Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Stable isotopes show food web changes after invasion by the predatory cladoceran Cercopagis pengoi in a Baltic Sea bay
Stockholm University, Faculty of Science, Department of Systems Ecology.
Stockholm University, Faculty of Science, Department of Systems Ecology.
Stockholm University, Faculty of Science, Department of Systems Ecology.
Stockholm University, Faculty of Science, Department of Systems Ecology.
2005 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 143, no 2, 251-259 p.Article in journal (Refereed) Published
Abstract [en]

Cercopagis pengoi, a recent invader to the Baltic Sea and the Laurentian Great Lakes, is a potential competitor with fish for zooplankton prey. We used stable C and N isotope ratios to elucidate trophic relationships between C. pengoi, zooplankton (microzooplankton, 90–200 m, mostly copepod nauplii and rotifers; mesozooplankton, >200 m, mostly copepods), and zooplanktivorous fish (herring, size range 5–15 cm and sprat, 9–11 cm) in a coastal area of the northern Baltic Sea. The isotope ratios in C. pengoi and fish were much higher than those of zooplankton, showing general trends of enrichment with trophic level. Young-of-the-year (YOY) herring had a significantly higher 15N/14N ratio than C. pengoi, suggesting of a trophic linkage between the two species. To evaluate the possible relative importance of different food sources for C. pengoi and YOY herring, two-source isotope-mixing models for N were used, with micro- and mesozooplankton as prey for C. pengoi and mesozooplankton and C. pengoi as prey for YOY herring. These models indicate that mesozooplankton was the major food source of both species. However, microzooplankton may be important prey for young stages of C. pengoi. Comparative analyses of the herring trophic position before and after the invasion by C. pengoi showed a trophic level shift from 2.6 to 3.4, indicating substantial alterations in the food web structure. Our findings contribute to a growing body of evidence, showing that C. pengoi can modify food webs and trophic interactions in invaded ecosystems.

Place, publisher, year, edition, pages
2005. Vol. 143, no 2, 251-259 p.
Keyword [en]
Diet, Effects of preservation and storage, Invasive species, Zooplankton, Zooplanktivorous fish
National Category
Ecology
Identifiers
URN: urn:nbn:se:su:diva-25730DOI: 10.1007/s00442-004-1791-0OAI: oai:DiVA.org:su-25730DiVA: diva2:200386
Available from: 2009-02-19 Created: 2009-02-11 Last updated: 2017-12-13Bibliographically 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.
Keyword
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
Ecology
Research subject
Marine Ecology
Identifiers
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
Opponent
Supervisors
Available from: 2009-02-19 Created: 2009-02-11Bibliographically approved
2. Studies of Baltic Sea plankton - spatial and temporal patterns
Open this publication in new window or tab >>Studies of Baltic Sea plankton - spatial and temporal patterns
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis examines the spatial and temporal patterns of Baltic Sea phyto- and zooplankton. Studies of such patterns are important to gain a better understanding of the offshore nutrient dynamics of the Baltic Sea (Papers I and II) and how to manage eutrophication and invasive species in coastal areas (Papers III and IV).

During the spring phytoplankton bloom, diatoms rapidly depleted inorganic nitrogen in the shallow mixed layer, but were replaced by dinoflagellates when a seasonal pycnocline developed early in spring due to riverine freshwater inputs (Paper I). The settling of diatoms from the mixed water column was species-specific (Paper I). Vertically migrating dinoflagellates were able to exploit nutrients to considerable depth. The settling of primary produced carbon was low, only 12% as particulate organic carbon (POC) at 100 m and 2% as identifiable cells (Paper I). Profound alterations in species composition during settling will hinder interpretation of paleoecological records.

During summer cyanobacterial blooms, vertically separated diazotrophic and mixotrophic species dominated the phytoplankton community. Unicellular and colony-forming picocyanobacteria, a hitherto underestimated group, made up a substantial part of phytoplankton biomass late in the bloom (Paper II). Dominant species during the blooms exhibited species-specific depth distributions, suggesting niche-separation to decrease competition.

Management of coastal eutrophication is of major concern, particularly in estuaries and enclosed seas with limited water exchange. In Himmerfjärden, a eutrophicated Baltic Sea bay, filamentous nitrogen-fixing cyanobacteria increased substantially following a drastic reduction in nitrogen load from a modern sewage treatment plant (STP). Seston <10 µm responded to the 15N-enriched nitrogen from the STP with a δ15N-value of near 8‰ close to the discharge point, compared to only 2‰ in the open Baltic. In contrast, filamentous nitrogen-fixing cyanobacteria had δ15N-values of -3.0‰ to -0.2‰ (average -1.5‰) independent of distance to the STP (Paper III), indicating that they used only dinitrogen for growth. When cyanobacteria were abundant, total nitrogen concentrations increased and δ15N decreased in seston <10 µm and zooplankton >200 µm (Paper III), indicating that fixed nitrogen was transferred to other trophic levels. During a later deliberate experimental discharge of nitrogen designed to suppress cyanobacterial growth, cyanobacteria used some dissolved inorganic nitrogen but their biomass was not markedly reduced (Paper III).

The cladoceran zooplankton Cercopagis pengoi, a recent invader to the Baltic Sea, is a potential competitor with fish for zooplankton prey. Stable nitrogen isotope studies imply that invasion by C. pengoi has changed the pelagic food web structure in the bay Himmerfjärden by competing with small pelagic fishes for zooplankton, and by providing a new prey for these fishes (Paper IV). These results indicate the risk of cascading effects on other trophic levels and the necessity of whole ecosystem analysis when evaluating effects of invasive species (Paper IV).

Place, publisher, year, edition, pages
Stockholm: Institutionen för systemekologi, 2004. 43 p.
Keyword
Phytoplankton, Vertical distribution, Sedimentation, Baltic Sea, Cyanobacteria, Stable istopes, Cercopagis pengoi, Zooplankton
National Category
Ecology
Identifiers
urn:nbn:se:su:diva-323 (URN)91-7265-989-0 (ISBN)
Public defence
2005-01-28, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 8 C, Stockholm, 10:00
Opponent
Supervisors
Available from: 2004-12-21 Created: 2004-12-21 Last updated: 2010-08-10Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Gorokhova, ElenaHansson, StureHöglander, Helena
By organisation
Department of Systems Ecology
In the same journal
Oecologia
Ecology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 574 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf