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Grantee Research Project Results

NCER Grantee Research Project Results

Metabolic Responses of Aquatic Ecosystems to Climate Warming

EPA Grant Number: FP917469
Title: Metabolic Responses of Aquatic Ecosystems to Climate Warming
Investigators: Jankowski, KathiJo
Institution: University of Washington
EPA Project Officer: Jones, Brandon
Project Period: September 1, 2012 through August 31, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012)
Research Category: Academic Fellowships , Fellowship - Aquatic Ecology and Ecosystems

Description:

Objective:

The capacity for landscapes to sequester carbon and how landscape features regulate sequestration remain poorly understood under current and future climate conditions. The growing appreciation for the importance of aquatic ecosystems in understanding the capacity of watersheds to sequester carbon, and in fact the global carbon cycle, reinforces the need for improved understanding of their response to global change. Therefore, this research will evaluate how watershed context, by regulating both the physical template of aquatic ecosystems (e.g., temperature, light, hydrology) and the quality and amount of carbon delivered to them from the terrestrial landscape, influences the sensitivity of aquatic carbon cycling and metabolism to climate change.

Approach:

This research will quantify the landscape-scale variation in temperature sensitivity of stream metabolism and resulting CO2 flux from streams in the Wood River system of southwestern Alaska, a region showing the fastest warming trends globally. Field surveys of O2 and CO2 dynamics and small-scale incubations will be used to reformulate an existing ecosystem metabolic model to include temperature dependence of stream metabolism, that is, respiration (CO2 source) and primary productivity (CO2 sink). These results then will be linked to existing geographic information system (GIS) data on watershed characteristics that control the delivery of carbon, nutrients, water and light to streams to create functional relationships between the temperature sensitivity of stream metabolism and readily available watershed-scale data on watershed slope, watershed area, vegetation cover and so forth. This approach allows for an evaluation of temperature dependence of stream metabolism at an ecosystem scale and the projection of watershed responses to ongoing climate change.

Expected Results:

There is increasing evidence that stream metabolic processes that increase CO2 flux to the atmosphere will be highly sensitive to rising temperatures, changing precipitation patterns and shifts in carbon loading from watersheds. In addition, preliminary data suggest that the thermal scaling of organic matter processing in these Alaskan watersheds correspond with watershed geomorphic features. This research aims to develop functional relationships between watershed-scale data and stream metabolism to include aquatic ecosystems in assessments of watershed carbon storage. This research also will incorporate state-of-the-art statistical approaches that enable formal uncertainty analysis of aquatic ecosystem metabolism estimates that are critical for the evaluation of ecosystem responses to environmental change at scales relevant to management and policy making.

Potential to Further Environmental/Human Health Protection

Climate change threatens human health and economies by altering the services provided by intact ecosystems such as food production, clean water and carbon storage. Freshwater ecosystems not only provide valuable food and water but also play a large role in the carbon balance of watersheds. Therefore, understanding how climate change will affect the carbon cycle in aquatic ecosystems will improve the ability to predict how watersheds and the carbon sequestration services they provide will respond to climate change.

Supplemental Keywords:

climate change, freshwater, ecosystem services

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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