Freshwater Invertebrate Assimilation Nutrients from Detrital Biofilms Under Light and Phosphorus Manipulation

<p>Anthropogenic influences are increasing algal biomass and activity within aquatic ecosystems, stimulating debate regarding interactions between “green” and “brown” food webs. Specifically, in forested streams, the removal of forest canopy or riparian zones increases light exposure and nutrient fluxes to streams affecting primary productivity and carbon (C) flows across aquatic food webs. Further understanding the synergistic effects of light and nutrients on detrital biofilms may explain how aquatic detritivores respond to anthropogenic change. The objective of this study was to employ C and phosphorus (P) isotopic radiolabels to understand how microbial biofilm constituents (i.e heterotroph and autotroph) contribute C and P to detritivore nutrition under raised light and nutrient regimes. I conducted a feeding study using detritivorous caddisflies (i.e. <em>Pycnopsyche </em>sp.) and conditioned leaf litter across a fully-factorial experimental set up and fed radiolabeled litter in the lab. Additionally, I used dual labels of ¹⁴C and ³³P to trace radiolabeled C and P into caddisfly tissues. I quantified microbial biomass and production rates, caddisfly consumption and egestion rates, and radiolabel assimilation, and incorporation efficiency. The results of my study report that 94-97% of detritivore C was incorporated from fungi and 1-3% from bacteria and algae. My study shows light and nutrients stimulate heterotrophic activity and determine the microbial quality of C and P available to detritivores. Future studies should assess physiological performance (i.e. growth rates) of caddisflies in response to light and nutrient exposed litter to understand how caddisflies are responding to potential elemental ratio imbalance</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2018

Author dc:creator

• Price, Taylor

Contributors dc:contributor

• Kevin Kuehn
• Halvor Halvorson
• Jake Schaefer

• Biofilms
• nutrients
• insect nutrition
• autotrophs
• decomposition

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/599

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1446