 4 at a depth of 10-25 m with 4 taxa representing 1.94% of all targeted. The Simpson's index is close to 0, varying between 0 and 0.049, it shows a great diversity especially in the first stratum of 10 to 25 m. This study allows to evaluate species diversity in different fishing areas and consequences of the significant increase of fishing pressure on the stand and not only to focus on a few populations of species of commercial interest.

The present study aims to estimate the age and the growth of Brachydeuterus auritus, off Togo waters, in order to stock assessment. The otoliths were extracted from commercial landings by Togolese marine fisheries and analyzed in the Spanish Institute of Oceanography laboratories in Tenerife. The results showed that Total Length of the fish (TL) is linked to the otoliths weight (OW): TL = 5.171*ln (Ow) + 28.805 (R2 =0.9227). The mean length by age-class from the Age-Length key for the age-classes 1 to 4 were 10.6, 13.2, 15.1 and 16.8 cm, respectively. Length and age data were fitted to von Bertalanffy equation, and the growth parameters estimated were L∞ = 23.15 cm; K= 0.225 year-1 and t0 = -1.722 year. The current results, comparable globally to those obtained, in Gulf of Guinea, such as in Togo waters with the marking and recapture method. Therefore, these results could be useful for the stock assessment of this species off Togo waters., Sí

The global objectives of this campaign were to assess biomass and map the distribution of stocks of small coastal pelagic fish from Côte d''Ivoire, Ghana, Togo and Benin. The study was carried out with the help of hydroacoustic method. Besides, one of the other objectives was to describe the hydrographic conditions in the area during 3 days in 2012. It was found that the fish density was rather less in comparison with Nansen’s survey (2002-2006). However, it should be noted that both researches were made during different time periods. The analysis of the obtained data has shown that Ilisha africana is the most important pelagic fish. This species was caught by most of the fishermen using non-motorized boats. The main pelagic species biomass is 3490 tons, including biomass of Ilisha africana that equals 310 tons, while the other species of pelagic fish are 3180 tons. Apart from Ilisha africana, there were other pelagic fish such as horse mackerel, mackerel and barracuda. Some bottom fishes were inaccessible. This study should promote more effective control of fishery at the continental shelf.

The drift net is one of the most used fishing gear in Benin. It is easy to use and requires very little energy. The net has high interselectivity for ground fish that gives mixed results in many regions. Physical impact of drift nets on the seabed is not a matter of concern. The ecological risk from interselectivity of the net is also insignificant and mainly occurs as a result of their abundant usage, for example, by the artisanal fishermen deployed in the area of fishing during the strong sea conditions. The purest, in terms of ecology, nets are gillnets for the sardinella catching, which are placed at 10 cm deep below the surface with numerous floats. They drift freely under the influence of the water current or with the boats if they are moored. The old model of the net is used as an ecologically pure drift net at 12 to 20 m deep with a length of 360-400 meters per a set. A fisherman can deploy about 4-5 sets of sardinella nets. Madeiran sardinella (Sardinella maderensis) is the most widespread sardinella species in Benin continental shelf. Round sardinella are very few in the catch. The fishing objects are generally called sardinella. Fishing nets are called Sardinella nets. The number of fishes for the old kind of net varied from 120 to 600 fishes per 3.5 kg, and for the new model 40 fishes per 5 kg. The fisherman's annual revenue increases from 2500 to 3000 CFA francs (Financial collaboration of the Countries of the Central Africa) while using the old kind of net and to 4000 CFA francs when using the new one. Respect of this selectivity participates in renewal of the stock.