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The effects of phosphate on energy reserves in Chironomus tepperi
Molly Hoak PhD Student CAPIM Research Summit, August 2016
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Background: Phosphorus
Essential nutrient for plants and animals Important component of ATP Occurs naturally as phosphate (PO4) Image: Peter Woodward
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Background: Why Phosphate?
Enters waterways through agricultural and urban runoff, sewage effluent, and leaking septic systems Causes algal blooms More important than other nutrients as a contributor to eutrophication Photo: Lori Volkart
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Background: Why Phosphate?
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Aim To determine how different levels of phosphate affect the development and energy use of Chironomus tepperi
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Chironomids Exposed to contaminants in sediment and pore-water
One of the families recorded in site bioassessments Easy to culture in laboratory
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Effects of Phosphate: Prior experiments
Water-only chronic exposure (to emergence) Chironomus tepperi 2nd instar larvae 0, Control (0.5), 5, 10, 20, 40, 80 mg/L Early emergence in 10 mg/L p ≤ 0.05
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Methods Sediment exposure Laboratory culture of chironomids
Overlying water dosed with KH2PO4 Concentrations of 0, Control (0.5), 5, 10, 20, 40 mg/L 8 replicates, 4 sacrificed after 96 hrs Laboratory culture of chironomids Exposed from 2nd Instar (5 days old) 4 replicates sacrificed at 96 hrs for growth, protein, lipid, and glycogen tests 4 replicates exposed until emergence
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Results: Emergence
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Results: Emergence
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Results: Growth
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Results: Protein
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Results: Lipid
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Results: Glycogen
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Results: Summary The effect on emergence is much less pronounced in sediment tests than in water-only tests There is still high variability in the 10 mg/L concentration Glycogen and lipid concentrations trend lower in the 5 and 10 mg/L concentrations Protein concentration trends lower at high levels of phosphate
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Conclusions Sediment makes it more complicated
Energy reserves of C. tepperi seem to be lower at 5 and 10 mg/L of phosphate However, does not necessarily translate to developmental effects Lower energy reserves in combination with other stressors could have developmental effects
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