Náttúrufræðingurinn - 2016, Side 40

Náttúrufræðingurinn
40
ty at the highest elevation is that of
Eyrarselsvatn (site no. 9), at about 630 m
a.s.l.
The size of false lake balls is given in
Tab. 1. The balls measured from 20 to
195 mm in length, while the broadest
specimen measured 125 mm. Lake balls
from Ormarsá (no. 5) were on average
the largest.
Tab. 2 lists the moss species identified
from sites nos 4–6 and 9–17. From these
sites 34 moss species (and in some cases
only higher taxa) were identified. The
moss species from sites nos 1–3 and 7
had been identified earlier. Four addi-
tional moss species were found at those
sites, i.e. Kiaeria falcata, Sarmentypnum
exannulatum, Scorpidium revolvens, and
Meesia uliginosa. Therefore, a total of 38
moss species have been discovered in
false lake balls from Iceland. No speci-
mens were available from site no. 8.
The number of moss species or gen-
era identified per site varied from 1 at
the coastal lake Nýlenduvatn (no. 11) to
15 at the coastal lagoon Nýpslón (no. 14).
Half of the 12 sites in Tab. 2 had 10–15
species in the moss balls found.
Excepting Nýlenduvatn, the number of
identified taxa did not differ much be-
tween lakes and rivers, but was slightly
higher at coastal river mouths. The spe-
cies composition in lakes differed sig-
nificantly from that of rivers or coastal
river mouths. Differences were also
found between rivers and coastal river
mouths.
Almost all the lake balls examined
consisted of dead or in a few cases dying
moss (mixed with some other materials).
One exception were the specimens from
Hraunsfjarðarvatn (no. 7), which con-
sisted of living moss (Fig. 2) of the spe-
cies Kiaeria falcata, which was found no-
where else.
Some of the species that normally
grow in terrestrial habitats, dry or wet,
such as Climacium dendroides, Pleurozium
schreberi, Pterigynandrum filiforme, and
Sanionia uncinata, have most likely fallen
into the water accidentally, and there-
fore do not represent any specific limnic
environments. Further, Fontinalis antipy-
retica grows in both lentic and lotic envi-
ronments, and both base-poor and base-
rich habitats. This species therefore does
not distinguish false moss balls from a
specific environment. Species typical of
running water, such as the two
Hygrohypnum species and Rhyncho-
stegium riparioides, were found exclu-
sively (or almost exclusively) and in
large amounts, in lake balls from rivers
or coastal river mouths. Other species
that were found mostly in the balls from
such environments, included Bryum
species, Pohlia wahlenbergii, and some
Racomitrium species. Interestingly,
Philonotis was especially abundant in
lake balls from coastal river mouths.
The larger number of species around
coastal river mouths would be explained
by somewhat more diverse habitats
here compared to more homogeneous
environments further upstream. Typical
fen species, such as most members of
Calli ergon, Sarmentypnum, and Scorp-
idium, were mainly found in moss balls
from lakes. The occurrence of Calliergon
giganteum, C. richardsonii, Drepanocladus
turgescens, Sarmentypnum tundrae, and
Scorpidium cossonii, as well as the com-
plete absence of Sphagnum in balls from
lakes suggest that those lakes or the sur-
rounding fens are alkaline.18
False lake balls seem to be rather rare
in Iceland since they have not been re-
corded more often than indicated here.
One reason is that naturalists may not
have taken much notice of them.
However, the wide but sparse distribu-
tion implies that additional sites remain
to be discovered, especially lakes.
Formation of false lake balls in rivers
appears to require more specific situa-
tions. These are where the rivers widen
into rather calm slow-streaming broads
with eddies before flowing through a
narrow channel to sea.
Þakkir
Ýmsum ber að þakka fyrir aðstoð við þessa ritgerð. Öllum finnendum
vatnamúsa er þakkað þeirra framlag, svo og Tom Barry sem gerði kortið.
Freddy Laustsen, Guðjón Gamalíelsson og Ólafur Finnsson fá þakkir fyrir
nánari ábendingar um vatnamýs. Skúla Ragnarssyni á Ytra-Álandi í
Þistilfirði eru þökkuð greið svör um vatnamýs og vatnafar í Sandá. Bergþór
Jóhannsson (sem lést árið 2006) greindi mosana í sýnum frá þremur fyrstu
stöðunum þar sem vatnamýs uppgötvuðust og einum til viðbótar.
Heimildir
1. Ævar Petersen 1988. Vatnamýs. Náttúrufræðingurinn 58(1). 31–35.
2. Luther, H. 1979. Aquatic moss balls in southern Finland. Annales
Botanici Fennici 16. 163–172.
3. Árni Einarsson 1985. Botn Mývatns. Fortíð, nútíð, framtíð. Náttúru-
fræðingurinn 55(4). 153–173.
4. Árni Einarsson 2014. The lake balls of Mývatn in memoriam. /
Kúluskíturinn í Mývatni. Minningarorð. Náttúrurannsóknastöðin við
Mývatn, Skútustaðaheppi. 64 bls.
5. Helgi Hallgrímsson 1979. Kaflinn „Blaðmosar (Musci)“ bls. 98–99 í
Veröldin í vatninu. Handbók um vatnalíf á Íslandi. Askur, Reykjavík. 217
bls.
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Náttúrufræðingurinn 70(4). 179–184.
7. Huntsman, A.G. 1935. On the formation of lake balls. Science 82(2122).
191–192.
8. Tirén, T. 1983. Om sjöbollar. Fauna och Flora, Uppsala 78. 73–74.
9. Schloesser, D.W., Hiltunen, J.K. & Owens, R.W. 1983. Rediscovery of lake
balls in Lake Michigan. Journal of Freshwater Ecology 2(2). 159–163.
10. Quigley, D.T.G. & Flannery, K. 2014. An exceptionally large ‘Seaball’
discovered on Inch Strand, Co. Kerry. The Irish Naturalists’ Journal 33(2).
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11. Guðmundur P. Ólafsson 2007. Þjórsárver. Hernaðurinn gegn landinu.
Mál og menning, Reykjavík. 288 bls.
12. Benóný Jónsson & Karólína Einarsdóttir 2008. Áhrif vegagerðar um Öxi
og Berufjarðarbotn á vatnalíf. Veiðimálastofnun. VMST/08029. 35 bls.
13. Bergþór Jóhannsson 1996. Íslenskir mosar. Fossmosaætt, ármosaætt,
flosmosaætt, leskjumosaætt, voðmosaætt og rjúpumosaætt. Fjölrit
Náttúrufræðistofnunar 30. 55 bls.
14. Veðurstofa Íslands 2013. Myndskeið af Sandá í Þistilfirði í júní 2013.
Skoðað 1. maí 2014 á https://www.facebook.com/akureyrivikublad/
posts/464849536932732
15. Veðurstofa Íslands 2013. Ársskýrsla 2013. Veðurstofa Íslands, Reykjavík.
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Náttúru fræðistofnunar 19. 119 bls.
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