Protozoan grazing on bacteria at the sediment-water interface of an acidified lake

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7152833

Tremaine, S C

Protozoan grazing on bacteria has been hypothesized to link the detrital and grazer food chains in aquatic ecosystems. The current study of protozoan bacterivory, evaluated methods, quantified bacterivory, and evaluated the role of protozoa at the sediment-water interface of an acidified lake ecosystem, Lake Anna, Virginia. Three limnetic methods for determining protozoan bacterivory were tested for applicability at the sediment-water interface. The eucaryote inhibitor, cycloheximide, was found unsatisfactory because it did not uniformly inhibit growth of target eucaryotes, and because it inhibited non-target anaerobic procaryotes. The filtration method was found to have limited application in sediment systems due to filtrational loss of particle-associated bacteria. The dilution method was tested for violations of its critical assumptions: bacterial growth is exponential; grazing mortality is proportional to the dilution factor; and bacterial growth rates are unaltered under experimental conditions. These assumptions were found not to be violated, and this method was used in subsequent grazing experiments. Carbon loading to the acidified arm of Lake Anna was 41 {times} 10{sup 6} g C {times} y{sup {minus}1}. This appears to be adequate carbon loading to support bacterial production and, in turn, protozoan bacterivory and production. Though there is no direct evidence that zooplankton graze on protozoa in this system, however, there is sufficient protozoan production to support an additional trophic level.

• Research Organization: Virginia Univ., Charlottesville, VA (USA)
• OSTI ID: 7152833
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540310* -- Environment
Aquatic-- Basic Studies-- (1990-)
540320 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ACIDIFICATION
ANIMALS
AQUATIC ECOSYSTEMS
BACTERIA
DATA
ECOLOGY
ECOSYSTEMS
EXPERIMENTAL DATA
FOOD CHAINS
INFORMATION
INTERFACES
INVERTEBRATES
LAKES
MICROORGANISMS
NUMERICAL DATA
PRODUCTIVITY
PROTOZOA
SEDIMENT-WATER INTERFACES
SURFACE WATERS