Asterionella japonica
Polykrikos kofoidi Thalassionema
nitzschiodes Gyrodinium uncatenum
Prorocentrum micans
Map of Selected Stations
Susquehanna
Patapsco
Bay Bridge
Patuxent
Potomac
MD Mid Bay - Choptank
Bluegreen Algae Trends in the Potomac during
Low Flow and High Flow Years |
Phytoplankton (algae) communities reflect
existing nutrient levels. An over abundance of nutrients often results in dense algae
blooms. These blooms reduce light penetration thereby reducing the chance that beneficial
submerged aquatic vegatation will grow. Oxygen levels are also impacted. Extremely dense
algal blooms send oxygen levels skyrocketing on sunny days while the algae are
photosynthesizing. At night or on cloudy days their large numbers can use up all the
oxygen from the water column leaving aquatic animals (fish) to suffocate. In lesser
densities algal blooms burden the system when they die. The decomposition of their dead
cells can use all the oxygen available in the bottom waters. Excess nutrients also alter
the structure of the phytoplankton community. Just as weeds can take over a garden
tolerant (bluegreens) or opportunistic species (pigmented flagellates) can dominate. This
alteration of the algal community can cause several problems. An excess of bluegreen algae
in the water column can cause a green latex paint appearance to the water surface
(Potomac-Indianhead). An over abundance of pigmented flagellates can impart a coffee color
to the water (Mahogany Tide). This problem is more common in small tidal creeks (Patapsco
drainage) from late spring to late summer. The graphs generated for these sites will
show how the phytoplankton community in the Bay and tributaries change from one month to
the next not only in the number of algae present but also in the general kind of algal
groups present. By comparing the graphs you can track the changing algal community. The
data graphed is mostly from surface grab samples, although bottom samples for
phytoplankton are collected for two stations (Chesapeake Bay-Cedar Pt. and Chesapeake
Bay-Sandy Pt.). This is also graphed. |
This page was created by Walter
L. Butler any comments or suggestions should be forwarded to Email address -wbutler@dnr.state.md.us
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