Toolik Lake NEON / TOOK

The climate at TOOK is characterized by long, cold winters; short, cool summers; and extreme seasonal variation. In the absence of sunlight, winters are long and bitterly cold, with temperatures sometimes reaching -40°C (-40°F) or lower. The summer period brings 24-hour solar input for much of June-August; as a result, it is the only time of year where average temperatures exceed 0°C (32°F). TOOK has an average mean temperature of -9°C (16°F) and it receives a mean annual precipitation of 316 mm (12.4 in). [6] [22]

Toolik Lake is situated on glacial and alluvial deposits aged 120-150 thousand years ago (Itkillik 1, late Pleistocene) and 25-11.5 thousand years ago (Itkillik II, late Pleistocene). Glacial outwash extends into the lake, creating multiple shoals and bays. The substrate within the lake is made up of cobble and silt. [1] [14]

TOOK sits in a continuous permafrost zone, although taliks—small pockets of non-frozen material—often exist beneath lakes and rivers. TOOK is located on rolling till plains and moraines. The lowlands have a thick organic layer, while the higher located soils are gelic (frost-churned) and exposed at the surface. The soils at the nearby terrestrial site, TOOL, are characterized as Typic Histoturbels in the order Gelisols. These soils contain permafrost and have a thick layer of organic matter at the surface and are often saturated for long periods of time. The high organic matter in the soils at TOOL is mostly due to persistent cold temperatures that limit decomposition and promote the accumulation of organic material from vegetation. This organic material insulates the underlying permafrost. [7] [8] [9] [13]

Toolik Lake is part of a lake district consisting of numerous kettle lakes formed by glaciers. The lake is fed by snowmelt, rain, and a system of streams and smaller kettle lakes with headwaters in the Brooks Range, located to the south. Ice forms on the lake in early October and completely disappears by late June. It is thermally stratified through much of July and August. It extremely oligotrophic, has a surface area of 1.48 km² (366 acres), volume of 12,602,474 m³ (445 million ft³), and a maximum depth of 26.2 m (86 ft.). Its outlet is a tributary of the Kuparuk River. [1] [11] [12]

The Arctic tundra is composed of hundreds of meters of permafrost - soil that remains consistently frozen for two or more years and leads to low plant diversity. Vegetation cover in the Toolik Lake area is mainly tundra shrubs and herbaceous flowering plants. The dominant shrubs include willows (Salix spp.), blueberry (Vaccinium uliginosum), and dwarf birch (Betula nana). There is little to no overhanging vegetation around the lake as the shrubs are typically less than 1 m (3.3 ft.) tall. [1]

NEON provides data on the only five fish species that inhabit Toolik Lake. They are lake trout (Salvelinus namaycush), burbot (Lota lota), slimy sculpin (Cottus cognatus), arctic grayling (Thymallus arcticus), and round whitefish (Prosopium cylindraceum). Other common fish in nearby lakes and streams are Dolly Varden (Salvelinus malma) Arctic Char (Salvelinus alpinus). [3] [15]

The Brooks Range has been populated for centuries by Alaskan native groups, the Iñupiat and Athabascan, and by their ancestors for thousands of years before that. The Iñupiat are a part of the Inuit culture, and their traditional lands extend along the northern coast from the western edge of Alaska into Canada. They hunt mostly aquatic animals such as bowhead and beluga whales, seals, walruses, and other marine mammals. They fish and gather berries, roots, and shoots. The inland Iñupiat also hunt caribou, mountain sheep, bears, and moose. The Athabascan's traditional lands comprise the interior of Alaska and western Canada. They hunt and fish for moose, caribou, and salmon, and gather seasonal plants and berries. Settlers of European descent began moving into Alaska in the 1800s, and by the late 19th century the Alaskan natives’ semi-nomadic lifestyles had been greatly altered and they began to settle into villages. Although their way of life has changed with the introduction of new technologies and different cultures, many communities continue to hunt and fish as their ancestors did.

Access to the interior areas of Alaska’s North Slope was very limited until the construction of the Alaska oil pipeline and Dalton Highway in 1974-1976. In July 1975, The University of Alaska – Fairbanks Institute of Marine Science installed a 16-foot travel trailer at the north end of Toolik Lake, officially establishing the Toolik Lake Field Station. Toolik Lake was also selected as the aquatic research site for the Research on Arctic Tundra Environments (RATE) project, which was supported by the National Science Foundation (NSF). After the RATE project came the Arctic Lake Process Study (ALPS), which studied controls over key ecosystem processes, and the Tests of Arctic Predictions (TAPS) project, which studied experimental manipulations of aquatic ecosystems. In the late 1970s, the Department of Energy (DOE) supported research into the effects of oil spills. Toolik Lake became a part of the Long-Term Ecological Research (LTER) program in 1987. Research that followed included studies on basic biology and biogeochemistry of Toolik Lake and surrounding lakes and ponds, nutrient cycles, trophic structure and food webs, and linkages between terrestrial and aquatic ecosystems. [3] [4] [16] [18] [19] [20]

The Toolik Field Station is operated and managed by the Institute of Arctic Biology at the University of Alaska Fairbanks (UAF). It is supported by the Division of Polar Programs, Directorate for Geosciences at the National Science Foundation (NSF). It is also a part of the Arctic Long-Term Research Program, which is located in the foothills of the Brooks Range and includes the Toolik Lake and upper Kuparuk River watersheds. Most ongoing research projects at Toolik are studying the effects of climate change on various ecosystem functions, such as trophic structure and food webs, nutrient exchange, and hydrological fluxes. [3] [4] [17]

The aquatic observation system (AOS) for Toolik Lake began sampling in November 2016. The aquatic instrumentation system (AIS) began streaming in November 2017. The surface water sampling strategy for D18 Toolik Lake is based on annual air temperature data collected from NOAA National Climatic Data Center (NCDC) and from the near-real time NEON data collected at the meteorological stations. Because Toolik Lake is ice-covered throughout part of the year, surface water samples can be taken on a semi-monthly basis combined with more intensive sampling around ice-on and ice-off, while organismal sampling is based on accumulation of growing degree days throughout the season.