Research Themes

Research in our lab is focused on freshwater community and ecosystem ecology. We have active research programs in both tropical and temperate regions of the world, with a primary focus in Mesoamerica and the southeastern United States. Our work has been funded through local collaborations, the state government, the National Science Foundation, the Department of Energy, National Geographic, the PADI Foundation, and the Fulbright and Fulbright-Hays Programs. We design our research programs to fill fundamental gaps in our understanding of ecological processes, while simultaneously addressing pressing environmental problems. We are excited to build and support a community of ecologists from diverse backgrounds that bring new and exciting perspectives to our team. We have listed the predominant themes we study below and are happy to consider anyone with interest in these themes to join our team.

  • If you are interested in learning more about some of our actively-funded projects, please visit this page.
  • If you are interested in learning more about our collaborative work on wastewater infrastructure (septic and work with the wastewater treatment plants) with Athens-Clarke County and other local governments, please visit this page.

We study an invasive group of armored catfish (Siluriformes: Loricariidae) and their impacts in the Usumacinta watershed in Chiapas, Mexico. Loricariids, also known as “plecos” and “algae eaters” in the aquarium trade, are a large family of catfish. More than 700 species of loricariids have been identified and the list is still growing. They are amazing catfish native to tropical areas in South America, Costa Rica, and Panama. Unfortunately, several species of armored catfish have been introduced throughout the world. This work has been funded by the National Science Foundation, the Fulbright-Hays Program, The National Geographic Society, The PADI Foundation, The American Cichlid Association, and others. Currently, armored catfish research is funded by a National Science Foundation Grant (1). 

We are excited to develop new collaborations focused on armored catfish invasion. Please feel free to contact me if you are interested in pursuing a collaboration.

Over the past few decades, a large body of research has begun to elucidate the functional role animals play in ecosystem function. Animals influence nutrient dynamics by consuming, metabolizing, and releasing organic and inorganic forms of nutrients through excretion, egestion, and the decomposition of tissue. These processes, also termed consumer-driven nutrient dynamics, can be an important part of biogeochemical cycling in rivers.  Nutrients are often excreted in inorganic forms such as ammonium and phosphate, and thus are available to primary producers, but other forms of waste, such as urea and feces, are organic in nature and require additional processing by microbes to be available for uptake and assimilation. Because nutrient availability can strongly limit the overall productivity of a stream ecosystem, high rates of consumption and secondary production can stimulate rates of nutrient cycling. Furthermore, because many species are mobile, animals can play important roles in transporting energy and nutrients, or spatial subsidies, between ecosystems that can, in turn, alter the community structure and ecosystem dynamics in recipient systems. Work in the Capps Lab has conducted work on consumer-driven nutrient dynamics in rivers and wetlands on invertebrates and vertebrates (including humans). We are especially excited to answer questions about how consumer-driven nutrient dynamics change along environmental gradients and how they are altered by anthropogenic activities. This work is currently funded by two grants from the National Science Foundation (12). 

This research theme integrates all of the other themes that we study in the lab, and will continue to be a primary research emphasis in the Capps Lab. The interdisciplinary nature of this research necessitates diverse research collaborations with disease ecologists, microbial ecologists, chemists, hydrologists, geologists and other soil scientists, engineers, social scientists, lawyers and other policy-oriented researchers, and local, state, and federal governments in the US and in Mexico. This work is currently funded by a state seed grant, four grants from the National Science Foundation, and one grant from the Mexican Science Foundation. We hope that this work, which actively integrates social, ecological, and technical systems, will inform our understanding of the influence of human-derived wastewater on the structure and function of rivers and streams at the local, regional, and global levels. This work is currently funded by a state seed grant, four grants from the National Science Foundation (12, 3, 4) and a grant from el Consejo Nacional de Ciencia y Tecnología (CONACYT), the Mexican National Science Foundation.

Please visit this page to learn more about our some of our projects and collaborators.

Please visit this page if you would like to learn how we are collaborating with local and regional governments in Georgia to advance our understanding of the ecology of urban environments, and help inform local decision-making. 

Researchers in the Capps Lab collaborate with investigators at the Savannah River Ecology Laboratory, Auburn University, The Jones Center at Ichauway, and the River Basin Center at UGA to study the ecology of streams and freshwater wetlands in the southeast. We also actively collaborate with regional environmental managers and stakeholder groups in Athens-Clarke County, Butts County, and the city of Atlanta to support natural resource management. This work is currently funded by grants from the National Science Foundation (1), the  state of Georgia, the Savannah River Site, and collaborative agreements with the Jones Center at Ichauway.

Much of what we know about the structure and function of rivers and streams has been learned in the temperate zone. There is still much left to be studied in the tropics. Tropical research in the Capps Lab has primarily been focused on rivers in Mesoamerica (see below); however, we are excited to welcome students and collaborators from other tropical regions of the globe. Our projects have primarily asked questions addressing how anthropogenic activities including, urbanization, species introduction, and agricultural development, have altered aquatic community structure and biogeochemical processes.

Mesoamerica, a region that extends from southern Mexico to Panama, includes numerous freshwater bodies that define international boundaries. This region is characterized by high biodiversity and impoverished human populations that rely on the integrity of freshwaters; however, the ecology of Mesoamerican watersheds is relatively understudied. Our research in Mesoamerica will continue to address the effects of armored catfish on freshwater communities and ecosystems and will continue asking basic research questions focused on understanding linkages among species identity, ecological stoichiometry, consumer-driven nutrient dynamics, and ecosystem processes. This work is currently funded by two grants from the National Science Foundation (12) and a grant from el Consejo Nacional de Ciencia y Tecnología (CONACYT), the Mexican National Science Foundation. 

Conservation and management of freshwater resources throughout the world are challenged by mismatches in spatial and temporal variability among ecological processes, management decisions, and the construction and maintenance of infrastructure. Urban watershed research in the Capps Lab supports local (Athens-Clarke County) and regional (the Oconee Watershed and watersheds in Atlanta) research. We are excited to support students and initiate new collaborations to investigate how urbanization will alter freshwater structure and function and the provisioning of freshwater ecosystem services throughout the southeastern US. 

Research in urban stream ecology has largely been limited to smaller systems in temperate climates in relatively wealthy countries. However, we remain largely ignorant of the effects of urbanization on the structure and function and the ecosystems services provided by streams in tropical, impoverished regions of the globe. Urbanization occurs at much faster rates in lower-income economies, and researchers have argued the great majority of the net increase in global population will be in cities in the developing world. Increased population densities may have proportionally larger impacts on the structure and function of watersheds, as cities in lower-income economies frequently lack appropriate infrastructure for wastewater treatment. Therefore, the Capps Lab also supports international research in urban systems. Much of our work has been conducted in the Neotropics, but we are excited to develop collaborative projects to study urban watersheds throughout the globe. This work is currently funded by a state seed grant, four grants from the National Science Foundation (12, 3, 4) and a grant from el Consejo Nacional de Ciencia y Tecnología (CONACYT), the Mexican National Science Foundation.