THE ROLE OF ROAD SALT DEICER AND RESOURCE BIODIVERSITY ON AQUATIC CONSUMER FEEDING DYNAMICS
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Author/Creator ORCID
Date
2021-01-01
Type of Work
Department
Geography and Environmental Systems
Program
Geography and Environmental Systems
Citation of Original Publication
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Distribution Rights granted to UMBC by the author.
Access limited to the UMBC community. Item may possibly be obtained via Interlibrary Loan thorugh a local library, pending author/copyright holder's permission.
Abstract
Road salt deicer is a growing pollutant of concern in the United States as urbanizationand human expansion continues at a rapid rate. Deicer infiltrates surface waters through
stormwater runoff and increases chloride concentrations in freshwater ecosystems. The
purpose of this study was to evaluate the effects of road deicer on a critical function of
freshwater ecosystems - leaf litter breakdown. I hypothesized that increased chloride
concentrations would decrease breakdown rates through decreased invertebrate consumer
activity. To examine the impacts of chloride breakdown rates, a multi-factorial laboratory
experiment was designed to test the effect of chloride on aquatic consumer feeding rates
and examine the role of heterogeneous leaf litter under these conditions. Leaf litter and
aquatic invertebrates (Gammarus sp.) were collected from headwater streams in
Maryland (USA). Microcosms were inoculated with stream water and subjected to a
chloride treatment (0 or 600mg/L), a leaf litter treatment (F. grandifolia, A. rubrum, or
"mixed”), and an invertebrate treatment (presence or absence). After 28 days, mass loss
rate was calculated for all treatments. In the single-species litter treatments, mass loss
increased under the presence of chloride in both the presence and absence of the
invertebrate consumer. Regardless of invertebrate presence, chloride only decreased mass
loss in the mixed leaf litter assemblages. Further, the results showed a diversity effect
between the single and mixed-species litter treatments but only in the invertebrate absent
treatments. Therefore, the presence of an invertebrate eliminated the diversity effect
regardless of chloride concentration. In short, increased chloride concentrations altered
feeding rates though differently than predicted while a diversity effect was observed only
in the absence of the invertebrate. The results suggest a complex interaction between
chloride, heterogeneous leaf litter, and aquatic consumers that requires additional
research to further understand the relationship between these factors.