Changes in lichen diversity and community structure with fur seal population increase on Signy Island, South Orkney Islands

Signy Island has experienced a dramatic increase in fur seal numbers over recent decades, which has led to the devastation of lowland terrestrial vegetation, with the eradication of moss turfs and carpets being the most prominent feature. Here we demonstrate that fur seals also affect the other majo...

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Bibliographic Details
Published in:Antarctic science 2011-02, Vol.23 (1), p.65-77
Main Authors: FAVERO-LONGO, Sergio E, CANNONE, Nicoletta, WORLAND, M. Roger, CONVEY, Peter, PIERVITTORI, Rosanna, GUGLIELMIN, Mauro
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Aquatic birds
Aquatic mammals
Aquatic plants
Biological and medical sciences
Community structure
Fundamental and applied biological sciences. Psychology
Lichenes
Lichens
Marine
Multivariate analysis
Ordination
Particular ecosystems
Plant cytology, morphology, systematics, chorology and evolution
Seals
Soil chemistry
Surface temperature
Synecology
Thallophyta
Trampling
Vegetation
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Summary:Signy Island has experienced a dramatic increase in fur seal numbers over recent decades, which has led to the devastation of lowland terrestrial vegetation, with the eradication of moss turfs and carpets being the most prominent feature. Here we demonstrate that fur seals also affect the other major component of this region’s typical cryptogamic vegetation, the lichens, although with a lower decrease in variability and abundance than for bryophytes. Classification (UPGMA) and ordination (Principal Coordinate Analysis) of vegetation data highlight differences in composition and abundance of lichen communities between areas invaded by fur seals and contiguous areas protected from these animals. Multivariate analysis relating lichen communities to environmental parameters, including animal abundance and soil chemistry (Canonical Correspondence Analysis), suggests that fur seal trampling results in the destruction of muscicolous-terricolous lichens, including several cosmopolitan and bipolar fruticose species. In addition, animal excretion favours an increase in nitrophilous crustose species, a group which typically characterizes areas influenced by seabirds and includes several Antarctic endemics. The potential effect of such animal-driven changes in vegetation on the fragile terrestrial ecosystem (e.g. through modification of the ground surface temperature) confirms the importance of indirect environmental processes in Antarctica.
ISSN:0954-1020
1365-2079
DOI:10.1017/S0954102010000684