Are populations of Gammarus fossarum able to reflect stream drying?
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| Year of publication | 2019 |
| Type | Appeared in Conference without Proceedings |
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| Description | Stream intermittency is one of the typical consequences of climate change with longterm effects on aquatic biota. Dry episodes are becoming more frequent in the Czech Republic. Especially during supra-seasonal drought, they can completely change a population structure of permanent fauna. Gammarus fossarum is key taxa (ecosystem engineer), strongly affected by stream intermittency. Mostly because it inhabits small, often drying streams across the whole Czech Republic and lacks any drought-resistant stages. We compared its population structure (sex ratio and size distribution) on 12 pairs of intermittent and perennial streams during 2012-2016. Populations from intermittent streams after the dry period had a higher proportion of larger males and a lower proportion of juveniles in comparison to populations of neighboring perennial streams. This result supports a hypothesis, suggesting a higher male recolonization ability resulting from their larger body size which enables higher mobility in comparison to smaller females andjuveniles. Fecundity analyses of the same species in residual pools persisting in otherwise dry riverbed of intermittent streams showed a lower proportion of breeding females in residual pools than in comparable nearby perennial streams. This difference can be explained by an increase in predation of overcrowded refuge pools or overall stress in this highly unstable habitat, leading to possible egg loss, indicating a limited possibility of rapid population recovery from residual pools after flow resumption. Our study confirms that alterations in the population structure of Gammarus fossarum could indicate an impact of previous dry episodes on small streams of Central Europe. |
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