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U.S. Department of the Interior
U.S. Geological Survey
OFR-00-361

Geochemical Productivity Monitoring in Florida Bay

Introduction | SHARQ | Basin Productivity | Bank Productivity | References

BASIN PRODUCTIVITY

Calcification, photosynthesis, and respiration were measured during winter (March) and Summer (September) of 1999 on seagrass beds located in basins near Buchanon Bank (latitude 24o 55.416' N, longitude 80o 45.942' W) and Russell Bank (latitude 25o 03.756' N, longitude 80o 36.850' W) using the SHARQ. Geochemical parameters including pH, dissolved oxygen, fluorescence, and temperature were measured continuously through the SHARQ's flow-through analytical system (Figure 6 and 7) throughout the duration of incubation periods (from 20-28 hours). Water samples were removed from sample ports every 4 hours for alkalinity measurements via the Gran titration method using methods of Millero (1979). Dissolved oxygen, pH and alkalinity data were used to calculate rates of net calcification, photosynthesis, and respiration for each 4-hour interval between alkalinity measurements during incubation periods. Productivity parameters were calculated using the alkalinity anomaly technique (Smith and Key, 1975) and carbonate system equations of Millero (1979), whereby delta concentration of each parameter/deltaT x SHARQ volume/SHARQ surface area = g C m-2 s-1. Sample interval rates were then used to calculate net daily production rates that were then used to derive average hourly rates of calcification, photosynthesis, and respiration.

Buchanon Bank Basin
A.  S.H.A.R.Q. Dissolved Oxygen
Buchanon Bank Basin, Winter

Buchanon Bank Basin winter DO graph
B.  S.H.A.R.Q. pH
Buchanon Bank Basin, Winter

Buchanon Bank Basin winter pH graph
C.  S.H.A.R.Q. Dissolved Oxygen
Buchanon Bank Basin, Summer

Buchanon Bank Basin summer DO graph
D.  S.H.A.R.Q. pH
Buchanon Bank Basin, Summer

Buchanon Bank Basin summer pH graph
Figure 6. Dissolved oxygen and pH data from SHARQ deployment on seagrass bed in basin near Buchanon Bank during winter (a and b) and summer (c and d).  Dissolved oxygen logged every 2 minutes, pH logged every 5 minutes during incubation periods.  Red dots indicate ambient (outside of SHARQ) dissolved oxygen.
(Click on graphs above for larger versions.)



Russell Bank Basin
A.  S.H.A.R.Q. Dissolved Oxygen
Russell Bank Basin, Winter

Russell Bank Basin winter DO graph
B.  S.H.A.R.Q. pH
Russell Bank Basin, Winter

Russell Bank Basin winter pH graph
C.  S.H.A.R.Q. Dissolved Oxygen
Russell Bank, Summer

Russell Bank summer DO graph
D.  S.H.A.R.Q. pH
Russell Bank Basin, Summer

Russell Bank Basin summer pH graph
Figure 7. Dissolved oxygen and pH data from SHARQ deployment on seagrass bed in basin near Russell Bank during winter (a and b) and summer (c and d).  Dissolved oxygen logged every 2 minutes, pH logged every 5 minutes during incubation periods.
(Click on graphs above for larger versions.)

Preliminary results indicate net dissolution of carbonate sediments in basins near Russell and Buchanon Banks ranging from approximately - 6 x 10-3 to - 0.11 g CaCO3/m2/hr, shown graphically as negative calcification values (Figure 8). Photosynthesis shows seasonal variation in both basins with highest rates of photosynthesis occurring during winter. It must be noted, however, that salinity and temperature were high relative to annual averages in both basins during summer measurements (salinity 42 and temperature 28.5-31oC near Russell Bank, and salinity 36.5 and temperature 28.2-29oC near Buchanon Bank). Additionally, a summer algal bloom near Russell Bank reduced photosynthetically active radiation (PAR) to 8% of surface values from water surface to bottom (4 ft. depth). These conditions are likely to have stressed the benthos resulting in net oxygen consumption and negative photosynthesis values for both sites, and higher respiration values for the basin near Russell Bank shown in Figure 8.

Basin Productivity

A.  Average Rates Calcification, Photosynthesis, Respiration
Basins
Graph showing avg. rates of calcification, photosynthesis, and respiration in grams of carbon

B.  Basin Carbonate Sediment Production
Graph showing carbonate sediment in grams of CaCO3

Figure 8. Average rates of calcification, photosynthesis, and respiration in grams of carbon (a.) and carbonate sediment in grams of calcium carbonate (b.) for basins near Russell and Buchanon Banks measured using SHARQ during winter and summer.
(Click on graphs above for larger versions.)



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