 |
|
Oligotrophic Dimictic Lake |
 Printer Friendly Version (PDF) |
System: Lacustrine
SubSystem: Natural Lakes And Ponds State Protection: Not Listed Federal Protection: Not Listed State Rarity Rank: S3 
A State Rarity Rank of S3 means: Typically 21 to 100 occurrences, limited acreage, or miles of stream in New York State. Global Rarity Rank: G4
A Global Rarity Rank of G4 means: Apparently secure globally, though it may be quite rare in parts of its range, especially at the periphery. Did you know? Oligotrophic lakes are low in nutrients and primary production, rich in oxygen throughout, and have good water clarity. Dimictic lakes turn over twice a year, during the spring and the fall. This remixes dissolved oxygen and nutrients, needed by plants and animals in the lake. In the fall, the surface water becomes cooler and denser than the bottom waters. This cooler water sinks to the bottom, mixing the lake water. In the winter as temperatures drop further, ice forms on top of the lake and stops any further mixing. During the spring, the lake is heated by the sun and the cooler, less dense water floats to the top and the warmer, denser water extends to the bottom. As summer progresses, the temperature and density differences between upper and lower water layers become more distinct. These lakes generally become physically stratified into three identifiable layers in the summer and winter. |
||||
| State Ranking Justification | [-] |
There are several thousand occurrences statewide. Many documented occurrences have good viability and are protected on public land or private conservation land. This community has statewide distribution, and includes several high quality examples. The current trend of this community is probably stable for occurrences on public land, or declining slightly elsewhere due to moderate threats related to lakeshore development, invasive species, and atmospheric deposition.
| Short-term Trends | [-] |
The number and acres of oligotrophic dimictic lakes in New York have probably remained stable in recent decades as a result of local lake protection efforts and state wetland protection regulations. Atmospheric deposition of pollutants (e.g., acid rain and heavy metals) may diminish oligotrophic dimictic lakes, especially in the Adirondack Mountains.
| Long-term Trends | [-] |
The number and acres of oligotrophic dimictic lakes in New York are probably comparable to historical numbers, but the water quality of several of these lakes has likely declined significantly as a result of several human caused disturbances (e.g., atmospheric deposition, impoundments, nutrient and pollution run-off, invasive species, watershed development, etc.)
|
Home | Advanced Search | About Us Animal Guides | Plant Guides | Community Guides © 2004-2012 New York Natural Heritage Program, a partnership between the New York State Department of Environmental Conservation and the State University of New York College of Environmental Science and Forestry Please cite this page as:
New York Natural Heritage Program. 2013. Online Conservation Guide for Oligotrophic Dimictic Lake. Available from: http://acris.nynhp.org/guide.php?id=9880. Accessed May 25th, 2013. 
|