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BENTHIC-PELAGIC PROCESSES IN PENSACOLA BAY, FL: EFFECTS OF LIGHT ON OXYGEN FLUXES
Citation:
Murrell, M C., J. Hagy, J.D., III, J G. Campbell, AND Caffrey. BENTHIC-PELAGIC PROCESSES IN PENSACOLA BAY, FL: EFFECTS OF LIGHT ON OXYGEN FLUXES. Presented at SWS/GERS Joint Society Meeting, Pensacola Beach, FL, March 30 - April 02, 2005.
Impact/Purpose:
Conference presentation
Description:
Eutrophication caused by excess nutrients can exacerbate hypoxia by increasing bottom water and sediment respiration. However, in shallow sub-tropical estuaries, the euphotic zone often extends below the pycnocline allowing oxygen fluxes in Pensacola Bay, FL, USA. Measurements were made during summer 2003 at 8 sites distributed along depth and estuarine salinity gradients. Sediment and water samples were exposed to several light levels ranging from 0 to 800 Einsteins/m2/s. Benthic and water column dark respiration averaged 7.5 and 42 mmol o2/m2/d, respectively. The benthos accounted for 18% (range: 1% to 45%) of total water column respiration and 33% (range: 4% to 76%) of below-pycnocline respiration, suggesting that the benthos plays a relatively minor role in total oxygen demand. Furthermore, six benthic stations and all water samples had significant oxygen production when exposed to light, which tended to offset respiration in the euphotic zone. Much of Pensacola Bay is so shallow that significant light reaches the bottom, suggesting that benthic and sub-pycnocline oxygen production can reduce net respiration thereby reducing the severity of hypoxia that develops.