69 Insights from Microfossils: From Geoarchaeology and Pollution Remediation to Climate and Sea-Level Change (Posters)

Tuesday, 16 March 2010
8:00 AM - 12:05 PM
International ABCDF

INVESTIGATION OF OPEN LAKE AND WETLAND CORES TO DETERMINE RELATIVE LAKE LEVEL CHANGE IN SENECA LAKE, NEW YORK

Paper number: 69-6
Program: Theme Sessions
Time: 8:00 AM – 12:05 PM

Authors

Abstract

A transect of sediment cores were collected from the profundal to the littoral zone of Seneca Lake and the marsh of the Catherine Creek Wetland area south of the lake to determine the history of relative lake level change. Open lake cores were taken using a piston corer, and the wetland cores were taken using a vibra-corer. Cores were described, photographed, analyzed for magnetic susceptibility (MS), and sampled for loss-on-ignition analyses, grain size analyses, and microfossil identification and quantification. Cores collected from the lake contain laminated silt or sand whereas those from the wetland are massive silt and sand with preserved peat beds.

Failure of the vibra-core core catcher prevented us from recovering the bottom 4 m of the 8.3 m of sediment penetrated in the wetland. In the 4.3 meters collected there is a striking change in the weight percent carbonate and MS observed in each core, which can be used to correlate between the lake and wetland area. Microfossils in the wetland cores provide a means of estimating water depth. The presence of oogonia (reproductive structures of the aquatic macroalgae Chara) and an abundance of Candona spp. ostracodes in the lower section of the core indicate open fresh water with a depth of less than 5 m. Increasing sand content followed by increasing organic material up-core indicate shallowing and eutrophication.