PP31C-1155:
Diatoms as Proxies for Abrupt Events in the Hudson River Estuary

Wednesday, 17 December 2014
William Skorski1, Dallas H Abbott2, Cristina Recasens2 and Dee L Breger3, (1)Rensselaer Polytechnic Institute, Troy, NY, United States, (2)Lamont -Doherty Earth Observatory, Palisades, NY, United States, (3)Micrographic arts, Saratoga Springs, NY, United States
Abstract:
The Hudson River estuary has been subject to many abrupt events throughout its history including hurricanes, droughts and pluvials. Hurricanes in particular are rare, discrete events that if fingerprinted can be used to develop better age models for Hudson River sediments. Proxies use observed physical characteristics or biological assemblages (e.g. diatom and foraminiferal assemblages) as tools to reconstruct past conditions prior to the modern instrumental record. Using a sediment core taken from the Hudson River (CDO2-29A), in New York City, drought and pluvial layers were selected based on Cs-137 dating while hurricane layers were determined from occurrences of tropical to subtropical foraminifera.

Contrary to previous studies (Weaver, 1970, Weiss et al, 1978), more than sixty different diatom species have been identified using a scanning electron microscope (SEM). Cosmopolitan, hurricane and drought assemblages have begun to be identified after observing multiple layers (Table 1). Tropical foraminifera dominated by Globigerinoides ruber pink were also found in a hurricane layer that we infer was deposited during Hurricane Belle in 1976. More diatom abundance analyses and cataloged SEM pictures will provide further insight into these proxies.

Table 1

Diatom Genera and Species

Environment

Clarification

Cyclotella caspia

Planktonic, marine-brackish

Cosmopolitan

Karayevia clevei

Freshwater

Cosmopolitan

Melosira sp

Planktonic, marine

Cosmopolitan

Thalassiosira sp

Marine, brackish

Cosmopolitan

Staurosirella leptostauron

Benthic, freshwater

Cosmopolitan

Actinoptychus senarius

Planktonic or benthic, freshwater to brackish

Hurricane and pluvial layers

Amphora aff. sp

Benthic, marine or freshwater

Hurricane layers only

Nitzschia sp

Benthic, marine or freshwater

Hurricane layers only

Gomphonema sp

Freshwater

Hurricane layers only

Surirella sp

Marine-brackish

Drought layer only

Triceratium sp

Marine

Drought layer only

Other Genera and species

Environment

Clarification

Globigerinoides ruber pink

Tropical

Hurricane layers only

Silicoflagellate sp

Planktonic, marine

Hurricane layers only