HR: 1340h
AN: OS43A-0541    [Abstracts]
TI: Long-term Observations of Crater Lake, Oregon: Energy, Carbon, and Nutrient Cycles in an Ultra-oligotrophic Ecosystem
AU: * Collier, R
EM: rcollier@coas.oregonstate.edu
AF: COAS, Oregon State University, Corvallis, OR 97331 United States
AU: Crawford, G
EM: gbc3@humboldt.edu
AF: Oceanography, Humboldt State University, Arcata, CA 95521
AU: Fennel, K
EM: kfennel@imcs.marine.rutgers.edu
AF: IMCS, Rutgers University, New Brunswick, NJ 08901
AU: Larson, G
EM: gary\_l.\_larson@usgs.gov
AF: USGS-BRD, FRESC, Corvallis, OR 97330
AU: Buktenica, M
EM: Mark\_Buktenica@nps.gov
AF: Crater Lake National Park, PO Box 7, Crater Lake, OR 97604
AU: Dymond, J
AF: COAS, Oregon State University, Corvallis, OR 97331 United States
AB: Large, deep lakes offer a unique resource for the study of the interaction of the atmosphere and aquatic biogeochemical cycles. The remarkable properties of Crater Lake result in the vertical stratification of the ecosystem reminiscent of pelagic marine systems. This ultraoligotrophic lake provides a powerful natural laboratory to study the coupling of biological processes, element cycles, and the physics of the environment. Over 20 years ago, Jack Dymond established a long-term, high-resolution biogeochemical study, including sediment traps, which today provides a powerful tool to constrain processes operating over seasonal and interannual time scales. These studies enable the validation of appropriate process models, leading to a better predictive capacity in this and other large aquatic ecosystems. - We have demonstrated and modeled relationships between climate-driven vertical mixing and the upwelling of hypolimnetic nitrogen into the euphotic zone. The impacts of this nitrogen on the ecosystem are complex and are not simply reflected in export production. - The lake edges are a locus of this vertical mixing, and mass balance calculations suggest they support elevated primary production which must contribute significant particulate organic matter to the interior hypolimnion. - The extended time-series observations have allowed us to observe interannual variations in vertical mixing, deep water ventilation, and the accumulation of salt and nitrogen. - The observations have constrained models of lake physics which help evaluate the first-order impact of climate change scenarios. A nitrogen-based ecosystem model has been coupled to the physical model and validated against biological time series observations. - The functioning of large lake ecosystems are finally reflected in their sediments and may provide one of the most powerful paleorecords of climate variability on the continents.. Because Crater Lake is the centerpiece of one of the premier National Parks in the USA, it provides a unique setting to directly engage the public with compelling educational experiences demonstrating the function of complex aquatic ecosystems and the methods of interdisciplinary field research.
DE: 9345 Large bodies of water (e.g., lakes and inland seas)
DE: 4239 Limnology
DE: 1615 Biogeochemical processes (4805)
DE: 0400 Biogeosciences
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting