Presenter Information

Kimberly BrayFollow

Presentation Type

Poster

Abstract

MACROINVERBRATE FOOD WEBS OF A METAL-CONTAMINATED RIVER: IMPORTANCE OF ALGAL BLOOMS

Kim Bray, Marc Peipoch, Jessica Jenne, & H. Maurice Valett

River food webs associated with summer blooms of filamentous green algae have previously illustrated the number of trophic levels successfully predicts the relative importance of bottom-up and top-down influences. Unidentified causes for significantly lower trout abundance in Reach C of the metal-contaminated Upper Clark Fork River (UCFR, 20-30 fish/km), compared to upstream reaches (200-300 fish/km) and nearby rivers (600 – 3,000 fish/km) in Montana, USA, are of concern to restoration practitioners working in what is now the largest superfund site in the nation. Metal contamination of floodplain sediments throughout the UCFR reflect its mining history, but Reach C, without significant metal pollution but with greatest algal growth, displays lowest trout abundance. Low abundance of top predators is concordant with HSS-Fretwell prediction that an odd number of trophic levels will result in nutrient-limited algal productivity. Nitrogen limiting conditions are repeatedly observed during summer time in the UCFR (3) and N-fixing cyanobacteria (i.e., Nostoc sp.) become abundant by late-summer. Assessment of food web structure (i.e., trophic levels and relations) is necessary before considering other restoration practices to recover trout abundance in the UCFR. Long-term data on benthic macroinvertebrate data (greatest abundances of 14.4% Chironomidae, 29.3 % Baetis, and 8.74% inermis) and insect body burdens for multiple metals (Cu, As, Zn, Pb, Cd), and stable isotope composition (13C and 15N) were used in a Bayesian stable isotope mixing model approach to discern the trophic structure in Reach C and linked to trout consumers through fish stomach analysis.

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Life Sciences

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Apr 28th, 11:00 AM Apr 28th, 12:00 PM

Macroinvertebrate Food Webs of a Metal-Contaminated River: Importance of Algal Blooms

UC South Ballroom

MACROINVERBRATE FOOD WEBS OF A METAL-CONTAMINATED RIVER: IMPORTANCE OF ALGAL BLOOMS

Kim Bray, Marc Peipoch, Jessica Jenne, & H. Maurice Valett

River food webs associated with summer blooms of filamentous green algae have previously illustrated the number of trophic levels successfully predicts the relative importance of bottom-up and top-down influences. Unidentified causes for significantly lower trout abundance in Reach C of the metal-contaminated Upper Clark Fork River (UCFR, 20-30 fish/km), compared to upstream reaches (200-300 fish/km) and nearby rivers (600 – 3,000 fish/km) in Montana, USA, are of concern to restoration practitioners working in what is now the largest superfund site in the nation. Metal contamination of floodplain sediments throughout the UCFR reflect its mining history, but Reach C, without significant metal pollution but with greatest algal growth, displays lowest trout abundance. Low abundance of top predators is concordant with HSS-Fretwell prediction that an odd number of trophic levels will result in nutrient-limited algal productivity. Nitrogen limiting conditions are repeatedly observed during summer time in the UCFR (3) and N-fixing cyanobacteria (i.e., Nostoc sp.) become abundant by late-summer. Assessment of food web structure (i.e., trophic levels and relations) is necessary before considering other restoration practices to recover trout abundance in the UCFR. Long-term data on benthic macroinvertebrate data (greatest abundances of 14.4% Chironomidae, 29.3 % Baetis, and 8.74% inermis) and insect body burdens for multiple metals (Cu, As, Zn, Pb, Cd), and stable isotope composition (13C and 15N) were used in a Bayesian stable isotope mixing model approach to discern the trophic structure in Reach C and linked to trout consumers through fish stomach analysis.