Aquatic Sciences Meeting, Albuquerque 2001

CS28 Phytoplankton: Distributions in Space and Time

Date: Thursday, February 15, 2001, Time: 10:45:00 AM

Location: Dona Ana

Delahaye, S, R, University of Michigan, Center for Great Lakes and Aquatic Sciences, Ann Arbor, USA, sdelahay@umich.edu

Julius, M, L, University of Michigan, Center for Great Lakes and Aquatic Sciences, Ann Arbor, USA, mjulius@umich.edu

Goad, L, M, University of Michigan, Center for Great Lakes and Aquatic Sciences, Ann Arbor, USA, lgoad@umich.edu

THALASSIOSIROID DIATOM POPULATIONS AND THEIR POTENTIAL IMPACT ON LAKE ERIE'S ECOSYSTEM FROM 1819 TO 1991

Diatoms from a 210Pb dated Lake Erie sediment core were examined to observe change over the past 170 years. One hundred frustule diameters from 15 sediment intervals were measured. Results found thalassiosiroid diatoms decreased in diameter as time progressed. Prior to 1865 the average thalassiosiroid diameter was 53 micrometers. By 1991, the average diameter had decreased to 12 micrometers. This decline in size occurred at a rapid rate. The decline generally corresponds to major environmental perturbations over the last two centuries. The initial decline in diameter relates to deforestation around Lake Erie's basin, while subsequent declines relate to modifications in the lake's chemical composition. This change in average diameter of the diatoms is a function of replacement in the lake's indigenous diatom flora with more cosmopolitan thalassiosiroid species. This alteration in the average size of the group may have significant effects on other trophic levels, because the decrease in diameter reduces the average biovolume of individual diatom cells exponentially. This results in a poorer food quality, due to higher silica to carbon ratio, encountered by grazers on the diatom population.

This Session Listing

Aquatic Sciences Meeting, Albuquerque 2001

Quicklinks