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The feeding biology of invasive predatory cladocerans
Stockholm University, Faculty of Science, Department of Systems Ecology.
Manuscript (Other academic)
URN: urn:nbn:se:su:diva-25729OAI: diva2:200385
Part of urn:nbn:se:su:diva-8506Available from: 2009-02-19 Created: 2009-02-11 Last updated: 2010-01-13Bibliographically approved
In thesis
1. Non-indigenous zooplankton: the role of predatory cladocerans and of copepods in trophic dynamics
Open this publication in new window or tab >>Non-indigenous zooplankton: the role of predatory cladocerans and of copepods in trophic dynamics
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Human-mediated introductions of non-indigenous species now threaten to homogenize the biota of the Globe, causing huge economic and ecological damage. This thesis studies the ecological role of 3 invasive planktonic crustaceans, the omnivorous copepod Acartia tonsa (western Atlantic and Indo-Pacific) and the predatory cladocerans, Cercopagis pengoi (Ponto-Caspian) and Bythotrephes longimanus (Eurasian). B. longimanus invaded the North American Great Lakes in 1982, C. pengoi the Baltic in 1992 and the Great Lakes in 1999, while A. tonsa has an extensive invasion history that includes the Baltic.

We review current knowledge on feeding biology of the predatory cladocerans. A study of stable C and N isotope ratios indicated mesozooplankton as the main food source of C. pengoi in the northern Baltic Sea proper, with young C. pengoi also eating microzooplankton, such as rotifers. Young-of-the-year herring did eat C. pengoi and herring trophic position shifted from 2.6 before the invasion to 3.4 after, indicating that C. pengoi had been “sandwiched” into the modified food web between mesozooplankton and fish.

Salinity tolerance experiments on Acartia tonsa and co-occurring Acartia clausi showed the formers euryhaline character and high grazing potential. Energy partitioning between ingestion, production and respiration was rather constant over the tested salinity range of 2 to 33, with small differences in gross growth efficiency and cost of growth, but maximum ingestion at 10-20. Egg hatching in A. tonsa was only reduced at the lowest salinity. Extreme changes in salinity were needed to cause significant mortality of A. tonsa in the field, but its feeding activity could be severely reduced by salinity changes likely to occur in estuaries. A study of a hypertrophic estuary showed that A. tonsa can sustain a population despite very high mortality rates, caused by predation, high pH and low oxygen, helping explain the success of A. tonsa as an invader of estuaries.

Place, publisher, year, edition, pages
Stockholm: Systemekologiska institutionen, 2009. 53 p.
Acartia tonsa, Bythotrephes longimanus, Cercopagis pengoi, egg production, fitness, food web changes, ingestion rates, invasive species, metabolic balance, mortality, non-indigenous zooplankton, predation impact, salinity tolerance, stable isotopes
National Category
Research subject
Marine Ecology
urn:nbn:se:su:diva-8506 (URN)978-91-7155-822-0 (ISBN)
Public defence
2009-03-13, sal G, Arrheniuslaboratorierna, Svante Arrhenius väg 14-18, Stockholm, 13:00
Available from: 2009-02-19 Created: 2009-02-11Bibliographically approved

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