Rain-pools on peat moorland as island habitats for midge larvae
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Abstract
A common aquatic habitat on peat moorland is a pool, often only a few centimetres deep. Many have a shorter average duration than that of the inhabitants but they are, nonetheless, inhabited by the larval stages of several chironomid species at moderately high densities. Because of their durational characteristics, these pools might be expected to have an endemic fauna, as is the case in similar ephemeral island habitats elsewhere. However, we find no such fauna. Indeed, we find no qualitative difference between them and permanent pools of the same substratum.
We identify three reasons for the apparent absence of endemism. First, the midge fauna is able to survive dry periods in the moist mud, so that even the smallest pools are effectively permanent from the adaptive point of view. Second, although seasonal freezing eliminates the fauna of smaller pools, larvae are able to complete their development in the preceding summer. Third, nearby permanent pools which do not dry and in which the mud does not freeze, may act as refugia for re-invasion.
Key words
temporary habitats peat pools habitat islands chironomids condensed running head: temporary pools on peatPreview
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