Coleópteros acuáticos de los estanys de Capmany (Girona):Hydradephaga

  1. J. Isart
  2. I. Ribera
  3. J. A. Régil
Scientia gerundensis

ISSN: 2385-4758 0213-5930

Year of publication: 1994

Issue: 20

Pages: 17-34

Type: Article

More publications in: Scientia gerundensis


The Capmany fens are two medium-sized temporary ponds associated with which are some artificial habitats. They fill with rain water on an irregular cycle. The Hydradephaga of five habitats are studied in detail over one complete cycle lasting two years. Forty-nine species have been found, one of them new for the iberian Peninsula [Hydaticu seminiger (DeGeer, 1774)l. Study of the variation in nurnber of species and of the relative abundance of individual populations indicates that there are two cycles: an irregular, external and unpredictable cycle, caused by variations in the amount of rain, being superimposed on a regular, internal and predictable cycle, associated with the natural life cycles of the species. When this two cycles are in phase, there is a large increase in the number of individuals. The diversity within different habitats is more constant, being almost the same all the year around during the whole of the cycle. The Hydradephaga are adapted to use the irregular pulse of mass production typical of these kind of temporary, immature habitats. There are two different strategies among the resident species. One group lives exclusively in the fens, has their maximum density of adults at the beginning of the cycle, and reproduces after this maximum. When the fen dries, they disappear, probably as drought resistant forms, till the next wet episode. These can be considered species typical of big temporary habitats. The second group are present in all the habitats of the area, including the artificial ones. When the fens are filled some adults colonize them, reproduce and reach the maximum density when the fens are beginning to dry. The adults then concentrate in the remaining water bodies and in the artificial habitats, and then disperse or disappear, keeping only residual populations unti1 the next wet episode. They can be considered opportunistic species