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The seasonal dynamics and distribution of Chaoborus flavicans larvae in adjacent lake basins of different morphometry and degree of eutrophication
Author(s) -
LILJENDAHLNURMINEN ANNE,
HORPPILA JUKKA,
ELORANTA PERTTI,
MALINEN TOMMI,
UUSITALO LAURA
Publication year - 2002
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1046/j.1365-2427.2002.00867.x
Subject(s) - limnetic zone , benthic zone , eutrophication , population density , ecology , population , spatial distribution , chironomidae , environmental science , profundal zone , larva , biology , oceanography , geography , geology , littoral zone , nutrient , demography , remote sensing , sociology
1. Seasonal dynamics, spatial distribution and population size of the phantom midge Chaoborus flavicans in different parts of the eutrophic Lake Hiidenvesi (30.3 km 2 ) were studied. 2. Density of larvae was low in the shallow, most eutrophic parts of the lake, while the deep Kiihkelyksenselkä basin was inhabited by a dense population. In the deepest part of Kiihkelyksenselkä (33 m) density was 13 989 ± 3542 m –2 in May, declined to 1102 ± 274 m –2 in July and recovered to 7225 ± 1314 m –2 by October. In spring and autumn the majority of larvae were benthic while, during high summer, few larvae were found in the sediment. 3. Horizontal distribution fluctuated seasonally. On 3 June < 5% of the population inhabited areas shallower than 10 m. On 6 July the limnetic fraction was still restricted to regions deeper than 10 m, but 43% of benthic larvae were found between 6 and 10 m depths. In October both limnetic and benthic larvae were concentrated in areas deeper than 20 m. 4. Within the lake, distribution was mainly regulated by stratification characteristics, degree of eutrophy being less important. The seasonal horizontal movements were probably induced by food shortage. Larvae could not meet their energetic demands in stratified areas and dispersed to shallower water, reducing predation risk by use of the benthic habitat.