Observations de la temperature et des courants sur le plateau continental ivoirien

The Centre de Recherches Océanographiques d'Abidjan has carried out the HYDROBIOCLIMAT program in order to study the seasonal and interannual fluctuations of the physical and biological parameters over the continental shelf of Ivory Coast ; two subsurface moorings with from one to three AANDERAA current meters fixed on the lines, were deployed in front of Abidjan and San Pedro. Temperature and current measurement records are presented at these two locations.

Synopsis de la classification des larves et des nymphes de diptères chironomidae des ecosystèmes dulçaquicoles de l'Afrique de l'Ouest: clés de détermination des sous-familles, des tribus et des genres

Synopsis of this numerically very important Diptera category, which is dominant and consequently of relevance in most aquatic environments.

Statistiques de pêche en Lagune Aby (Côte d'Ivoire): évolution de l'effort et des captures de 1979 à 1990

Two kinds of fishing gears insure the exploitation in Aby lagoon: the individual gears are represented essentially by gill nets and collective gears by seines. The number of gill nets varies between 1500 in 1981 and 5600 in 1986. The beach seines, which number varies between 40 and 60, are regularly used. The purse seines (15-30) have been superseded by "syndicat" seines (15) in 1990.

Biologie de l'Ethmalose, Ethmalosa fimbriata (Bowdich), en Côte d'Ivoire. 1 - Description de la reproduction et des premiers stades larvaires

Descriptions of spawning and larval development of Ethmalosa, up to the vitelline vesicle resorption stage, are made from plankton samplings in the Ebrié coastal lagoon and from artificially fertilized eggs. Spawning takes place from November to June in waters with salinities of 18 to 26 parts per thousand, and temperatures of 22.8 to 30.2 degrees, for 13-14 cm long fishes.

L'oxygène dissous en Lagune Ebrié: Influences de l'hydroclimat et des pollutions

The hydrology of the Ebrie coastal lagoon in Abidjan area is summarized. The authors describe the oxygenation in that area during the two extreme seasons of the hydrological cycle: the low-water season (March-April) and the high-water season (Sept-Oct). The influences of the continental and oceanic waters, photosynthesis, exchanges with the atmosphere and pollution are considered. The oxigen consumption of primary organic pollution represents from 9 to 12% of the content of the waters that circulates in the area. It is geographically very heterogeneous. The central basin, swept by strong marine and fresh water currents, shows a rather high level of water oxygenation. In the peripheric bays, water circulation and mixing are less important and pollution accelerates the natural eutrophic processes. During the low-water season, a vertical stratification is responsible for a bottom anoxic layer and the deposit of reduced organic silts. On the contrary, supersaturations, up to 200%, are recorded on the surface layer. During the high-water season the break of the vertical stratification sets the loose reduced silts into suspension and partly reoxygenates the bottom waters. A classification of the different areas, based on the oxygen vertical profiles is proposed.

Méthodes des mesures des biovolumes, poids secs, poids secs sans cendres et des éléments C, N, P du mésozooplancton utilisées au C.R.O. d'Abidjan

Methods for the estimation of zooplankton biomasses, used in the Oceanographic Research Center of Abidjan are presented. They deal with settled and displacement volumes, dry weight and ash-free dry weight, elementary carbon, nitrogen and phosphorus composition. The dry weight method is detailed: elimination of salt by a fresh water stream, preservation of dry samples at -20 degrees Celsius, rehydration during weighing. A few comments on the 'CHN' analysed values are made: at 1,100 degrees Celsius, most of the carbon is organic, only 10% of the mineral fraction being analysed.