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|Title:||Effect of dredging on benthic-pelagic production in the mouth of Cross River Estuary (off the Gulf of Guinea), S. E. Nigeria|
Asuquo, F. Emile
|Keywords:||Benthic-pelagic production;Dredging;Detritus;Phytoplankton;Cross River Estuary;Nigeria|
|Abstract:||The effect of high turbidity on benthic-pelagic production at the mouth of Cross River Estuary (South Eastern Nigeria) was investigated following the dredging of the river channel in 1998. Annual phytoplankton production in the estuary was higher (25.9g C/m²/yr) before dredging than after (20.7g C/m²/yr). The seasonal distribution of chlorophyll-a correlated positively with that of primary production before (r = 0.82, P<0.001) and after dredging (r = 0.65, p <0.001). Primary production values were higher in the rainy season than in the dry season. Reduction in chlorophyll-a concentration (primary production) shortly after dredging, could be attributed to the significant reduction in light penetration, the physical smothering of benthic algae and disruption of benthic habitats. The patterns of seasonal copepod densities closely paralleled that of algal biomass. The efficiency of energy transfer from primary production to copepod production was lower after dredging (8%) than before (15%). Copepod grazing rates were high and greater on larger phytoplankton species which had < 10 % of algal carbon needed for secondary production.|
|Appears in Collections:||IJMS Vol.37(3) [September 2008]|
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