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LONG-TERM ECOLOGICAL RESEARCH
Ecology has taken its place among science's vital, strategic disciplines, thanks to an ever-greater awareness of how the web of life and the Earth's other dynamic processes constitute a closed and coherent system. As part of this evolution, the National Science Foundation's Long-Term Ecological Research (LTER) Program, begun in 1980, has grown into a network of 24 research sites, established to acquire long-term data sets from Alaska to Puerto Rico to Antarctica. Such a geographical spread is necessary to collect information on a variety of ecosystem types, such as grassland, desert, forest, tundra, lake, stream, river, and agricultural and coastal systems.
To enhance understanding of ecological phenomena, the program focuses on the role of cyclical/episodic events (ranging from years to decades to centuries) in the structure and function of these distinctive ecosystems. The Antarctic Biology and Medicine Program supports two of these LTER project sites to facilitate research on unique aspects of antarctic ecology: one near Palmer Station in the Antarctic Peninsula and the other in the McMurdo Dry Valleys.
The Palmer Station/Antarctic Peninsula LTER program is ideally sited to probe a fundamental issue: As the pack ice varies (seasonally and year by year), what happens to the antarctic marine community? That is, how do ecological processes influence organisms at different trophic levels? The Palmer Station LTER Program was initiated during the 1991-1992 season with the installation of an automatic meteorological station, annual research cruises in the austral summer, and a focused research program at the station facility. During the austral fall and spring seasons, process-study research cruises develop data that can be compared with data collected from other coastal systems in the Antarctic Peninsula.
Due to its unique site, the McMurdo Dry Valleys LTER project is more wide ranging and focuses on the interdisciplinary study of aquatic and terrestrial ecosystems in a cold desert region of Antarctica. The area is one of the most fascinating and contrarian spots on Earth. In fact, it is almost unearthly. National Aeronautics and Space Administration scientists who wondered what conditions might be like on Mars came here, an island of rock in a sea of ice, the largest ice-free area in Antarctica, where winds howl, where what little water there is dessicates or evaporates, and where the only creatures that can survive are microorganisms, mosses, lichens, and relatively few groups of invertebrates. Higher forms of life are virtually nonexistent.
Thus, LTER projects based here take advantage of perhaps the coldest and driest ecosystem on Earth, where life approaches its environmental limits; as such, this may be seen as an "end-member" in the spectrum of environments included in the LTER network. Why is it necessary to conduct long-term ecological research in such a place? All ecosystems depend on liquid water and are shaped to varying degrees by climate and material transport; but nowhere is this more apparent than in the McMurdo Dry Valleys. In very few of Earth's environments do minor changes in solar radiation and temperature so dramatically affect the capabilities of organisms to grow and reproduce as in the Dry Valleys. Therefore, this site may well be an important natural, regional-scale laboratory for studying the biological effects of climate changes attributable to human activity. While the antarctic ice sheets respond to climate change on the order of thousands of years, the glaciers, streams, and ice-covered lakes in the McMurdo Dry Valleys often experience nearly immediate (and sometimes profound) change. As such, this area would be one of the first to show the effects of climate change in Antarctica.
The overall objectives of the McMurdo Dry Valleys LTER are to understand the influence of physical and biological constraints on the structure and function of Dry Valley ecosystems and to understand the modifying effects of material transport on these ecosystems. Though driven by the same basic processes found in all ecosystems (microbial use and remineralization of nutrients, for example), the Dry Valley ecosystems lack many of the confounding variables, such as diverse and fecund biota and many levels of plants and higher animals, inherent in other ecosystem research.
Palmer Long-Term Ecological Research Project: Climate change, ecological migration, and teleconnections in an ice-dominated environment.
Hugh W. Ducklow, College of William and Mary.
The Palmer Long-Term Ecological Research Project (PAL LTER) seeks to understand the structure and function of the antarctic marine and terrestrial ecosystem in the context of physical forcing by seasonal to interannual variability in atmospheric and sea-ice dynamics, as well as long-term climate change. The PAL LTER grid is designed to study marine and terrestrial food webs consisting principally of diatom primary producers, the dominant herbivore antarctic krill, Euphausia superba, and the apex predator Adélie penguin, Pygoscelis adeliae. An attenuated microbial food web, consisting of planktonic bacteria and Archaea and bacterivorous protozoa, is also a focus of study.
This project monitors western Antarctic Peninsula ecosystems annually over a grid of oceanographic stations and seasonally at Palmer Station. The extent and variability of sea ice affect changes at all trophic levels. In recent years, sea ice has diminished in response to a general regional warming. A long-term population decline of ice-dependent Adélie penguins provides a clear example of the impact of this trend in the Palmer region. Adélie populations at the five major rookeries located near Palmer Station and studied for the past 30 years have all shown a gradual decrease in numbers. The western Antarctic Peninsula, the site of PAL-LTER research, runs perpendicular to a strong climatic gradient between the cold, dry continental regime to the south, characteristic of the interior, and the warm, moist maritime regime to the north. More maritime conditions appear to be replacing the original polar ecosystem in the northern part of the peninsula as the climatic gradient shifts southward. To date, this shift appears to be matched by an ecosystem shift along the Peninsula, as evidenced by declines in Adélie penguins, which require longer snow-cover seasons.
We hypothesize that ecosystem migration is most clearly manifested by changes in upper-level predators (penguins) and certain polar fishes in predator-foraging environments because these longer-lived species integrate recent climate trends and because individual species are more sensitive indicators than aggregated functional groups. We hypothesize that in the years ahead, analogous modifications will also become evident at lower trophic levels, although these changes are likely to be seen only through long-term studies of ecosystem boundaries along the Peninsula.
By studying extant food webs in both the marine and terrestrial environments, we will continue to investigate ecosystem changes at lower trophic levels; changes in response to continued, dramatic warming; and shifts in the poleward climatic gradient along the western Antarctic Peninsula.
During the 2003-2004 field season, the following studies will be conducted as part of the LTER project:
Palmer Long-Term Ecological Research Project: Climate change, ecological migration, and teleconnections in an ice-dominated environment. (B-013-L/P; NSF/OPP 02-17282)
Palmer Long-Term Ecological Research Project: Climate change, ecological migration, and teleconnections in an ice-dominated environment. (B-016-L/P; NSF/OPP 02-17282)
Palmer Long-Term Ecological Research Project: Climate change, ecological migration, and teleconnections in an ice-dominated environment (modeling component). (B-021-L; NSF/OPP 02-17282)
Palmer Long-Term Ecological Research Project: Climate change, ecological migration, and teleconnections in an ice-dominated environment (prey component). (B-028-L/P; NSF/OPP 02-17282)
Palmer Long-Term Ecological Research Project: Climate change, ecological migration, and teleconnections in an ice-dominated environment. (B-032-L/P; NSF/OPP 02-17282)
Palmer Long-Term Ecological Research Project: Climate change, ecological migration, and teleconnections in an ice-dominated environment. (B-045-L/P; NSF/OPP 02-17282)
Transport and fate of persistent organic pollutants in antarctic coastal seas. (B-045-L/P; NSF/OPP 00-87872
The role of natural legacy on ecosystem structure and function in a polar desert: The McMurdo Dry Valley Long-Term Ecological Research Project.
W. Berry Lyons, Ohio State University.
The largest ice-free area in Antarctica is found in the McMurdo Dry Valleys, located on the western shore of McMurdo Sound. Among the most extreme deserts in the world, the Dry Valleys are the coldest and driest of all the Long-Term Ecological Research (LTER) sites. Consequently, biological systems are limited to microbial populations, microinvertebrates, mosses, and lichens. Yet complex trophic interactions and biogeochemical nutrient cycles develop in the lakes, streams, and soils of the Dry Valleys. In the austral summer, solar energy produces glacial meltwater, providing vital water and nutrients that have a primary influence on the ecosystems. Such material transport and climatic influences shape all ecosystems, but nowhere is this more apparent than in the McMurdo Dry Valleys.
The McMurdo LTER project focuses on the aquatic and terrestrial ecosystems in the Dry Valley landscape as a context to studying biological processes and to exploring material transport and migration. During the second phase of this LTER project, we are extending our research by continuing to investigate the McMurdo Dry Valleys as an end-member system, hoping to better ascertain the role of past climatic legacies on ecosystem structure and function. We will test a series of eight hypotheses in three major focus areas--hydrology, biological activity/diversity, and biogeochemical processes--by continuing monitoring projects and long-term experiments.
Understanding the structure and function of the McMurdo Dry Valleys ecosystem requires deciphering the hydrological response to climate, both now and in the past. Current patterns of biological activity and diversity reflect past and present distributions of water, nutrients, organic carbon, and biota. Biogeochemical processes responsible for the transport, immobilization, and mineralization of nutrients and other chemicals provide the linkages between the region's biota and the physical environment. The timing, duration, and location of biogeochemical processes in the past and present are controlled by the availability of water. We continue to focus on the integration of the biological processes within and among the lakes, streams, and terrestrial ecosystems that comprise the McMurdo Dry Valley landscape. Our interdisciplinary research team will continue to use modeling and other integrative studies to synthesize data and to examine the McMurdo Dry Valleys ecosystem.
During the 2003-2004 field season, the following studies will be conducted in the McMurdo Dry Valleys as part of the LTER project:
Study of consequences of a January 2003 hydrocarbon spill on the ice cover of Lake Fryxell, McMurdo Dry Valleys.
Taylor Valley in the McMurdo Dry Valleys of East Antarctica is the site of a Long-Term Ecological Research (LTER) project. The pristine Taylor Valley has three major closed-basin, perennially ice-covered lakes (Hoare, Fryxell and Bonney). On 17 January 2003, a Bell 212 helicopter crashed on the 5-meter-thick ice cover of Lake Fryxell, spilling about 730 liters of diesel fuel, as well as small amounts of synthetic lubricants and hydraulic fluids. Although cleanup efforts by personnel based at McMurdo Station began within 4 days of the crash, at least half of the spilled fluids could not be recovered because of the condition of the ice and the unavoidable close of the field season in early February, which precluded further access to the site. These fluids will remain trapped in the ice until the spring melt season starts in December 2003. The site will become accessible in November 2003, when ice cores and water samples can be collected for detailed analyses.
This coordinated research effort is aimed at documenting the fate and transport of hydrocarbons within the ice and water of the lake. Our goals are to understand the physical, chemical, and biological changes that have occurred since the spill and what, if any, its longer-term impact will be. The results of our research will also provide important information to help improve accident response policies in the Dry Valleys.
Study of natural attenuation of contaminants derived from a January 2003 helicopter fluids spill at Lake Fryxell (McMurdo Dry Valleys), a Long-Term Ecological Research site.
Fabien Kenig and Peter Doran, University of Illinois-Chicago.
In this component of the project, we will document the natural attenuation of helicopter fluids in the lake ice. We have two major objectives:
Physical and biological consequences of a hydrocarbon spill on the ice cover of Lake Fryxell, Antarctica.
John Priscu and Edward Adams, Montana State University-Bozeman.
In this component of the project, we will conduct a variety of physical and biological experiments to determine the fate of hydrocarbons within the ice and their influence on biological activity and diversity. Undergraduate, graduate, and postdoctoral students will participate in this research. (NSF/OPP 03-46272)
Field sampling coordination and mathematical modeling of a hydrocarbon spill on the ice cover of Lake Fryxell, Antarctica.
W. Berry Lyons and Anne Carey, Ohio State University.
In this component of the project, we will coordinate the field sampling in the 2003-2004 season, integrate the data, and develop a mathematical model to better predict hydrocarbon movement within the ice cover of the lake. (B-429-M; NSF/OPP 03-47219)^ top