Despite marine traits, the endemic brown algae Fucus radicans is restricted to the Baltic Sea
(English)Manuscript (preprint) (Other academic)
Many of the marine species that were introduced to the Baltic Sea during the Littorina stage (c. 8500-3000 years BP) have adapted to the present low salinity e.g. Fucus vesiculosus and F. serratus. Common for all these marine species is a distribution pattern going from marine conditions into the lower salinity environment. In this paper we ask why the recently discovered endemic brown algae Fucus radicans, shows the opposite distribution range. Fucus radicans is only present in the northern parts of the Baltic Sea, the low saline Bothnian Sea (4-6 psu). Possibly, the fitness of F. radicans might be reduced in higher salinities if it is more adapted to brackish conditions. We hypothesize, however, that the southern distribution limit of F. radicans is set by biotic interactions, e.g. competition by F. vesiculosus and higher grazing pressure by Idotea balthica and not salinity.Our results show that the reproductive output of F. radicans is limited by low salinity but increases in higher salinities. However, the southern distribution limit was shown to be negatively impacted by biotic factors, where the additive effects from shading by taller F. vesiculosus thalli and grazing on F. radicans by the isopod I. balthica limited the biomass production of F. radicans. We suggest that F. radicans still maintains marine traits due to its clonal nature and is restricted to the Bothnian Sea by interactions with F. vesiculosus and I. balthica. We also propose that increased precipitation due to climate change might affect the northern range limit and that F. radicans could be expected to spread further into the Baltic Proper.
distribution range, egg production, fertilization, grazing, Idotea balthica, reproductive success, salinity, shading
Research subject Plant Ecology
IdentifiersURN: urn:nbn:se:su:diva-117574OAI: oai:DiVA.org:su-117574DiVA: diva2:813702
FunderSwedish Research Council Formas