Long-Term Ecological Research (LTER)/NTL003: Plankton in North Temperate Lakes Primary Study Lakes

LTER - Long-Term Ecological Research Program/North Temperate Lakes (NTL)

LTER/NTL003 [Summary adapted from the LTER Core Data Set Catalog]:

Planktonic data include chlorophyll a, phytoplanktonic primary production, and zooplankton species abundance. These parameters are measured concurrently with physical limnology in the deepest part of each lake. Chlorophyll samples are collected from the seven primary study lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes and unnamed lakes 27-02, and 12-15) at two to 10 depths and analyzed spectrophotometrically. Primary production on three lakes (Crystal, Sparkling, Trout) is measured using C14 laboratory incubation under controlled temperature and light conditions. Zooplankton samples are collected from the seven primary lakes at two to nine depths using a 2 m long Schindler Patalas trap and with vertical tows using a Wisconsin net. Zooplankton samples are preserved in buffered formalin and archived. Data are summed over sex and stage and integrated volumetrically over the water column to provide an estimate of organisms per liter for each species. Phytoplankton samples are collected, stored in Lugol's, and archived.

Special Comments: These measurements are made concurrently with parameters listed in physical (NTL001) and chemical (NTL002) databases. Derived data sets containing epilimnetic averages and hypsometrically weighted averages over depths are also available for chlorophyll a and phaeopigment concentrations.

The North Temperate Lakes (NTL) site is affiliated with the Center for Limnology at the University of Wisconsin, Madison. The NTL site focuses its research on north temperate lake ecosystems in the Northern Highland Lakes District of Wisconsin. The Northern Highland Lakes District, has an area of approximately 10,000 sq. km. and has one of the highest concentrations of lakes in the world. Lakes range in size from 0.1 to 1,500 ha, in depth from 1 to 33 m, and in fertility from oligotrophic to eutrophic. Other representative limnological conditions include: rainwater dominated, groundwater dominated and drainage lakes; dystrophic lakes; lakes with varved sediments, winterkill lakes, temporary and permanent forest ponds, and reservoirs. Lakes are influenced by strong seasonality and are usually ice covered from late November to late April. Lakes within the Northern Highland exhibit near-natural water quality conditions. Nearly 80% of the land area and two-thirds of the lake frontage are protected.

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