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          Institute: MPI für Evolutionsbiologie     Collection: Ecophysiology     Display Documents

ID: 121653.0, MPI für Evolutionsbiologie / Ecophysiology
A new approach to historical reconstruction: Combining descriptive and experimental paleolimnology.
Authors:Kerfoot, W. Charles; Robbins, John A.; Weider, Lawrence J.
Date of Publication (YYYY-MM-DD):1999-07
Title of Journal:Limnology and Oceanography
Journal Abbrev.:Limnol. Oceanogr.
Issue / Number:5
Start Page:1232
End Page:1247
Copyright:Jahrbuch 2000, Copyright MPG 2000
Review Status:not specified
Audience:Not Specified
Intended Educational Use:No
Abstract / Description:Here we introduce a combined experimental and descriptive approach (termed resurrection ecology) to reconstructing historical perturbations, pointing out how direct tests with sediments and hatched resting eggs complement the traditional descriptive calculation of microfossil fluxes. In the Keweenaw Waterway, a freshwater estuary off Lake Superior, turn-of-the-century copper mining impacted the resident biota. Remain fluxes document that diatom, rhizopod, and Bosmina production all declined during stamp sand discharges but recovered rapidly after World War II, moving above background levels due to developing eutrophication. In addition to biogenic silica, we discovered that bromine flux holds promise as an indicator of diatom production and confirmed that this element is present in several genera. Fluxes of Daphnia resting eggs also increased dramatically since the 1940s, dominated by a hybrid apparently produced from crosses between offshore and interior Waterway species, after channeling promoted greater mixing of water masses. Toxicity studies with sediments and Daphnia clones directly tested recovery of environments after cessation of mining activities. The studies document that increased concentrations and fluxes of copper in the Waterway during mining discharges were toxic to invertebrates. Once stamp sand discharges ceased,the biota recovered rapidly due to a combination of decreased copper cycling and organic complexation. Although sedimentation has returned to near-background conditions and surficial sediments in much of Portage Lake are no longer toxic, eutrophication and faunal exchange with Lake superior make it unlikely that the original zooplankton community composition will return to the Waterway system.
External Publication Status:published
Document Type:Article
Affiliations:MPI für Evolutionsbiologie/Abt. Ökophysiologie
External Affiliations:Michigan Technol Univ, Lake Super Ecosyst Res Ctr, Houghton, MI 49931 USA; Michigan Technol Univ, Dept Biol Sci, Houghton, MI 49931 USA; NOAA, Great Lakes Environm Res Lab, Ann Arbor, MI 48105 USA
Identifiers:ISSN:0024-3590 [ID-No:1]
LOCALID:1811/S 37457 [Listen-Nummer/S-Nummer]
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