Impact of Rainfall and Some Water Abiotic Factors on theAbundance Dynamic of Vibrio and Aeromonas Adhered toCopepods Surface in Some Coastal Streams and Rivers inCameroon (Central Africa)

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Koji, E. | Arfao, A. Tamsa | Djimeli, C. Lontsi | Ewoti, O.V. Noah | Nougang, M.E. | Bricheux, Geneviève | Nola, M. | Sime-Ngando, T.

Edité par CCSD ; Academicians research center -

International audience. A study was carried out on the tributaries draining into Rivers in the coastal region of Cameroon(Central Africa). It aimed at assessing the abundance of Vibrio and Aeromonas cells adhered to copepods withrespect to some considered abiotic factors. It has been noted that the tributaries are substantially concentratedin organic matter and these fluctuated, depending on the amount of rainfall received by the rivers throughoutthe period of the study. The abundance of Aeromonas cells adhered to copepod fraction ranged from 38CFU.Ind-1 to 8×103 CFU.Ind-1. That of Vibrio cells ranged from 75×102 CFU.Ind-1 to 42.4×103 CFU.Ind-1. Ofthe total bacteria identified in this study, V. cholerae relatively dominated the bacterial community (38%),followed by A. sobria (30%), A. hydrophila (27%) and other species namely V. alginoticus, V.parahaemolyticus, V. mimicus, V. vulnificus, A. cavia, Aeromonas sp. represented 5%. From the PrincipalComponent Analysis (PCA) assessing the influence of abiotic factors in the abundance changes of bacteriaattached to copepods, it appears that the first cloud of points includes the rainfall, pH, Aeromonas and Vibriowhile the second cloud on the left pole groups namely water temperature, salinity, carbon dioxide andoxydability. Vibrio and Aeromonas cells preferentially colonized copious quantities of copepods during theperiod of excess flood when the concentration of nutrients in the water column regressed. A complex network ofabiotic factors thus acts in synergy to influence the attachment of Aeromonas and Vibrio cells to copepods. Toprevent the risk of cholera outbreaks and non-cholera infections, ecological monitoring should be furtherenhanced during the period of excess rainfall.

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