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The impact of cormo...
The impact of cormorant nesting colonies on plants and arthropods
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- Kolb, Gundula S., 1978- (författare)
- Stockholms universitet,Botaniska institutionen,Plant ecology
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- Hambäck, Peter, Professor (preses)
- Stockholms universitet,Botaniska institutionen
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- Jerling, Lenn, Professor (preses)
- Stockholms universitet,Botaniska institutionen
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- David, Post, Associate Professor (opponent)
- Yale University, Center for Field Ecology
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(creator_code:org_t)
- ISBN 9789174471472
- Stockholm : Department of Botany, Stockholm University, 2010
- Engelska 80 s.
- Relaterad länk:
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Abstract
Ämnesord
Stäng
- Seabirds concentrate large amounts of marine nutrients on their nesting islands. This nutrient input can have large consequences for island food webs and community structure. The high nutrient load may also cause runoff into surrounding waters and affect marine communities. In my thesis, I studied the effect of cormorant nesting colonies on the stoichiometry, abundance, species richness, and species composition of plants, algae, and invertebrates on land and in costal waters and investigated if differences in the elemental composition or homeostasis can explain differences in the numerical response among invertebrate groups. δ15N analysis indicated that ornithogenic nitrogen provided a significant nitrogen source for plants and arthropods on nesting islands and around high nest density islands also for brackish algae and invertebrates. Furthermore, nutrient runoff created a potential feed-back loop to spiders via chironomids. Cormorant nutrient input changed island vegetation and increased plant P and N content and epiphytic algae:Fucus ratio, but decreased plant species richness and vegetation cover. Invertebrates responded indirectly to these qualitative and quantitative changes in their food source and habitat, but also directly to cormorant subsidies. However not all taxonomic and feeding groups were affected and responses were both positive and negative. Differences in the numerical response among taxonomic groups could not be explained by differences in the level of homeostasis, since, generally, all invertebrates were strongly homeostatic. Similarly, consumer nutrient content was a poor predictor for displayed responses. I conclude that cormorant colonies have strong impacts on island vegetation and some consumer groups. However, even if they can decrease the species richness of some organism groups on their nesting islands, they increase the habitat heterogeneity in an archipelago and thus may increase the regional species diversity.
Ämnesord
- NATURVETENSKAP -- Biologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences (hsv//eng)
Nyckelord
- seabirds
- cormorants
- islands
- nitrogen
- phosphorus
- plants
- arthropods
- δ15N
- Baltic Sea
- ecological stoichiometry
- species richness
- species composition
- numeric response
- Biology
- Biologi
- Plant Ecology
- växtekologi
Publikations- och innehållstyp
- vet (ämneskategori)
- dok (ämneskategori)
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