Antarctic Cyanobacteria PAUL A. BROADY School of Biological Sciences, University of

advertisement
Antarctic Cyanobacteria
An eclectic selection of their habitats and diversity
PAUL A. BROADY
School of Biological Sciences, University of
Canterbury, Christchurch, New Zealand
Online with Ecology of Cyanobacteria II (Chap. 28)
Whitton BA (ed.) (2012) Springer, Dordrecht.
Images (other than maps) copyright of author of article
[email protected]
CONTENTS
3 The Antarctic
4-6 Vestfold Hills: environment, temperature and organisms
7 Epilithic communities dominated by Gloeocapsa
8 Cape Geology melt water
9 Small pools on Cape Royds, Ross Island
10-12 Ponds with Phormidium mats and Nostoc colonies
13 Garwood Valley, southern Victoria Land, with stranded cyanobacteria
14 McMurdo Dry Valley
15-16 McMurdo Ice Shelf: fresh to hypersaline
17 Fertilization by animal waste on South Orkney Islands
18 Victoria Valley (McMurdo Dry Valleys) with Microcoleus
19 Human introductions
20 Cryonite ponds, including Crinalium glaciale
21 La Gorce Mountains have the furthest south cyanobacteria
22 Mt Roland with Ammatoidea and Gloeocapsa
23 Ammatoidea normani
24 Ice-covered pools on moraine over stagnant ice
25 Phormidium autumnale dominates here
26 Two of the three active volcanoes: Mt Erebus, Mt Melbourne
27-28 Cyanobacteria on Mt Erebus include Mastigocladus laminosus
29 Cyanobacterica on Mt Melbourne include Stigonema
30 Some literature
Acknowledgements
The Mount Blackburn maps on p.21 and p.24 are from Antarctica, SV 1-10/11, U.S. Geological Survey, 1968
(with permission, courtesy of U.S. Geological Survey)
2
3
* Antarctic terrestrial biota is unique in being hugely dominated by
microorganisms.
* Cyanobacteria dominate photoautotrophic biomass.
* These images present a glimpse of their diversity and habitats. They
occupy niches that range from the relatively benign conditions of freshwater
lakes to those that are hyper-saline and hyper-arid.
All the images are copies from photographic transparencies obtained between 1971 and
1997, so their quality can be a little lacking. Apologies!
Hopefully, the wilderness, scientific and educational values of Antarctica
will prevail over those of minerals exploitation and mass tourism!
Vestfold Hills
Hypolithic communities
covering the undersurfaces of
translucent quartz stones
resting on the surface of the
cold desert soils. Dominated
by cf. Leptolyngbya spp.
4
5
+ 10
+
Temp.
oC
-
Light
intensity
Soil below
stone
0
-5
Air
0
1200
2400
Solar time
Temperature changes in the hypolithic habitat on a clear, midsummer day
at Vestfold Hills
6
1 cm
1 cm
Chasmoendolithic cyanobacteria occur below thin flakes
of granitic rocks and in cracks penetrating vertically down
into quartz stones. Top left shows a mixture of green
crusts of the chlorophyte Prasiococcus calcarius and
blue-green crusts of the cyanobacterium cf.
Chroococcidiopsis. Growths in the quartz stone (right)
were dominated by the latter.
7
Epilithic cyanobacteria develop as dark crusts down-slope from melting snowbanks and ice
fields. Frequently observed in coastal regions of Continental Antarctica. Dominated by
Gloeocapsa spp.
8
10 cm
1 m
At coastal locations, such as Cape Geology,
southern Victoria Land, melt water
percolations stimulate moss growth. The
exposed upper surfaces of moss cushions and
carpets can become heavily encrusted with
dark crusts of Nostoc sp. and Gloeocapsa spp.
9
Small ponds can evaporate during
summer, exposing cyanobacterial
mats to elevated salinities and
desiccation. This small pond is at
Cape Royds on Ross Island.
10
1 m
Ponds containing cyanobacterial mats
dominated by Phormidium spp. are a wellknown feature of coastal regions of
Antarctica.
11
During strong winds, mats become dislodged
from the sediments of ice-free ponds. In
permanently ice-covered lakes, portions of mat
can break free, float up to the ice undersurface
and then melt up through the ice from where
they can be dispersed by winds.
12
1 cm
At Cape Royds ice-free area
on Ross island, freshwater
ponds with low conductivity
water often contain abundant
near spherical colonies of
Nostoc sp.
13
This lake is in Garwood Valley,
southern Victoria Land.
Cyanobacterial mats of Phormidium
and Nostoc become stranded along the
shoreline just like detached coastal
seaweeds. They can be used as
indicators of previous lake levels and
act as an organic carbon subsidy that
can be used by soil microbes.
14
McMurdo Dry Valleys are not dry where
there is persistent supply of meltwater.
There are several hectares of boggy
ground covered by Nostoc sp. at this
location close to the terminal ice walls of
Joyce Glacier.
10 cm
15
~ 100 m
~1 m
McMurdo Ice Shelf is a bizarre environment with tens of thousands of ponds melted into the
sand-covered ice. Mats of Phormidium spp. and Nostoc sp. occupy the more stable ponds.
16
The salinities of pond water on the
McMurdo Ice Shelf range from fresh to
hypersaline. These are hypersaline ponds
with salts crystalising around their
margins and on portions of Phormidium
mats that are exposed to the air. In these
examples the dominant salt is mirabilite
(sodium sulphate).
17
1 cm
Mats of
oscillatorialeans can
be extensive where
there is massive
fertilization from the
wastes and carcasses
of marine birds and
mammals. Here, in
the South Orkney
Islands, their growth
is stimulated by a
persistent supply of
water.
18
Victoria Valley is one of the driest
of the McMurdo Dry Valleys. On
the valley-sides, growths of
vegetation are rarely visible on soil
surfaces. In the image below a
cyanobacterial mat lies in front of
the note-book.
These thin mats occur in depressions
and on the lee side of large boulders
where snow persists for longer than
elsewhere following occasional
snowfall. They are dominated by
Microcoleus vaginatus.
19
Undoubtedly there have been introductions of
non-indigenous microorganisms into Antarctica
by humans. These include cyanobacteria.
Cylindrospermum is unknown from natural
habitats, but was cultured from soil residues on a
lettuce leaf at Scott Base, Ross Island. Around
research stations there are usually habitats where
these introductions could possibly gain a
foothold prior to wider dispersal. Temporary
pools at Scott Base contain cyanobacterial mats.
20
Close to the termini of McMurdo
Dry Valley glaciers, numerous
cryoconite ponds form in the
melting ice surface. In summer,
dark mineral material is warmed
by the sun and melts into the ice.
The smallest ponds are
cylindrical and about 5 cm
diameter. Crinalium glaciale was
first described from amongst the
mineral sediment at the bottom of
one of these ponds.
10 μm
21
La Gorce Mountains are nunataks,
mountain tops protruding through
surrounding ice fields. The image below is
a view as shown by the red arrow on the
map. They lie about 350 km north of the
South Pole. Other than Harrison Bluff,
they are the farthest south location of
cyanobacteria, eukaryotic algae and
lichens.
86o30’S
2000 m
10 km
From Antarctica, SV 1-10/11, U.S. Geological Survey,
1968, courtesy N
of U.S. Geological Survey)
22
Mt Roland was the only location
where a visible mat of cyanobacteria
occurred (Ammatoidea normanii and
Gloeocapsa sp.). This was in a rock
fissure irrigated with melt-water (see
photo). On a mid-summer day, air
temperatures were about minus 10°C,
but rock surfaces were warmed to
about +5°C by solar radiation.
10 μm
23
20 μm
25 μm
10 μm
Farthest South cyanobacteria. Ammatoidea normanii
from La Gorce Mtns.
Left Field sample
Right Material from a 6-week culture growing on
agarized distilled water
24
86oS
Extensive areas of moraine on stagnant ice are covered by thousands of shallow ice-covered
ponds. 25-34 cm thickness of ice covered about 15-35 cm depth of water.
Map is from Antarctica, SV 1-10/11, U.S. Geological Survey, 1968, courtesy of U.S. Geological Survey)
25
10 μm
Phormidium autumnale dominated mats
that thinly cover bottom sediments. The
diatom Luticola muticopsis was rare. At
several locations freeze-dried mat
fragments were found on exposed
moraine surfaces. It was apparent that
pond positions shifted as underlying ice
melted and pond-dwelling mats became
exposed.
26
Mt. Melbourne - 2733 m
Three volcanoes in continental
Antarctica are currently or recently
active. Mt. Melbourne and Mt.
Rittman are in northern Victoria Land
and Mt. Erebus is on Ross Island.
Close to the summits of all three, are
areas of exposed, geothermally
heated ground that support the growth
of moss and algae, including
cyanobacteria.
Mt. Erebus - 3794 m
Mt. Erebus summit crater with its
steaming lava lake
27
Freezing steam forms ice towers and
hummocks on the flank of Mt Erebus.
Warm ground inside these supports
microbial communities. The most
extensive warm ground is exposed during
summer at least and is about a hectare in
extent.
28
10 μm
Ground temperatures become rapidly cooler with
distance from small steaming vents and air
temperatures are freezing just a few centimetres above
the ground. On the warmest ground at about +45oC,
cyanobacterial crusts are dominated by Mastigocladus
laminosus. On progressively cooler ground, mats of
Leptolyngbya sp. and then coccoid chlorophytes and
protonematous moss encrust the surface.
29
The summit crater of Mt. Melbourne is filled
with ice but one rounded ridge has exposed
geothermal ground. The orange-brown mats
of Leptolyngbya sp. were similar to those on
Mt. Erebus. However, Stigonema cf.
ocellatum (left) occurred only on Mt.
Melbourne., as did Tolypothrix cf. bouteillei
and Gloeocapsa cf. magma.
10 μm
30
Broady PA (1996) Diversity, distribution and dispersal of Antarctic terrestrial
algae. Biodiversity and Conservation 5 (11): 1307-1335
This review provides extensive references to prior studies
Broady PA, Weinstein R (1998) Algae, lichens and fungi in La Gorce
Mountains, Antarctica. Antarctic Science 10(4): 376-385
Broady PA, Ingerfeld M (1999) Ammatoidea normanii (Cyanobacteria,
Homoeotrichaceae) from La Gorce Mountains, Antarctica. Algological Studies
95: 1-13
Broady PA (2005) The distribution of terrestrial and hydro-terrestrial algal
associations at three contrasting locations in southern Victoria Land, Antarctica.
Algological Studies 118: 95-112.
Broady PA (2007) Algae. In: B. Riffenburgh (ed.), Encyclopedia of the
Antarctic. Routledge, New York. Vol. 1, pp 22-27
Download