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Department of Ecosystem Science and Sustainability

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https://hdl.handle.net/10217/100401

These digital collections include theses, dissertations, faculty publications, and datasets from the Department of Ecosystem Science and Sustainability. Due to departmental name changes, materials from the following historical departments are also included here: Cooperative Watershed Management Unit; Earth Resources; Geology.

Of special note are digital copies of materials referenced by emeritus Earth Resources professor James R. Meiman in a literature review titled Little South Poudre Watershed and Pingree Park Campus (Colorado State University, College of Forestry and Natural Resources, 1971). These materials can be found here (re watershed science) and in departmental collections related to forestry, geology, and wildlife biology.

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Browsing Department of Ecosystem Science and Sustainability by Subject "algae"

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    Confounding factors in algal phosphorus limitation experiments
    (Colorado State University. Libraries, 2018-10-18) Beck, Whitney S., author; Hall, Ed K., author; PLOS ONE, publisher
    Assessing algal nutrient limitation is critical for understanding the interaction of primary production and nutrient cycling in streams, and nutrient diffusing substrate (NDS) experiments are often used to determine limiting nutrients such as nitrogen (N) and phosphorus (P). Unexpectedly, many experiments have also shown decreased algal biomass on NDS P treatments compared to controls. To address whether inhibition of algal growth results from direct P toxicity, NDS preparation artifacts, or environmental covariates, we first quantified the frequency of nutrient inhibition in published experiments. We also conducted a meta-analysis to determine whether heterotrophic microbial competition or selective grazing could explain decreases in algal biomass with P additions. We then deployed field experiments to determine whether P-inhibition of algal growth could be explained by P toxicity, differences in phosphate cation (K vs. Na), differences in phosphate form (monobasic vs. dibasic), or production of H2O2 during NDS preparation. We found significant inhibition of algal growth in 12.9% of published NDS P experiments as compared to 4.7% and 3.6% of N and NP experiments. The meta-analysis linear models did not show enhanced heterotrophy on NDS P treatments or selective grazing of P-rich algae. Our field experiments did not show inhibition of autotrophic growth with P additions, but we found significantly lower gross primary productivity (GPP) and biomass-specific GPP of benthic algae on monobasic phosphate salts as compared to dibasic phosphate salts, likely because of reduced pH levels. Additionally, we note that past field experiments and meta-analyses support the plausibility of direct P toxicity or phosphate form (monobasic vs. dibasic) leading to inhibition of algal growth, particularly when other resources such as N or light are limiting. Given that multiple mechanisms may be acting simultaneously, we recommend practical, cost-effective steps to minimize the potential for P- inhibition of algal growth as an artifact of NDS experimental design.
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    ItemOpen Access
    Water quality and survivability of Didymosphenia geminata
    (Colorado State University. Libraries, 2012) Beeby, Johannes, author; Stednick, John D., advisor; Fassnacht, Steven R., advisor; Clements, William H., committee member
    Didymosphenia geminata or Didymo has become a world-wide invasive aquatic species. During blooms, the algae can form thick mats covering entire reaches of stream bottom, which in turn creates negative aesthetic, ecologic, and economic impacts. Although Didymo is historically present in the United States, it is spreading quickly into areas that were previously free of it, and is even growing in waters that were thought not ideal habitat for Didymo. Previous research on how water quality affects Didymo growth and spreading appear to be influenced by streamflow rates and water pH levels. Other water quality parameters have not been fully tested on Didymo, which would contribute to a better understanding of what controls Didymo growth. The first goal of this study was to colonize Didymo in an artificial stream within a laboratory setting. The second goal was to evaluate the survivability of Didymo by exposing it to different water quality parameters. Artificial stream configurations with various light intensity and duration, water temperature and velocity, source water chemistry, and different growth media were used. In all attempts colonization of Didymo was unsuccessful as Didymo slowly deteriorated and became covered by other algae that were more successful in the artificial conditions. Didymo survivability as affected by a 60 minute exposure to different water quality parameters followed previously determined results in that known algaecides did affect cell viability, while other non-toxic parameters showed no effect on Didymo. Nitrate, nitrite, phosphate, chloride, calcium, and magnesium did not affect Didymo survivability. Ammonia also did not affect Didymo but signs of cells lysis were observed and possible mortality may occur with longer exposure times. Copper, zinc, chlorine, and pH affected Didymo survivability. Copper showed the greatest affect on Didymo survivability with the median lethal concentrations (LC50) for copper at 9.3°C and 13.0°C being 3.3 mg/L and 5.4 mg/L respectively at pH 7.7. For copper toxicity in waters with a lower pH (6.7) the resulting LC50 was 33 mg/L. Generally, both colder water temperature and higher pH increased copper toxicity on Didymo. The affect of temperature on copper toxicity was shown to be statistically significant (p-value 0.02). However, there was no statistically significant affect of pH on copper toxicity (p-value 0.07). The LC50 could also not be determined for all three zinc tests but the highest zinc concentration of 40 mg/L had on average 56% of Didymo cells surviving. No apparent trend on the affect of temperature to zinc toxicity on Didymo could be determined; however, the interaction of temperature on zinc toxicity was statistically significant (p-value 0.02). Chlorine at temperatures of 11.5°C and 17.3°C had LC50s of 5.67 and 8.46 mg/L respectively. The affect of temperature on chlorine toxicity was statistically significant (p-value <0.001). Didymo survivability was affected in water with pH 4.3 but not in water with pH 5.9 and 6.9. Cell lysis was occurring in water with pH 10.7 but no sign of any affect on Didymo survivability was found in water with pH 9.9.