Análise multitemporal da superfície de manguezal do litoral Norte de Pernambuco : a participação da Aquicultura na conversão de áreas de mangue em viveiro

Abstract

The conversion of mangrove areas to nurseries in Brazil has been reported since the 18th century, mainly in the Northeast region. Due to this history and in addition to the rapid growth of Brazilian shrimp farming, this activity has been blamed for losses of mangrove areas along the Brazilian coast. In order to determine the true participation of aquaculture in this process, a multitemporal study of the mangrove cover of the northern coast of the State of Pernambuco was carried out using remote sensing and geographic information system (GIS) techniques. The time series analyzed were from 1973 to 2005, using satellite images obtained from different sensors (MSS / LANDSAT-1 - 1973; TM / LANDSAT-5 - 1988; TM / LANDSAT-5 - 1999; ETM + / LANSAT-7 - 2001 and CCD / CBERS-2 - 2005). For the mapping of mangroves, only the areas covered by mangrove vegetation were considered, with apicum classified with a distinct class of mangrove class. The study identified that the extension and distribution of the mangrove forest varied considerably during the last three decades in the studied area, with different phases, characterized by the increase and reduction of the mangrove cover. The results obtained were: 1973 = 7,101ha, 1988 = 5,821ha, 1999 = 6,442ha, 2001 = 6,187ha and 2005 = 6,575ha. The areas occupied by nurseries were also evaluated and presented an exponential growth, the latter being more pronounced in recent years, with the following values: 1973 = 0ha, 1988 = 7ha, 1999 = 366ha, 2001 = 1,157ha and 2005 = 1,474ha. The study showed that between 1973 and 2005, there was a reduction of 2,052ha of mangroves, of which 197ha were reduced by conversion to nurseries. In this way, it is possible to affirm that the real contribution of shrimp farming in the conversion of these areas was 9.6% of the total area reduced and that other activities of anthropic origin, such as agriculture, urban expansion and tourism were the main responsible for this scenario Of reduction of mangrove areas in the northern coast of the state of Pernambuco