Breena Riley

Breena Riley, Photo from ResearchGate

Breena Riley, Photo from ResearchGate

Breena Riley
(PhD Student)

Email: breena.mitchell@gmail.com
Tarleton State University


Project

Photosynthesis to Respiration Ratios and Diatom Assemblages Along Stream Lengths in Northern Sweden

Investigators at the Climate Impacts Research Centre (CIRC) of Umeå University seek to understand how carbon cycles through aquatic systems. Determining stream trophic status (heterotrophic versus autotrophic) is a tool which may be used to better understand carbon cycling in streams. To date, no research describes in-stream carbon cycling and trophic status in relation to phytoplankton in northern Sweden. Diatom indices are a well-established technique to determine water quality and to elucidate trophic status. Photosynthesis to respiration (P/R) ratios are also used to determine both qualities. Tools to measure both parameters are readily available at CIRC or may be easily obtained from the student’s home institution. Three types of samples will be collected from each site: diatom samples, isotopic oxygen (18O-DO), and nutrient samples. Diatom samples will be used to determine diatom indices. Isotopic oxygen will measure P/R ratios. Nutrient samples (e.g., nitrogen, phosphorus) will determine water quality. Data collected from each site will be compared within stream sites and across streams locations to determine stream trophic status. It is predicted that streams will change from autotrophic at the headwaters to increasingly heterotrophic further downstream. Data collected from Sweden may potentially be compared to stream conditions in Texas to assess stream trophic status at a broader scale

Dates: 15 June - 28 July