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- Godhe, Anna, 1967, et al.
(author)
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Long-term patterns of net phytoplankton and hydrography in the coastal SE Arabian Sea: What can be inferred from genus level data?
- 2015
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In: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 162:5, s. 69-75
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Journal article (peer-reviewed)abstract
- Based on 21 years of phytoplankton and environmental monitoring data from the surface water of coastal southeast Arabian Sea, we demonstrate a shift in phytoplankton community towards higher sample genus richness and diatom abundance during the two decades of observations. Analyses were based on 587 water samples collected between 1990 and 2010 and additionally revealed marked long-term changes in sea surface temperature (SST), sea surface salinity (SSS) and turbidity (Secchi depth). The abundances of dinoflagellate genera were positively correlated to SST, particularly during and after the 1997–1998 El Niño Southern Oscillation event. Several diatom genera increased in abundances with decreasing turbidity around and after 1995–2000, mainly the large celled genera Coscinodiscus spp, Odontella spp and Ditylum spp. In 1996–2000, sample genus richness increased from mean of 8–14, and decreased to 11 thereafter. The increase in sample genus richness was linked to the more frequent presence of most taxa during 1996–2000. Increasing Secchi depth and abundance of frequently encountered large-celled diatoms concurrent with decreasing abundances of Trichodesmium spp might signal the alleviation of the nitrogen limitation in the region, favouring diatoms.
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| 2. |
- Kaur-Kahlon, G., et al.
(author)
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Response of a coastal tropical pelagic microbial community to changed salinity and temperature
- 2016
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In: Aquatic Microbial Ecology. - 0948-3055 .- 1616-1564. ; 77:1, s. 37-50
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Journal article (peer-reviewed)abstract
- Studies on the responses of tropical microbial communities to changing hydrographic conditions are presently poorly represented. We present here the results from a mesocosm experiment conducted in southwest (SW) coastal India to investigate how changes in temperature and salinity may affect a coastal tropic microbial community. The onset of algal and bacterial blooms, the maximum production and biomass, and the interrelation between phytoplankton and bacteria were studied in replicated mesocosms. The treatments were set up featuring ambient conditions (28 °C, 35 PSU), hyposalinity (31 PSU), warming (31 °C) and a double manipulated treatment with warming and hyposalinity (31 °C, 31 PSU). The hyposaline treatment had the most considerable influence manifested as significantly lower primary production, and the most dissimilar microphytoplankton species community. The increased temperature acted as a catalyst in the double manipulated treatment and higher primary production was maintained. We investigated the dynamics of the microbial community with a structural equation model approach, and found a significant interrelation between phytoplankton biomass and bacterial abundance. Using this methodology, it became evident that temperature and salinity changes, individually and together, mediate direct and indirect effects that influence different compartments of the microbial loop. In the face of climate change, we suggest that in relatively nutrient replete tropical coastal zones, salinity and temperature changes will affect nutrient assimilation with subsequent significant effects on the quantity of microbial biomass and production.
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