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In the South Indian Ocean, French territories include Reunion (Mascarene archipelago), Mayotte (Comoros archipelago) and the remote Iles Eparses in the Mozambique Channel (Glorieuses, Juan de Nova, Bassas da India, Europa), and Tromelin, North-East of Madagascar. Their coral reefs are varied, from 18 km2 of fringing reefs in Reunion to 1500 km2 of fringing, barrier and double barrier reefs in Mayotte, caye reefs in Glorieuses and Tromelin to atolls in Juan de Nova, Bassas da India and Europa. Pressures on them vary from 850,000 inhabitants in Reunion to no permanent inhabitants in Iles Eparses. Annual monitoring of Reunion and Mayotte shows a gradual decrease in coral cover and fish biomass, due to overfishing. Yet an exceptional biodiversity is recorded in Mayotte, mainly due to its geographical position at the center of the WIO coral triangle, and the variety of reef habitats. In the remote Iles Eparses, more recent monitoring showed a remarkable state of coral reefs and their exceptional fish biomass. These coral reefs are under human threats mainly due to coastal development and land-based pollution, except for Iles Eparses. Climate change has an impact through coral bleaching whose effects are stronger for reefs in the North of the Mozambique Channel. The impact of the 2016 bleaching event was variable on islands but most corals showed signs of resistance with a good recovery of coral colonies. In order to limit degradation and overexploitation of reef resources, national marine protected areas (MPAs) have been made in all French islands: 2007 in Reunion, 2010 in Mayotte, and 2012 in Glorieuses while all Iles Eparses have been under protection for more than 20 years. Despite this, Iles Eparses are beginning to suffer from illegal fishing, including collection of holothurians and perhaps shells, particularly since 2012. Long-term monitoring is essential to describe trends in coral communities in the context of increasing human impact and climate change.

International audience; An annotated checklist of the fish species of the Madagascar EEZ (southwestern Indian Ocean) comprises a total of 1,798 species in 247 families. 158 species are recorded from Madagascar for the first time. The majority of the species is autochthonous; 28 species have been introduced, mainly in freshwater habitats. The fish fauna is mostly marine (95.4% of the total number of native fish species), with the Gobiidae, Labridae, Serranidae, Pomacentridae and Apogonidae being the families with most representatives; among the 90 native freshwater fish species (adults mainly occurring in freshwater), the Cichlidae are the dominating family, but there are also two endemic families, the Bedotiidae (16 species) and Anchariidae (6 species). The fish fauna at Madagascar is typical for offshore, high islands in the southwestern Indian Ocean. Zoogeographically, the main element of the marine fish fauna of Madagascar consists of widespread tropical Indo-Pacific species (978 species, 58.3% of the total native marine species). A total of 13 species (3.3%) are found worldwide, either circumtropical or circumtropical including warm temperate zones. A total of 215 species (12.8%) are found worldwide, either circumtropical or circumtropical including warm temperate zones. An additional 453 species (27.0%) are Indian Ocean endemics, including 233 western Indian Ocean endemics (13.9%), 73 southwestern Indian Ocean endemics (4.4%), 16 species endemic to Madagascar and Mascarenes (1.0%), 4 species endemic to Madagascar and Comoros (0.2%), 3 species endemic to Madagascar and Madagascar Ridge(0.2%), and 37 marine species endemic to Madagascar (2.2%). Most of the autochthonous freshwater fishes are endemic to Madagascar (87 species, 96.7% of the native freshwater species).

The scientific Lengguru 2017 Expedition aimed at assessing the functional, genetic and morphological diversity of several marine biotas (reef fishes, echinoderms, hard corals, and gorgonians). Several methods were implemented: observations, sampling with DNA barcoding inventory and morphological description, baited remote underwater video systems (BRUVS) and environmental DNA. Environmental measurements and opportunistic observations (marine mammals...) were also performed. Lengguru 2017 focused also on the mountain avifauna prevailing in Kaimana Regency (Lengguru and Kumawa). Exploration and sampling effort were concentrated for the marine part on several reef slopes located in front of Kumawa and Lengguru ranges, in and off shore of Triton Bay (from -100 m to the surface). The expedition occurred between 1st October 2017 and 30th November 2017. The fieldwork in Kaimana Regency was done between 17th October and 20th November 2017 with the vessel ‘Airaha 2’. Lengguru 2017 was a joint expedition of France and Indonesia Research Institutions.

The equilibrium of inland hydrosystems is presently a cause for concern, with species extinction rates there estimated to be 5 times higher than for terrestrial fauna in the 21st century. Urgent measures must be taken to conserve these ecosystems particularly with regard to fishes, which represent an especially rich and diverse evolutionary heritage. Fishes were long unaffected by human activity on the African continent, but anthropogenic pressure has increased in recent decades. Good management of African continental waters is thus of paramount importance in terms of heritage and economics, as fishes are a vital natural resource for the people in sub-Saharan Africa. In view of biodiversity conservation, African fishes are investigated here as a biological model owing to their enormous ecological and genetic diversity. It is essential to know the ecology and structure of various communities, and to understand the impact of human activity. This book discusses the diversity of environments, the origin and evolution of species, survival and adaptive strategies, the structure of fish communities, and the impact of human activity. It also devotes a section to fisheries and fish culture. This ambitious project summarizes the current state of knowledge on African fishes and their populations, highlighting the mechanisms regulating their equilibrium and the causes contributing to their erosion. It is a reference not just for readers involved in African aquatic environments, but for anyone interested in biodiversity conservation in general.

The Chondrostoma genus is widespread in Europe, with numerous endemic species in northern Mediterranean rivers. We reconstructed the phylogenetic relationships of this genus, using the whole cytochrome b sequence and compared the two freshwater fish dispersion hypotheses: (1) dispersion around the Mediterranean Sea during the Lago Mare phase of the Messinian salinity crisis (Bianco's hypothesis) and (2) an older and more gradual colonization of the Mediterranean rivers (Banarescu's hypothesis). All phylogenetic analyses identified two levels of divergences, implying two radiation events in the Chondrostoma genus. The first radiation mainly concerned Mediterranean species, whereas the second one includes Danubian and Mesopotamian species. This phylogeographic pattern was already observed for the genus Squalius, which exhibits a similar geographic range distribution in Europe and probably is shared with several other Mediterranean genera, such as Scardinius, Rutilus, and TELESTES: Furthermore, assuming a molecular clock of 1% per million years, the first radiation appears consistent with a Messinian dispersion during the Lago Mare, 5.3 million years ago, whereas the second one may correspond to a Mesopotamian dispersion through the Black Sea to the Danube system. According to our results, the Lago Mare theory is strengthened, and a more recent and pre-Pleistocene colonization of the Danube from Mesopotamian freshwater fishes is suggested.

Coral reef fish are bound to the pelagic environment throughout their larval stage, although they spend most of their adult life on reefs. Thus, the morphology of a lagoon and the location of a reef within the lagoon may influence the nature of its fish assemblage. Because of its asymetrical shape, the SW lagoon of New Caledonia allows us to test such a hypothesis. Several fringing reefs located 4–34 km from the open ocean were compared with one another. No influence of the reef-ocean distance could be found on the global values of diversity, density or biomass. However, presence-absence data of the 343 taxa encountered are related to this distance. Similarly, ecological structures based on diet, size and mobility of fish present strong correlations with reef—ocean distance. Thus, the major effects of an increase in reef—ocean distance concern both taxinomical and ecological structures. Suggested explicative hypotheses are linked to the fish feeding habits closely related to the environment but also to their utilisation of space. Territorial behaviour seems indeed to be important in structuring reef fish assemblage.

INTRODUCTION Une etude pluridisciplinaire des mangroves de la zone des Rivieres du Sud se doit d’evoquer, au chapitre ecologie, l’importance de la faune aquatique et particulierement de sa composante ichtyologique. Le domaine aquatique des Rivieres du Sud incluant la frange cotiere, les chenaux, les plaines inondables et les estuaires, nous ne traiterons ici que de ce dernier milieu. Les estuaires sont definis au sens large comme des « indentations de la cote en contact restreint avec l’ocean...

Length-weight relationships of 335 species of fish of New Caledonia, belonging to 65 families of coral reef fishes, were computed (80%) or assembled from the literature (20% of all cases) to facilitate, among other things, estimation of coral reef fish biomass from visual census.

The history of ichthyology in Africa is reviewed. From the time of the Ancient Egyptians to the present, more than 3200 species have been discovered, drawn and described. Michel Adanson initiated the first material collections during the 18th century. During the 19th century, the work of travelling scientists (Etienne Geoffroy Saint-Hilaire, Andrew Smith) and explorers (including Mungo Park, Pierre Savorgnan de Brazza and Henry Morton Stanley) added substantially to developing zoological collections from their field trips. At that time, many species descriptions were based on fish preserved in these collections. Towards the end of the 19th and into the early part of the 20th century, knowledge of African fishes was greatly enhanced, especially through the work of Georges A. Boulenger, Albert C.L.G. Gunther and Franz Steindachner, who, respectively, described 640, 119 and 53 species. The majority of the naturalists working in Africa during the middle and later parts of the 20th century tended to s...

The precise number of extant fish species remains to be determined. About 28,900 species were listed in FishBase in 2005, but some experts feel that the final total may be considerably higher. Freshwater fishes comprise until now almost 13,000 species (and 2,513 genera) (including only freshwater and strictly peripheral species), or about 15,000 if all species occurring from fresh to brackishwaters are included. Noteworthy is the fact that the estimated 13,000 strictly freshwater fish species live in lakes and rivers that cover only 1% of the earth’s surface, while the remaining 16,000 species live in salt water covering a full 70%. While freshwater species belong to some 170 families (or 207 if peripheral species are also considered), the bulk of species occur in a relatively few groups: the Characiformes, Cypriniformes, Siluriformes, and Gymnotiformes, the Perciformes (noteably the family Cichlidae), and the Cyprinodontiformes. Biogeographically the distribution of strictly freshwater species and genera are, respectively 4,035 species (705 genera) in the Neotropical region, 2,938 (390 genera) in the Afrotropical, 2,345 (440 genera) in the Oriental, 1,844 (380 genera) in the Palaearctic, 1,411 (298 genera) in the Nearctic, and 261 (94 genera) in the Australian. For each continent, the main characteristics of the ichthyofauna are briefly outlined. At this continental scale, ichthyologists have also attempted to identify ichthyological ‘‘provinces’’ that are regions with a distinctive evolutionary history and hence more or less characteristic biota at the species level. Ichthyoregions are currently identified in each continent, except for Asia. An exceptionally high faunal diversity occurs in ancient lakes, where one of the most noteworthy features is the existence of radiations of species that apparently result from intra-lacustrine speciation. Numerous fish-species flocks have been identified in various ancient lakes that are exceptional natural sites for the study of speciation. The major threats to fish biodiversity are intense and have been relatively well documented: overexploitation, flow modification, destruction of habitats, invasion by exotic species, pollution including the worldwide phenomena of eutrophication and sedimentation, all of which are interacting.

Onchocerciasis is a widespread disease in intertropical Africa, which, ultimately, causes irreversible blindness. The disease is transmitted by a small blackfly, Simulium damnosum (Diptera), which has aquatic larval and pupal stages. The breeding sites of the blackflies are riffles. These river reaches are the targets of the control campaign of the Onchocerciasis Control Programme in West Africa (OCP). An aquatic monitoring network covering the totality of the area exposed to the insecticide was set up to evaluate environmental impact. In this paper, we present results from the OCP 20-year period of monitoring of the ichthyofauna regularly exposed to larvicides. We do not record any measurable effects of pesticides on the CPUE, abundance of species, trophic structure, community structure or fish health. However, we detect the emergence of a number of medium-term tendencies. These tendencies may relate to climatic conditions that have a consequent effect on hydrology. Thus, we note a constant decrease in the CPUE from the beginning of the monitoring until 1995. The rivers were treated during that time until 1990 or 1993, depending on the station. But even after the treatments ended, the number of catches continued to decrease. As a result, we consider other factors to be the cause of that decline. The average level of annual discharges in this region has been decreasing regularly from the beginning of the 1970s. The production of fish fluctuates in all the rivers according to the flood rate. Important floods inundate larger areas, making greater quantifies of food available, and thus improving the conditions for reproduction. The determining factor of the ichthyological stock abundance seems to depend both on the extern and the duration of the flood. In our catches, the observed effect was not immediately evident but appeared a few years later as a cumulative effect of poor hydrological conditions. An increase in the CPUE since 1996 has been related to improved hydrological conditions. In these last few years, we have observed an intensification of the basic flow leading to a ground water renewal. Furthermore, on three of the stations investigated, it appeared that the impediment of rivers (dams) could induce different and/or antagonistic effects. In some cases, we have observed that in spite of unfavourable hydrological conditions, certain species appear to be favoured by the presence of the dam. But, the damming of the river has a negative effect on other species, particularly on the coefficient of condition of migratory fishes. The impact of these factors is enhanced by the fact they exist conjointly. © 1999 Ifremer/Cnrs/Inra/Ird/Cemagref/Éditions scientifiques et médicales Elsevier SAS Résumé — Maladie largement répandue en Afrique intertropicale l’onchocercose est un fléau qui provoque, à son stade ultime, une cécité irréversible. La maladie est transmise par un petit Diptère, Simulium damnosum, qui présente une phase larvaire et nymphale aquatique. Ce sont les gîtes larvaires de ce vecteur, biefs à courant rapide des rivières, que le Programme de lutte contre l’onchocercose en Afrique de l’Ouest (OCP: Onchocerciasis Control Programme in West Africa) traite lors de ses campagnes de lutte. Comme toute lutte insecticide, OCP représentait une menace importante pour l’environnement. C’est pourquoi le programme s’est doté d’un réseau de surveillance des écosystèmes aquatiques, couvrant l’ensemble de la zone exposée aux épandages d’insecticides. Ce sont les résultats de vingt années de surveillance de l’ichtyofaune, régulièrement exposée aux traitements larvicides, qui sont présentés ici. Les différentes variables étudiées dans cette étude, ne permettent pas de mettre en évidence un effet décelable des pesticides sur la structure et la richesse spécifique des peuplements. De même, la composition trophique ou la santé des poissons ne semblent pas affectées. Cependant, nous observons parfois certaines tendances, à moyen terme, qui semblent être essentiellement sous l’influence des conditions climatiques, probablement hydrologiques. Ainsi, nous observons une diminution régulière des prises par unité d’effort (PUE) du début de la surveillance jusque vers 1995. Durant cette période, les rivières ont été, selon les stations, traitées jusque 1990 ou 1993. Mais, alors que les traitements étaient terminés, la diminution des captures s’est poursuivie. Nous pouvons donc estimer que d’autres facteurs en sont la cause. Si nous considérons les crues moyennes annuelles et régionales, nous observons une diminution régulière depuis le début des années 1970. Dans toutes les rivières, la production de poisson fluctue en fonction du régime d’inondation. Lorsque les crues sont favorables, elles inondent des superficies plus grandes, ce qui favorise la disponibilité en nourriture, et améliore donc les conditions pour la pérennité des espèces. En fait, le facteur déterminant de la production halieutique semble être lié à la fois à l’étendue et à la durabilité de l’inondation. Dans nos captures, l'effet apparaît avec quelques années de retard comme s’il y avait eu un effet cumulatif des mauvaises conditions hydrologiques. Inversement, l’accroissement des PUE depuis 1996 paraît bien corrélé aux meilleures conditions de crue observées. Ces dernières années, nous notons un renforcement de l’écoulement de base qui se traduit par une recharge des nappes phréatiques. Enfin, sur trois stations étudiées, les barrages peuvent induite différents effets, antagonistes ou non. Dans certains cas, nous observons qu’en dépit de mauvaises conditions hydrologiques, certaines espèces semblent être favorisées par le barrage et sa retenue d’eau. Inversement, le barrage du fleuve peut avoir un effet négatif sur certaines autres espèces, particulièrement sur celles qui effectuent des migrations longitudinales. Tous ces facteurs semblent montrer une pression d’autant plus importante qu’ils se produisent en synergie. © 1999 Ifremer/Cnrs/Inra/Ird/Cemagref/Éditions scientifiques et médicales Elsevier SAS

© Ifremer/A. Guillou Introduction Dans la Caraïbe, les écosystèmes marins les plus florissants, situés en bordure des côtes, supportent des peuplements originaux. En effet, depuis la fermeture progressive de l’isthme de Panama, commencée durant l’ère tertiaire et achevée il y a environ 3,5 millions d’années, les espèces ont évolué séparément et la faune actuelle de la Caraïbe est différente de celle de l’Indo-Pacifique. Avec près de 70 espèces de coraux, 1 200 de mollusques et 600 de poissons...

We present in this chapter the regional approach of the BIOBAB project, whose aim was to define homogeneous regions as regards the ecological functioning of running waters. The approach consisted of identifying at different hierarchical levels the ecohydrological links between physical control factors and ecosystem structures. Such an approach should provide a global outlook of the natural diversity of aquatic ecosystems in the basin, and by understanding the distribution of the main functional types, to allow some spatial prediction of their most important physical characteristics and associated biota. We shall define, map, and briefly describe the "hydro-ecoregions" of the Bolivian Amazonian basin and present some important aquatic ecosystem characteristics about morphology, hydro-chemistry, and fish and invertebrate communities in the Andean zone. This work is the first attempt to regionalize running water ecosystems in South America, with the end objective to provide a geographical frame for management and conservation., Nous présentons dans ce chapitre l'approche régionale du projet BIOBAB, dont le but était de définir des régions homogènes par rapport au fonctionnement écologique des eaux courantes. L'approche consiste à identifier à différents niveaux hiérarchiques les liens hydroécologiques entre les facteurs de contrôle physiques et les structures des écosystèmes. Une telle approche devrait fournir des perspectives globales sur la diversité naturelle des écosystèmes aquatiques au niveau du bassin, et par la compréhension de la distribution des principaux types fonctionnels, devrait permettre des prédictions spatiales de leurs plus importantes caractéristiques physiques et des peuplements associés. Nous définirons, cartographierons, et décrirons brièvement les "hydro-écoregions" du bassin Amazonien Bolivien et présenterons certaines caractéristiques importantes des écosystèmes aquatiques concernant la morphologie, l'hydro-chimie, et les communautés de poissons et d'invertébrés de la zone andine. Ce travail est la première tentative de régionalisation des écosystèmes d'eau courante en Amérique du Sud, avec pour objectif final de fournir un cadre géographique pour la gestion et la conservation.

Les relations entre la richesse spécifique des Poissons et les caractéristiques physico-chimiques du milieu ont été étudiées sur deux fleuves côtiers de Côte d'Ivoire, l'Agnébi et la Bia. Ces deux fleuves sont soumis respectivement aux effets d'aménagements hydro-agricoles et hydroélectriques. Il en ressort que les cours supérieurs ont des compositions spécifiques proches, alors que le cours moyen ou la partie lacustre et l'aval sont distincts en raison de la présence des barrages Ayamé I et II. Ces retenues ont engendré une répartition longitudinale des peuplements ichtyologiques dans la Bia. A l'opposé, dans l'Agnébi, l'effet amont-aval est moins marqué du fait de la position excentrée des petites retenues hydro-agricoles par rapport au lit majeur du fleuve. Les eaux des fleuves Agnébi et Bia présentent des caractéristiques physico-chimiques proches. Les facteurs discriminants sont la conductivité, la teneur en matières dissoutes et dans une moindre mesure, la dureté totale de l'eau. On observe une faible rythmicité saisonnière de la qualité des eaux, associée à la température de l'eau et à sa teneur en composés azotés. Par ailleurs, l'analyse de co-inertie mettant en relation taxons et variables physico-chimiques a permis de répertorier cinq groupes de poissons présentant des affinités pour des conditions particulières du milieu. (Résumé d'auteur)