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Trophic interactions in Zostera marina beds along the Swedish coast

Jephson, Therese LU ; Nyström, Per LU ; Moksnes, Per-Olav and Baden, Susanne P. (2008) In Marine Ecology - Progress Series 369. p.63-76
Abstract
We compared eelgrass Zostera marina communities in 3 regions in Sweden believed to be affected by eutrophication and overfishing, to determine whether bottom-up or top-down processes control the biomass of epiphytic macroalgae and grazers. Nitrogen and carbon isotope signatures were analyzed to explore the food webs and to identify the grazing species feeding on filamentous algae and/or eelgrass. Mixing model (IsoSource version 1.3.1) analysis of the isotope signatures indicated that the amphipods Gammarus locusta and Microdeutopus gryllotalpa fed primarily on filamentous algae and that only 2 small gastropod species consumed eelgrass. Moreover, the grass shrimp Palaemon elegans and F adspersus were ca. 1 trophic level above amphipods and... (More)
We compared eelgrass Zostera marina communities in 3 regions in Sweden believed to be affected by eutrophication and overfishing, to determine whether bottom-up or top-down processes control the biomass of epiphytic macroalgae and grazers. Nitrogen and carbon isotope signatures were analyzed to explore the food webs and to identify the grazing species feeding on filamentous algae and/or eelgrass. Mixing model (IsoSource version 1.3.1) analysis of the isotope signatures indicated that the amphipods Gammarus locusta and Microdeutopus gryllotalpa fed primarily on filamentous algae and that only 2 small gastropod species consumed eelgrass. Moreover, the grass shrimp Palaemon elegans and F adspersus were ca. 1 trophic level above amphipods and algae, but according to the mixing model played different trophic roles in the different areas. The highest biomass of filamentous algae was found in the west coast beds housing grazers with the lowest biomass and mean size (predominantly G. locusta and M. gryllotalpa, 0.5 to 3 mm). In contrast, the Baltic Sea beds had low algal biomass, but the grazers (mostly G. locusta and Idotea baltica) had higher biomass and were significantly larger (mean size ca. 10 mm). An overall negative correlation was found between grazer biomass and biomass of filamentous algae. The significantly smaller grazers and absence of isopod grazers on the west coast may be due to substantial consumption by small predatory fish. This supports the suggestions that, in Swedish eelgrass beds, grazers are top-down controlled, and overexploitation. of large predators and eutrophication play an important role in the recent increases in algal biomass. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
interactions, Trophic, Mixing model, Stable isotopes, Zostera, Seagrass, Eelgrass
in
Marine Ecology - Progress Series
volume
369
pages
63 - 76
publisher
Inter-Research
external identifiers
  • wos:000260873400006
  • scopus:56149114744
ISSN
1616-1599
DOI
10.3354/meps07646
language
English
LU publication?
yes
id
61d328a6-f344-4038-9e1d-35efb5d8c003 (old id 1283029)
date added to LUP
2009-02-10 12:58:10
date last changed
2017-07-30 03:56:30
@article{61d328a6-f344-4038-9e1d-35efb5d8c003,
  abstract     = {We compared eelgrass Zostera marina communities in 3 regions in Sweden believed to be affected by eutrophication and overfishing, to determine whether bottom-up or top-down processes control the biomass of epiphytic macroalgae and grazers. Nitrogen and carbon isotope signatures were analyzed to explore the food webs and to identify the grazing species feeding on filamentous algae and/or eelgrass. Mixing model (IsoSource version 1.3.1) analysis of the isotope signatures indicated that the amphipods Gammarus locusta and Microdeutopus gryllotalpa fed primarily on filamentous algae and that only 2 small gastropod species consumed eelgrass. Moreover, the grass shrimp Palaemon elegans and F adspersus were ca. 1 trophic level above amphipods and algae, but according to the mixing model played different trophic roles in the different areas. The highest biomass of filamentous algae was found in the west coast beds housing grazers with the lowest biomass and mean size (predominantly G. locusta and M. gryllotalpa, 0.5 to 3 mm). In contrast, the Baltic Sea beds had low algal biomass, but the grazers (mostly G. locusta and Idotea baltica) had higher biomass and were significantly larger (mean size ca. 10 mm). An overall negative correlation was found between grazer biomass and biomass of filamentous algae. The significantly smaller grazers and absence of isopod grazers on the west coast may be due to substantial consumption by small predatory fish. This supports the suggestions that, in Swedish eelgrass beds, grazers are top-down controlled, and overexploitation. of large predators and eutrophication play an important role in the recent increases in algal biomass.},
  author       = {Jephson, Therese and Nyström, Per and Moksnes, Per-Olav and Baden, Susanne P.},
  issn         = {1616-1599},
  keyword      = {interactions,Trophic,Mixing model,Stable isotopes,Zostera,Seagrass,Eelgrass},
  language     = {eng},
  pages        = {63--76},
  publisher    = {Inter-Research},
  series       = {Marine Ecology - Progress Series},
  title        = {Trophic interactions in Zostera marina beds along the Swedish coast},
  url          = {http://dx.doi.org/10.3354/meps07646},
  volume       = {369},
  year         = {2008},
}