Everything about Hypolith totally explained
In
Arctic and
Antarctic ecology, a
hypolith is a
photosynthetic organism that livesunderneath
rocks in
climatically extreme
deserts such as
Cornwallis Island and
Devon Island in the
Canadian high Arctic. The community itself is the
hypolithon.
Hypolithons are protected from harsh
ultraviolet radiation and
wind scouring by their rock, which can also trap moisture. The rocks are generally
translucent to allow for the penetration of
light. Writing in
Nature, ecologist
Charles S. Cockell of the
British Antarctic Survey and Dale Stokes describe how hypoliths reported to date (until 2004) had been found under
quartz, which is one of the most common translucent rocks .
However, Cockell reported that on Cornwallis Island and Devon Island, 94-95% of a
random sample of 850
opaque dolomitic rocks were colonized by hypoliths, and found that the communities were dominated by
cyanobacteria. The rocks chosen were visually indistinguishable from those nearby, and were about 10cm across; the hypolithon was visible as a greenish coloured band. Cockell proposed that rock sorting by
periglacial action, including that during freeze–thaw cycles, improves light penetration around the edges of rocks (see
granular material and
Brazil nut effect).
Cockell and Stokes went on to estimate the
productivity of the Arctic communities by monitoring the uptake of
sodium bicarbonate labelled with
Carbon-14 and found that (for Devon Island) productivity of the hypolithon was comparable to that of
plants,
lichens, and
bryophytes combined (0.8 ± 0.3 g m
-2 y
-1 and 1 ± 0.4 g m
-2 y
-1 respectively) and concluded that the polar hypolithon may double previous estimates of the productivity of that region of the rocky polar desert.
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