Event Description
Nina Desianti, BEES PhD Student, Drexel University
Major Adviser: Marina Potapova, PhD
"Indicative Properties
of Diatoms in Mid-Atlantic Coastal Wetlands"
Diatoms are known as important
bioindicators, but the potential and limitations of their use for
reconstructing past and monitoring present environmental conditions in coastal
wetlands have not been sufficiently quantified. I collated several diatom
datasets collected in mid-Atlantic coastal wetlands to estimate utility of
diatoms as sea level, habitat and nutrient enrichment indicators in these
ecosystems. Multivariate regression trees and ordination analyzes confirmed
that benthic/soil diatom assemblages were mostly controlled by tidal elevation,
salinity, sediment texture and nutrient content, while the relative importance
of these factors varied among datasets focused on different environmental
gradients. A Multiresponse Permutation Procedure demonstrated statistically
significant differences among diatom assemblages of major habitat types, such
as low- and high salt marshes, mudflats, tidal pools/ salt pans, macroalgae,
subtidal and supratidal zones. An Indicator Species Analysis revealed habitat
preferences of common diatoms, while a Linear Discriminant Analysis
demonstrated that habitat type could be correctly inferred from diatom
assemblage composition in approximately 80 percent of samples. A greater level of
classification accuracy is unlikely to be achieved due to redistributing of
diatom frustules by tides across intertidal zone. Reasonably strong transfer
functions were developed for inferring sediment nitrogen content and tidal
exposure from diatom assemblage composition.
If you would like to meet with Nina Desianti,
please contact her at nd425@drexel.edu
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