A chemostatic system was developed for the long term studies
of population dynamics of chain forming diatoms. Vessel volume
rather than flow rate was varied in these systems to obtain different
growth rates at steady state in systems with an equal capacity to
produce.
Population level responses to high dilution rates were examined
for Skeletonema costatum both in long term steady state and under
non-steady state conditions. Development of populations were observed
from small innocula through steady state dilution rates
approaching the maximum growth rate of the population. Populations
were characterized in terms of particulate carbon and nitrogen,
particle numbers and volumes, particle size distributions, and the
relationship of production and specific growth rate to biomass.
Qualitative observations were made on cell dimensions, morphology,
and bouyancy.
Four phases of growth were identified in some or all of the
systems: selection phase in which population concentrations declined,
but significant changes in population characteristics occurred; exponential
phase in which populations increased in a uniform and density-independent
fashion; transition phase in which adjustments were made
in population characteristics; and, finally, steady state in which populations
were stable. Selection phase was observed when small innocula
were placed in high dilution rate systems or when steady state
cultures were transfered to higher dilution rates. Those cultures
experiencing selection phase showed changes in physical cell
dimensions and in nutrient cell size.
Physical cell dimensions and nutrient cell size and their relationship
to growth rate are discussed. The work of Caperon (1968) is
examined for similar selectional effects. A method using curves of
nutrient per cell versus residence time of a particle in a chemostat
is suggested to separate selection and dilution rate effects in dynamic
systems. A model summarizing the ides of nutrient reservoirs is
suggested. / Graduation date: 1975
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28655 |
| Date | 30 August 1973 |
| Creators | Donaghay, Percy L. |
| Contributors | Small, Lawrence F. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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