10 research outputs found
Données sur la reproduction d'un tilapia estuarien (
Des paramĂštres de la reproduction d'une population
isolée du tilapia Sarotherodon melanotheron ont
été étudiés durant 2 années consécutives
et comparés avec les données de la littérature obtenues
sur des populations vivant dans son milieu naturel. Le sexe-ratio
(année 1 : 1:2,69; année 2 : 1:1,96) en faveur des femelles
varie de façon saisonniÚre. Les mùles atteignent la maturité
sexuelle plus rapidement (année 1 : 129 mm LS ; année 2 : 126 mm LS) que
les femelles (année 1 : 135 mm ; année 2 : 136 mm LS). Le cycle de
maturation des gonades est continu. Ces résultats sont dans l'ensemble
semblables Ă ceux obtenus dans le milieu naturel de l'espĂšce. Cependant,
une fécondité inférieure et un diamÚtre ovocytaire plus grand
sont notés dans le lac d'Ayamé. Le facteur de condition moyen des
populations du lac, intermédiaire entre des valeurs observées dans les
milieux lagunaires, indique une bonne adaptation de l'espĂšce aux conditions
d'eau douce du lac
Length-weight Relationships of 30 Fish Species in Aby Lagoon, Southeastern CĂŽte d' Ivoire
Abstract: Most West African lagoons are very productive ecosystems that support important fishery activities. However, increases in human populations put heavy pressure on their resources. This raised the importance of sustainable management tools for these ecosystems. Length-Weight Relationships (LWRs) which is an important fish stock assessment tool was investigated in the Aby lagoon, southeastern CĂŽte d'Ivoire. Fishes were caught monthly from February 2012 through March 2013 using gillnets. Fishes captured were identified, weighted to the nearest gram and standard length was measured to the nearest millimeter. The 30 fish species selected for this study belong to 18 families. The highest species number (n = 7) was recorded for Cichlidae family. All length-weight regressions were significant with a coefficient of determination (rÂČ) varying from 0.462 (Parailia pellucida) to 0.984 (Elops lacerta). Growth coefficient, b of the LWR ranged from 2.229 (P. pellucida) to 3.811 (Eleotris vittata). Nineteen species exhibited negative allometric growth pattern while 11 had positive allometric growth. These results are useful references for West African coastal lagoon management and particularly for that of the Aby lagoon system
Engineering and Technology (A High Impact Factor
Abstract: Some biological features (length-weight relationship, size at first sexual maturity, eggs variation in diameter, gonado-somatic index, hepato-somatic index, somatic condition and fecundity) and histological characteristics of frigate tuna Auxis thazard were studied. The study was carried out on 496 female fish caught in gillnets and measuring in size between 25 and 48 cm FL (centimetre Fork Length) collected from January to December 2004. The results indicated that female frigate tuna reach maturity at 29.88 cm FL. Spawning started in June while females at stage IV numbered 36.36% but it lessened in November. The peak value of gonado-somatic index, GSI (3.21 ± 0.93%), was attained in August and GSI thereafter decreased gradually from September to December. There is a direct correlation between GSI and hepato-somatic index (HSI), and an inverse correlation of these factors to the somatic condition (K c ). Absolute fecundity has linear relationship with the weights of specimens (AF = -9.3792 + 0.5485Ń
W) as well as with the weights of ovaries (AF = 136.11 + 13.416Ń
OW). Eggs frequency distribution within the maturity stages III (maturing or developing), IV (spawning), and V (post spawning) were also shown in the study
Aspects of the reproductive biology of the blue shark Prionace glauca (Linnaeus, 1758) in the coastal waters of Ivory Coast, West Africa
Length-Weight Relationships and Condition Factor of Twenty-Four Freshwater Fish Species from Lake Buyo, CĂŽte DâIvoire
Population dynamics of 15 fish species in Grand-Lahou lagoon (West Africa, CĂŽte d'Ivoire) | IJB 2022
This study described growth, mortality, recruitment patterns and exploitation rates of 15 fish species in Grand-Lahou lagoon (CĂŽte dâIvoire). Monthly length-frequency data collected from artisanal fisheries from November 2013 to October 2014 were analyzed with FiSAT software using the ELEFAN package to estimate the population parameters of fishes. Asymptotic values for total length (Lâ) ranged from 15.75 cm for Synodontis schall to 59.80 cm for Trachinotus teraia. Growth rate (k) varied from 0.19 for Coptodon guineensis to 0.98 for Caranx hippos. The growth performance index estimates were close to the values found by other authors for most of the fish species. The total mortality (Z) high values were recorded for Synodontis schall (Z= 4.15 year-1; M = 2.50 year-1) Schilbe mandibularis (Z= 2.19 year-1; M=1.33 year-1). Fishing mortality (F) and exploitation rate (E) were found to be less than the optimum levels of exploitation for most fish species. The exploitation rate (E) was higher than the maximum sustainable yield (Emax) for Caranx hippos and higher than E0.5 for Eucinostomus melanopterus, Elops lacerta and Synodontis schall. Recruitment was noted as year-round and bimodal for most studied populations. These results demonstrate that some fish stocks necessitate effective management measures particularly C. hippos, E. melanopterus, E. lacerta and S. schall.
Published by the International Journal of Biosciences | IJ
Impact Des AmĂ©nagements HydroĂ©lectriques Sur Le Peuplement Des Poissons Du Lac De Barrage De Buyo Et De La Zone PĂ©riphĂ©rique (CĂŽte dâIvoire)
Lâobjectif de ce travail Ă©tait de dĂ©terminer lâimpact des variations des niveaux dâeau sur la distribution des poissons dans le lac de Buyo et le cours principal du fleuve Sassandra. Les campagnes ont lieu de Juin 2018 Ă Mai 2019. Les changements hydrologiques ont Ă©tĂ© observĂ©s aprĂšs la mise en eau dâun deuxiĂšme barrage sur le fleuve Sassandra. Ces changements hydrologiques ont eu un impact sur la diversitĂ© piscicole. Les poissons ont Ă©tĂ© capturĂ©s Ă lâaide des filets maillants et des nasses artisanales. Ces poissons sont repartis en 6 ordres, 14 familles et 42 espĂšces. Dans le lac de Buyo, lâespĂšce Synodontis punctifer domine le peuplement en pĂ©riode de crue alors que Coptodon zillii est prĂ©pondĂ©rante en pĂ©riode de dĂ©crue. Dans le cours principal lâespĂšce Synodontis punctifer domine le peuplement durant les pĂ©riodes dâouverture et de fermeture des vannes du barrage, cette espĂšce est plus adaptĂ©e aux changements hydrologiques. Une bonne organisation du peuplement est observĂ©e en pĂ©riode de crue dans le lac. Dans le cours principal, une bonne organisation du peuplement est avĂ©rĂ©e en pĂ©riode de dĂ©crue lorsque les vannes du barrage sont fermĂ©es. Le modĂšle de prĂ©vision a montrĂ© que dans le lac de Buyo, la richesse spĂ©cifique est influencĂ©e positivement les cotes de retenue mais nĂ©gativement par le dĂ©bit dâapport dâeau et le volume dâeau dĂ©versĂ©. Dans le milieu fluviatile, le modĂšle a montrĂ© que la richesse spĂ©cifique est influencĂ©e nĂ©gativement par la profondeur et le dĂ©bit dâeau turbinĂ© mais influencĂ© positivement par la vitesse du courant.
The objective of this work was to determine the impact of water level variations on fish distribution in Lake Buyo and the main course of the Sassandra River. The campaigns will take place from June 2018 to May 2019. The hydrological changes are proven after the impoundment of a second dam on the Sassandra River. These hydrological changes have had an impact on fish diversity. The fish were caught using gillnets and artisanal traps. These fish are divided into 6 orders, 14 families and 42 species. In Lake Buyo, the species Synodontis punctifer dominates the population during the flood period while Coptodon zillii is predominant during the low water season. In the mainstream, the species Synodontis punctifer dominates the population during the periods of opening and closing of the gates of the dam, this species is more adapted to hydrological changes. A good organization of the population is observed during the period of flooding in the lake. In the main river, a good organization of the population is proven during the flood period when the gates of the dam are closed. The predictive model showed that in Lake Buyo, the species richness is positively influenced by the impoundment rating but negatively by the inflow rate and the volume of water discharged. In the fluvial environment, the model showed that the specific richness is negatively influenced by the depth and the turbinated water flow but positively influenced by the current speed
Peuplement de la faune de crevettes de la ForĂȘt des Marais TanoĂ©-Ehy (Sud-Est de la CĂŽte dâIvoire)
Objectif : Cette Ă©tude se propose dâĂ©tudier lâĂ©cologie et la diversitĂ© des communautĂ©s de crevettes dans la ForĂȘt des Marais TanoĂ©-Ehy (Sud-Est de la CĂŽte dâIvoire, Afrique de lâOuest).MĂ©thode et rĂ©sultats : Les Ă©chantillonnages ont Ă©tĂ© menĂ©s mensuellement, dâavril 2012 Ă mars 2013 Ă lâaide dâune Ă©puisette et des nasses. Six espĂšces de crevettes ont Ă©tĂ© capturĂ©es : Desmocaris trispinosa (Desmocarididae), Macrobrachium dux, M. equidens, M. macrobrachion, M. vollenhovenii et M. thysi (Palaemonidae). Desmocaris trispinosa est la plus largement distribuĂ©e (100 % dâoccurrence et 92,27 % dâabondance relative). Lâanalyse de redondance (RDA) a montrĂ© que les variables environnementales telles que le taux dâoxygĂšne dissous, la conductivitĂ©, la tempĂ©rature de l'eau, la transparence, les dĂ©bris vĂ©gĂ©taux, les plantes aquatiques et le taux de fermeture de la canopĂ©e influencent fortement la diversitĂ© taxonomique.Conclusion et application des rĂ©sultats : Cette Ă©tude a permis de dĂ©terminer lâinfluence des variables environnementales sur la diversitĂ© et lâabondance de la faune de crevettes dans la ForĂȘt des Marais TanoĂ©-Ehy et confirme la possibilitĂ© dâutiliser lâespĂšce M. thysi pour Ă©valuer la qualitĂ© des habitats. Aussi, a-t-elle dĂ©montrĂ© le caractĂšre exceptionnel de cette forĂȘt par sa spĂ©cificitĂ© et recommande vivement sa prĂ©servation.Mots clĂ©s : crevettes, Ă©cologie, diversitĂ©, ForĂȘt des Marais de la TanoĂ©-Ehy, CĂŽte dâIvoire
Distribution du zooplancton en relation avec les caractĂ©ristiques environnementales de quatre riviĂšres cĂŽtiĂšres du Sud-est de la CĂŽte dâIvoire (Afrique de lâouest)
Objectifs: Cette Ă©tude vise Ă dĂ©terminer la distribution spatio temporelle du zooplancton en relation avec les caractĂ©ristiques environnementales dans quatre riviĂšres cĂŽtiĂšres du Sud-est de la CĂŽte dâIvoire.MĂ©thode et rĂ©sultats: Le zooplancton a Ă©tĂ© Ă©chantillonnĂ© mensuellement de mars 2012 Ă fĂ©vrier 2013 Ă lâaide dâun filet Ă plancton de 64 Gm de vide de maille. Au total 28 taxons ont Ă©tĂ© observĂ©s (15 RotifĂšres, 6 CopĂ©podes, 4 CladocĂšres et 3 autres organismes). Les RotifĂšres constituent le groupe dominant avec 67% de lâabondance totale. Rotaria sp. est le taxon le plus abondant (52%). Globalement, la richesse taxonomique et lâabondance les plus faibles ont Ă©tĂ© enregistrĂ©es dans les riviĂšres recevant les effluents dâunitĂ© agroindustrielles de palmier Ă huile (Ehania, Boulo1). Les rĂ©sultats de lâanalyse de redondance (RDA) montrent que les variables Influençant fortement la diversitĂ© taxonomique et lâabondance sont la vitesse du courant, la conductivitĂ©, la tempĂ©rature, le taux de fermeture de la canopĂ©e et la proportion des dĂ©bris vĂ©gĂ©taux.Conclusion et application: Cette Ă©tude Ă permis de dĂ©terminer lâinfluence des variables environnementales sur la distribution du zooplancton dans 4 riviĂšres cĂŽtiĂšres du Sud-est de la CĂŽte dâIvoire et confirme la possibilitĂ©Â dâutiliser Rotaria sp. comme indicateur de pollution.Mots clĂ©s: Zooplancton, diversitĂ©, abondance, effluents industrielsEnglish Title: Distribution of zooplankton in relation with environmental characteristics of four coastal rivers in South-Eastern CĂŽte dâIvoire (West Africa)English AbstractObjectives: This study aims to determine the distribution of zooplankton in relation with environmental variables in four coastal rivers in South East CĂŽte dâIvoire.Method and results: Zooplankton samples were collected monthly from March 2012 to February 2013 in six sampling sites with a cylindro-conical net of 64-Gm mesh-size. 28 taxa of zooplankton belonging to Rotifera (15 taxa), Copepoda (6 taxa), Cladoceran (4 taxa) and others zooplankton (3) were identified. Rotifers constituted the most abundant group (67%). Rotaria sp. was the most abundant taxa (52% of total abundance). Overall, taxa diversity and abundance were lower in rivers receiving palm oil mill effluents in their catchment area. The ReDundancy Analysis (RDA) performed showed that environmental variables such as current velocity, conductivity, water temperature, canopy closure and vegetal debris occurrence influence strongly diversity and abundance of zooplankton.Conclusion and application: This study allowed to identify environmental factors, which influence the distribution of zooplankton taxa and show the possibility to use Rotaria sp. as pollution indicator.Keywords: Zooplankton, diversity, abundance, industrial effluent
Characteristics of HIV-2 and HIV-1/HIV-2 Dually Seropositive Adults in West Africa Presenting for Care and Antiretroviral Therapy: The IeDEA-West Africa HIV-2 Cohort Study.
HIV-2 is endemic in West Africa. There is a lack of evidence-based guidelines on the diagnosis, management and antiretroviral therapy (ART) for HIV-2 or HIV-1/HIV-2 dual infections. Because of these issues, we designed a West African collaborative cohort for HIV-2 infection within the framework of the International epidemiological Databases to Evaluate AIDS (IeDEA).We collected data on all HIV-2 and HIV-1/HIV-2 dually seropositive patients (both ARV-naive and starting ART) and followed-up in clinical centres in the IeDEA-WA network including a total of 13 clinics in five countries: Benin, Burkina-Faso CĂŽte d'Ivoire, Mali, and Senegal, in the West Africa region.Data was merged for 1,754 patients (56% female), including 1,021 HIV-2 infected patients (551 on ART) and 733 dually seropositive for both HIV-1 and HIV 2 (463 on ART). At ART initiation, the median age of HIV-2 patients was 45.3 years, IQR: (38.3-51.7) and 42.4 years, IQR (37.0-47.3) for dually seropositive patients (pâ=â0.048). Overall, 16.7% of HIV-2 patients on ART had an advanced clinical stage (WHO IV or CDC-C). The median CD4 count at the ART initiation is 166 cells/mm(3), IQR (83-247) among HIV-2 infected patients and 146 cells/mm(3), IQR (55-249) among dually seropositive patients. Overall, in ART-treated patients, the CD4 count increased 126 cells/mm(3) after 24 months on ART for HIV-2 patients and 169 cells/mm(3) for dually seropositive patients. Of 551 HIV-2 patients on ART, 5.8% died and 10.2% were lost to follow-up during the median time on ART of 2.4 years, IQR (0.7-4.3).This large multi-country study of HIV-2 and HIV-1/HIV-2 dual infection in West Africa suggests that routine clinical care is less than optimal and that management and treatment of HIV-2 could be further informed by ongoing studies and randomized clinical trials in this population