Sphagnum mosses as a microhabitat for invertebrates in acidified lakes and the colour adaptation and substrate preference in Leucorrhinia dubia (Odonata, Anisoptera)

Abstract

BHtt-Inger HenriksonHennkson, B -I 1993 Sphagnum mosses as a microhabitat for invertebrates in acidified lakes and the colour adaptation and substrate preference in Leucorrhinia dubia (Odonata, Anisoptera) -Ecography 16 143-153The increase of peat mosses. Sphagnum spp , in acidified lakes leads to a changed microhabitat structure for benthic invertebrates The importance of this change was investigated for some benthic invertebrates Comparisons between quantitative samples of Sphagnum and debris within the acidified Lake Stora Hastevatten, m the Lake Gardsjon catchment of SW Sweden, showed significantly higher abundances of Chironomidae, Ceratopogonidae, Odonata, Trichoptera, Cladocera and Argyroneta aquatica (Araneae) in Sphagnum For Chironomidae and Cladocera the differences were tenfold Special reference was made to the libellulid Leucorrhinia dubia which is common in acid lakes In a laboratory test, late lnstar larvae of L dubia were shown to be able to change colour to correspond to the brown and green colour of Sphagnum This result was completed with a field test where larvae of L dubia were significantly more common in Sphagnum of the same colour as the larvae The ability to change colour may have an adaptive value when coexisting with visual predators Small larvae, 4-5 mm, were significantly more prevalent in Sphagnum and they also showed significant preference for this substrate in the laboratory test For mediumsized larvae, 12-14 mm, a tendency to prefer Sphagnum was found in the laboratory test Larvae of L dubia were shown to be more successful as predators on Asellus aquaticus in Sphagnum substrate than in debris in the laboratory test Laboratory predation tests with Notonecta glauca, Corixa dentipes, Acilius sulcatus, Hyphydrus ovatus and L dubia showed that they could all feed on larvae of L dubia The complex habitat structure of Sphagnum is probably the reason for the high abundance of invertebrates since it may serve as both shelter against predation and as foraging sites It is probably important as a key habitat for young instars of, for example, L dubia In lakes with large Sphagnum mats, L dubia can coexist with fish The expansion of Sphagnum due to acidification will probably benefit many acidtolerant invertebrate species B -I Henrikson,

Vertical Micro‐Zonation of Testate Amoebae and Ciliates in Peatland Waters in Relation to Potential Food Resources and Grazing Pressure

“…So in case of hollows the bottom water zone dominated by Sphagnum may create a refuge for both testate amoebae and ciliates. Similar results were obtained by HENRIKSON (1993), who also found that the complex habitat structure of Sphagnum influences the increase in the abundance of invertebrates. He also suggested that the heterogenic architecture of a moss mat serves the inhabiting organisms as both shelter against predation and as foraging sites.…”

Ecological status of shallow Lake Gorbacz (NE Poland) in its final stage before drying up

“…dm -3 ) and it was nearly three times higher than the count of Crustacea in the water body. Similar results were observed by Henrikson (1993), who stated that Sphagnum microhabitats have an influence on the Table 4 Percentage species similarity of Rotifer communities from 5 sites located along the transect running from the lake shore to the end of the Sphagnum bog. increase of the number of invertebrates, even ten times in the case of Cladocera.…”

Appropriate experimental design to evaluate preferences for microhabitat: an example of preferences by species of microgastropods

“…Such experiments usually use a "choice chamber" into which individuals are released to move freely among different types of microhabitat (e.g. Barnes and Greenwood 1978;Carefoot 1979;Morton 1980;Johns and Mann 1987;Durante and Chia 1991;Henrikson 1993;Herler et al 1999;Jones and Boulding 1999).…”