Cory R.M.,University of North Carolina at Chapel Hill |
Kaplan L.A.,Stroud Water Research Center
Limnology and Oceanography | Year: 2012
We investigated the biological lability of fluorescent dissolved organic matter (FDOM) from a temperate Piedmont stream. Plug-flow bioreactors, colonized and maintained with natural stream water, were used to determine the concentrations of stream-water biodegradable dissolved organic carbon (BDOC) and relative concentrations of FDOM within operationally defined biodegradability classes. Labile molecules with turnover times of hours are metabolized within the stream reach where they originated; semi-labile molecules with turnover times of days travel out of the reach and are transported downstream before being metabolized; and a more recalcitrant class with a longer but undetermined turnover time flows through the river network without being metabolized. Between 26% and 31% of the DOC was biodegradable, with 8.6% labile and the balance semi-labile. Humic-like FDOM was a proxy for more recalcitrant DOM, exhibiting a ± 2% change as a function of increased bioreactor residence time. Humic-like FDOM represents only the more recalcitrant and perhaps the more hydrophobic constituents and not the ecologically important semi-labile humic substances within the BDOC pool. Tyrosine-like and tryptophan-like FDOM constituents included not only labile DOM, but also semi-labile, and more recalcitrant moieties. For example, 13% of the tryptophan-like FDOM was labile, 14% was semi-labile, and 73% was more recalcitrant, while tyrosine-like FDOM was 100% biodegraded and the majority (44-69%) was classified as labile. Collectively our results challenge some previous assessments of FDOM lability classifications and highlight the need to connect fluorescence characteristics of DOM to residence times of different carbon pools that spiral through a river network. © 2012, by the Association for the Sciences of Limnology and Oceanography, Inc. Source
Agency: NSF | Branch: Continuing grant | Program: | Phase: Integrative Ecologi Physiology | Award Amount: 369.68K | Year: 2015
Freshwater ecosystems support a disproportionate percentage of Earths biodiversity and are among the most threatened by human activities and global climate change. Insects dominate fresh-water ecosystems in terms of animal biodiversity and ecological processes. Temperature controls insect growth, developmental timing, survival, and reproduction, which influence both the distributions of individual species and the specific set of species that occur in different freshwater ecosystems. Thus, many effects of global change and other anthropogenic activities on freshwater ecosystems will likely be manifested through their thermal effects on aquatic insects. The thermal limits of individual freshwater insect taxa and the underlying physiological mechanisms that determine those limits still remain poorly understood. This research has practical importance because resource agencies use aquatic insects and other invertebrates to make inferences about ecological health and water quality. However, these data are often difficult to interpret, because we have a poor understanding of how and why species are differentially responsive to elevated temperatures. This collaborative project links researchers with a broad range of expertise to understand how temperature affects organismal physiology, life-history outcomes, and ultimately the distribution of species across entire landscapes.
The research team will experimentally manipulate thermal regimes to quantify the effects of temperature on life-history outcomes (survival, growth rates, development times, size and fecundity) of a diversity of mayfly (Ephemeroptera) species. Laboratory experiments will identify how the specific physiological processes that affect life-history outcomes (respiration, energy allocation, the production of metabolites, and gene expression) respond to different temperatures. These laboratory studies will be used to refine ecological niche models (empirically derived relationships between environmental temperatures and species distributions in time and space) that are used in freshwater biodiversity assessment and monitoring. In particular, these studies will clarify which descriptors of environmental temperatures (e.g. mean annual temperature, mean summer temperature, the magnitude of diel thermal change, etc.) are most important to species performance. Ultimately, these studies are intended to provide a robust understanding of the linkages between thermal physiology, life-history variation, and species distributions. Robust outreach efforts will make this understanding useful to the large ecological monitoring community.
Agency: NSF | Branch: Continuing grant | Program: | Phase: ECOSYSTEM STUDIES | Award Amount: 51.29K | Year: 2016
Many of the worlds environmental problems are exacerbated by changes in both biological and physical conditions that jointly influence sediment erosion. In freshwater habitats, major progress toward clearly linking biology and geomorphology to address environmental problems includes incorporating the role of the many small animals that live in streams into our understanding of erosion. This research project investigates how bottom-dwelling invertebrates in streams influence flood disturbance by regulating the stability of the riverbed. Sediment erosion is a critical variable in freshwater ecosystems because it influences freshwater biodiversity, insect and fish egg survival, changes the composition and activity of algae, and alters carbon and nutrient cycling. An understanding of sediment erosion that includes the impacts of bottom-dwelling animals will address a range of practical problems relevant to society, including informing models to predict erosion in landscapes altered by land use, predicting the impacts of floods that are being altered worldwide as a result of changes to water levels caused by climate warming and diversion for agriculture, and protecting and restoring habitat for threatened freshwater organisms such as fish. This project will provide research opportunities for one PhD student, two Master students, and four undergraduate students, develop workshops to teach concepts related to bottom-dwelling invertebrate influences on sediment erosion to high school teachers, and produce outreach videos documenting sediment erosion.
To investigate how animals in streams influence physical resistance to flood disturbance with consequences for aquatic benthic communities and ecosystem processes, the researchers will study common aquatic ecosystem engineers, web-spinning hydropsychid caddisfly larvae (Trichoptera:Hydropsychidae). These aquatic insects build silk structures that can bind riverbed sediment together, increase the force required to move sediments, and reduce bedload flux. The researchers will quantify sediment stabilization effects by caddisfly larvae from grain to landscape scales. They will also document how changes in sediment disturbance due to caddisfly silk structures influence ecosystem productivity, nutrient cycling, and the recovery of benthic communities following floods. The researchers will use a combination of controlled laboratory experiments, caddisfly density manipulations in natural streams, field surveys, and sediment transport models to identify how caddisfly ecosystem engineering affects sediment transport regimes across landscapes. Together, the series of studies will quantify how much these abundant ecosystem engineers can regulate erosional processes in streams.
Agency: NSF | Branch: Standard Grant | Program: | Phase: GEOBIOLOGY & LOW TEMP GEOCHEM | Award Amount: 1.37M | Year: 2013
The Critical Zone (CZ) science community takes as its charge the effort to integrate theory, models and data from the multitude of disciplines collectively studying processes on the Earths surface. The Critical Zone is Earths permeable near-surface layer - from the atmosphere at the vegetations canopy to the lower boundary of actively circulating groundwaters. The Critical Zone was a term coined by the National Research Councils Basic Research Opportunities in the Earth Sciences (BROES) Report (2001) to highlight the imperative for a new approach to thoroughly multi-disciplinary research on the zone of the Earth?s surface that is critical to sustaining terrestrial life on our planet. In January 2013, 103 members of the CZ community met for the CZ-EarthCube Domain Workshop (NSF Award #1252238) to prioritize the CZ communitys key science drivers, key computational and information technology (cyber) challenges and key cyber needs. They identified that the central scientific challenge of the critical zone science community is to develop a grand unifying theory of the critical zone through a theory-model-data fusion approach. Work participants unanimously described that the key missing need of this approach was a future cyberinfrastructure for seamless 4D visual exploration of the integrated knowledge (data, model outputs and interpolations) from all the bio and geoscience disciplines relevant to critical zone structure and function, similar to today?s ability to easily explore historical satellite imagery and photographs of the earths surface using Google Earth. This project takes the first BiG steps toward answering that need.
The overall goal of this project is to co-develop with the CZ science and broader community, including natural resource managers and stakeholders, a web-based integration and visualization environment for joint analysis of cross-scale bio and geoscience processes in the critical zone (BiG CZ), spanning experimental and observational designs. Our Project Objectives are to: (1) Engage the CZ and broader community to co-develop and deploy the BiG CZ software stack; (2) Develop the BiG CZ Portal web application for intuitive, high-performance map-based discovery, visualization, access and publication of data by scientists, resource managers, educators and the general public; (3) Develop the BiG CZ Toolbox to enable cyber-savvy CZ scientists to access BiG CZ Application Programming Interfaces (APIs); and (4) Develop the BiG CZ Central software stack to bridge data systems developed for multiple critical zone domains into a single metadata catalog. The entire BiG CZ Software system will be developed on public repositories as a modular suite of fully open source software projects. It will be built around a new Observations Data Model Version 2.0 (ODM2) that is being developed by members of the BiG CZ project team, with community input, under separate funding (NSF Award #1224638).
Agency: NSF | Branch: Continuing grant | Program: | Phase: DISCOVERY RESEARCH K-12 | Award Amount: 1.00M | Year: 2014
This project will develop curricula for environmental/geoscience disciplines for high-school classrooms. It will teach a systems approach to problem solving through hands-on activities based on local data and issues. This will provide an opportunity for students to act in their communities while engaging in solving problems they find interesting, and require synthesis of prior learning. The Model My Watershed (MMW) v2 app will bring new environmental datasets and geospatial capabilities into the classroom, to provide a cloud-based learning and analysis platform accessible from a web browser on any computer or mobile device, thus overcoming the cost and technical obstacles to integrating Geographic Information System technology in secondary education. It will also integrate new low-cost environmental sensors that allow students to collect and upload their own data and compare them to data visualized on the new MMW v2. This project will transform the ability of teachers throughout the nation to introduce hands-on geospatial analysis activities in the classroom, to explore a wide range of geographic, social, political and environmental concepts and problems beyond the projects specific curricular focus.
The Next Generation Science Standards state that authentic research experiences are necessary to enhance STEM learning. A combination of computational modeling and data collection and analysis will be integrated into this project to address this need. Placing STEM content within a place- and problem-based framework enhances STEM learning. Students, working in groups, will not only design solutions, they will be required to defend them within the application portal through the creation of multimedia products such as videos, articles and web 2.0 presentations. The research plan tests the overall hypothesis that students are much more likely to develop an interest in careers that require systems thinking and/or spatial thinking, such as environmental sciences, if they are provided with problem-based, place-based, hands-on learning experiences using real data, authentic geospatial analysis tools and models, and opportunities to collect their own supporting data. The MMW v2 web app will include a data visualization tool that streams data related to the modeling application. This database will be modified to integrate student data so teachers and students can easily compare their data to data collected by other students and the government and research data. All data will be easily downloadable so that students can increase the use of real data to support the educational exercises. As a complement to the model-based activities, the project partners will design, manufacture, and distribute a low-cost environmental monitoring device, called the Watershed Tracker. This device will allow students to collect real-world data to enhance their understanding of watershed dynamics. Featuring temperature, light, humidity, and soil moisture sensors, the Watershed Tracker will be designed to connect to tablets and smartphones through the audio jack common to all of these devices.