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Langmuir circulations disturb the low‐oxygen refuge of phantom midge larvae
Author(s) -
Malinen Tommi,
Horppila Jukka,
Liljendahl-Nurminen Anne
Publication year - 2001
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2001.46.3.0689
Subject(s) - epilimnion , smelt , upwelling , thermocline , midge , oceanography , environmental science , eutrophication , ecology , biology , fishery , fish <actinopterygii> , larva , hypolimnion , geology , nutrient
The previously unknown effects of wind‐induced Langmuir circulations on the distribution of phantom midge larvae ( Chaoborus flavicans ) were studied by echosounding. The study was carried out in the eutrophic Lake Hiidenvesi, where chaoborids use a metalimnetic oxygen minimum as a daytime refuge against fish predation. At a wind velocity of 8—9 m s −1 , the upwelling water circulations snatched clouds of chaoborids from the metalimnion (12‐15 m depth) to the more oxygenated epilimnion. The average density of C. flavicans in the clouds was 790 ind. m −2 , whereas, elsewhere in the epilimnion, it was 380 ind. m −2 . Planktivorous fish (smelt Osmerus eperlanus ) were actively aggregated in the upwellings. When the wind velocity decreased to 3 m s −1 , chaoborids disappeared from the epilimnion. The results suggest that Langmuir circulations may affect the abundance of chaoborids by disturbing their low‐oxygen refuges.