Assessment of ecosystem services of an urbanized tropical estuary with a focus on habitats and scenarios

Tropical estuaries are one of the most valuable ecosystems on the planet because of the number of ecosystem services they provide. The increasing anthropogenic pressure to which these estuaries are subject has caused a reduction in their natural capital stock. Therefore, the application of a pragmatic and rational ecosystem-based management approach to sustainably manage the multiple ecosystem services provided by this ecosystem is necessary. The aim of our study is to present an approach that combines prospective scenarios with habitat-based perspective to assess the supply capacity of ecosystem services, plus determine the impact of protected areas in an urbanized tropical estuary. The current situation and two scenarios were generated to evaluate the capacity of habitats to supply ecosystem services. This type of assessment will allow the decision makers to visualize the effect of their choices or the occurrence of events which might produce significant changes in the estuary. Thus, over time, measures can be taken to sustain the supply of ecosystem services. We determined that the establishment of protected areas have a positive impact; however, the effect is not the same for all of them. Consequently, indicating that actions such as community participation, research, education, management planning and infrastructure development must accompany the development of a protected area

Evaluation de l'efficacité des Aires Marines Protégées comme outil de restauration des ressources marines et de gestion des stocks halieutiques : l'expérience ouest africaine

This thesis focuses on the study of the effectiveness of Marine Protected Areas (MPAs) as restoration tools of marine resources and fish stocks management in tropical West Africa. The study involves three MPAs. The first one is the Bamboung MPA, a marine reserve located in estuarine areas (with marine influence), closed to fishing since 2004. The second is the Urok Islands MPA established in 2005 and located in the biosphere Reserve of Bijagos archipelago in the coastal part of Guinea-Bissau. It is divided into three areas and fishing is allowed there with a fishing pressure becoming stronger from the central area to peripheral area. The third MPA is the Banc d‟Arguin National Marine Park located along the coast of Mauritania. It was created in 1976 and fishing activities are restricted. Many AMP were evaluated worldwide and the results are in the main part positive. In tropical zones, the variability of environmental parameters affects the spatial and temporal organization of fish assemblage. Therefore, the MPA establishment in a tropical zone has raised questions about their effectiveness inrelation to the influence of environmental parameters. According to the AMP, spatial or temporal approach will be used to answer questions. Comparison analysis will be used. The analysis of biological data comes after those of the physicochemical parameters that show strong seasonal variability in each MPA. This result justifies the choice of seasonal analysis of biological data in order to minimize the influence of environmental variations.Regarding the Bamboung MPA, the results of global approach clearly confirm that it is an effective tool for restoring marine resources. The seasonal approach shows this role in cold season, but not in hot and wet seasons. In 9 years of protection, the Bamboung MPA contributed to attract big fish in the Bamboung bolon. The spillover effect in Bamboung MPA is not clearly demonstrated according to our results. A downward trend of biological indicators according to the distance to the MPA has been observed especially in hot season and wet season. Similarly, the analysis of indicators related to reproduction does not show that the Bamboung MPA improve fish reproduction. Regarding Urok Islands MPA and Banc d’Arguin National marine Park, the results do not confirm that these AMP are fish stock management tools (improved yields of fishing activities and fish reproduction). However, for Urok islands MPA the observed trends suggest a biomass concentration in the central area, an equilibrium role played by the intermediate area and a role of fish biomass provider of the peripheral area. For Banc d’Arguin National Marine Parc, the inside area seems to contribute to the enrichment of the external area by transferring fish biomass. Non-specific results could be explained by the small data collected in the MPAs. So the idea to conduct a short-term biological monitoring and to analyze reproduction indicators in population level has been considered for the three MPA to find clear results on their role in the management of fish stocks.Cette thèse porte sur l'étude de l’efficacité d’une Aire Marine Protégée (AMP) comme outil de restauration des ressources marines et de gestion des stocks halieutiques en zone tropicale ouest africaine. L’étude concerne trois AMP. Il s’agit de l’AMP de Bamboung située en zone estuarienne (sous influence marine), à l'intérieur d'un delta et fermée à l’exploitation halieutique depuis 2004. La deuxième AMP est celle des îles d’Urok créée en 2005 et située dans la réserve de biosphère de l’archipel des Bijagos dans la partie littorale de la Guinée-Bissau. Elle est divisée en trois zones et la pêche y est autorisée avec une pression de pêche de plus en plus forte de la zone centrale vers la zone périphérique. La troisième AMP est le Parc National du Banc d’Arguin situé le long de la côte mauritanienne. Il a été créé en 1976 et les activités de pêche y sont pratiquées de façon réglementée. Beaucoup d’AMP ont été évaluées à travers le monde et les résultats obtenus sont dans la majeure partie des cas positifs. Dans les milieux tropicaux, les variabilités interannuelles et intra-annuelles des paramètres environnementaux influent sur l’organisation spatio-temporelle des peuplements de poissons. Par conséquent, la mise en place d’AMP dans une zone tropicale a suscité des interrogations quant à leur efficacité en rapport avec l’influence des paramètres de l’environnement. Selon l’AMP étudiée, une approche spatiale ou temporelle sera utilisée pour répondre aux questions posées. Les méthodes d’analyse utilisées sont de type comparatif. L’analyse des données biologiques est précédée par celle des paramètres physico-chimiques qui a mis en évidence des variabilités saisonnières dans chaque AMP. Ce résultat justifie le choix d’analyser les données biologiques par saison afin de minimiser au mieux l’influence des variations environnementales. En ce qui concerne l’AMP de Bamboung, les résultats de l’analyse suivant une approche globale ont clairement montré son rôle positif dans la restauration des ressources marines. L’approche saisonnière a mis en évidence ce rôle de restauration mais en saison froide et non en saison chaude et humide. En 9 années de protection, l'AMP de Bamboung a contribué au retour de gros poissons dans le bolon de Bamboung. Son rôle dans l’enrichissement de la zone proximale à travers le phénomène de «Spillover» n’a pas pu être mis en évidence. Une tendance à la baisse des indicateurs biologiques en fonction de la distance à l'AMP a été observée surtout en saison chaude et en saison humide. De même l’analyse des indicateurs liés à la reproduction ne montre pas que l’AMP de Bamboung améliore la reproduction des poissons. Concernant, l’AMP des îles d’Urok et le Parc National du Banc d’Arguin, les analyses n’ont pas donné de résultats clairs quant à leur rôle dans l’amélioration des rendements de pêche et de la reproduction des poissons. Cependant, pour l’AMP des îles d’Urok, les tendances observées semble montrer une forte concentration de biomasse dans la zone centrale, un rôle d’équilibre joué par la zone intermédiaire et un rôle de pourvoyeur de biomasse de poisson de la zone périphérique. Pour le PNBA, le secteur intérieur semble contribuer à l’enrichissement du secteur extérieur par un transfert de biomasse. La faible quantité de données récoltées dans les AMP pourrait être à l’origine des résultats négatifs. Ainsi, l’idée d'effectuer des suivis biologiques à court terme et d'analyser les indicateurs liés à la reproduction au niveau population ont été envisagés pour les trois AMP afin de trouver des résultats clairs quant à leur rôle dans la gestion des stocks halieutiques

Contribution to a better knowledge of bycatch of fixed gillnets of shrimps (Farfantepenaeus notialis) in the Casamance estuary in Southern Senegal

International audienceThis study was carried out in Ziguinchor (Senegal) in southern Senegal where the coastal shrimp Farfantepenaeusnotialisis exploited by a small-scale fishery whose activities have been mainly oriented for several years. Data were collected downstream Casamance Estuary from 26 July to 31 August 2016 at two landing sites: from July 26 to August 12 in Boudodyand then from August 16 to 31under the bridge Emile Badiane. During this period, the landings of 61 fishermen were studied. Those fishermenwere selected at random or through contacts established by the Ziguinchor Regional Fisheries and Surveillance Service. Thecollection was carried out three times a week with fishermen returning from fishing between 9 PMand 10 AM.Juvenile fish are the main bycatch of thistype of fishing gear (86.85%), followed by crustaceans (13.13%) and cephalopod molluscs(0.02%). Most ofthese captures (89.54%) are discarded, 10.46% are retained. Some 39 species constitute the bycatch of fixed net used inshrimp fisherydownstream Casamance estuary. Therearefour species regularly found in fishermen's nets, 1 quite frequently, 5 of them are retrieved occasionally and 29 are erratic. Ethmalosa fimbriata, accounting for almost 60.74%of catches, is the main bycatch species found in fixed net. 64% of species caught belong to the category of minor concernsand 10% are labelledas threatened species(vulnerable and endangered). Out of those 39 species, 13 are estuarine of marine origin and 13 are marine estuarineand 21 of them are predatory species of the second trophic level. Bycatchdiscards account for 140 kg. Some species, mainly juvenilefish, discarded by fishermen are salvaged for human and / or animal consumption. Others arekept by fishermen and are eate

Brycinus epuluensis, a new species from the Epulu River (Congo basin), Africa (Teleostei: Alestidae)

WOS:000374721700005International audienceBrycinus epuluensis, new species, is described from the Epulu River, an affluent of the Ituri River (Aruwimi basin, Middle Congo basin, DR Congo). It most closely resembles the widespread species B. imberi from the nurse group, although it has a broad black mid-lateral band on the body, which is absent in B. imberi. This black band is, however, also present in specimens from the neighbouring population in the Ituri River itself. Brycinus epuluensis differs from the types of B. imberi and its five junior synonyms, as well as from the neighbouring Ituri population, mainly in having only 6 instead of 8 premaxillary teeth, arranged in a single row. This low number of premaxillary teeth is characteristic for species of the longipinnis group. However, B. epuluensis differs from all members of the longipinnis group by the absence of a fronto-parietal fontanelle in adults and the following combination of characteristics: 18-22 lateral line scales and 12-15 branched anal-fin rays. The Ituri population could not be separated from B. imberi and most of its synonyms on morphometrics, but does differ by the presence of the black mid-lateral band

International conference ICAWA 2016 : extended book of abstract : the AWA project : ecosystem approach to the management of fisheries and the marine environment in West African waters

The efforts to conserve biodiversity has been stimulated by the creation of large marine protected areas at sea, in addition to small sites in the coastal waters of many countries. The objectives of creating MPAs are diverse and may appear to be conflicting. Scientists and managers are interest in their effectiveness as tools for restoring biodiversity and tools for fish stock management. Many AMP were evaluated worldwide and the results are in the main part positive. Then, MPAs are predicted to benefit adjacent fisheries through net emigration of adults and juveniles across borders, termed "spillover". This phenomenon is favored by high density in MPAs, species mobility and habitat connectivity. MPAs can contribute to an increase of abundance and biomass due to the Spillover effect, especially near a reserve. The objective of this work is to verify whether an MPA can contribute to the improvement of fisheries yields near its borders. The question is whether fishing parameters such as abundance, biomass, average size and maximum size decrease with distance to Bamboung MPA. It means to examine spatial patterns of these fishing parameters across the boundary of Bamboung MPA. The present study is conducted in a part of Diomboss area, located in the estuary of Saloum, near the border of Bamboung AMP where fishing activities are banned. The data were collected during 3 fishing surveys in 2012, carried out during the three main hydro-climatic seasons of the region in March (end of the cool dry season), June (end of the h t dry season) and October (end of the wet season). Samples were fished with a baited longline. The results show in the cool season, an increases of abundance away from the MPA border, whereas in the dry season, it decreases away from the MPA. The biomass did not evolve with the distance to the MPA. The average size of fish decreases when moving away from the MPA in both the cool and wet seasons. The maximum size decreases away from the MPA in the wet season. The spillover effect in Bamboung MPA is not clearly demonstrated according to our results. A downward trend of biological indicators according to the distance to the MPA has been observed especially in hot season and wet season. These results would reveal the possibility of an improving artisanal fishery yields near the boundaries of the Bamboung MPA in dry and wet seasons

Impact assessment of a marine and coastal protected area on fishing households through a counterfactual approach. A Senegalese case study (West Africa)

International audienceThe setting up of marine and coastal protected areas, one of most significant strategies of coastal management employed worldwide to maintain ecosystem services and mitigate biodiversity loss, has to be accompanied by an impact evaluation to guide decision-makers, practitioners and the relevant population. This paper presents a counterfactual approach of fishing households' profitability and vulnerability after the setting up of a marine and coastal protected area (MPA). By using the DID method (Difference-in-Differences), this approach is a comparison of average change in outcome over time for the treated group (fishing households with a main fishing ground adjacent to the MPA) and for the control group (fishing households with a main fishing ground remote from the MPA). From a dataset made up of 183 fishing households in Betenti Islands (Saloum, Delta, Senegal) surveyed twice (one year before the MPA's setting up and six years after it) and divided in two geographical strata, the main result is the applicability and confirmation of the value of a counterfactual approach to assess the positive effect of proximity with a MPA on fishing households' income and vulnerability, independently of fishing productive assets and conditions, and of any change that have affected them during the period taken in consideration. This counterfactual assessment should help to calibrate the necessary investments and to adapt the functioning of a MPA but also to target adequate mitigation and compensation measures for the non-beneficiary households