Effects of Light and Macroinvertebrate Consumers on Detrital Microbial Biofilms in Streams

<p>In lotic freshwater systems, aquatic macroinvertebrates are key processors of biofilms that grow upon organic matter. Although macroinvertebrate effects on biofilms may depend on light availability, the combined effects of consumers and light remain unexplored. Here, I conducted experiments to test effects of presence/absence of the omnivorous shrimp <em>Macrobrachium ohione</em> and the shredding caddisfly <em>Pycnopsyche</em> sp. on <em>Liriodendron tulipifera</em> litter biofilms in experimental streams under light or darkness. I measured litter-associated algal, fungal and bacterial biomasses and production rates, as well as litter decomposition, over 49 days. Both experiments exhibited significant positive effects of light on algal productivity and interactions of <em>Macrobrachium </em>and <em>Pycnopsyche </em>presence with time and light. Light increased bacterial productivity in the <em>Pycnopsyche </em>experiment, but not in the <em>Macrobrachium </em>experiment, in which time, light, and <em>Macrobrachium </em>interactively affected bacterial production. Litter decomposition was unaffected by light or <em>Macrobrachium</em> presence, but <em>Pycnopsyche </em>presence<em> </em>increased decomposition rates. My results suggest that light strongly affects litter biofilms, whereas consumers primarily affect the timing and succession of periphytic microbial colonization of organic matter. Compared to omnivores, shredder-detritivores may exert stronger effects on turnover and decomposition of organic material within lotic systems.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2019

Author dc:creator

• Brady, Cheyenne M.

Contributors dc:contributor

• Kevin Kuehn
• Halvor Halvorson
• Jake Schaefer

• macroinvertebrates
• microbial ecology
• decomposition
• biofilms
• riparian streams
• stream detritus
• Terrestrial and Aquatic Ecology

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/680

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1723