Study: Brazil Has More Species of Fish

[piaba <piabinha at yahoo_com>]

May 12, 2003
Study: Brazil Has More Species of Fish
By THE ASSOCIATED PRESS

 
Filed at 11:40 a.m. ET

RIO DE JANEIRO, Brazil (AP) -- It's not the case of
the one that got away but of the thousands of fish
that until now escaped scientists' grasp. A new study
shows that Brazil -- thought to have the world's
greatest variety of freshwater fish -- has more than
twice as many species as had been thought.

It was estimated the country's massive rivers and
flood plains were home to 1,300 or so species, but a
six-year survey now nearing completion has catalogued
nearly 3,000 strains. By comparison, the United States
has only about 790 species and China is estimated to
have 700-800.

Scientists found entirely new species -- including one
with a quirky way of luring female fish. But they also
found their work was more urgent than expected since
Brazil's fish are vanishing at an alarming rate due to
forest destruction that robs rivers of nutrients.

``How can we know what needs to be preserved if we
don't even know how many species exist?'' said Naercio
Menezes, a professor at the University of Sao Paulo
who coordinated the survey.

The government-funded study also examined Brazil's
vast Atlantic coast, but it turned up fewer surprises
because the saltwater species are better known.

Since 1997, researchers from four major Brazilian
universities have conducted more than 30 expeditions
to rivers, lakes and streams in the nation's
heartland, collecting some 50,000 specimens.

The surprises began when scientists started simply
adding up the number of species documented by
researchers working separately at different
institutions across Brazil -- something no one had
bothered to do before. The number of recorded species
was more than double what was believed.

But the survey also found hundreds of species that
were unknown to science. Menezes estimated the number
of new species at 10 to 15 percent of the total.

Researchers expect the final tally to take years,
because of the time required to describe and catalogue
new species.

A scientific description of one new species,
Hyphessobrycon heliacus, already has been published in
the scientific journal Copeia. The fish is a
golden-colored tetra, just 1.26 inches long, with
yellowish-red fins and a large black spot on its tail.

Another as-yet-unnamed species, a tiny bluish fish
measuring about 1.5 inches, is to be described in the
prestigious scientific journal Proceedings of the
Biological Society of Washington.

Scientists say the species is unique because the
sexually active males have a special gland on their
anal fin which secretes pheromone, a substance that
excites females of the species during courtship.

No other known species has such a gland on that fin,
said Stanley Weitzman of the Smithsonian Institute in
Washington, D.C., who is a co-author of the fish's
scientific description.

``It's giving us a new view on the diversity of fishes
in South America,'' he said.

Weitzman said that one reason for the diversity in
Brazil is its varied geological and climatic history.
Isolated by elevation and accompanying temperature
differences, fish were separated by natural barriers
that allowed species to evolve differently over
thousands of years.

``Some waters are acid, others are neutral or somewhat
alkaline,'' Weitzman said. ``There are so many
tributaries to the main Amazon river, many with a
different ecology.''

To make the most of their limited resources,
researchers concentrated on the headwaters of
little-studied rivers in Brazil's remote interior.
Given the nation's sheer size -- larger than the 48
continental United States -- they believe many species
remain to be discovered.

But the study also suggested what scientists had
feared: A number of species may have disappeared for
good, victims of pollution and deforestation.

``We have to document what exists as rapidly as
possible,'' said Menezes. ``We are convinced there are
species that have already disappeared without being
scientifically described.''

The inventory, which is being put on the Internet,
will allow users to create distribution maps showing
where the fish live. Researchers hope the documented
existence of rare species will encourage policy-makers
to preserve them.

``There's a very direct link between the health of the
forests and the number of fish in the rivers,'' said
Paulo Buckup of Rio de Janeiro's National Museum, who
is in charge of putting the catalogue on the Internet.

Buckup said the number of species in a well-forested
area can easily reach 70 or 80, dropping dramatically
to just four or five in an area where the surrounding
forest has been cut down.

The loss of forests changes the alkaline balance in
the rivers, he said. Some fish also live on the fruit
that drops from trees, and when the trees are gone
they starve.

The expansion of agriculture, especially soybeans,
also has hurt the fish population as pesticides kill
insects that are an important food source.

------

On the Net:

http://www.mnrj.ufrj.br/catalogo/


__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo.com