2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 52-12
Presentation Time: 11:45 AM

DIATOMS AS PROXIES FOR ABRUPT EVENTS IN THE HUDSON RIVER ESTUARY


SKORSKI, William1, ABBOTT, Dallas H.2, RECASENS, Cristina2 and BREGER, Dee3, (1)Earth and Environmental Sciences, Rensselaer Polytechnic Institution, 1999 Burdett Avenue, E-Complex, Hearne 034, Troy, NY 12180, (2)LDEO of Columbia University, 61 Rt. 9W, Palisades, NY 10964, (3)Micrographic Arts, Greenfield, NY 19104, william.skorski@gmail.com

The Hudson River estuary has been subject to many abrupt events throughout its history including hurricanes, droughts and pluvials. In order to document these events, we use sedimentary and biological proxies to look back into the past further than modern instrumental records can observe. Proxies are ways of using observed physical characteristics (e.g. magnetic susceptibility) or biological assemblages (e.g. diatom and foraminiferal assemblages) as tools to reconstruct past conditions. Using a sediment core taken in the Hudson River (CDO2-29A), around 63rdstreet in New York City, drought and pluvial layers were selected based on Cs dating and hurricane layers based on occurrences of tropical to subtropical foraminifera.

After observing at least one sample from each event, cosmopolitan, hurricane and drought assemblages have begun to be recognized (Table 1). Tropical foraminifera dominated by Globigerinoides ruber pink were also found in a known hurricane layer that we infer was deposited during Hurricane Belle in 1976.1More work must be done in order to fully catalog and understand which species are truly indicative of these events. Diatom abundance analyses and more SEM pictures and cataloging will provide further insight into how these proxies can be fully understood.

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

Typical rainfall

Actinoptychus senarius

Planktonic or benthic, freshwater to brackish

Both hurricane and pluvial layers

Amphora aff. sp

Benthic, marine or freshwater

Hurricane layers only

Nitzschia sp

Benthic, marine or 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

1 Abbott, Dallas, Kyle Monahan, Bärbel Hönisch, Dee Breger, and Jon Stelling. Depositional Mechanisms for Tropical to Subtropical Foraminifera in the Hudson River (2014): 1-16. Web. 20 July 2014.