In light of increasing harmful algal blooms
and the need to protect human health and
aquatic resources through proactive
management, theoretical findings of this
nature merit further study. For this purpose I
conducted field samplings to characterize
plankton community composition and
laboratory experiments to test some
approaches to new management schemes in
the lower Rincon Delta. On site
measurements and microscopic analysis
showed that environmental parameters and
plankton community composition varied
considerably among sampling stations and
sampling dates. A recent modeling study
suggested that manipulation of freshwater
inflow to estuaries might prevent
phytoplankton blooms and enhance
secondary productivity. To test this theory I
conducted three semi-continuous design and
flow-through incubation design experiments
using natural plankton assemblages. I
investigated the effect of two different pulsing
regimes of inflow and nutrient loading on
zooplankton densities, and phytoplankton
biomass and diversity. Despite differences in
zooplankton structure and phytoplankton
community composition between the two
experiment designs, trends in the model
predictions by Roelke (2000) were supported,
which suggests that pulsed inflows might
alter plankton dynamics. My findings showed
that 3-day pulse treatments consistently
supported greater zooplankton densities and
higher phytoplankton species diversity when
compared to 1-day pulse treatments. In
addition, accumulation of phytoplankton
biovolume remained low during 3-day pulse
treatments. Differences in zooplankton
performance between 3-day pulse and 1-day
pulse inflow treatments were likely due to the
ability of phytoplankton to uptake and store
greater amount of nutrients under conditions
of 3-day pulse inflow. This resulted in food of
higher quality for zooplankton, and might have
supported greater zooplankton population
growth rates. Additionally, in an attempt to
understand the mechanisms leading high
biodiversity in aquatic ecosystems, I built a
resource storage model and studied the
effects of resource storage on competition of
multiple phytoplankton species on multiple
abiotic resources. I compared this model with
a well-established multi-species competition
model. My results showed that for certain
species combinations a resource storage
based model can generate more predictable
outcomes when compared to a model without
resource storage.