Características limnológicas da coluna d'água e dos efluentes de viveiros de criação de camarões-da-amazônia

Os objetivos neste trabalho foram caracterizar os efluentes de viveiros de Macrobrachium amazonicum criados em diferentes densidades de cultivo e analisar a variação nictemeral (24 horas) do perfil vertical da temperatura e da saturação de oxigênio da coluna d'água dos viveiros. O experimento foi realizado durante um período de três meses utilizando-se 12 viveiros retangulares de 100 m² povoados com camarões-da-amazônia em quatro densidades de cultivo (40, 60, 80 e 100 indivíduos/m²), cada uma avaliada com três repetições. Mensalmente, foi realizado nos viveiros (superfície até o fundo) o acompanhamento da variação nictemeral da temperatura e da saturação de oxigênio dissolvido. Nos efluentes gerados pela criação de camarões foram determinados os valores de N-total, N-amoniacal, N-nitrito, N-nitrato, P-total, P-ortofosfato e turbidez. Foram constatadas estratificações e desestratificações diárias de temperatura e da saturação de oxigênio, independentemente da densidade de cultivo, caracterizando os viveiros como um sistema de circulação polimítico. Quanto maior a densidade de cultivo de camarões-da-amazônia, maiores os valores de P-total, N-total, P-ortofostato, N-amoniacal e turbidez nos efluentes.The objective of this research was to characterize the effluents of fish ponds of Macrobrachium amazonicum cultured in different densities of farming and to analyze the daily variation (24 hours) of the vertical temperature and oxygen saturation profile of the water column of the ponds. The study was conducted during a period of three months using 12 rectangular 100 m² earthen ponds supplied with M. amazonicum individuals in four densities of farming (40, 60, 80 and 100 individuals/m²), each one evaluated with three replicates. Follow-up of the daily variation of the temperature and of the saturation of the dissolved oxygen was monthly carried out in the fish ponds (from the surface to the bottom). It was determined, in the effluent caused by the prawn farming, the values of total-N, ammoniacal-N, nitrite-N, nitrate-N, total-P, orthophosphate-P and turbidity. Daily stratifications and desestratifications of temperature and of the saturation oxygen were recorded, irrespective of farming density, characterizing the ponds as a polimitic system of circulation. The higher the density of cultivation of M. amazonicum, the higher the values of total-P, total-N, orthophosphate-P, N-ammoniacal and turbidity

Social, economic and environmental inequalities in coastal communities: understanding the context for integrated management

In modern western democratic society the processes of governance are largely directed towards the reduction of inequalities in wealth. These inequalities are often causal factors in further inequalities of health, education, skills, individual contribution to society, and democratic engagement. Environmental inequalities can exacerbate inequalities of wealth in contrasting ways: communities may be rich or poor in environmental resources that may be exploited to create wealth, or the intrinsic value of environmental resources may be such that they are protected and not available for wealth creation. In this latter case, their very occupation of physical space that may otherwise have been occupied by exploitable resources is a further inequality. In order to manage the coast in an integrated way it is the responsibility of government and its institutions to understand these inequalities so that management interventions are effectively directed towards their eradication in a sustainable manner. To date European research (and policy) have concentrated largely on understanding the nature of the natural environment of the coast. Little effort has been directed at understanding the social condition of coastal communities, the internal dynamic of coastal economies or their wider role in national economies. This paper draws on experiences in the UK to illustrate the nature of some of these social, economic and environmental inequalities, and to suggest ways in which they might be better addressed through processes of integrated coastal management