TROPICAL FJORD : SACK OF MAMANGUÁ
PARATY - RJ - BRAZIL
POR : ROBERTO ÁVILA BERNARDES
In the last decades the human occupation, as well as the industrial and exploratory activities in the Brazilian coast have been contributing to the degradation of the environment and of the natural resources you renewed.
The superexplotacao produced highly by the fishing activity through techniques destructive, as the nets of I drag of fund, it has been causing reductions in the coastal stocks in alarming rates. The action of those fishing nets interferes in the balance of the populations, because they capture very young individuals and they also destroy the alimentary resources of the same ones, provoking low food readiness for the fish and other organisms that compose the alimentary chain. As a result of that, it happens a fall in the natural productivity and ecological and economically important elimination of species, with aggravating social consequences.
In 1989, the Oceanografic Institut of São Paulo's University began a great project on the Ecosystem of the Sack of close located Mamanguá to the city of Parati - Rio de Janeiro, that behaves as a system estuarino-lagunar with low circulation of water and muddies sediment, presents a swamp to the fund, beaches along its extension and small rivers. The Atlantic forest, that surrounds the area, possesses quite conserved natural characteristics.
During that project it was studied the diversity bioiógica, the readiness of nutritious elements and the hydrodynamic of that atmosphere. Degradation signs and alteration were observed due to the human action felt mainly by the low readiness of the fishing resources. It was heard several complaints of the community caiçara with relationship to the disappearance of the fish. For two years of research we observed that 100 fish species, 3 shrimp species, 2 siri species and several species of another organisms live permanent or temporarily in Mamanguá, that constitutes an important ecosystem for the survival and conservation of those species, serving as reproduction area, protection of juvenile and adult, besides feeding area.
However, an intensive fishing has been practiced in that it sets, placing in risk the permanence and development of the species and affecting, directly the fishing production and the quality of life of the community Caiçara.
For being of a restricted atmosphere in its form and of a predatory fishing the fishing of the casuao, that fact becomes more added difficulty. The own fishermen are unanimous in saying that the fishing stock reduced enough in the last years. With that, the fishing activity comes if turning precarious, bringing as consequence the retraçao in the family income and the people's displacement for the city, in search of other sources of income.
If that fishing continues, in little time the fauna of Mamanguá will be so committed, that will be difficult to revert the process. Starting from that verification, we felt the need to develop some work for recovery of the marine fauna and protection of that area.
In August of 1991 I began studies in search of techniques, when through bibliographies, I discovered among other, the artificial reefs. It is close to they Love " her " Association of the Inhabitants and Friends of Mamanguá, represented by Moraes Bjorkstrom's, sociologist Elizabeth, Roberto, it was initiate a discussion work on that technique with the community caiçara, involving the Clerkship of the environment of Paraty and Municipal City hall.
In 1992, the first prototype was placed in the water and in nine months it was observed that the tires were totally covered by algae, anemones and other organisms, what checked the effectiveness of the technique. The following year, in a fortnight of environmental education on the ecosystem of Mamanguá accomplished in Paraty, they were exposed the projects of " IOUSP " and the one of Artificial Reefs with lectures to the fishermen and population.
In July of this year, in a debate in ECOTV of Paraty, with the presence of fishermen, Secretary of the environment, a Representative of the Captaincy of Portos and Representatives of the City hall of Angra dos Reis, aspects of the fishing were discussed and of the project of artificial reefs. The same exhibition is now no Oceanografic Institut of USP, that gave total support to the project.
Tends in view the difficulty of the competent organs in inspect and to preserve the coastal area, the solution would be to implant artificial reefs in strategic points of the coast to recover the degraded fauna.
Its main functions are:
- To increase the natural productivity for the readiness of new habitats for organisms sésseis or fixed, and for the establishment of an associated alimentary chain;
- To protect juvenile organisms and areas of reproduction area of the action of the fishing nets;
- To supply e/ou to recover the fishing resource of the communities caiçaras and to limit the fishing in areas where the commercial fishing competes with the handmade.
Some countries as United States, Indonesia, Japan and other, worried with the conservation and increase of the natural resources, they have already been implanting there are some decades the artificial reefs as mechanisms to alleviate problems of readiness of resources, as food source, employment, income and recreation. However, the most important qualification for them is its economic viability and its contribution for the good to be social of the people involved with the handling and use of them.
Success signs blunt for organisms that live in the fund of the sea, as lobsters, octopi, shrimps and fish. Futuramente, is waited that constitute a natural submarine laboratory for the development of ecology studies, for the academic ensilio and for the lazer.
Many reefs are built with discarded materials, as car carcasses or ships. However, some can pollute the marine atmosphere for the chemical reaction with the water of the sea and to inhibit the growth and to alter habitats, due to its s toxic. Experiences have been showing that old tires are the most appropriate, due to the bass cost, physical and chemical stability under the water, that is to say, they don't pollute, high durability. The number of cavities and proportionate surfaces, and for the easiness of I handle.
Concrete structures present excellent characteristics physical, big durability and chemical stability, but its use is limited by virtue of the high cost. That material type is more employee in Japan. An experience was also accomplished in the llhas Cánárias mainly Gran Canária that suffered larger destruction due to the tourism.
Developed by the American Museum of Natural History of New York, in that 10 nets inserted with 150 biocos of concrete were installed. In three months they already appeared fish.
The knowledge on the behavior and aspects of the cycle of life of the marine organisms is extremely important for the determination of the types of structures they be she installed, in the way and of the size of the reef. The results are observed the medium and short periods in the measure in that will be impeded the trawlnet of the commercial fishing in local specific and they will be available new habitats for the recruitment and colonization for the fauna and marine flora.
CHARACTERISTICS AND LOCATION
Some physical characteristics are important and they should be considered in the choice of the best structure, as height, horizontal extension, design, orientation, space arrangement, number of cameras and openings, I space instersticial and texture of the material.
The reefs are formed by modules and each module built with subunits formed by 4 tires. Each subunit has a height of 70 centimeters on the average, and the number of subunit of each module is determined in agreement with the local depth and variations of tides. The modules are anchored with poitas in stone or concrete.
A planning fact close to the community caiçara will favor the handmade fishing, because the placement points will be certain strategicly. The idea is to do with that the community caiçara wraps up with the project of form totaly and participating to be continuos. And, at the same time, to create understanding about the viability of a maintainable development in the area.
The reefs substitute old rudimentary techniques of attraction and aggregation of fish, since they promote the recover, of the alimentary chain.
Such techniques consist of the placement of wood logs and branches of trees in the fund of the sea, just working as snare, could cause like this the over fishing and elimination of the species.
Now, the project needs the approval for the DHN-department of Hidrografia and Sailing of the Navy - for the installation, besides financing for the implantation and manegenent, since it is an initiative without direct institutional entails, just counting with the support of IOUSP, of the City hall of Paraty of handmade fishermen.
The knowledge on the aspects of the cycle of life of the marine organisms is important to determine the types structures they be she installed, in the way and of the size of the recífe.
The Project " Artificial " Reefs, in spite of being an innovation for a community in way of traditional life as the community cai,cara, it is recognized by them as being a technical eficientc for the recolonizaçao of the marine fauna, according to sociologist Elizabeth. Her confirm that with two depositions, as of the Mr. Afonso Espíndola, born and servant in the margin west of the Sack of Mamanguá, that always when it is consulted on the subject, he/she affirms: " In my almost 70 years of fishing safe cost that passed some months under water the reef will attract many fish and everybody will want to fish knowing quc there he/she has fish hiden.
As well as him, other pescádor that was born at the margin east of the Sack, Big Benedito, says that " is alone to wait the time of incrustacao in the pncus to fill near of fish the reefs ". And complete: " Who won't like they are the ships of I drag, but for the small fishermen it is the best than it can happen.
Oc. ROBERTO ÁVILA BERNARDES, Dr.
ONG : The Inhabitants' Association and Mamanguá Friends - AMAM (011) 3064-1861