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Ecology

Life and death on the sand

Biologists from Rio assess the degree of destruction of 17 restingas (coastal strips), where exclusive species still live

The expedition finished with a melancholy flavor. In the course of five months, 20 biologists covered 1,600 kilometers of Brazilian coastline, from the south of Rio de Janeiro to the south of Bahia. Almost inch by inch, they examined plants and animals that live in the midst of the restinga, where a low and humid vegetation grows on the sand, between the sea and the mountains. They found 12 species of animals that inhabit this environment exclusively, like Xenohyla truncata, 3 centimeter long frog, which hides in the inside of bromeliads. But as they carried on, in the face of swamps and continuous rain, the researchers felt that the satisfaction from the discoveries was being transformed into despondency, as they saw the gradual disappearance of this environment. Luxury condominiums and shantytowns advanced into the coastal strips, which were also used as an illegal waste tip and a clandestine source of sand for the building industry. Where it is still a paradise, the restingas suffered from disorderly tourism and the opening up of parking lots and trails.

Coordinated by four professors from the Rio de Janeiro State University (UERJ) – Monique Van Sluys, Carlos Frederico Duarte da Rocha, Helena de Godoy Bergallo and Maria Alice Alves -, the team that took care of this survey assessed each one of the human activities that threaten the ten coastal strips originally analyzed – five of them in the so-called biodiversity corridor of the Serra do Mar (Sea Ridge) (Grumari, Maricá, Massambaba, Jurubatiba and Grussaí), four in the central corridor of the Atlantic Rain Forest (Setiba, Guriri, Prado and Trancoso) and one in the far south of Espírito Santo (Praia das Neves). Each human action – from the building of roads to the opening up of trails giving access to the beaches – was given a mark, from nil to two, according to the impact on the environment.

The sum of the marks resulted in a first precise diagnosis of the conditions of conservation of the restingas of this piece of the Brazilian coastline. “The restinga with the worst level of conservation is Prado, in Bahia, with 20 points”, Rocha discloses. To be found in an equally critical situation are two restingas in the state of Rio do Janeiro, Grumari and Grussaí, both with 15 points, closely followed by Setiba, in Espírito Santo, and Massambaba, another one from Rio, each with 12 points. “We can now see in a more concrete way the dimension of the damage”, says Luiz Paulo de Souza Pinto, a director of the Biodiversity Conservation Center of Conservation International – Brazil, one of UERJ’s partners in the project.

Although the area of the coastal strips has shrunk 500 hectares between 1995 and 2000 in the states of Rio de Janeiro and Espírito Santo, according to a study by the non- governmental organization SOS Mata Atlântica, there are still stretches in a good state of conservation. Today, the survey covers 17 coastal strips, of which seven are well preserved, three at an intermediate stage, and seven quite degraded (see the map on page 47). “At Trancoso, in Bahia, only the stretch next to the Frade river mouth was left”, Rocha comments. “The rest has already been destroyed.” It is only because they are relatively isolated from towns and from tourists that some areas have still escaped from what seems to be the destiny of this group of seaside vegetation, called the gateway to the Atlantic Rain Forest.

This is precisely one of the problems. Souza Pinto recalls that the restingas have practically disappeared before the Atlantic Rain Forest, a more exuberant vegetation to which they are attached – and one equally devastated since the European colonizers beached their caravels. Even today, the coastal strips are studied very little, although they sprawl over a range of some 5,000 kilometers of the Brazilian coastline, the most occupied stretch of the territory, with 87 inhabitants per square meter, five times the national average.

Formed by sand and other sediments building up on flat regions from which the sea has drawn back over the last 5,000 years, the coastal strips show different features. On sandy soil, poor in nutrients and with high salinity, only trailing vegetation grows, made up basically of grasses – this is the stretch most exposed to human action and the most difficult to recompose, precisely because of the soil. As one draws away from the beaches, bushes and thickets arise, 2 to 5 meters high, with climbing plants, bromeliads and cacti.

Only further ahead, 1 or 2 kilometers from the see, do medium and large sized trees appear, which may get to 20 meters in height, like the tall fig tree, the pau d’arco, purple glory trees and the guapuruvu. “This change in the structure of the coastal strip was already well known”, says Monique. “It is the studies of the vertebrate fauna in the coastal strips that were kept in the background.” This gap has in part been cleared up by this survey. In the course of the expedition, carried out between November 1999 and March 2000, the team from Rio de Janeiro cataloged 147 species of animals that live in the coastal strips. Birds predominate (96 species), followed by amphibians (28 species), small mammals (12) and reptiles (11).

Exclusive animals
The inventory of biological diversity revealed 12 species exclusive to the region – for this reason called endemic -, described by the UERJ team in their book A Biodiversidade nos Grandes Remanescentes Florestais do Estado do Rio de Janeiro e nas Restingas da Mata Atlântica [Biodiversity in the Large Forestry Remains of the State of Rio de Janeiro and in the Restingas of the Atlantic Rain Forest], launched in June by the RiMa publishing house. This is the case of Xenohyla truncata, a frog of up to 3 centimeters in length and weighing a little over 4 grams, which shows an uncommon behavior for amphibians: it feeds on small fruits, besides insects, as it usually happens among these animals, and thus works on the propagation of plants, by spreading their seeds in the Maracá restinga, where it was found.

Then in the coastal strips of Rio de Janeiro from Marambaia to Cabo Frio, there lives a lizard with small brown and orange stripes on its back – this is the Liolaemus lutzae, also called sand lizard. Abundant up to the 70’s, this species is nowadays running the risk of extinction, as its habitat vanishes with human occupation. In some areas, like Prainha, in the municipality of Rio, Barra Nova, in Saquarema, and Praia dos Anjos, in Arraial do Cabo, in the north of the state, the little reptile is no longer seen. Up to 7 centimeters long, without the tail, it is one of the favorite preys for owls and hawks, but it sometimes manages to escape, with a peculiar trick: when persecuted, the lizard drops its tail – the movement that it makes on the sand after becoming detached from the body attracts the attention of the predators, which is how they do not always notice the animal escaping.

Amongst the birds, the only endemic species of the coastal strip is the restinga antwren (Formicivora littoralis), recorded only in one of the areas studied in the state of Rio – and threatened by extinction, due to the accelerated degradation of its habitat. Another species that lives in the coastal strips and also has its survival at stake is the tropical mockingbird (Mimus gilvus). In Latin, mimus means mimic – and its capacity for reproducing songs of other birds is one of the marked characteristics of this bird, which can reach up to 25 centimeters. With its long tail and light gray plumage on its back and white on the eyelashes, it is reminiscent of species from the thrush family, like the rufous-bellied thrush.

Endemism concentrated
In the restingas, the endemic species are concentrated in two regions – evidently, those that enjoy the best state of conservation, still little visited by tourists and the condominiums builders. The first consists of isolated stretches along the 500 kilometers from Linhares and Guriri, in the north of Espírito Santo, to Prado and Trancoso, in the south of Bahia. It is there that one finds, for example, the Cnemidophorus nativo, a lizard with two lateral white stripes and one dorsal one of a salmon color, over an olive green body. Described in an article in the Herpetologica scientific magazine, this species of up to 6 centimeters in length exhibits a characteristic that is rare amongst reptiles: it is made up only by females, which reproduce through a process known as parthenogenesis – the ovum develops into an adult without the need of fertilization by a spermatozoid.

To the south, endemism is high in the coastal strips of Maricá and Jurubatiba, in Rio. It is only there that another small lizard lives, similar to C. nativo, the Cnemidophorus littoralis, shown in the Copeia magazine. “The concentration of endemic species in these regions”, says Rocha, “is probably due to the variations that have taken place over the last 10,000 years in the level of the ocean, which caused populations to become isolated from their ancestors, and so they diverged genetically and came to constitute differentiated species.”

But, after all, will the restingas disappear? If it depends on the researchers from Rio, they will not. In a book that details the discoveries of the expedition, they show what could be done, at least to reduce the human impact. The actions regarded as a priority are: expanding the extent of the regions now protected by law and carrying out more wide-ranging surveys of the species of plants and animals found in the coastal strips, besides developing environmental education programs in the coastal areas.

The researchers are also proposing the transformation of areas with the environment more degraded – like the coastal strip of Grussaí, in the north of Rio, Praia das Neves, in the municipality of Presidente Kennedy, Espírito Santo, and Trancoso, in Bahia – into full protection units, in which only it would only be allowed to carry out scientific research and educational and recreational activities. “In Grussaí, there is still an important remaining area in a good state, which ought to be preserved, although it is small”, Rocha recommends. “The environs are very degraded, because of the irregular occupation of the land.”

According to him, another relic that should be preserved is the coastal strip of Praia das Neves, which boasts a rare wealth and diversity of species, although there is no conservation area yet in the region. The diagnosis of the state of conservation of the coastal strips confirms the relationship between the degree of destruction of an environment and the absence of public policies. In the so-called full protection areas, such as the National Park of the Coastal Strip of Jurubatiba, which includes the most preserved of the coastal strips studied, the predatory action of man is much reduced. Without protection or inspection, though, human impact tends to eliminate the natural vegetation and reduce the chances for survival of the animals that live there. Even the climate in the cities may change without the dunes and the coastal vegetation, which help to regulate the temperature. “The pace of destruction is very rapid”, Monique laments.

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