Date of Award

Spring 2021

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Biology

College

College of Science

First Advisor

Vladislav Gulis

Abstract/Description

Fungi, such as aquatic hyphomycetes, are important decomposers of plant litter in temperate forested headwater streams providing energy and nutrients for the higher trophic levels in these ecosystems. According to current climate change predictions, stream water temperatures are expected to rise significantly in the near future. This project addressed the effects of temperature on sporulation rates and community structure of aquatic hyphomycetes on substrates of different carbon quality (maple and rhododendron leaf litter and wood veneers). The experiment was conducted in streamside channels fed with stream water (ambient, +2°C and +4°C) and set up to mimic small streams. We found that temperature increases did cause changes to the fungal assemblages as some species became less common and others increased their relative abundances at higher temperatures. Sporulation rates of aquatic hyphomycetes were found to be affected by temperature only on rhododendron leaf litter but not on maple leaf litter or wood veneers. The temperature sensitivity of sporulation on rhododendron appeared to be very high with estimates of apparent activation energy, Ea, of >2.63 eV, being higher than canonical estimates for respiration (0.65 eV). Sporulation rates on rhododendron also strongly correlated with both fungal growth rate and production suggesting tight coupling of reproductive output and vegetative growth. Our findings suggest that the water temperature increases caused by climate change may have a stimulating effect on sporulation rate of aquatic hyphomycetes in temperate headwater streams during colder months when temperatures do not exceed 18°C as well as affect the fungal community structure and potentially stream ecosystem functioning.

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