905 resultados para Human ecology - History


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Marine inshore communities, including biogenic habitats have undergone dramatic changes as a result of exploitation, pollution, land-use changes and introduced species. The Firth of Forth on the east coast of Scotland was once home to the most important oyster (Ostrea edulis Linnaeus, 1758) beds in Scotland. 19th and early 20th century fisheries scientists documented the degradation and loss of these beds, yet transformation of the wider benthic community has been little studied. We undertook archival searches, ecological surveys and shell community analysis using radioisotope dated sediment cores to investigate the history of decline of Forth oyster beds over the last 200 years and the changes to its wider biological communities. Quadrat analysis of the present day benthos reveal that soft-sediment communities dominate the Firth of Forth, with little remaining evidence of past oyster beds in places where abundant shell remains were picked up by a survey undertaken in 1895. Queen scallops (Aequipecten opercularis Linnaeus, 1758) and horse mussels (Modiolus modiolus Linnaeus, 1758) were once common within the Forth but have also markedly decreased compared to the earlier survey. Ouranalyses of shell remains suggest that overall mollusc biomass and species richness declined throughout the 19th century and early 20th century, suggesting broader-scale community change as human impacts increased and as habitats degraded. Inshore communities in the Firth of Forth today are less productive and less diverse compared to past states, with evidence suggesting that most of the damage was done by early bottom trawling and dredging activities. Given the pervasive nature of intensive trawling over the past 150 years, the kind of degradation we document for the Firth of Forth is likely to be commonplace within UK inshore communities.

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In 1991, the National Trust of NSW classified the Regeneration Reserves surrounding the City of Broken Hill as an essential cultural heritage asset of the City of Broken Hill, and in 2015 the City of Broken Hill, including the reserves, were elevated to the National Heritage List under the Commonwealth's Environment Protection and Biodiversity Conservation Act 1999. This tract of land, and its proponents, Albert and Margaret Morris, are recognised as pioneers of arid zone revegetation science in Australia; a point noted in the National Heritage List citation. They created at Broken Hill a unique revegetation ‘greenbelt’ of national ecological, landscape architectural and town planning significance. The Morris’ led the advancement of arid zone botanical investigation and taxonomic inquiry, propagation innovation, and revegetation sciencein the 1920s-40s in Australia and applied this spatially. Their research and practical applications, in crafting the regeneration reserves around Broken Hill, demonstrated the need for landscape harmonisation to occur to reduce erosion and dust damage to human and mining activities alike. This pioneering research and practice informs and underpins much arid zone mine reclamation and revegetation work in Australia today. This paper reviews the historical evolution of this cultural landscape, its integral importance to the cultural heritage and mining history of the City of Broken Hill, and its inclusion as part of the Broken Hill National Heritage List citation.

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Changes in fish assemblage structure caused by human activities, such as fishing, can alter trophic relations in fish assemblages. In this context, Marine Protected Areas (MPA) are efficient tools for habitat recovery and ideal environments for evaluating changes on the trophic structure resulting from human activities. The present work targeted fish assemblages from two no-take MPAs from the northern half of South Alentejo and Costa Vicentina Marine Park, established in 2011. Previous works reported positive effects on local fish assemblages after no-take MPA designation, and it is therefore important to further study its impact on local fish assemblages, especially concerning trophic interactions. Local fish assemblages were sampled (summer 2011, winter 2012, summer 2013 and winter 2013) using trammel nets. Diets were characterized and digestive tract contents of the 10 most abundant fish species were compared between the no take MPAs (treatment) and adjacent areas (controls), and changes evaluated as a function of time since protection. Results revealed significant differences between the diets of fish from protected and non protected areas, with crabs being the preferential prey in both protected and control areas but being more ingested outside the no-take areas. However, these differences were evident since the beginning of the study. Fish assemblages from the northern area presented significantly larger niche breadth and significantly increasing with time. This way, the main effects of no-take MPA implementation were directly visible on the niche breadth but did not directly impact the diet composition of the sampled fish assemblages, contributing however to reinforce the already naturally existent differences. This work provides important information regarding the effect of changes in the fish assemblage caused by MPA designation on the trophic ecology of fish.

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Procambarus clarkii is currently recorded from 16 European territories. On top of being a vector of crayfish plague, which is responsible for large-scale disappearance of native crayfish species, it causes severe impacts on diverse aquatic ecosystems, due to its rapid life cycle, dispersal capacities, burrowing activities and high population densities. The species has even been recently discovered in caves. This invasive crayfish is a polytrophic keystone species that can exert multiple pressures on ecosystems. Most studies deal with the decline of macrophytes and predation on several species (amphibians, molluscs, and macroinvertebrates), highlighting how this biodiversity loss leads to unbalanced food chains. At a management level, the species is considered as (a) a devastating digger of the water drainage systems in southern and central Europe, (b) an agricultural pest in Mediterranean territories, consuming, for example, young rice plants, and (c) a threat to the restoration of water bodies in north-western Europe. Indeed, among the high-risk species, P. clarkii consistently attained the highest risk rating. Its negative impacts on ecosystem services were evaluated. These may include the loss of provisioning services such as reductions in valued edible native species of regulatory and supporting services, inducing wide changes in ecological communities and increased costs to agriculture and water management. Finally, cultural services may be lost. The species fulfils the criteria of the Article 4(3) of Regulation (EU) No 1143/2014 of the European Parliament (species widely spread in Europe and impossible to eradicate in a cost-effective manner) and has been included in the “Union List”. Particularly, awareness of the ornamental trade through the internet must be reinforced within the European Community and import and trade regulations should be imposed to reduce the availability of this high-risk species.

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ResumenLa discriminación racial, la pobreza y la exclusión social son problemas estructurales que han afectadoa las minorías étnicas colombianas por décadas. De los grupos minoritarios del país, los(as)afrocolombianos(as) experimentan el más alto nivel de pobreza, hecho que se demuestra en sulimitado acceso a las políticas de educación, salud, empleo y demás servicios públicos y programassociales. De hecho, las regiones con fuerte presencia afrocolombiana presentan los peores indicadoressocio-económicos y la mayor parte de las víctimas (directas) del conflicto armado internoque afecta a la nación son las comunidades afrocolombianas. Las violaciones de derechos humanos contra los(as) afrocolombianos(as) han sido cometidas tanto por instituciones del Estado comopor actores no-estatales. Dichas violaciones son prohibidas por la Constitución Nacional y por lostratados de derechos humanos ratificados por el Estado colombiano. Sin embargo, los efectos de lasmismas siguen sin ser analizados a profundidad. En este texto se estudia en detalle las normas dederechos humanos que buscan proteger a la población afrocolombiana como grupo étnico minoritario.También se estudian las principales consecuencias de las prácticas racistas contra las comunidadesafrocolombianas y los retos de éstas en el marco del conflicto armado interno. El artículo se convierteen una de las pocas investigaciones que explica la compleja situación de derechos humanos de lascomunidades afrocolombianas en la historia reciente del país.Palabras clave: Afrocolombianos(as), minorías, derechos y discriminación. AbstractRacial discrimination, poverty and social exclusion are structural problems that have affected the Colombianethnic minorities for decades. Among these minority groups, Afro-Colombians experience the highest levelof poverty, which is demonstrated by their limited access to education, health, employment, and other socialprograms and services. In fact, most regions with Afro-Colombian presence endure the worst socio-economicindicators, and the main victims of the internal armed conflict are the Afro-Colombian communities. Humanrights violations against Afro-Colombians have been committed by both state and non-state actors.These violations are prohibited by the new Colombian Constitution (approved in 1991) and human rightstreaties ratified by the Colombian state. However, their effects on Afro-Colombians have not been extensivelyexplored. This paper analyzes in depth the domestic human rights framework that seeks the protectionof Afro-Colombians as an ethnic minority. Also, it studies in detail the consequences of racist practicestowards the Afro-Colombian communities and the challenges of their struggle for human rights in the frameof the internal armed conflict. The text represents one of the few works of its kind that explains the mainaspects of the complex human rights situation of Afro-Colombians throughout the nation’s recent history.Keywords: Afro-Colombians, minorities, rights and discrimination.