Spatio-temporal Variations of Abundance, Biomass, and Reproductive Parameters of Pseudodiaptomus hessei (Mrazek, 1895) (Copepoda Calanoida) in a West African Coastal Lagoon (Grand-Lahou, Côte d’Ivoire)

The spatio-seasonal variations of Pseudodiaptomus hessei abundance, biomass and reproductive parameters were investigated in the Grand-Lahou lagoon at five stations during the dry and wet (or rainy) seasons from September 2005 to August 2006. In all sampling stations, abundance and biomass of P. hessei in the dry season were higher (0.16 to 2.17 ind.L-1, 0.45 to 4.97 μgC.L-1) than in the wet season (< 1 ind.L-1, 0.03 to 2.36 μgC.L-1). During the two seasons, abundances and biomass of P. hessei in the north part of the lagoon (stations 1 and 2) was higher (0.23 to 2.17 ind.L-1, 1.05 to 4.97 μgC.L-1) than in the inner part of the lagoon (stations 3 to 5: < 0.5 ind.L-1, < 1 μgC.L-1). Ovigerous females were mainly observed in the north part of the lagoon during the dry season and at stations 1 and 3 during wet season. Besides, all reproductive parameters of P. hessei present the same spatio-temporal variation. Correlation analyses showed that P. hessei abundance and biomass were negatively correlated with temperature, salinity and dissolved oxygen during the dry season. From these results, all reproductive parameters are significantly and positively correlated with nitrites and phosphates concentrations. During the wet season, P. hessei abundance were significantly and positively correlated with ammonium while biomass was significantly and positively correlated with dissolved oxygen and ammonium concentrations. During this season, no reproductive parameter of P. hessei was significantly correlated to the environmental variables. However, all reproductive characteristics were positively correlated (no significantly) with dissolved oxygen, nitrites and phosphates concentrations on the one hand, and negatively correlated with water temperature, salinity, pH and ammonia on the other hand.Key words: Pseudodiaptomus hessei, spatio-temporal variability, biomass and production, Tropical coastal Lagoon (Côte d’Ivoire)

Typologie de la pêche en lagune Aghien-Potou (Côte d’Ivoire, Afrique de l’Ouest) : acteurs et engins de pêche

La pêche dans le système lagunaire Aghien-Potou (Côte d’Ivoire, Afrique de l’Ouest) est de type artisanal. Elle est pratiquée tant par des pêcheurs professionnels (étrangers) qu’occasionnels (ivoiriens de l’ethnie Gwa et Appolo) et concerne principalement les adultes. Les techniques de pêche sont individuelles (filets maillants, nasses, bambou-pièges, palangres et éperviers) ou collectives (sennes de plage). La densité de pêcheurs (14 pêcheurs/km²) est très élevée.Mots-clés : Pêche artisanale, techniques de capture, lagune Aghien-Potou, Côte d’Ivoire

Régime alimentaire de Distichodus rostratus (Characiformes, Distichodontidae) dans un bassin Ouest africain (fleuve Bandama, Côte d\'Ivoire)

La morphologie du tube digestif et le régime alimentaire en fonction du stade de maturité et de la saison de Distichodus rostratus (Günther, 1864) ont été étudiés en milieu naturel entre deux barrages hydroélectriques du fleuve Bandama (Kossou et Taabo). L\'analyse a porté sur 220 individus de longueur standard comprise entre 131 et 610 mm. La description du tube digestif a révélé la présence d\'un estomac peu développé et un intestin long (2,34 < CI < 5,16), rapprochant ainsi l\'espèce de la catégorie des poissons phytophages. D. rostratus consomme essentiellement des macrophytes (Ip = 99,98%) surtout de Cymodecea sp. (Ip = 57,8 %) et de débris végétaux (Ip = 41,4 %). L\'indice de Schoener ( ) montre de façon générale une grande similitude du régime alimentaire des poissons en fonction de la taille et des saisons.Studies of the digestive tract morphology and the feeding habits of Distichodus rostratus from the hydrosystem located between the hydroelectric dams of Kossou and Taabo (Bandama river) is undertaken for the first time. About 220 individuals of measuring between 131 and 610 mm length were examined. The digestive tract morphology had less developed stomach with a relatively long intestine (2,34 < CI < 5,16) allowing the classification this species as a micro/ macrophytophagous fish. The identification of the items found the stomach contents revealed that the dominants food items were the Cymodocea sp. (Ip = 57,8 %) and macrophyte fragments (Ip = 41,4 %) in general. Young specimens food fed on mainly macrophyte fragments (Ip = 61,5 %) and Cymodocea sp. (Ip = 38,4 %). Or while adults were concern with the Cymodocea sp. (Ip = 66,5 %) and macrophyte fragments (Ip = 31,2 %). The macrophyte fragments (Ip = 52,18%) was mainly eaten during the dry season whereas Cymodocea sp. (Ip = 64,3 %) was mainly eaten during the rainy season. Schoener overlap index showed the similary in the diet composition in relation with size of the fishes and with the season. Keywords: Distichodus rostratus- Diet - Bandama River - Côte d\'Ivoire.Sciences & Nature Vol. 5 (2) 2008: pp. 167-17

Effets de la couverture des cages flottantes et de la période de distribution de l\'aliment sur la survie et la croissance des alevins du poisson-chat africain Heterobranchus longifilis Valenciennes 1840 en élevage intensif

L\'influence du recouvrement des cages flottantes par des bâches plastiques noires non transparentes et de la période (jour ou nuit) de distribution de l\'aliment sur la survie et la croissance du poisson-chat africain Heterobranchus longifilis a été évaluée. L\'expérience a consisté à observer le jour et la nuit des alevins nourris en quatre repas, dans deux types de cages flottantes : cages couvertes et cages non couvertes. Quelle que soit la période de distribution de l\'aliment, les meilleurs taux de survie ont été observés dans les cages couvertes (73,0 ± 2,6 % le jour et 75,0 ± 1,7 % la nuit contre 64,0 ± 3,5 % le jour et 67,0 ± 2,0 % la nuit). Les poids moyens finaux des poissons enregistrés dans ces cages sont de 16,9 ± 1,9 g le jour et 17,8 ± 1,9 g la nuit. Ces poids sont comparables à ceux observés dans les cages non couvertes avec distribution nocturne de l\'aliment (16,8 ± 1,1 g). Ces résultats montrent qu\'en cages couvertes, la période de distribution de l\'aliment n\'a aucune influence sur la croissance des poissons.The effects of covering the breeding floating cages with a black plastic canvas and the feeding period (day or night) on the survival and growth of the african cat-fish Heterobranchus longifilis have been investigated. Juvenile individuals of this species fed four times during daytime and nighttime were reared in two types of floating cages : covered with black plastic canvas and without any canvas. Whatever the feeding period, the best survival rates were recorded in covered cages (73,0 ± 2,6 % for daytime and 75,0 ± 1,7 % for nighttime, against 64,0 ± 3,5 % for daytime and 67,0 ± 2,0 % for nighttime). In these cages, final mean weights of fishes recorded were 16,9 ± 1,9 g for daytime and 17,8 ± 1,9 g for nighttime. These data were similar to those recorded in non covered floating cage with nighttime feeding. Results suggest that there is no effect of the feeding period on the growth of H. longifilis reared in cages with canvas. Keywords: Heterobranchus longifilis, alevinage, cage flottante, éclairement, horaires de nourrissage./Heterobranchus longifilis, fry rearing, floating cage, light, feeding time.Sciences & Nature Vol. 4 (1) 2007: pp. 85-9

Spatiotemporal variations in the abundance, biomass, fecundity, and production of Oithona brevicornis (Copepoda : Cyclopoida) in a West African tropical coastal lagoon (Grand-Lahou, Cote d'Ivoire)

Raphael N'doua Etile, Maryse N'guessan Aka, Aka Marcel Kouassi, Marc Pagano, and Valentin N'douba (2012) Spatiotemporal variations in the abundance, biomass, fecundity, and production of Oithona brevicornis (Copepoda: Cyclopoida) in a West African tropical coastal lagoon (Grand-Lahou, Cote d'Ivoire). Zoological Studies 51(5): 627-643. Oithona brevicornis is a very important zooplankton species in coastal and estuarine aquatic ecosystems of West Africa and was recorded in very high abundances in coastal lagoons of Cote d'Ivoire. To better understand the functional role of this key species, spatio-seasonal variations in O. brevicornis abundance, biomass, fecundity, and production were investigated at 21 stations in Grand-Lahou Lagoon during an annual cycle from Jan. to Dec. 2004. The abundance and biomass showed more or less important spatiotemporal variations. Two peaks were recorded for the mean spatial values in Feb.-Mar. and Sept. During the long (LDS) and short dry seasons (SDS), all developmental stages showed their weakest density and biomass in the channel zone and near the mouth of the Boubo River. During the long (LRS) and short rainy seasons (SRS), O. brevicornis almost disappeared or showed very low abundances (< 1 individual/L) in the northern part and near the channel. Spatiotemporal variations in O. brevicornis fecundity and production showed no particular pattern during the dry seasons (LDS and SDS), while during the rainy seasons (LRS and SRS), very low fecundity and production values were recorded at stations influenced by river inputs. Correlation analyses showed that temperature and salinity were the main variables explaining these spatio-seasonal variations. http://zoolstud.sinica.edu.tw/Journals/51.5/627.pd

Espèces nouvelles du genre

Les auteurs décrivent Annulotrema macropenis n. sp. et Annulotrema biaensis n. sp., parasites de Hepsetus odoe (Bloch, 1794) en Côte d'lvoire et amendent et précisent la description de A. hepseti Paperna et Thurston, 1969

Espèces nouvelles du genre Annulotrema Paperna et Thurston, 1969 (Monogenea, Ancyrocephalidae) parasites de Hepsetus odoe (Bloch, 1794) (Teleostei, Hepsetidae) en Côte d'Ivoire

Les auteurs décrivent #Annulotrema macropenis n. sp. et #Annulotrema biaensis n. sp., parasites de #Hepsetus odoe (Bloch, 1794) en Côte d'Ivoire et amendent et précisent la description de #A. hepseti Paperna et Thurston, 1969. (Résumé d'auteur

Régime alimentaire de Ctenopoma petherici (Perciformes, Anabantidae) dans la rivière Agnéby et dans le lac de barrage hydroélectrique d'Ayamé 2 (Côte d'Ivoire)

Feeding Diets of Ctenopoma petherici (Perciformes, Anabantidae) from the Agneby River and from the Hydroelectric Lake Dam of Ayame 2 (Côte d'Ivoire). The present study describes the feeding habits of Ctenopoma petherici (Perciformes, Anabantidae) in the Agneby River and in the hydroelectric Lake dam of Ayame 2. Fishes were caught monthly using gill-nets from September 2015 to August 2016. Stomach contents of 425 specimens were analysed under a magnifying glass and a microscope. The Relative Importance of Food Index has been calculated to assess the relative abundance of the preys. The general profile of the diet indicated that C. petherici feeds on insects, arachnids, molluscs, batrachians, macrophytes and algae. The insects provide the main part of the feeding and they constitute the principal prey category. Macrophytes were the secondary item while arachnids, molluscs, batrachians and algae were accessory preys. These results indicate that this species is omnivorous with an insectivorous tendency. This feeding pattern is seasonally affected, particularly in the Agneby River. However, there is no variation in the diet according to the size of the individuals

Паразито-хозяинные коэволюционные отношения клещей рода Riccardoella (Prostigmata, Ereynetidae) с наземными моллюсками

В лабораторной культуре паразитических клещей Riccardoella (Proriccardoella) oudemansi Thor, 1932 на их хозяине — слизне Deroceras reticulatum (Gastropoda) изучено поведение и паразито-хозяинные отношения между этими видами, а также влияние оптимальных и экстремальных условий на паразита. Прослежено развитие R. (P). oudemansi от яйца до половозрелых стадий, колебание численности каждой стадии в оптимальных и экстремальных условиях. Определено негативное воздействие клещей при питании их на хозяине — слизне, приводящее к отставанию в развитии и летальному исходу. Показан паразитический статус R. (P). oudemansi как не устоявшийся, переходящий в экстремальных условиях в факультативный.In a laboratorial culture of parasitic mites Riccardoella (Proriccardoella) oudemansi Thor, 1932 on their host — slug Deroceras reticulatum (Gastropoda) — the behavior and host-parasite relationships between these species and the effect of optimal and extreme conditions on the parasite were studied on their host, slug Deroceras reticulatum (Gastropoda). The development of R. (P). oudemansi from egg to mature stages, variation of the number of each stage in the optimal and extreme conditions were traced. The negative effect of mites on their host, a slug, while feeding leads to underdevelopment and death of the host was detected. Parasitic status of R. (P). oudemansi was elucidated to be not well-established with transition to the optional under the extreme conditions

n. Sp. (Dactylogyridea) Monogene parasite de

Les auteurs décrivent chez Schilbe mandibularis (Günther, 1867) (Schilbeidae) des rivières Bia et Agnéby de Côte d'Ivoire une nouvelle espèce de Monogène, parasite branchial, du genre Schilbetrematoides Kritsky & Kulo, 1992. S. manizani n sp. diffère essentiellement de S. pseudodactylogyrus Kritsky & Kulo, 1992 parasite de Schilbe intermedius Ruppell, 1832 par la morphologie très particulière des gripi