from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The layer of water in a thermally stratified lake that lies below the thermocline, is noncirculating, and remains perpetually cold.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun geography the perpetually cold layer of water that lies beneath the thermocline of a thermally stratified lake


from The American Heritage® Dictionary of the English Language, 4th Edition

[hypo– + Greek limnē, lake, pool.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Ancient Greek ὑπο- (hypo-), combining form of ὑπό (hypó, "under") + λιμνίον (limnion), diminutive of λίμνη (limnē, "lake").


  • At the same time the bottom 20 calculated for each sampling station on each sampling date. m water temperatures increased by about 0. 3°C throughout In the remainder of this study, the term hypolimnion refers the strati fi ed season, indicating a small, steady downward to the 20-m layer above the bottom (Fig. 3). transfer of heat (Fig. 4).

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  • This is likely to lower oxygen concentrations in the hypolimnion and increase stress on cold-water organisms [36].

    Effects of climate change on general hydro-ecology in the Arctic

  • Lake populations needing to avoid temperature extremes are very likely to be confined to the hypolimnion during the warmest months provided anoxic conditions do not develop.

    Climate change effects on arctic freshwater fish populations

  • This mesotrophic area of the lake has a narrow hypolimnion that is often deficient of oxygen.

    Lake Erie, Ontario

  • The lake's water is permanently stratified, having a warm epilimnion overlying a cooler hypolimnion and is remarkably clear.

    Lake Malawi National Park, Malawi

  • In addition, the prolonged thermal stratification that is likely to accompany rising temperatures could possibly lead to lower oxygen concentrations and increased phosphorus concentrations in the hypolimnion, benefiting nutrient-limited primary production.

    Effects of climate change on general hydro-ecology in the Arctic

  • In eutrophic lakes that are stratified, concentrations of N2 may decline in the epilimnion because of reduced solubility as temperatures rise and increase in the hypolimnion from denitrification of nitrate (NO3) to nitrite (NO2) to inorganic nitrogen (N2).

    Chemical properties of lakes

  • Nitrite (NO2) rarely accumulates except in the metalimnion and hypolimnion of eutrophic lakes.

    Chemical properties of lakes

  • In oligotrophic lakes, high oxygen concentrations permit metabolism of ammonia to nitrate, resulting in low levels of nitrite and ammonia and high levels of nitrate in the hypolimnion.

    Chemical properties of lakes

  • The oxygen content of the hypolimnion is higher than that of the epilimnion because the saturated colder water from spring turnover experiences limited oxygen consumption.

    Chemical properties of lakes


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  • In a stratified lake, the cooler layer of water below the thermocline.

    April 6, 2008