Save the Rio Aripauna Ecosystem

The rain forests of Brazil are well known for their biodiversity, but the Rio Aripuana basin is especially rich in species.  (The Rio Aripuana is a tributary of the Rio Madeira which in turn is a tributary of the Amazon River.) At least 181 species of mammals (half of which are bats), and over 600 species of birds live in this region.  The Amazon River basin hosts an astounding 750 species of fish.

Location of the Rio Aripuana.  The satellite photo is of an island in the middle of the river where a new species of plant was found.

Photo of Rio Aripuana shoreline.  The Rio Aripuana ecosystem includes closed canopy forests, seasonally flooded forests, savannah woodlands, and an environment local scientists refer to as white sand savannah.  This region was geographically isolated from the rest of South America for over a million years resulting in numerous examples of speciation.

The Rio Aripuana basin has a geological history of shifting river systems and lakes.  A massive prehistoric lake and a network of white water rivers cut off the Rio Aripuana region from the rest of South America about 1.2 million years ago.  The resulting isolation caused many ancestral populations of mammals to evolve into new species.  Less than 10,000 years ago, the Madeira River changed course and became a tributary of the Amazon River causing a drainage of the prehistoric lake into the mighty outlet.  The former lake bed became the Tenharim Savannah which proved to be no barrier to wildlife.  Common mammals from elsewhere on the continent colonized the dry savannah woodlands adjacent to the Rio Aripuana basin.  Many of the colonizing species are in the process of outcompeting the endemic species that evolved here in isolation.  The region is a living laboratory of evolution.

The biogeographical history of the Rio Aripuana ecosystem explains why there are so many different species of closely related mammals here.  Within the last 15 years Marc van Roosmalen, a world renowned primatologist, has identified 12 species new to science, and he claims there are an additional 18 more, but not enough information is known yet to designate them as accepted new species.  I should note that some scientists are doubtful about the true status of many of these species, and they believe some merely deserve subspecies status.  Genetic studies of new species of peccary and brocket deer suggest they split from their closest living kin 1.2 million years ago–the approximate time that the region became isolated.  Some scientists disagree with this interpetation, however.  The new species accepted by most scientists include 4 kinds of marmosets, 3 of titi monkeys, the giant peccary (Peccari maximus), a dwarf porcupine, a dwarf manatee, a dwarf tapir, the fair brocket deer, and a new species of Brazil nut.  Dr. Roosmalen also believes there are at least 13 additional species of monkeys, a tree-climbing giant anteater, a black giant otter, an orange coatimundi, and most excitingly, a large species of black jaguar with a white throat–all possibly new to science.  Species of birds, large-fruited plants, and mussels, all unknown to science, are thought to occur here too.

Photo of the giant peccary.  Genetic studies suggest it split from collared peccaries about 1.2 million years ago.  It is on average 33% larger than a collared peccary and doesn’t root as much for its food.  Canines show less wear.  Collared peccaries and white-lipped peccaries colonized the region within the last 10,000 years and co-exist with the giant peccary.  Dr. Roosmalen believes 2 additional species of peccaries new to science also live here, but not enough evidence has been found to designate them as new species. Some scientists aren’t convinced the giant peccary is a unique species, and think it’s merely a large subspecies of collared peccary.

Prince Bernhard’s titi monkey (Callicebus bernhardii).  Dr. Roosmalen named some of his new species after generous benefactors.  Officials in the Brazilian government did not like this at all.

Dwarf manatee (Trichesus pygmaeus).  They evolved to a smaller size because the waterway where they became isolated  provided less food than the region their ancestors lived in prior to 1.2 million years ago.

Amazon pink dolphin (Inia geoffrensis).  This fascinating species has a flexible neck and a long snout built to help them navigate through flooded forests and extract fish hiding in holes.  Only the males are pink.  The pink color is scar tissue from fights between males over mating rights.  Ignorant fishermen kill them for catfish bait.  Freshwater dolphins have evolved independently in 4 different regions in the world–a great example of convergent evolution.  Sadly, the Chinese freshwater dolphin is now extinct due to pollution.  China is an environmental apocalypse.

This skull of a  big cat is the only scientific evidence of the black white-throated jaguar.  It’s canines are larger than the species of jaguar known to science.  The natives know it literally (in translation) as the black- white-throated cat-that-is-bigger-than-a-jaguar-and-hunts-in-pairs.   They hunt in pairs and recently a pair killed a 9 year old girl.

Presently, the Rio Aripuana region is officially considered a “sustainable development reserve.”  This means that some areas are protected, but logging, gold and gravel mining, cattle ranching, and soybean and sugar cane monoculture are allowed.  Dr. Roosmalen believes the area is deserving of full protection under National Park status.  The Brazilian government is about as progressive when it comes to environmental issues as the United States, perhaps more so.  Brazil has slowed the rate of deforestation, and they have strict rules for hydroelectric projects.  When rivers are dammed, they are designed not to flood large areas with reservoirs, and fish ladders are constructed to help migratory species reach their ancient spawning grounds.  On the other hand the Brazilian government oppresses scientific research with ridiculous regulations, and protected areas are underpoliced.  Reportedly, they only employ 5 botanists…for the entire Amazon!  Squatters destroy about as much land as government-approved, corporate-owned projects.

Much of accessible Brazil probably looks like this.  The government protects forests on hillsides and the land immediately adjacent to the hills.  Land is cleared for cattle ranching and sugar cane or soybean fields near roads.  This is good for animals that thrive in fragmented habitat.  But it’s not enough land for some species of monkeys which will eventually die out from inbreeding.

The Rio Aripuana region has survived partial development in the past.  Some of the richest soils in the area have an anthropogenic origin.  Indians enriched the acidic forest soils with a combination of compost, charcoal, and ground mussel shells. These sophisticated agricultural practices made them successful farmers. Much of the wilderness actually grew back after European diseases decimated the Indian civilizations here.  This land is resilient.  Hopefully, the Brazilian government will do more to protect this unique ecosystem where there seems to be at least 2 of a kind of everything.


4 Responses to “Save the Rio Aripauna Ecosystem”

  1. jrobertsmith Says:

    I despair of us protecting anything left in the natural world.

  2. jrobertsmith Says:

    Also…that jaguar skull looks almost like that of a scimitar cat!

  3. markgelbart Says:

    Scientists are afraid the ecosystem there is going to be destroyed before they have a chance to catalogue all the unique species in it.

  4. Kester Pereira Says:

    The diversity in the Amazon region needs to be protected. In doing so, the government should focus on people-centered development.

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