Seasonal abundance and vertical distribution of siphonophores in western Norwegian fjords
2008 (English)In: Journal of Plankton Research, Vol. 30, no 8, 951-962 p.Article in journal (Refereed) Published
Seasonal abundance of siphonophores in Korsfjord and Fanafjord was studied by net sampling. Nanomia cara, Lensia conoidea and Dimophyes arctica were dominant species present throughout the year. Abundance of N. cara colonies peaked in late May and early June. Low numbers of relatively large colonies and high numbers of siphonulae were observed during winter. Dimophyes arctica and L. conoidea had a generation shift in March, when large over-wintering and small young polygastric colonies co-existed briefly before the former disappeared. Abundances were lowest during winter, and eudoxids were consistently more numerous than polygastric colonies for both species. Maximum abundances of polygastric D. arctica and L. conoidea occurred in early May and late June, respectively. Lensia conoidea may have more than one annual generation in Korsfjord. Vertical distributions of siphonophores were studied with an remotely operated vehicle in nine fjords. The distributions of agalmatid physonects, probably mostly N. cara, differed significantly between the fjords, with the weighted mean depths of the distributions ranging from 99 to 412 m. Results from Sognefjord suggested diel vertical migration. The bulk of the adult colonies in each fjord occurred below sill depth. Siphonophores were not observed at localities known to host persistent populations of Periphylla periphylla.
Place, publisher, year, edition, pages
2008. Vol. 30, no 8, 951-962 p.
IdentifiersURN: urn:nbn:se:umu:diva-11357DOI: doi:10.1093/plankt/fbn045OAI: oai:DiVA.org:umu-11357DiVA: diva2:151028