Bacterioplankton abundance and production in Indian Ocean regions
2009; American Geophysical Union; Linguagem: Inglês
10.1029/2008gm000711
ISSN2328-8779
AutoresN. Ramaiah, Veronica Fernandes, Veera Rodrigues, Jane T. Paul, Mangesh Gauns,
Tópico(s)Marine Biology and Ecology Research
ResumoMicrobes mediating biological and many geochemical processes are the key components in marine ecosystems. In this chapter, we provide information on spatiotemporal variations in heterotrophic bacterial (Hbac) abundance and production in three ecologically disparate regions: Arabian Sea (AS), Bay of Bengal (BoB), and equatorial Indian Ocean (EIO). In the AS, Hbac abundances were the largest during fall intermonsoon (FIM) (0.35―1.51 × 10 9 L ―1 ), moderate during southwest monsoon (SWM) (0.20―0.45 x 10 9 cells L ―1 ), and least during northeast monsoon (NEM) (0.05―0.35 × 10 9 L ―1 ). Bacterial production (BP), ranging from 2.86 to 22.93 mg C m ―3 d ―1 , was the highest during spring intermonsoon (SIM) when autotrophic production was the least. In the BoB, Hbac abundance was more during FIM (0.07―1.85 x 10 9 L ―1 in the 0- to 120-m column) and lower during SIM (0.02-0.36 × 10 9 L ―1 ). Spatial and temporal variations were clearly seen in BP too, which was higher during SWM (0.18―6.75 mg C m ―3 d ―1 ) and NEM (0.35―18.56 mg C m ―3 d ―1 ), moderate during FIM (0.01―4.19 mg C m ―3 d ―1 ), and least during SIM (0.001―2.49 mg C m ―3 d ―1 ). Annual BP accounted for up to 56% of primary production (PP) in the BoB. Despite the lowest Hbac abundance and production, BP:PP ratios were high in the oligotrophic EIO. As evidenced from sizable Hbac carbon biomass and from the often high BP:PP ratios (≥1.0), Hbac-biogeochemical and trophodynamic processes are very important in some regions/seasons of low autotrophic production.
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