Navegando por Assunto "Anthropogenic impact"

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Acesso aberto (Open Access)
Diversidade de insetos aquáticos em riachos urbanos: a importância de fragmentos florestais
(Universidade Federal do Pará, 2024-12-13) JORDAN BOUCHON, Yildiz Thais; BEASLEY, Colin Robert; http://lattes.cnpq.br/6310836748316181; HTTPS://ORCID.ORG/0000-0003-1413-1469; QUINTEIRO, Fábio Batagini; http://lattes.cnpq.br/1531054078905516
Urban expansion is a reality in the Amazon biome, which has transformed aquatic ecosystems, with a decrease in water quality and a reduction in the diversity of organisms. Groups of species, such as aquatic insects, can indicate the biotic condition of the ecosystem through the frequency and occurrence of taxa indicators. The environmental disturbances caused by urbanization can be detrimental to the survival of some sensitive aquatic insects in Amazon rivers. The aim of our study was to evaluate the environmental condition and diversity of aquatic insects in streams in secondary forest and urban streams in the municipality of Bragança, Pará, Brazil. Data on insect groups, environmental variables and levels of disturbance (using the Habitat Integrity Index, HII) were collected between October and December 2023. A total of 423 individuals were collected, 69 in the streams of the secondary forest and 354 in the urban streams, distributed in the orders Ephemeroptera, Trichoptera, Odonata, Diptera, Coleoptera and Hemiptera. Twenty-two families were recorded in urban streams and 12 families in the secondary forest. The patterns of abundance and richness showed a decrease as the months progressed in both environments. The BergerParker dominance index in both environments showed an increase as the months went by, indicating a change between the insect communities. On the other hand, the Margalef diversity index in both environments decreased over the months. According to the levels of environmental disturbance assessed, both environments were classified as “altered” (IIH<0.70) A positive association was demonstrated between the abundance of Hydropsychidae and the variables of electrical conductivity and total dissolved solids. Environmental variables such as electrical conductivity, total dissolved solids, phosphate and dissolved oxygen are associated with variation in the composition of aquatic insect groups. Strong relationships were recorded between the distribution of Gomphidae and phosphate concentrations. Corduliidae was related to total dissolved solids and electrical conductivity. Coenagrionidae and Caenidae showed positive responses to dissolved oxygen. The study showed a greater number of aquatic insect families in the area with strong anthropogenic pressure than in the secondary forest area, possibly due to a high diversity of microhabitats. In addition, urbanization factors could be negatively affecting both environments.
Acesso aberto (Open Access)
Relationship of Neotropical otter vestiges with environmental and anthropogenic factors
(Instituto Nacional de Pesquisas da Amazônia, 2019-09) COSTA, Ana Marta Andrade; ARCOVERDE, Danilo Leal; ALBERNAZ, Ana Luisa Kerti Mangabeira
The Neotropical otter, Lontra longicaudis (Mustelidae) is a semi-aquatic mustelid that exploits a variety of freshwater habitats. To understand the relative influence of human activities and environmental factors affecting its distribution and habitat use, we conducted systematic, seasonal surveys of otter signs along the middle Guamá River, in Pará state in the eastern Brazilian Amazon. We applied generalized additive models to compare distribution of otters along the river with data collected on environmental factors (landcover type derived from satellite imagery, and in situ measurements of physicochemical water characteristics) and anthropogenic factors (fishing gear in the river and human habitation along the river). Most otter signs (indicators of otter habitat use) occurred along the shoreline of the main river channel during the dry season; we observed fewer signs during peak flow, probably because the shoreline and floodplain are flooded, which hid signs and made access to the floodplain difficult. The best-fit model included variables for proportion of forest, presence of fishing gear and boats, bank steepness, and presence of rock formations and sand banks. Otter occurrence was negatively related to forested area and positively related to the presence of fishing gear and boats. Otters are likely attracted to fish trapped in fishing gear because they can easily predate on the trapped fish.