Mesotrophic lakes have moderate levels of nutrients; they are intermediate in richness between eutrophic and oligotrophic lakes. 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.
There are several hundred occurrences statewide and currently includes bays and coves of larger lakes, such as Lake Champlain. Few occurrences are presumed to have good viability and are protected on public land or private conservation land. This community has statewide distribution, and includes several large, 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.
The numbers and acreage of mesotrophic dimictic lakes in New York have probably remained stable in recent decades as a result of wetland protection regulations. However, the condition of some of these lakes may have declined slightly to moderately due to the spread of invasive aquatic species. There may be a few cases of slight decline due to alteration of hydrology (e.g., ditching and impoundments) and reduced water quality from nutrient input from surrounding developed uplands.
The numbers and acreage of eutrophic dimictic lakes in New York have probably remained stable in recent decades as a result of wetland protection regulations. However, the condition of some of these lakes may have declined slightly to moderately due to the spread of invasive aquatic species. There may be a few cases of slight decline due to alteration of hydrology (e.g., ditching and impoundments) and reduced water quality from nutrient input from surrounding developed uplands.
Where practical, establish and maintain a lakeshore buffer to reduce storm-water, pollution, and nutrient run-off, while simultaneously capturing sediments before they reach the lake. Buffer width should take into account the erodibility of the surrounding soils, slope steepness, and current land use. If possible, minimize the number and size of impervious surfaces in the surrounding landscape. Avoid habitat alteration within the lake and surrounding landscape. For example, roads should not be routed through the lakeshore buffer area. If a lake must be crossed, then bridges and boardwalks are preferred over filling and culverts. Restore lakes that have been affected by unnatural disturbance (e.g., remove obsolete impoundments and ditches in order to restore the natural hydrology). Prevent the spread of invasive exotic species into the lake through appropriate direct management, and by minimizing potential dispersal corridors.
Mesorophic dimictic lakes are threatened by shoreline development and its associated run-off (e.g., residential, commercial, agricultural, and roads), recreational overuse (e.g., powerboats, intensive fish stocking and removal), and habitat alteration in the adjacent landscape (e.g., excessive land clearing, pollution run-off, and increased impervious surfaces within the watershed). Many of these lakes are threatened by the spread of aquatic invasive species, such as alewife (Alosa pseudoharengus), fishhook waterflea (Cercopagis pengoi), common carp (Cyprinus carpio), Asian clam (Corbicula fluminea), zebra mussel (Dreissena polymorpha), scud (Echinogammarus ischnus), green sunfish (Lepomis cyanellus), Eurasian watermilfoil (Myriophyllum spicatum), brittle naiad (Najas minor), starry stonewort (Nitellopsis obtusa), curly leafed pondweed (Potamogeton crispus), rudd (Scardinius erythrophthalmus), and water chestnut (Trapa natans).
Where practical, establish and maintain a lakeshore buffer to reduce storm-water, pollution, and nutrient run-off, while simultaneously capturing sediments before they reach the lake. Buffer width should take into account the erodibility of the surrounding soils, slope steepness, and current land use. If possible, minimize the number and size of impervious surfaces in the surrounding landscape. Avoid habitat alteration within the lake and surrounding landscape. For example, roads should not be routed through the lakeshore buffer area. If a lake must be crossed, then bridges and boardwalks are preferred over filling and culverts. Restore lakes that have been affected by unnatural disturbance (e.g., remove obsolete impoundments and ditches in order to restore the natural hydrology). Prevent the spread of invasive exotic species into the lake through appropriate direct management, and by minimizing potential dispersal corridors.
When considering road construction and other development activities, minimize actions that will change what water carries and how water travels to this lake community, both on the surface and underground. Water traveling over-the-ground as run-off usually carries an abundance of silt, clay, and other particulates during (and often after) a construction project. While still suspended in the water, these particulates make it difficult for aquatic animals to find food; after settling to the bottom of the lake, these particulates bury small plants and animals and alter the natural functions of the community in many other ways. Thus, road construction and development activities near this lake type should strive to minimize particulate-laden run-off into this community. Water traveling on the ground or seeping through the ground also carries dissolved minerals and chemicals. Road salt, for example, is becoming an increasing problem both to natural communities and as a contaminant in household wells. Fertilizers, detergents, and other chemicals that increase the nutrient levels in lakes cause algae blooms and eventually an oxygen-depleted environment where few animals can live. Herbicides and pesticides often travel far from where they are applied and have lasting effects on the quality of the natural community. So, road construction and other development activities should strive to consider: 1. how water moves through the ground, 2. the types of dissolved substances these development activities may release, and 3. how to minimize the potential for these dissolved substances to reach this natural community.
Survey for occurrences statewide to advance documentation and classification of mesotrophic dimictic lakes. A statewide review of mesotrophic dimictic lakes is desirable. Continue searching for large lakes in good condition (A- to AB-ranked). Review and incorporate data on occurrences in NY gathered by the Adirondack Lakes Survey Corporation, the Adirondack Park Invasive Plant Program, and the New York State Federation of Lake Associations, Inc.
There is a need to research the composition of mesotrophic dimictic lakes statewide in order to characterize variations. Continued research is needed on the impacts that atmospheric deposition has on this community. Research is needed to inform the classification of the mesophic bays and coves along the margins of larger summer-stratified monomictic lakes lakes (e.g., King Bay and Monty Bay in Lake Champlain).
This community is widespread throughout New York State, and includes the following lakes: Hemlock Lake, Livingston and Ontario Counties; Canadice Lake, Ontario County; Conesus Lake, Livingston County; Otisco Lake, Onondaga County; Lower St. Regis Lake, Franklin County; Rich Lake, Essex County; Yellow Lake, St. Lawrence County.
This broadly-defined community may be worldwide. Examples with the greatest biotic affinities to New York occurrences are suspected to span north to southern Canada, west to Minnesota, southwest to Indiana and Tennessee, and southeast to North Carolina.
The aquatic community of a lake that is intermediate between an oligotrophic lake and a eutrophic lake. These lakes are dimictic: they have two periods of mixing or turnover (spring and fall), they are thermally stratified in the summer (warmest water at the surface), and they freeze over and become inversely stratified in the winter (coldest water at the surface). Profundal and pelagic species assemblages are usually well developed. Characteristic fishes are mostly warmwater fishes, such as yellow perch (Perca flavescens), largemouth bass (Micropterus salmoides), northern pike (Esox lucius), bluegill (Lepomis macrochirus), and pumpkinseed (Lepomis gibbosus). Smallmouth bass (Micropterus dolomieui) is a characteristic cool water fish in these lakes. Characteristic invertebrates may include pea clams (Pisidium spp.) and mayflies (Hexagenia spp.). These lakes typically have a diverse mixture of submerged macrophytes, such as several species of pondweeds (Potamogeton amplifolius, P. praelongus, P. robbinsii), water celery or tape grass (Vallisneria americana), and bladderworts (Utricularia spp.). Characteristic plankton may include the phytoplankton Asterionella and the zooplankton Daphnia dubia. More data on this community are needed. This community may occur as a single lake basin, or part of a larger lake type. Relatively shallow, mesotrophic bays and coves of large, deep summer-stratified monomictic lakes are included under this type (e.g., King Bay and Monty Bay in Lake Champlain).
Characteristic features of a mesotrophic lake include the following: water with medium transparency (Secchi disk depths of 2 to 4 m); water with moderate amounts of plant nutrients; moderate primary productivity (inorganic carbon fixed = 25 to 75 g/m2/yr); lake sediments with moderate amounts of organic matter; and moderately well-oxygenated water. Alkalinity is typically moderate (slightly greater than 12.5 mg/l calcium carbonate). These lakes typically have a diverse mixture of submerged macrophytes, such as several species of pondweeds (Potamogeton amplifolius, P. praelongus, P. robbinsii), water celery or tape grass (Vallisneria americana), and bladderworts (Utricularia spp.).
Known examples of this community have been found at elevations between 80 feet and 1,567 feet.
Mesotrophic dimictic lakes can be easily observed from the shoreline where there is public access, or by boat in mid- to late summer when fragrant white water lily and spatter dock are in bloom in the shallow areas.
Percent cover
This figure helps visualize the structure and "look" or "feel" of a typical Mesotrophic Dimictic Lake. Each bar represents the amount of "coverage" for all the species growing at that height. Because layers overlap (shrubs may grow under trees, for example), the shaded regions can add up to more than 100%.
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Cole, G.A. 1979. Textbook of limnology. The C.V. Mosby Co., Saint Louis, MO.
Edinger, G. J., D. J. Evans, S. Gebauer, T. G. Howard, D. M. Hunt, and A. M. Olivero (editors). 2014. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke’s Ecological Communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation, Albany, NY. https://www.nynhp.org/ecological-communities/
Maitland, P.S. 1978. Biology of fresh waters. John Wiley, and Sons, New York.
New York Natural Heritage Program. 2023. New York Natural Heritage Program Databases. Albany, NY.
Nichols, W. F. 2015. Natural Freshwater Lakes and Ponds in New Hampshire: Draft Classification. NH Natural Heritage Bureau, Concord, NH.
Olivero-Sheldon, A. and M.G. Anderson. 2016. Northeast Lake and Pond Classification. The Nature Conservancy, Eastern Conservation Science, Eastern Regional Office. Boston, MA.
Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.
This guide was authored by: Gregory J. Edinger
Information for this guide was last updated on: June 3, 2021
Please cite this page as:
New York Natural Heritage Program. 2023.
Online Conservation Guide for
Mesotrophic dimictic lake.
Available from: https://guides.nynhp.org/mesotrophic-dimictic-lake/.
Accessed October 3, 2023.