DEPTH, m
PLANKTONIC BACTERIAL
PRODUCTION, mg C m
-2 .d -1
PHYTOPLANKTON
PROOUCTION, mg C m -2 .d -1
( % DOC )
BACTERIAL
AS % OF
PHYTOPLANKTON
STATIO N
5
15.8
43 0
b
1500 (2)
2.9
STATION 1
2.4
116 °
b
3000 ( 4 )
3.9
LOWER STATION
5
60 0
990 (N.D.)c
6.1
UPPER STATION
1.5
43°
c
650 (N.D.)
6.9
N.D. ■ no data
a • based en 100 mg C.cm -3 cell volume
(Follon et al 1963)
b - from Thomas (1966, 1970)
c-from Pomeroy 8 Wieger t
(1901); E. Sherr, pers. comm.
Table 1 : Comparison of bacterial and phytoplankton carbon production in the nearshore ocean and Duplin
River estuary.
however, of the same order of magnitude as the estimated DOC output from
phytoplankton (Thomas, 1970). Overall, in comparison with other studies of bacterial
production based on thymidine incorporation, bacterial production in Georgia coastal
planktonic systems appears to be quite small in relation to primary production. Our data
fall at the bottom end of the wide range of estimates reported from the literature (bacterial
production as cell C = 0.6 — 42 %of primary production) (Bell et al., 1983 ; Fuhrman and
Azam, 1982 ; Ducklow and Kirchman, 1983 ; Moriarty, in press ; Moriarty and Pollard,
1982 ; Riemann et al., 1982). Also, one must keep in mind that from the estuary out to
about 10 km offshore, the planktonic community is receiving some DOC input from the
marshes. Some of this too may be available for bacterial production. Thus, relative to
other carbon fluxes in the planktonic system, planktonic bacterial production appears to
be rather low. No clear explanation for this observation is available. However, one
possible hypothesis is that in this shallow, well mixed system, much of the heterotrophic
processing occurs in the benthos. Data on sedimentary bacterial production and nutrient
regeneration support this hypothesis (Newell and Fallon, 1982 ; Fallon et al., 1983) ; but
more data are needed in order to fully explain these relationships.
GROWTH RATE, h - 1
GENERATION TIME, h
MEAN
O.O16
43
NEARSHORE
OCEAN
RANGE
0.0021— 0.0458
330-15.1
DUPLIN
RIVER
MEAN
0.028
24
RANGE
0.004- 0.076
173- 9.1
Table 2 : Mean and ranges for planktonic bacterial growth rates and generation times across the coastal region.
143
PLANKTONIC BACTERIAL
PRODUCTION, mg C m
-2 .d -1
PHYTOPLANKTON
PROOUCTION, mg C m -2 .d -1
( % DOC )
BACTERIAL
AS % OF
PHYTOPLANKTON
STATIO N
5
15.8
43 0
b
1500 (2)
2.9
STATION 1
2.4
116 °
b
3000 ( 4 )
3.9
LOWER STATION
5
60 0
990 (N.D.)c
6.1
UPPER STATION
1.5
43°
c
650 (N.D.)
6.9
N.D. ■ no data
a • based en 100 mg C.cm -3 cell volume
(Follon et al 1963)
b - from Thomas (1966, 1970)
c-from Pomeroy 8 Wieger t
(1901); E. Sherr, pers. comm.
Table 1 : Comparison of bacterial and phytoplankton carbon production in the nearshore ocean and Duplin
River estuary.
however, of the same order of magnitude as the estimated DOC output from
phytoplankton (Thomas, 1970). Overall, in comparison with other studies of bacterial
production based on thymidine incorporation, bacterial production in Georgia coastal
planktonic systems appears to be quite small in relation to primary production. Our data
fall at the bottom end of the wide range of estimates reported from the literature (bacterial
production as cell C = 0.6 — 42 %of primary production) (Bell et al., 1983 ; Fuhrman and
Azam, 1982 ; Ducklow and Kirchman, 1983 ; Moriarty, in press ; Moriarty and Pollard,
1982 ; Riemann et al., 1982). Also, one must keep in mind that from the estuary out to
about 10 km offshore, the planktonic community is receiving some DOC input from the
marshes. Some of this too may be available for bacterial production. Thus, relative to
other carbon fluxes in the planktonic system, planktonic bacterial production appears to
be rather low. No clear explanation for this observation is available. However, one
possible hypothesis is that in this shallow, well mixed system, much of the heterotrophic
processing occurs in the benthos. Data on sedimentary bacterial production and nutrient
regeneration support this hypothesis (Newell and Fallon, 1982 ; Fallon et al., 1983) ; but
more data are needed in order to fully explain these relationships.
GROWTH RATE, h - 1
GENERATION TIME, h
MEAN
O.O16
43
NEARSHORE
OCEAN
RANGE
0.0021— 0.0458
330-15.1
DUPLIN
RIVER
MEAN
0.028
24
RANGE
0.004- 0.076
173- 9.1
Table 2 : Mean and ranges for planktonic bacterial growth rates and generation times across the coastal region.
143