RESEARCH PROJECTS

The projects listed below give brief descriptions of some of our current research in ecology at UTA. Please see individual faculty webpages for additional research areas.

Plant Species Diversity and Trophic Interactions in Alaskan Tundra

Dr. Laura Gough has been investigating the determinants of plant species composition in arctic tundra in northern Alaska since 1996. Her current research is a collaborative project with Dr. John Moore, University of Northern Colorado, funded by NSF (2004-2007). Gough and Moore are attempting to determine the direct linkages among soil nutrients, plants, small mammals, insects, and soil fauna in two common Alaskan tundra types, moist acidic tussock and dry heath. Using long-term manipulations (begun in 1996) of mammal abundance and soil nutrients maintained by the Arctic Long-Term Ecological Research (LTER) project, Gough and her students are monitoring vegetation change in response to these treatments, while Moore is focusing on soil responses. This research has two important applications. First, results will provide a test of how increased productivity affects higher trophic levels in a relatively simple, low productivity ecosystem to determine if responses correspond to theoretical predictions. Second, understanding trophic linkages in a warming Arctic is of great importance to predicting future changes. As the Arctic continues to warm, soil nutrient availability increases as soil microbes are able to decompose organic matter at a higher rate, making more nutrients available to plants. The effect of these changes on the plant community have been documented, but subsequent effects on mammalian herbivores have not been studied nor have direct feedbacks between soil organisms and plants. Results will be used to expand a soil food web model completed by Moore based on earlier data collection

Golden Algae in Texas Reservoirs

Prymnesium parvum, also called “golden algae”, occurs worldwide and is responsible for large fish kills in coastal and inland water environments. Blooms of golden algae have been identified in fresh and brackish water environments from Australia to Texas, where they have impacted community revenues from tourism, fishing, and hatchery production. Blooms in Texas have affected over 20 reservoirs in five river basins, killing over 17.5 million fish with economic losses of several million dollars. Dr. James Grover and colleagues at UT-Austin, Texas A&M University and Baylor University are investigating the ecology of golden algae, with sponsorship from the Texas Parks & Wildlife Department (http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/ga/). This research integrates laboratory and field experiments with mathematical modeling and toxicology. Previous research has established that blooms in Texas occur in winter, under conditions of temperature and salinity that are not optimal for growth of the algae, but which do enhance the toxicity of golden algae to fish. The absence of golden algae blooms in warmer weather, which supports more rapid growth, remains unexplained. Ongoing research will address hypotheses that the competitors (other algae) and grazers present in summer suppress the growth of golden algae.

Effects of Stoichiometry on Microbial Competition and Predation

Drs. James Grover and Thomas Chrzanowski are investigating the impact of variable stoichiometry on predation and competition by developing microbial experimental models, in a project funded by NSF (2005-2008). This project addresses how variations in the chemical composition (“stoichiometry”) of microorganisms affect their interactions with other species. In theory, variations in composition of the nutrient elements carbon, nitrogen, and phosphorus, affect competition between bacterial species, and also affect the relationship of bacterial prey with the larger microorganisms that consume them. Recently developed mathematical models of these processes are being tested using laboratory cultures of two bacterial species and a consumer microorganism, a chrysophyte flagellate. Specific predictions being tested include the proposal that the capability to reduce the cellular content of a nutrient indicates efficient nutrient use and can improve a species’ competitive ability, the proposal that consumers alter the outcome of competition between prey species, and the notion that this effect depends on details of chemical composition and the processing and recycling of nutrients on the part of the consumer. This project will provide insights into processes governing abundances of microorganisms in nature, including some species of “harmful algae” whose lifestyle includes feeding upon bacteria.

Algal communities as indicators of streambed instability and restoration.

Human-mediated geomorphic degradation of streams and rivers is a serious environmental problem with negative effects on aquatic biota and social infrastructure. Billions of dollars are spent for stream restoration in the US alone but it is still unknown how algal diversity is affected by these efforts. In this investigation, we studied a geomorphically stable and heterogeneous reach and two degraded and homogeneous reaches of Batavia Kill, a highland stream within the New York City Watershed. Spatial surveys of algae and geomorphic conditions were conducted in all three reaches for two years. After the first year of study, one of the two unstable reaches was subjected to a large scale streambed restoration, named the Big Hollow Project. Species-area relationships (SAR) were examined for the first time in local algal communities of stream periphyton. Alpha-diversity, which represents the species richness at a sample level, gamma-diversity, i.e. the species richness at a reach level, and cell density were also explored. In all reaches, SAR were fitted with semi-log models, which revealed that the rate of increase of species richness with area, i.e. algal beta-diversity, was significantly higher in the geomorphically stable reach than in the two degraded reaches. Gamma-diversity followed the same trend, whereas alpha-diversity and cell density were significantly higher in the unstable reaches. The present research on algal beta-diversity in stream reaches that were geomorphically degraded, restored or in natural conditions, suggests that human-induced habitat alterations may exert irreversible impact on algal communities, at least in the short term.

Lake Granbury Water Quality Study

Lake Granbury Water Quality Study. This project is sponsored by the US Department of Energy through a contract with the Texas Water Resources Institute, and involves investigators from Texas A&M University, Baylor University and the University of Texas at Arlington. The goal is to use high resolution spatial mapping of lake characteristics and mathematical modeling to identify factors affecting two water quality problems within the lake. Problems under investigation involve outbreaks of high numbers of bacteria indicating low water quality (E. coli, other fecal bacteria indicators), and harmful blooms of "golden algae" (Prymnesium parvum). Lake Granbury is a long, narrow reservoir whose shoreline is essentially completely developed, mostly as residential property. Only a minority of the residences around the lake is hooked to municipal sewage, and most homes rely on septic systems for sewage disposal. Leakage from these systems is one potential factor contributing to water quality problems.