TOXINOLOGY AND BIODIVERSITY OF THE CAATINGA

JARED C., ANTONIAZZI M.M.(1)

(1)Laboratory of Cell Biology, Instituto Butantan, São Paulo.

The Caatinga, the semi-arid region, constitutes a morphoclimatical domain embracing about 800,000 km2, representing 70% of the north-eastern area and 11% of the Brazilian territory. It is characterized by high temperatures and limited, unpredictable rainfall (300-800 mm/year) from January to March. The soil is sandy and rocky and the landscape is marked by sparse emergences of naked igneous rocks. The vegetation is composed by an expressive proportion of endemic species and is characterized by thorny, xeromorphic bushes and small trees with small leaves, and by an abundance of cacti. For most of the year the landscape remains brownish. After the rare occasions when rain falls, the vegetation rapidly becomes green and flourishes for a brief time. Because the rivers are all temporary, during the dry seasons, water supply is only available in weirs or in waterholes, usually dug at the riversides or in the dry riverbeds. In the fauna there is also a considerable number of endemic species. The herpetofauna is particularly abundant with 97 reptile species and 45 amphibian species, representing an important source for toxinological studies. Birds are represented by around 200 species. Mammals are less abundant with a few endemic species. The Caatinga is being severely affected by human activity and, due to the substitution of natural vegetation for plantations, the soil is passing through a gradual process of desertification. This brings serious consequences for maintenance of biodiversity, in special of the endemic species which are more susceptible to environmental modifications. In the last two decades, our group has dedicated special attention to the amphibian fauna of the Caatinga, studying many species and integrating data about their natural history, skin morphology and cutaneous secretion toxinology. With these studies we intend to contribute to the general knowledge of the amphibians of the semi-arid and, in particular, to indicate promissing species to be studied by the toxinological viewpoint.

KEY WORDS: Caatinga, semi-arid, biodiversity, toxinology, cutaneous secretions.

FINANCIAL SUPPORT: CNPq.

CORRESPONDENCE TO: Carlos Jared, Instituto Butantan, 05503-900, São Paulo, Phone: 11 3726-7222 ext. 2234, E-mail: jared@usp.br