Analysis of Anthropic Pressure on Urban Mangroves: Subsidies for Environmental Protection and Territorial Planning

Abstract

The mangrove is a transitional ecosystem between terrestrial and marine environments and represents an important ecological indicator for the ecosystem services provided. However, despite its ecological relevance, it still suffers anthropic pressures and has been losing in extent and environmental quality. In Brazil, and specifically in the municipality of Paranaguá, a mix of anthropogenic use has caused significant pressures on mangroves. In this sense, the aim of this study is to assess the degree of anthropization of the urban mangroves in the city of Paranaguá (PR), through the use of very high spatial resolution images, obtained from Remotely Piloted Aircraft in order to support municipal policies for land-use planning. From the methodological point of view, from field campaigns, maps were produced with the aid of QGIS 3.10 software, from the photointerpretation of orthomosaics. The legend of the anthropization classes covered: deposition of household waste (i), rubble (ii), discharge of untreated domestic effluents (iii) and manholes (iv). The results indicated a total of 475 points of anthropic pressure on the 22 mangrove patches analysed. The most prominent class was household waste, followed respectively by untreated domestic effluent discharge, debris (construction material) and, finally, shackle. In conclusion, the use of high-resolution orthomosaics proved to be an important and effective tool in the analysis of anthropization of urban mangroves, thus highlighting the areas with greater pressure and contributing to a continuous monitoring. The products of this research can help in the elaboration of land-use planning instruments for the municipality, highlighting the need for the construction of a holistic view in favor of mangrove conservation.