A survey made almost a hundred records of the smallest alligator in the world at the Taiamã Ecological Station. Until then, the species had restricted occurrence to the surroundings of the biome.
A survey of amphibians and reptiles (herpetofauna) carried out at the Ecological Station (ESEC) of Taiamã made a discovery that surprised Brazilian researchers in the Pantanal of Mato Grosso. For the first time, scientists have recorded the occurrence of dwarf caimans ( Paleosuchus palpebrosus ) in the biome’s floodplain. Considered the smallest species of alligator in the world – males measure an average of 1.7 m and females 1.2 m –, until then, the reptile had records of its occurrence restricted to the surroundings of the biome.
The result, which indicates the possibility that the dwarf alligator is expanding its range of occurrence, has just been published in a scientific note in the Brazilian Journal of Biology , which carried out the first herpetofauna survey at ESEC Taiamã , Conservation Unit (UC ) of more than 11 thousand hectares surrounded by the Paraguay River, and which is located in Cáceres, in Mato Grosso.
The researchers’ objective was to generate a list of amphibians and reptiles present in the ESEC of Taiamã. The article characterized the CU macrohabitat as being composed of floating fields (batumes), flooded fields, lakes, monospecific açaçurana forests ( Erythrina fusca ) and polyspecific forests – which are along rivers –, the latter being chosen as the area of study. “Because they have solid ground in the dry season and a suitable environment for installing traps in the soil”, says an excerpt from the publication.
The survey samplings took place in two different periods: August 2017 and January and February 2018. At the end of the collection, the researchers recorded 11 species of amphibians, 8 species of reptiles, six species of Squamata reptiles (snakes and lizards ) and two species of reptiles from the Crocodylia lineage: the marsh caiman ( Caiman yacare ) and the dwarf caiman ( Paleosuchus palpebrosus ).
“The lack of information on the herpetofauna in the ESEC of Taiamã makes this pioneering article and the results found important in general. Our results indicate that the ecological station may present a diversity of species greater than expected and ecological interactions not yet known for the group of herpetofauna”, said to ((o))eco the specialist biologist in herpetofauna Vancleber Divino, doctoral candidate in Environmental Sciences from the State University of Mato Grosso (Unemat) and first author of the article.
The case of the dwarf alligator
The result of the survey draws attention to the abundant population of dwarf caimans found in the Pantanal floodplain. In total, 99 records of the species were made at the ESEC in Taiamã. The index was even higher than the occurrence of marsh alligators, which had 85 records.
“We observed that individuals or groups of Paleosuchus palpebrosus (dwarf caiman) were close to the river bank, where there were branches, trunks or roots of bushes or trees, while Caiman yacare (swamp caiman) was found mainly in open areas, like small canals and bays”, adds another excerpt from the article.
At ((o))eco, biologist Jessica Rhaiza Mudrek, PhD in Ecology and Biodiversity Conservation at the Federal University of Mato Grosso (UFMT), and second author of the scientific note, says that the occurrence of dwarf caimans in the floodplain represents a novelty for the natural history of the species. “It is a kind of nocturnal species, the smallest species of alligator in the world. It is usually associated with small, narrow, flowing streams . That’s why it’s a surprise […] it’s unprecedented”.
According to the article, until then, studies had stated that the occurrence of the species was restricted to the surroundings of the wetland of the Pantanal, and there were no records inside the floodplain of the biome, as the researchers found. In 2004, for example, a study by Embrapa addressed the presence of the species in Serra do Amolar, a region located on the edges of the biome.
As this is a survey, the researchers did not analyze the factors that may have contributed to the occurrence of the dwarf caiman in the Pantanal floodplain. However, Mudrek says that this could be related to the adaptation of the species: “It could be expanding its range, adapting to new environments”, he adds.
For the biologist, the discovery reinforces the importance of preserving the ESEC of Taiamã as well as all the biodiversity sheltered by it. “One more reason to preserve”, she concludes.
Threats to the Taiamã ESEC
Considered one of the most fragile and conserved parts of the Pantanal, the Taiamã ESEC is surrounded by a silent threat: the advancement of projects that foresee the construction of ports and, also, the consolidation of the Paraguay-Paraná waterway. As ((o))eco showed , only this year two projects of this type received a preliminary license for implementation in this river, which, in addition to being the main source of the Pantanal, is also the river that surrounds the Taiamã ESEC.
The risk resides in the fact that the installation of ports, also as shown in a report by ((o))eco , must force permanent dredging, removal of rocks, curves and even islands of vegetation, to “rectify” the river and ensure navigation in the watercourse. With this removal of natural barriers, more water should flow into the river, which could reduce the annual flooding that keeps the Pantanal alive.
Geographer Clovis Vailant, a member of the Gaia Institute, an NGO from Cáceres (MT) that works in defense of the Pantanal, explains that CUs such as ESECs are important for preserving what is most important in Brazilian biomes. “An ecological station is always a conservation unit with restricted use. They are very important in the sense of representing what is most significant and representative for that ecosystem where it is established”, he explains.
In the specific case of the Taiamã ESEC, he highlights the unit’s role as a support point for research aimed at the conservation of the biome: “This new discovery reinforces the importance of this type of unit for the general conservation of the Pantanal”, he concludes.
Fonte: https://oeco.org.br/reportagens/pesquisadores-fazem-registro-inedito-de-jacare-anao-na-planicie-inundavel-do-pantanal/
