PLANET EARTH: FRESHWATER DVD
http://dsc.discovery.com/convergence/planetearth/guide/fresh-water.html
FRESHWATER
Just 3 percent of the planet's water is fresh and it is our most
precious resource. Rivers and lakes have shaped the earth,
carving out the world's most impressive gorges, valleys and
waterfalls. Unique behavior takes place in the presence of this
life force, such as dueling otters and crocodiles and diving
macaques.
An exceptionnal concentration of species
It is notably thanks to its size (20% of the total surface liquid
freshwater of the world and a depth of more than 1600m), age (at
least 20 million years) and isolation of the lake Baikal that its
amphipod crustaceans have developed an unprecedented adaptive
radiation. Already 300 species have been described from the lake
(totalling 20% of the world's freshwater species), 95% of them being
endemic, and some Russian researchers speculate at least as many
are still waiting to be discovered.
As their name suggest, the Abyssogammarus (60mm) species are
limited to the deepest parts of the lake (never shallower than 300m).
Macrohectopus branicki, an aberrant planktonic species, is the ecologic
equivalent of the antarctic krill. Its huge swarms constitute more than
90% of the amphipod biomass of the lake, and are the primary food
resource of several fishes of economic importance.
The key to polar gigantism
Moreover, Baikal amphipods are characterised by the world's most
extensive size range. The adult size of these animals varies from 2 to
90 mm (compare with the maximum size of 37 mm of the Bitish
species). The study of these organisms carried out at the Royal Belgian
institute of Natural Sciences has resulted in a new hypothesis
explaining polar gigantism, according to which the amount of dissolved
oxygen determines the maximum potential size of these animals.
Pallasea cancellus is a big opportunistic species (50mm). It adapts
remarkably to captivity (more than 3 years at the RBINS).
The wonderful Acanthogammarus maximus (65mm) belongs to the
same genus than the biggest species both for the lake and the world
freshwater, measuring 90mm. It lives in shallow water.
A rich collection
Two sucessive expeditions (1995; 1996) to lake Baikal have yielded
more than 100 species belonging to 25 genera, ranking the Royal
Belgian Institute of Natural Sciences' collections amongst the richest in
the world, particularly with respect to the biggest species. It is also at
our Institute that a handful of species have been studied in captivity,
for the first time outside the ex-USSR.
Ommatogammarus albinus, which can be sampled by thousands with
baited traps up to the greatest depths of the lake show a staggering
ecological convergence with the numerous necrophagous species of a
marine amphipod superfamily, the lysianassoids.
http://www.youtube.com/watch?v=I9KXRHk3AkU
http://k43.pbase.com/g6/45/743145/2/73366732.mBjXAKBU.jpg
http://fish.picturesargentina.com.ar/dorado.jpg
http://bugguide.net/node/view/14955
http://www.ucmp.berkeley.edu/exhibits/biomes/freshwater.p
hp
http://www.buzzle.com/articles/fresh-water-biomes.html
http://www.mbgnet.net/fresh/
http://www.worldbiomes.com/biomes_aquatic2.htm
http://www.aurumscience.com/environmental/4_ecosystems
/earth_freshwater.html
http://dsc.discovery.com/convergence/planetearth/guide/fresh-water.html
http://www.ucmp.berkeley.edu/exhibits/biomes/freshwater.p
hp
http://www.buzzle.com/articles/fresh-water-biomes.html
http://www.mbgnet.net/fresh/
http://www.worldbiomes.com/biomes_aquatic2.htm
http://www.aurumscience.com/environmental/4_ecosystems
/earth_freshwater.html
http://dsc.discovery.com/convergence/planetearth/guide/fresh-water.html
http://reaganess.weebly.com/uploads/2/7/5/6/2756971/fre
shwater.pdf