RESUMO
Sandy beaches are land-sea transitional habitats experiencing 'multidirectional' habitat loss due to coastal developments (e.g. armoring and/or conversion of natural vegetation into manmade structures) and beach erosion. This 'coastal squeeze' is a chronic and progressive process; however, its impacts on beach biodiversity across morphodynamic gradients are still to be unveiled. We hypothesized that the effects of multidirectional habitat loss would be more severe on dissipative than on reflective beaches, due to the higher elevation, amount of built up sediment, and width of the backshore compartment of the latter. We, thus, examined the effects of coastal developments and erosion on density and size structure of the Atlantic ghost crab, Ocypode quadrata, on beaches with different morphodynamics. Given that the living area of ghost crabs spans all cross-shore compartments and the whole dissipative-to-reflective morphodynamic gradient, they are appropriate organisms to access the synergic effects of coastal developments and beach erosion under different morphodynamic regimes. On dissipative beaches, density and mean crab size increased with moderate erosion, attributed to the effects of space loss, which might increase territorial competition, favoring the remaining larger individuals. However, mean size and density decreased with high erosion given the more intense reduction in the abundance of large-sized crabs living in up-shore habitats. Mean crab size also decreased in the presence of coastal development while crab density did not vary with loss of backshore habitats occupied by larger individuals. On reflective beaches, both density and crab size decreased with coastal development; the crab size decrease recorded under moderate erosion was more evident in the presence of coastal development. Under high erosion, mean crab sizes declined, reflecting those under low erosion conditions. Overall, populations on reflective beaches appeared more resilient to extreme erosion. Notwithstanding, coastal developments affected population structure across all beach types, and especially in areas subjected to high erosion, exhibiting a synergic effect. We predict that, in combination, these stressors may lead to functionally extinct populations where conditions necessary for individuals to reach sexual maturity (i.e. occurrence of only small-sized and immature individuals) are not met. Thus, the connectivity between water, beach compartments and dunes/coastal plain, on both local and regional scales, may be essential to maintain viable and connected populations of ghost crabs. Further, our results strongly suggest that both size and density (complemented with crab abundance) must be considered equally important and in combination in future efforts to assess anthropogenic stressors on ghost crab populations and when guiding conservation strategies and policies to prevent their local and regional extinctions.
Assuntos
Braquiúros , Humanos , Animais , Densidade Demográfica , Praias , Ecossistema , BiodiversidadeRESUMO
Environmental Education Programs (EEPs) are considered environmental management tools in Brazilian environmental licensing processes, within the scope of mitigatory and compensatory measures to the social, environmental, and economic impacts caused by development projects or new enterprises. Here, we assess the perceptions and expectations regarding environmental education programs of three groups of actors (communities, environmental managers, and environmental agency technicians) involved in the licensing processes of port activities in the region of Paranaguá, in the State of Paraná, Brazil. Paranaguá is the largest coastal municipality of the state of Paraná, in the southern region of Brazil, and is home to Brazil`s second largest port. Since this is environmental conservation area, the conflicts between the port activities, environmental protection and needs of the local communities require efficient environmental management practices, with EEPs as one of their main implementation tools. The evaluation was based on semi-structured interviews which were analyzed using the methods of content analysis and discourse of the collective subject. The actors understand that environmental education is a potentially effective tool to promote the mitigation or compensation of environmental impacts generated by port developments undergoing licensing processes. The groups considered that the continuity, promotion of social organization, and correlation with the actual environmental impacts related to each enterprise are essential qualities for good EEPs. The evaluated perceptions were complementary and indicate a complex but effective ideal scenario for EEPs in the region.
Assuntos
Conservação dos Recursos Naturais , Brasil , CidadesRESUMO
The influence of short-term (daily) variation in environmental conditions (rainfall, wind, tide, river flow) on debris accumulation was examined on two beaches at an estuarine outlet. Sampling occurred over 60 consecutive days along two sections (Internal Area, IA; and External Area, EA) of the Paranaguá Estuary Complex's southern outlet, in Paraná, southern Brazil. The IA is sheltered from direct wave action, whereas the EA is more exposed to wave and wind action from the open ocean. The IA accounted for 71% of the total debris, while the EA accounted for 29%. Debris abundance was highest after intermediate bouts of rainfall, although river flow only affected debris accumulation in the IA. Wind and tide influenced accumulation differently across sites. These results highlight the importance of short-term variation in the accumulation of marine debris on sandy beaches, which should be considered when designing and monitoring assessment programs and removal strategies.