[Taxacom] Ishavstaangen - the ice sea weed
Athanasios.Athanasiadis at marecol.gu.se
Wed Dec 16 05:37:13 CST 2009
The earliest notification of climatic changes affecting seaweed
distribution was published by the late Peter Dixon
(Biol.Signif.Clim.Changes in Britain: 113. 1965), where temperature
is postulated to be the cause of recent re-invasions in Europe, and
there are several examples in Scandinavian waters. Apart from those
mentioned by Dixon, the warm-temperate red alga Sphaerococcus
coronopifolius Stackhouse is presently considered to be an
established species in Sweden - the first confirmed records dating
since the 90's (and unconfirmed ones suggesting conspecifity with
Lyngbye's Desmia hornemanii described in 1819 from Oeresund). Several
European Delesseriaceae such as Hypoglossum Kuetzing and
Haraldiophyllum Zinova are new members of the Scandinavian flora
since a few decades. The possibility that such southern species could
be in fact glacial survivals exists but is remote. If so, we would
expect to see endemics as well - but to find the latter we have to
'botanize' along the maximum ice cover, apparently both in the south
and the northern border of the latest glaciation (Nord.J.Bot.24:
469-499. 2007; Taxon 57: 223-230. 2008).
Yet, the case of Fucus evanescens C. Agardh 1820 stands as unique.
Here we have a supposed Arctic species that in the past 100 years
expanded its distribution in the opposite direction. Until 1890, its
southern limit was near the polar circle (Kjellman,
Handb.Skand.havsalgfl.: 67. 1890), but in 1894 it was reported from
Oslofjord - a 'natural' jump of about 7°. Within 30 years it had
reached the Swedish west coast, and after another 70 years it was
recorded in Kiel's Bay (nearly 12° below the polar circle). The
arctic-like conditions of the Baltic might explain this event, but
the species was also reported from the Faeroes (Boergesen,
Mar.Alg.Faeroes: 465. 1902, as F. inflatus) and the Shetlands (Powell
in J.mar.bio.Assoc.U.K.36: 664-5. 1957, as subsp. edentatus).
Recently, Baltic hybrids with local F. serratus Linne have been
reported - although the two species coexist for thousands of years
above the polar circle. It was hypothesized that local hybridization
could be due to differences between the (isolated) Baltic F. serratus
and the polar populations (Proc.R.Soc.Lond.269: 1829-34. 2002), but
was that F. evanescens the same species originally described from
Kamtchatka, genetically more related to F. gardneri Silva from the
North Pacific (J.phycol.35: 389. 1999), and currently 'synonymized'
with F. inflatus Linne 1753 (type locality: Norway), F. edentatus
Pylaie 1829 (type locality: New Foundland), and F. bursigerus J.
Agardh 1868 (type locality: Spitsbergen) ?
A few months ago, several Fucus specimens surfaced unexpectedly in a
closet. They were sent away from a herbarium, thankfully not thrown
away without consultation. A closer look showed that they were
collected by D. Hylmoe at Varberg, on the Swedish west coast, between
February 1933 and April 1934. Lenghty comments on the labels such as
'Fucus serratus L. x inflatus..', 'Fucus inflatus L. x
vesiculosus...', '...x...', '...x...', '...x...', '...x...', reveal a
burning interest and intensive effort to find out. They were given a
place as the first collections of an introduced species in that part
of Sweden, deserving thorougher attention.
Was it the Arctic seaweed ?
with best wishes for the Holidays and the New Year,
and a reminder of the field courses the coming summer
Dr. A. Athanasiadis
University of Gothenburg
P.O. Box 461
SE 405 30 Gothenburg, Sweden
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