lnu.sePublications
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
Distribution and host plant preference of Idotea baltica (Pallas) (Crustacea: Isopoda) on shallow rocky shores in the central Baltic Sea
Norwegian Univ Sci & Technol, Dept Biol, NO-7491 Trondheim, Norway .ORCID iD: 0000-0002-1426-0036
University of Kalmar, School of Pure and Applied Natural Sciences.
2004 (English)In: Sarsia, ISSN 0036-4827, E-ISSN 1503-1128, Vol. 89, no 1, p. 1-7Article in journal (Refereed) Published
Abstract [en]

Partially due to the mass occurrence of the isopod Idotea baltica, the perennial fucoid vegetation in the Baltic Sea has been destroyed over large areas and replaced by filamentous algae. With a combination of field investigations and laboratory experiments, we tested whether I. baltica preferred Fucus serratus to the dominant red alga Polysiphonia fucoides. In the field, the I. baltica density was higher inside F. serratus than P. fucoides patches when measured per unit area, but the situation was reversed if measured per biomass algae. Diet in the field was well correlated with the distribution of the isopods. A large proportion of the isopod faecal pellets collected in the field contained remnants of microalgae, planktonic animals, and bacteria, but the dominating material was always cells from the actual host plant. In a host plant preference experiment, I. baltica distributed evenly between the two host plant types, but the isopods grazed more heavily on F. serratus. We conclude that although F. serratus is the preferred food item in a choice situation, P. fucoides appears to have the potential to support the I. baltica population with food and shelter. A possible relationship between the weak host plant preference and the low stocks of predatory fish is discussed.

Place, publisher, year, edition, pages
2004. Vol. 89, no 1, p. 1-7
Keywords [en]
Fucus, Polysiphonia, Filamentous algae, Structuring factors, Grazing, Herbivory
National Category
Ecology
Research subject
Natural Science, Aquatic Ecology
Identifiers
URN: urn:nbn:se:hik:diva-642DOI: 10.1080/00364820310003217OAI: oai:DiVA.org:hik-642DiVA, id: diva2:1897
Available from: 2007-11-29 Created: 2009-09-17 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Grazing in Macroalgae Communities of the Baltic Sea
Open this publication in new window or tab >>Grazing in Macroalgae Communities of the Baltic Sea
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Fucus vesiculosus and Fucus serratus are the only large, structuring perennial brown macroalgae in the low salinity waters of the Swedish coast of the Baltic Proper. Since the 1970s there are reports of declining Fucus vesiculosus stands from several locations around the Baltic Proper, but also indications of recoveries e.g. in Finland, in the Askö area of the northern Baltic proper and in the south east coast of Sweden. There are probably several causes for these changes. This thesis focuses on how, among biological and other factors, grazing may be the proximate factor to structure the rocky phytal zone of the Baltic Sea.

Destructive effects on F. vesiculosus may be connected to extreme densities of grazers. In a field survey large densities of the potential mesograzer Idotea baltica correlated positively with grazing injuries on and reduced depth penetration of Fucus vesiculosus. In a grazing experiment biomass of F. vesiculosus was halved within two weeks at a grazer density found in the field (80 I. baltica per 100 g of Fucus wet weight). In a second survey large numbers of the gastropods Theodoxus fluviatilis and Lymnaea peregra coincided with unsuccessful recruitment of F. vesiculosus. In an experiment these gastropods grazed germlings of F. vesiculosus up to sizes of 0.8 and 1.0 mm respectively. Abundances of gastropods were highest in autumn, indicating that autumn reproductive F. vesiculosus might be more influenced than spring reproductive F. vesiculosus as the latter would have surpassed the critical size in autumn.

Grazing may be modified by environmental factors. Comparatively small densities of Theodoxus fluviatilis correlated positively with abundances of Fucus vesiculosus and negatively with abundances of filamentous algae. Grazing effects advantageous to F. vesiculosus were tested in a field experiment with manipulation of grazers, nutrients and propagules of filamentous algae. At low nutrient loads grazers tended to clear the substrate from filamentous algae and strengthen the competitive ability of F. vesiculosus. At high nutrient loads the grazers could not prevent dominance of filamentous algae with detrimental effects to F. vesiculosus. Physical factors like wave-action may also modify grazing effects. In a wave-exposed coastline with mixed stands of perennial brown algae and frequent occurrences of grazing isopods, F. vesiculosus declined faster than F. serratus. In an experiment F. vesiculosus was more heavily grazed than F. serratus, but only at intense water motion. Thus F. serratus seem to have a competitive advantage to F. vesiculosus in wave exposed coasts where severe grazing occurs.

The fact that the grazer I. baltica often has been connected with F. vesiculosus, might indicate that this animal would be dependent on F. vesiculosus as habitat and/or food. In a wave-exposed habitat on the eastern coast of Öland, probably earlier dominated by F. vesiculosus but now holding discrete patches of either red algae {Polysiphonia fucoides) or saw-wrack (F. serratus) I. baltica used both species as habitat and food. In addition to the two macroalgae faecal pellets contained 30-40 % microalgae, indicating that mixed diets may be important for this species.

In monitoring programs of rocky bottom communities fixed sites may be revisited on a yearly bases to estimate the development of the community. There is an underlying assumption that the observations at a fixed site are representative to surrounding areas. This assumption was tested along a 350 km coastline in SE Sweden. 18 years of observations were evaluated and compared to complementary sites. Within areas of similar wave exposure there was good agreement between fixed sites and surrounding areas.

When all fixed sites within wave-protected areas were analysed together for long-term trends, there was an agreement in development between sites över the whole geographic area. The Fucus community increased its distribution during the 1980s, decreased during the early ]990s (probably from grazing as described above), to increase again in 2000-2001, that is an oscillating pattern is suggested. In wave-exposed sites, along a 100 km coastline, the F. vesiculosus stands were destroyed, seemingly by grazing as described above, around 1992-1994, with no signs of recovery as late as in 2002.

The results are discussed in the context of grazing, regulation of grazing by predation, eutrophication and physical factors. The importance of the lack of fish predators is suggested for further research.

Series
Dissertation series / University of Kalmar, Faculty of Natural Science, ISSN 1650-2779 ; 7
National Category
Natural Sciences
Research subject
Natural Science, Aquatic Ecology
Identifiers
urn:nbn:se:hik:diva-43 (URN)91-89584-16-3 (ISBN)
Public defence
(English)
Supervisors
Available from: 2007-11-29 Created: 2007-11-29 Last updated: 2010-03-09

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full text

Authority records BETA

Svensson, P. AndreasEngkvist, Roland

Search in DiVA

By author/editor
Svensson, P. AndreasEngkvist, Roland
By organisation
School of Pure and Applied Natural Sciences
In the same journal
Sarsia
Ecology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 129 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