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Daphnids - Keystone species for the pelagic food web structure and energy flow : a body size-related analysis linking seasonal changes at the populationand ecosystem levels

Daphnids - Keystone species for the pelagic food web structure and energy flow : a body size-related analysis linking seasonal changes at the populationand ecosystem levels

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GAEDKE, Ursula, Dietmar STRAILE, 1998. Daphnids - Keystone species for the pelagic food web structure and energy flow : a body size-related analysis linking seasonal changes at the populationand ecosystem levels. In: Advances in Limnology. 53, pp. 587-610

@article{Gaedke1998Daphn-7296, title={Daphnids - Keystone species for the pelagic food web structure and energy flow : a body size-related analysis linking seasonal changes at the populationand ecosystem levels}, year={1998}, volume={53}, journal={Advances in Limnology}, pages={587--610}, author={Gaedke, Ursula and Straile, Dietmar} }

<rdf:RDF xmlns:dcterms="http://purl.org/dc/terms/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:bibo="http://purl.org/ontology/bibo/" xmlns:dspace="http://digital-repositories.org/ontologies/dspace/0.1.0#" xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:void="http://rdfs.org/ns/void#" xmlns:xsd="http://www.w3.org/2001/XMLSchema#" > <rdf:Description rdf:about="https://kops.uni-konstanz.de/rdf/resource/123456789/7296"> <dcterms:isPartOf rdf:resource="https://kops.uni-konstanz.de/rdf/resource/123456789/28"/> <dcterms:rights rdf:resource="https://creativecommons.org/licenses/by-nc-nd/2.0/legalcode"/> <dc:format>application/pdf</dc:format> <dc:creator>Gaedke, Ursula</dc:creator> <dcterms:abstract xml:lang="eng">Seasonal changes of the impact of daphnids on the plankton biomass size distribution, the biomass within individual size ranges, the average predator-prey weight ratios, and the efficiency to transfer matter and energy from small to large organisms are analysed in large and deep Lake Constance based on comprehensive long-term observations. A comparison of daphnid biomass and production with those of other herbivorous groups (i.e., ciliates, rotifers, herbivorous crustaceans) reveals that in early spring daphnids play a minor role in relative and absolute values as compared to small fast-growing ciliates.During this time, small algae and ciliates dominate which gives rise to a decreasing Sheldon-type size spectrum, low predator-prey weight ratios, and alow transfer efficiency along the size gradient. Around June, daphnids reach maximum abundances and become keystone species for the shape of the biomass size distribution, the food web structure, and the energy flow. They accumulate biomass in their size range one order of magnitude above the average. The slope of the normalized biomass size spectrum is less negative and positively cor- related with daphnid biomass if the latter exceeds about 200 mgC/m2. This indicates a more efficient transfer along the size gradient with high predator- prey weight ratios and high trophic transfer efficiencies. The coefficients of determination of regression lines fitted to size distributions decrease with daphnid abundance, i.e., the size spectra become more irregular when daphnids dominate. In midsummer, daphnids lose their dominance and co-exist with other herbivores (especially ciliates) in a highly diverse plankton community. The latter gives rise to a relatively smooth and almost flat Sheldon-type size distribution, lower predator-prey weight ratios, and a slightly reduced transfer efficiency along the size gradient. In late spring/early summer, negative relationships are found between daphnid biomass and the biomasses in the size ranges of autotrophic picoplankton, small phytoplankton, heterotrophic flagellates, and small and medium-sized ciliates (0.06-32 pgC and 100-30,000 pgC). In mid- and late summer or on an annual average, hardly any of these relationships existed. This cannot solely be attributed to lower daphnid abundance, but points also to a more diverse control of small plankton organisms including nutrient limitation in summer. Ciliates influence the slope and shape of the size distribution much less than daphnids although they are at least of equal importance as daphnids in respect to herbivory and related fluxes in Lake Constance on an annual average. The findings on the impact of daphnids on the energy flow within the plankton food web derived from size distributions are compared to and are consistent with results obtained by mass-balanced carbon flow diagrams.</dcterms:abstract> <dc:contributor>Gaedke, Ursula</dc:contributor> <dspace:hasBitstream rdf:resource="https://kops.uni-konstanz.de/bitstream/123456789/7296/1/Daphnids_.pdf"/> <void:sparqlEndpoint rdf:resource="http://localhost/fuseki/dspace/sparql"/> <dcterms:title>Daphnids - Keystone species for the pelagic food web structure and energy flow : a body size-related analysis linking seasonal changes at the populationand ecosystem levels</dcterms:title> <dcterms:available rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-24T17:33:19Z</dcterms:available> <dcterms:bibliographicCitation>First publ. in: Advances in Limnology 53 (1998), pp. 587-610</dcterms:bibliographicCitation> <dcterms:issued>1998</dcterms:issued> <dspace:isPartOfCollection rdf:resource="https://kops.uni-konstanz.de/rdf/resource/123456789/28"/> <dc:creator>Straile, Dietmar</dc:creator> <dc:language>eng</dc:language> <bibo:uri rdf:resource="http://kops.uni-konstanz.de/handle/123456789/7296"/> <dcterms:hasPart rdf:resource="https://kops.uni-konstanz.de/bitstream/123456789/7296/1/Daphnids_.pdf"/> <dc:contributor>Straile, Dietmar</dc:contributor> <dc:rights>deposit-license</dc:rights> <foaf:homepage rdf:resource="http://localhost:8080/jspui"/> <dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-24T17:33:19Z</dc:date> </rdf:Description> </rdf:RDF>

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