Vibrio cholerae in waters of the Sunderban mangrove: relationship with biogeochemical parameters and chitin in seston size fractions.

LARA, R.J.; NEOGI, S.B.; ISLAM, S.M. ; MAHMUD, Z.; ISLAM, S.; DEMOZ. B.B, ; YAMASAKI, S.; NAIR, G.B.; KATTNER, GERHARD

WETLANDS ECOLOGY AND MANAGEMENT

SPRINGER

Lugar: Berlin; Año: 2011 vol. 19 p. 109 - 119

0923-4861

Wetland dynamics are probably linked tocholera endemicity in South Asia. We focus on linksbetween Vibrio cholerae abundance, chitin contentand suspended particle load in size fractions of suspendedparticulate matter (SPM) along the salinitygradient of Sunderban mangrove waters. SPM decreaseddownstream, while salinity increased from 0.2 to 4.Particulate organic carbon (90 ± 25 lM) and nitrogen(9.1 ± 3.3 lM) highly correlated with SPMand turbidity, suggesting a significant contributionof fine particles to organic matter. Total chitin ranged1?2 mg/l and decreased downstream. The distributionamong size fractions of SPM, chitin and V. choleraeO1 (the bacterial serogroup mainly associated withcholera epidemics) was similar, with *98% of thetotal in the fraction  lm. In comparison, thenumber of V. cholerae O1 attached to zooplanktonand microplankton size classes[20 lm was almostnegligible, in contrast to usual assumptions. Thus,microdetritus, nanoplankton and fungal cells in sizeclasses  lm represent a chitinaceous substrateon which V. cholerae can grow and survive. Totalbacteria, cultivable vibrios and V. cholera O1 increased5?10 times downstream, together with salinity andnitrite concentration. Overall, nitrate and silicateconcentrations were relatively constant ([22 lM Nand 100 lM Si). However, nitrite increased*9 timesin the outer sector, reaching *1.2 lM N, probably asa result of increased abundance of nitrate-reducingvibrios. A characterization of Vibrio habitats thattakes account of the presence of nitrate-reducingbacteria could improve the understanding of bothmangrove nitrogen cycling and cholera seasonality