dc.contributor.advisor |
Jones, R. Christian |
|
dc.contributor.author |
Hack, Brandon
|
|
dc.creator |
Hack, Brandon |
|
dc.date |
2014-12-05 |
|
dc.date.accessioned |
2015-03-24T15:30:54Z |
|
dc.date.available |
2015-03-24T15:30:54Z |
|
dc.date.issued |
2015-03-24 |
|
dc.identifier.uri |
https://hdl.handle.net/1920/9218 |
|
dc.description.abstract |
Numerous shallow aquatic ecosystems worldwide have demonstrated regime shifts from
dominance by submerged aquatic vegetation (SAV) to dominance by phytoplankton
under nutrient over-enrichment. SAV decline under nutrient enrichment involves
feedback mechanisms and is manifested as sudden shifts in many ecosystem components
rather than continuous, gradual changes in parallel with rates of increased nutrient
additions. There are few known examples of SAV recovery following nutrient reduction
in tidal freshwater ecosystems, and the return of SAV to Gunston Cove presents an
opportunity to investigate the response of phytoplankton assemblage to the abatement
efforts of chronic eutrophication.
A thirty-year record of phytoplankton species and water quality data in the tidal Potomac
River was used to evaluate shifts in phytoplankton community composition in response to
a change in environmental inputs. In particular, a clear and sustained increase in SAV in 2005 was postulated to represent a regime change. Three years before and after this
change were selected for comparison to determine if a clear pattern of change could be
found in phytoplankton assemblages. PC-ORD software and ordination techniques
including non-Metric Multidimensional Scaling (nMDS) and Multi-Response
Permutation Procedures (MRPP) were used to look for community level response and
specifically rapid shifts in phytoplankton assemblages following the re-emergence of
SAV in Gunston Cove, Va. There were statistically significant alterations in assemblage
structure following the re-emergence of SAV in addition to increases in taxonomic
diversity. Seasonal progression of the assemblage structure was influenced as well. The
use of multivariate analyses in tandem with historical observations, and insights from
resource economics furthers our understanding of the link between the phytoplankton
assemblage structure, SAV, and the ecological status of Gunston Cove. |
|
dc.language.iso |
en |
en_US |
dc.subject |
phytoplankton |
en_US |
dc.subject |
Gunston Cove |
en_US |
dc.subject |
eutrophication |
en_US |
dc.subject |
recovery |
en_US |
dc.subject |
submerged aquatic vegetation |
en_US |
dc.subject |
Virginia |
en_US |
dc.title |
Effects of Regime Shift on Phytoplankton Community Composition in Gunston Cove of the Tidal Potomac River |
en_US |
dc.type |
Thesis |
en |
thesis.degree.name |
Master of Science in Environmental Science and Policy |
en_US |
thesis.degree.level |
Master's |
en |
thesis.degree.discipline |
Environmental Science and Policy |
en |
thesis.degree.grantor |
George Mason University |
en |