investigated over time in relation to 

 the planted and nonplanted plots in the 

 mid-tide zone. Figures 8, 9, and 10 show 

 the bacterial populations between Janu- 

 ary and September for NP, SA, and SP 

 plots at three depths. In the surface 

 stratum, the bacterial populations were 

 generally greater than 5 X 10^ colony 

 forming units (CFU) per gram dry weight. 

 The populations were generally an order 

 of magnitude lower in the substrata than 

 in the surface stratum. 



The dredged materials at Buttermilk 

 Sound were essentially aerobic in Janu- 

 ary 1976. During the later part of the 

 year, black iron sulphide zones were 

 noticed in the substrata, and it was ex- 

 pected that the facultative anaerobic 

 population would increase relative to 

 the aerobic population. However, the 

 data (Figures 8, 9, 10) indicate that 

 there were no significant differences 

 between the numbers of anaerobes and 

 aerobes. Several reasons may account 

 for the low anaerobic bacterial popula- 

 tion. Methodology is the primary rea- 

 son: (1) 2216 Marine Agar is a selective 

 medium, preventing the expression of 

 certain anaerobes; (2) sensitivity of 

 strict anaerobes to 2 ; and (3) essen- 

 tial vitamins and minerals required by 

 fastidious anerobic bacteria were not 

 provided in the medium. The procedure 

 allowed only the expression of faculta- 

 tive heterotrophic anaerobes. 



The relative numbers of aerobes and 

 anaerobes in the dredged materials were 

 an order of magnitude lower than the 

 bacterial numbers in estuarine sediments 

 from the North Inlet Estuary, South Car- 

 olina (Stevenson et al. 1972). Grain 

 si-ze has a tremendous influence on bac- 

 terial numbers in sediments and the 

 medium to coarse sands at BSHDS may ac- 

 count for the low population density. 



YEAST BIOMASS 



The relative abundance of the yeast 

 populations in the middle tidal zone was 

 also investigated with respect to depth 

 and time (Figure 11). The yeast popula- 

 tion decreased with depth similar to 

 bacterial populations and ATP concentra- 

 tions. The yeast population was approx- 

 imately an order of magnitude lower than 

 the bacteria population. 



ALGAL POPULATIONS 



The diversity of the benthic algal 

 community increased between January and 

 September 1976 (Table 2). In January, 

 approximately 7 genera of diatoms were 

 observed whereas by September an addi- 

 tional 10 genera were observed at the 

 BSHDS. The increase in ATP concentra- 

 tions over time in the surface strata 

 may in part be due to the colonization 

 of these diatoms. Blue-green algae were 

 occasionally found but were not domi- 

 nant. Oscillatoria was the primary alga 

 found on the sediment surface. 



PROTOZOANS AND MEIOFAUNA POPULATIONS 



Protozoans and meiofauna have been 

 observed in most of the sediment stud- 

 ied. Qualitatively, the fauna were 

 more abundant towards the end of the 

 summer. Garbisch et al. (1975) and 

 Cammen (1976b), working with dredged 

 materials in Chesapeake Bay, reported an 

 invasion of microinvertebrates. Such an 

 invasion may be occurring at BSHDS, but 

 the impact on the microbial flora is 

 unknown. 



SIMPLE BOX MODEL FOR BSHDS 



A conceptualized view on the flow 

 of carbon (energy) in the system is 

 shown in Figure 12. Bacteria, yeast, 

 algae, and meiofauna are the major 

 biological components in the het- 

 erotrophic compartment. Most of the 

 heterotrophic energy is obtained via the 

 autotrophs (marsh plants and algae) 

 either as particulate organic carbon or 

 dissolved organic carbon. Tides support 

 some of the energy requirement of the 

 heterotrophs and enhance the overall 

 productivity of the coastal ecosystem 

 with the deposition of detritus. 



In addition to tidal deposition of 

 detritus, tides seed the habitat with 

 living organisms. In return they enhance 

 the flow of energy through the system. 

 Microbes and macrobes are well known as 

 decomposers and nutrient regenerators in 

 aquatic systems and probably are more 

 important in supplying nutrients to the 

 macrophytes than are rivers and oceanic 

 water of Georgia. Some preliminary stud- 

 ies in Georgia marshes indicate that 

 most of the annual Spartina production 



45 



