Environmental Engineering Reference
In-Depth Information
800
700
600
500
400
300
200
100
0
0
2
4
6
8
10
12
14
Particle concentration
(number mL
-1
)
FIGURE 18.8
Consumption of particles by the ciliated protozoan
Glaucoma scintillans
as
a function of particle concentration (reproduced with permission from Fenchel, 1980).
m in size may be the primary consumers of bacteria in
many pelagic environments (Porter
et al.,
1985; Sherr and Sherr, 1994). In
contrast, the benthos contains larger organisms that are able to process con-
siderable amounts of sediment and thus capture a significant number of bac-
teria per unit time (Fig. 18.9). In this case, invertebrate animals may equal or
exceed the ability of protozoa to ingest bacteria, even if rates are normalized
per unit biomass to account for the much larger size of the invertebrates.
Flagellates
20
Scrapers and Shredders
Organisms that eat detritus, either in the form of leaves and wood or
as finer benthic organic material, are essentially microbial predators. Most
10
6
10
5
10
4
10
3
10
2
10
1
10
0
10
-1
Cilliates
Microflagellates
Rotifers
Copepods
Nematodes
Oligocheates
Chironomids
FIGURE 18.9
Ranges of observed consumption rates of bacteria by several groups of ben-
thic organisms from marine and freshwaters (data from 12 laboratory and field studies com-
piled by Bott, 1995; reproduced with permission).
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