Microphytobenthic Producrion 



The primar)' producrion of microphytobenthos was 

 generally similar to water column rates, although the 

 range of water column primary production values was 

 more than two times larger (compare Figures 4-21 and 

 4-12). There was some indication that sediment 

 production was more likely to be high during winter 

 months, while water column production tended to be 

 highest in the summer, especially at the two Reference 

 stations. 



The sediment chlorophyll was not strongly related to 

 sediment primary production values (Figure 4-22). 

 This indicates that chlorophyll accumulation in the 

 sediments did not necessarily dominate the flux rates 

 of sediment primary production and was probably 

 attributed to a rather short residence time for 

 chlorophyll in the sediments before degradation 

 occurred. A direct comparison of water column and 

 sediment primary production rates indicates that there 

 was no correlative relationship (Figure 4-23) and that 

 most of the water column rates were 2 to 4 times larger 

 than the sediment rates. 



The total combined water column and sediment 

 primary production rates did not have a strong 

 relationship to salinity (Figure 4-24), but there was 

 certainly a general trend that showed the largest 

 production rates were at salinity concentrations below 

 60 psu. The upper limits of total primary production 

 over the entire range of salinity clearly showed an 

 inverse relationship with saltmty. 



Benthic Assimilation Index 



The primary production assimilation index for the 

 microphytobenthos (Figure 4-25) was not nearly as 

 dynamic as the water column index. During only one 

 monthly sampling period in the summer of 1995 did 

 the sediment assimilation index exceed a value of 

 30 gC/m"/day/Chl. This low range probably indicates 

 that severe conditions of limited Light, low nutrients 

 and possibly high temperatures found in the sediments 

 were not conducive to high rates of primary 

 production per unit of chlorophyll. 



1995 



1996 



1997 



1998 



1999 



Figure 4-21 : Sediment primary productivity concentrations at all water column stations (except Stations 62 

 and 68) for each sampling date. 



4-20 ♦ Water Column Productivity 



