Análise ecológica da ostracofauna (crustacea) e meiofauna bentônica associada como bioindicadores ambientais na ilha de Cotijuba, Belém (PA), Amazônia

Abstract

The uncontrolled occupation of environmental protection areas (APA) in Belém-PA and candidates for APA, such as Cotijuba Island, has intensified the environmental impacts in the region. To mitigate these effects, Conservation Paleobiology integrates historical data on the distribution of fauna and flora, connecting past, present, and future. In turn, ostracods, small crustaceans sensitive to environmental variations, which are part of the benthic meiofauna, provide information about changes in ecosystems through the analysis of their communities and shells, formed from the calcium carbonate in the water. In this way, the survey of the ostracofauna and associated meiofauna on the island of Cotijuba allowed the use of these groups as bioindicators. The research was conducted during the rainy, transitional, and less rainy seasons, at two beaches: Flexeira, less impacted, and Farol, more influenced by human activities. During the campaigns, surface samples were collected in the inframarine, intertidal and supramarine zones, as well as sediment cores, physico-chemical water measurements, and beach profiles. The results showed Farol beach as reflective and Flexeira beach as dissipative, in addition to physical-chemical parameters with low influence on the organisms. The benthic meiofauna recorded 10 distinct classes: Oligochaeta, Polychaeta, Insecta (Diptera and Trichoptera), Malacostraca (Amphipoda), Arachnida, Ostracoda, Hydrozoa, Gastropoda, Bivalvia, and Rhabditophora. Approximately 84% of the specimens are from Flexeira beach, with this proportion being higher when only ostracods are analyzed (89%). Despite the lower abundance at Farol beach, a large number of cocoons of Trichoptera pupae were observed, known for their sensitivity to pollution and environmental changes, indicating a relatively healthy environment. However, a low abundance of ostracods was observed, which may be related to abiotic factors, such as the type of beach and coarse sediments. Moreover, the overall abundance of meiofauna in Cotijuba was also considered low, even without indications of significant anthropogenic intervention, which suggests a relationship between the low number of specimens and hydrodynamic conditions that intensify erosive and depositional processes. The record of a new species is highlighted: Cyprideis cotijubensis sp. nov., as a potential bioindicator of recent ostracofauna in river estuaries in the Amazon. The project also resulted in the digital book “Cartilha Digital Preserva Amazônia”, aimed at raising awareness about the conservation of the Amazon.