Relationships between hydrological and limnological conditions in lakes of the Slave River Delta (NWT,Canada) and quantification of their roles on sedimentary diatom assemblages |
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| Authors: | Email author" target="_blank">Michael?A?SokalEmail author Roland?I?Hall Brent?B?Wolfe |
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| Institution: | (1) Department of Biology, University of Waterloo, Waterloo, ON, Canada, N2L 3G1;(2) Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON, Canada, N2L 3C5 |
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| Abstract: | Water chemistry and surface sediments were analyzed from 41 shallow lakes representing three previously-defined hydrological
categories in the Slave River Delta, Northwest Territories, Canada, in order to identify relationships between hydrological
and limnological conditions and their associations with recently deposited diatom assemblages. Evaporation-dominated lakes are physically removed from the influence of the Slave River, and are characterized by high alkalinity and high concentrations
of nutrients and ions. In contrast, flood-dominated lakes tend to receive a pulse of floodwater from the Slave River during the spring thaw and have low alkalinity and low concentrations
of most nutrients and ions. Exchange-dominated lakes are variably influenced by floodwaters from the Slave River and seiche events from Great Slave Lake throughout the
spring thaw and open-water season, and are characterized by a broad array of limnological conditions that are largely dependent
on the strength of the connection to these sources of floodwater. Specific diatom ‘indicator’ taxa have been identified that
can discriminate these three hydrological lake categories. Evaporation-dominated lakes are associated with high relative abundance
of common epiphytic diatom taxa, while diatoms indicative of flood- and exchange-dominated lakes span a wide range of habitat
types (epiphytic, benthic) but also include unique planktonic diatoms (Stephanodiscus and Cyclostephanos taxa) that were not found in surface sediments of evaporation-dominated lakes. The planktonic diatom taxa originate from
the Slave River, and thus are indicative of river influence. In complex, remote, freshwater ecosystems like the Slave River
Delta, integration of results from hydrological and limnological approaches provides a necessary foundation to assess present,
past and future hydroecological responses to changes in river discharge and climate. |
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| Keywords: | Slave River Delta Hydrology Limnology Surface sediments Diatoms Floodplain |
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