Náttúrufræðingurinn - 2020, Blaðsíða 63

Tímarit Hins íslenska náttúrufræðifélags
63
Ritrýnd grein / Peer reviewed
7. mynd. Urosolenia longiseta (O. Zacharias) Edlund & Stoermer (a) og Urosolenia eriensis (H.L. Smith) Round & R.M. Crawford (b) úr Þing-
vallavatni – Urosolenia longiseta (O. Zacharias) Edlund & Stoermer (a) and Urosolenia eriensis (H.L. Smith) Round & R.M. Crawford (b) from Lake
Thingvallavatn. Þvert yfir U. longiseta (a) og U. eriensis (b) liggja ljósari frumur tegundarinnar Asterionella formosa, sem fjallað verður um hér á
eftir. Eru þær ljósari vegna hærri kísilstyrks. Cells of Asterionella formosa (discussed here below) lie across the U. longiseta (a) and U. eriensis
(b) cells. They appear brighter because of higher silica content. Rafeindasmásjá / SEM.
8. mynd. Stjörnulaga þyrpingar Asterionella formosa Hassall (t.v.) og
Nitzschia holsatica Hustedt (t.h.) úr Þingvallavatni. – Star-forming
colonies of Asterionella formosa Hassall (left) and Nitzschia holsatica
Hustedt (right) from Lake Thingvallavatn. Rafeindasmásjá / SEM.
9. mynd. Dinobryon sociale (Ehrenberg) Ehrenberg úr Þingvallavatni.
– Dinobryon sociale (Ehrenberg) Ehrenberg in Lake Thingvallavatn.
Rafeindasmásjá / SEM.
kísilþörungum í Þingvallavatni. Mynd-
irnar hafa góða upplausn og góða dýpt-
arskerpu og henta vel til að greina erfið
þörungasýni til tegunda.
Hér hefur sjónum verið beint að
svifþörungum í Þingvallavatni. Þess er
vænst að botnþörungar vatnsins verði
athugaðir á hliðstæðan hátt.
ENGLISH SUMMARY
THE USE OF SCANNING ELECTRON
MICROSCOPY (SEM) FOR THE IDEN-
TIFICATION OF PHYTOPLANKTON
TAXA IN LAKE THINGVALLAVATN
A research and monitoring pro-
ject of phytoplankton species in Lake
Thingvallavatn was re-established in
2015.1 The last major phytoplankton
programme was executed in the seven-
ties and the eighties3 and before that in
1902 to 1903.2 One goal of the project is
to revise and update the phytoplankton
taxa list. A database with photographs
and general information about identi-
fied species is under construction, and
currently a list of 56 phytoplankton
species with photographs and biologi-
cal information is available.5 The data-
base will be of value for future research
and monitoring in the lake and the next
step is to expand the project to include
diatoms from the lake’s bottom. In this
paper, eight phytoplankton-diatom
(Bacillariophyceae) species in Lake
Thingvallavatn were examined with
scanning electron microscopy (SEM)
and the identification of these taxa eval-
uated. Additionally, the paper includes
one golden algal (Chrysophyceae) spe-
cies that has been a recent arrival to
the lake. Images from light and elec-
tron microscopy together with histor-
ical information relevant to the iden-
tification of these species in the lake
are presented.