Biology Reference
In-Depth Information
and batumes in Paraguay. These are fl oating mats several meters in diameter
made up of the fl oating fern
Salvinia auriculata
, the water hyacinth
Eichornia
crassipes
, and the water lettuce
Pistia stratiotes
(a search for
Pistia stratiotes
on, for example, the TROPICOS Web site will yield images, habitat, distri-
bution maps, and descriptions for this widespread tropical plant).
The balseiras may fuse into larger mats, lodging on roots or at river bends
and forming even larger fl oating islands, eventually developing a semiper-
manent fl ora and fauna. Occasionally they become dislodged and fl oat down
the Paraguay River carrying a serenely unaware jaguar or capybara into the
Paraná River and out to the Atlantic.
Also serenely unaware, at least toward the end of his life, was the re-
doubtable Count George Heinrich von Lanssdorff (1774-1852). The count
led expeditions into the Pantanal under the patronage of the czar of Russia;
but like many early explorers, he lost his collections, after which he went
mad and soon died. Theodore Roosevelt, another picturesque fi gure, vis-
ited the Pantanal in 1913.
The environments of shallow wetlands are notoriously variable, even
over short intervals. One of the biological consequences, like unstable habi-
tats on other shifting substrates (e.g., mangroves, coastal dunes), is that
they are not suitable for long-term adaptation and speciation by a wide va-
riety of organisms. Thus, they are usually inhabited by a limited number of
specialist species capable of coping with unpredictable environments. As
noted by Por:
The present conditions are too fl uctuating on a yearly and a secular basis,
and they were probably even more so in the longer range of the Pleistocene
climatic history. Perhaps with the exception of the isolated old hills [with
their caves], there has never been an environmental stability and a defi nition
of isolated areas conductive to in situ speciation. (1995, 39)
Only two endemic plants are prominent here,
Coccoloba cujabensis
(Polygo-
naceae) and
Mentzelia corumbaensis
(Loasaceae).
The Pantanal plays a critical role in fl ood abatement and water fi ltration,
and it provides the habitat for an estimated 656 species of birds, 263 species
of fi sh, 162 species of reptiles that include a population of caimans (
Caiman
yacare
) of over one million individuals, and 95 species of mammals (46 of
which are rare or endangered). These are conservative fi gures and the re-
gion is regarded as a “mother lode of unrecorded life” (Swarts 2000).
It is also true that 98 percent of the land is privately owned, and there is a
proposal for a waterway 3440 km long. The Hidrovia is intended to develop
