| 1. |
- Asplund, Maria E., et al.
(författare)
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Water column dynamics of Vibrio in relation to phytoplankton community composition and environmental conditions in a tropical coastal area
- 2011
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Ingår i: Environmental Microbiology. - 1462-2912 .- 1462-2920. ; 13:10, s. 2738-2751
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Tidskriftsartikel (refereegranskat)abstract
- Vibrio abundance generally displays seasonal patterns. In temperate coastal areas, temperature and salinity influence Vibrio growth, whereas in tropical areas this pattern is not obvious. The present study assessed the dynamics of Vibrio in the Arabian Sea, 1-2 km off Mangalore on the south-west coast of India, during temporally separated periods. The two sampling periods were signified by oligotrophic conditions, and stable temperatures and salinity. Vibrio abundance was estimated by culture-independent techniques in relation to phytoplankton community composition and environmental variables. The results showed that the Vibrio density during December 2007 was 10- to 100-fold higher compared with the February-March 2008 period. High Vibrio abundance in December coincided with a diatom-dominated phytoplankton assemblage. A partial least squares (PLS) regression model indicated that diatom biomass was the primary predictor variable. Low nutrient levels suggested high water column turnover rate, which bacteria compensated for by using organic molecules leaking from phytoplankton. The abundance of potential Vibrio predators was low during both sampling periods; therefore it is suggested that resource supply from primary producers is more important than top-down control by predators.
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| 2. |
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| 3. |
- Rehnstam-Holm, Ann-Sofi, 1959-, et al.
(författare)
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Association between phytoplankton and Vibrio spp. along the southwest coast of India : a mesocosm experiment
- 2010
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Ingår i: Aquatic Microbial Ecology. - 0948-3055 .- 1616-1564. ; 58:2, s. 127-139
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Tidskriftsartikel (refereegranskat)abstract
- We report the results from a mesocosm study investigating the interrelationship between microalgae and vibrios. The mesocosms were inoculated with plankton, plankton + sediment, or sediment. We followed the diatom bloom and increases in the abundance of Vibrio spp. and V parahaemolyticus in conjunction with several environmental variables in all mesocosms and at a reference site. The dominating diatom genera were also identified. Temperature, salinity, and pH were nearly invariant in the mesocosms and did not contribute to the results. The principal environmental variables that correlated to vibrio abundance were total bacterial plate counts, phosphorus and ammonia (positive relationship), and oxygen and silica (negative). Nitrate, total bacterial counts and chlorophyll a (chl a) did not correlate with vibrio growth. The highest diatom abundances were followed by increases in vibrios in all mesocosms. This was also observed in field sampling. Together, these results suggest that diatom blooms could support Vibrio spp. growth. V parahaemolyticus was initially favoured by sediment. The contribution of V parahaemolyticus to the total bacterial population was low, on average 0.5 %, but constituted a rather high proportion of the vibrio population in the mesocosm systems, i.e. on average 18 %. Some of the identified diatom genera, e.g. Chaetoceros and Skeletonema, were negatively correlated to vibrios, while Coscinodiscus was positively correlated. The results indicate that phytoplankton blooms, when recorded as high levels of chl a, should be used with caution as predictors for future vibrio epidemics, since the origin of the chl a might have a significant effect on vibrio abundance.
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| 4. |
- Rehnstam-Holm, Ann-Sofi, 1959, et al.
(författare)
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Association between Phytoplankton and Vibrio spp along the southwest coast of India- a mesocosm experiment.
- 2010
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Ingår i: Aquatic Microbial Ecology. - : Inter-Research. - 0948-3055 .- 1616-1564. ; 58, s. 127-139
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Tidskriftsartikel (refereegranskat)abstract
- We report the results from a mesocosm study investigating the interrelationship between microalgae and vibrios. The mesocosms were inoculated with plankton, plankton + sediment, or sediment. We followed the diatom bloom and increases in the abundance of Vibrio spp. and V parahaemolyticus in conjunction with several environmental variables in all mesocosms and at a reference site. The dominating diatom genera were also identified. Temperature, salinity, and pH were nearly invariant in the mesocosms and did not contribute to the results. The principal environmental variables that correlated to vibrio abundance were total bacterial plate counts, phosphorus and ammonia (positive relationship), and oxygen and silica (negative). Nitrate, total bacterial counts and chlorophyll a (chl a) did not correlate with vibrio growth. The highest diatom abundances were followed by increases in vibrios in all mesocosms. This was also observed in field sampling. Together, these results suggest that diatom blooms could support Vibrio spp. growth. V parahaemolyticus was initially favoured by sediment. The contribution of V parahaemolyticus to the total bacterial population was low, on average 0.5 %, but constituted a rather high proportion of the vibrio population in the mesocosm systems, i.e. on average 18 %. Some of the identified diatom genera, e.g. Chaetoceros and Skeletonema, were negatively correlated to vibrios, while Coscinodiscus was positively correlated. The results indicate that phytoplankton blooms, when recorded as high levels of chl a, should be used with caution as predictors for future vibrio epidemics, since the origin of the chl a might have a significant effect on vibrio abundance.
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