TY - JOUR
T1 - The impact of a small, alien invertebrate on a sub-Antarctic terrestrial ecosystem
T2 - Limnophyes minimus (Diptera, Chironomidae) at Marion Island
AU - Hänel, C.
AU - Chown, S. L.
PY - 1998/1/1
Y1 - 1998/1/1
N2 - Density and biomass of the larvae of a small, alien chironomid midge, Limnophyes minimus, whose parthenogenetic adult females do not feed, were quantified for ten major lowland plant communities at sub-Antarctic Marion Island (46°52'S 37°51'E) and compared with the density and biomass of indigenous macro-invertebrates in the same communities. An estimate of litter consumption by larvae of this midge was also made. L. minimus reached high densities in most of the plant communities sampled, with the highest density being recorded in the Cotula plumosa biotically influenced community (annual mean of 4,365 individuals m-2) and the lowest in the Crassula moschata salt spray community (annual mean of 41 individuals m-2). Estimates of litter ingestion indicated that L. minimus larvae are capable of consuming between 0.07 and 8.54 g((dry mass)) m-2 per year, depending on the community. In some communities this litter consumption amounted to an order of magnitude more than that consumed by Pringleophaga marioni (Lepidoptera, Tineidae). Although the larvae of this moth species are thought to represent the bottleneck to nutrient recycling on the island, this study showed that midge larvae may also contribute substantially to this process. As a consequence, the considerable changes that have been predicted to occur in Marion Island's terrestrial ecosystem as a consequence of enhanced predation by mice on P. marioni larvae may be retarded or obscured by the contribution of the midge larvae to nutrient cycling. Hence, it is suggested that greater attention be given to the small and inconspicuous elements of the alien sub-Antarctic faunas because such species may have profound consequences for ecosystem functioning on these islands.
AB - Density and biomass of the larvae of a small, alien chironomid midge, Limnophyes minimus, whose parthenogenetic adult females do not feed, were quantified for ten major lowland plant communities at sub-Antarctic Marion Island (46°52'S 37°51'E) and compared with the density and biomass of indigenous macro-invertebrates in the same communities. An estimate of litter consumption by larvae of this midge was also made. L. minimus reached high densities in most of the plant communities sampled, with the highest density being recorded in the Cotula plumosa biotically influenced community (annual mean of 4,365 individuals m-2) and the lowest in the Crassula moschata salt spray community (annual mean of 41 individuals m-2). Estimates of litter ingestion indicated that L. minimus larvae are capable of consuming between 0.07 and 8.54 g((dry mass)) m-2 per year, depending on the community. In some communities this litter consumption amounted to an order of magnitude more than that consumed by Pringleophaga marioni (Lepidoptera, Tineidae). Although the larvae of this moth species are thought to represent the bottleneck to nutrient recycling on the island, this study showed that midge larvae may also contribute substantially to this process. As a consequence, the considerable changes that have been predicted to occur in Marion Island's terrestrial ecosystem as a consequence of enhanced predation by mice on P. marioni larvae may be retarded or obscured by the contribution of the midge larvae to nutrient cycling. Hence, it is suggested that greater attention be given to the small and inconspicuous elements of the alien sub-Antarctic faunas because such species may have profound consequences for ecosystem functioning on these islands.
UR - http://www.scopus.com/inward/record.url?scp=0031880666&partnerID=8YFLogxK
U2 - 10.1007/s003000050282
DO - 10.1007/s003000050282
M3 - Article
AN - SCOPUS:0031880666
VL - 20
SP - 99
EP - 106
JO - Polar Biology
JF - Polar Biology
SN - 0722-4060
IS - 2
ER -