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