Dynamics of vibrio species in relation to zooplankton and other environmental parameters in ruvu estuary, Tanzania

The aim of this study was to investigate the population dynamics of Vibrio species in relation to the abundance of zooplankton and other environmental variables in Ruvu Estuary, Bagamoyo, Tanzania. Three sampling stations were established with station 1 in the fresh water, station 2 in the brackish waters and station 3 in marine waters. Sampling was done on a monthly basis from December 2012 to April 2013. Total Vibrio species abundance was quantified by using real time PCR. Zooplanktons were collected by using 80 µm plankton net and analysed in the laboratory using a stereo microscope. The highest mean zooplankton abundance of 466 ± 76.86 individuals/l was recorded at station 2 in January, while the lowest value was 8.66 ± 2.4 individuals/l at station 3 in March. Results showed no significant difference in zooplankton abundance among the sampling stations (KW = 5.308, p = 0.07). There was significant difference in the abundance of Vibrio species (KW = 12.471, p = 0.002) among the sampling stations. Dunn’s multiple comparison shows significant difference between station 1 and 3 (P < 0.01). The abundance of Vibrio species significantly correlated with that of zooplankton (r = 0.5412, p = 0.0137), salinity (r = 0.6264, p = 0.0031), secch depth (r = 0.6466, p = 0.0021), Conductivity (r = 0.6659, p = 0.0013) also negative significant correlated with Phosphorus (r = -0.4812, p = 0.0317) and turbidity (r = -0.4938, p = 0.02969). However, further monitoring program is required for Zooplankton abundance in relation to total Vibrio abundance.