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Long‐term signal of population disturbance after pulse exposure to an insecticide: Rapid recovery of abundance, persistent alteration of structure
Author(s) -
Liess Matthias,
Pieters Barry Johan,
Duquesne Sabine
Publication year - 2006
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/05-466r.1
Subject(s) - population , abundance (ecology) , biology , reproduction , population density , daphnia magna , fecundity , toxicology , zoology , ecology , toxicity , chemistry , medicine , environmental health , organic chemistry
Little is known about the effect of pulse exposure to toxicants on populations when density regulation is present. Yet, for a more realistic risk assessment, it is necessary to include effect and recovery at the population level. Here, we investigate the long‐term and delayed effects as well as the subsequent recovery of populations of Daphnia magna. A 24‐h pulse of the pyrethroid fenvalerate reduced the abundance at a concentration of 1.0 μg/L and higher. However, abundance recovered and reached control levels after one to two generation times (GTs) following reproduction of surviving individuals (GT = 8 d, from birth until first reproduction). At high concentrations above the acute median lethal concentration (3.2 μg/L), abundance initially decreased even more strongly but was then elevated compared to control values for an extended period of time. Population structure (size distribution) was affected at lower concentrations than abundance (≥0.8 μg/L). In addition, the alteration of population structure lasted for a long time, so that control levels were approached only after approximately six or seven GTs. Our results show that pulse exposure to toxicants may lead to a long‐term alteration of population structure even at sublethal concentrations. Possible mechanisms that sustain the effects of toxicants may be delayed life‐history effects on the individual level and elevated competition because of altered population structure on the population level.