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Abstract
Ozbay, G. ., M. Jackson, N. Munyei, and
M. Reiter. 2008. Temperature and salinity
dependent phytoplankton profiles for the St. Jones River Watershed, Delaware. JEMREST 4:29-38.
DOI:
10.4029/2007jemrest4no104
Point
and non-point pollution can disrupt the ecological functions of a watershed,
resulting in a decline in water quality while creating suitable conditions
for phytoplankton blooms. These blooms may be preceded by changes in
environmental variables impacted by heavy rains and agricultural or
industrial discharges. To study the significance of such variables,
phytoplankton distributions were analyzed microscopically to determine
assemblage characteristics in relation to temperature and salinity changes at
six selected study sites in the St. Jones River Watershed, Delaware. In June, the phytoplankton
assemblage contained 17% Euglenoids, 51% Bacillariophycaea, 23% Chlorophyta,
5% Cyanophyta and 4% Cryptophyta while other species and bacteria were less
than 1% of the total species identified.
In July and early August, samples contained 5% Euglenoids, 46%
Bacillariophycaea, 28% Chlorophyta, 17% Cyanophyta, and 5% Cryptophyta while
other species and bacteria made up less than 1% of the total sample. Bacillariophycaea were the dominant species
in the watershed system during the study months. The only significant differences
(P<0.05) were observed in Cyanophyta and Euglenoids distributions between
the study months of June and July. We obtained more than three-fold increase
in Cyanophyta concentrations while Euglenoids decreased three-fold from June
to July with rising temperatures. Higher temperature ranges favored high
temperature-resistant phytoplankton such as Cyanophyta. Temperature seems to
have more of an effect on the phytoplankton distribution pattern in St. Jones
River Watershed. Class Pyrrhophyta was
detected at two tidal sampling stations, Lebanon Landing and Lockerman where
the salinity gradients were 4.36 g/L and 0.9 g/L, respectively. Changes in salinity levels were minor in
five of the six study sites, so were unlikely to impact overall phytoplankton
distributions in the watershed.
Species inhabiting the watershed system appear to have a better
tolerance for salinity fluctuations as observed in previous studies. Such
analyses elucidate the phytoplankton dynamics of these waters and assist
state resource managers in making decisions concerning water use and
management of aquatic life.
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