The potential for soluble and transport loss of particulate aquaculture wastes
2000
Tlusty, M.F. | Snook, K. | Pepper, V.A. | Anderson, M.R.
The relative potential for soluble and transport losses of aquaculture waste was examined. The waste was collected at four junctures between introduction to the environment and the culmination of settlement, including samples of feed, faeces, particulate matter in the water column obtained from sediment traps, and the benthos. Organic matter was used as a model system to investigate the fate of these components because it was simple to analyse and previous research has found it to be correlated to carbon and nutrient levels in the samples. A narrow definition of each loss was considered. Soluble losses were examined by measuring change in organic matter content while the samples were in a stationary water field. The potential for transport losses was examined by determining if light and heavy fractions of a sample differed in their amount of organic matter. Faecal matter had a very high solubility potential, and lost approximately 50% of its organic matter in 12 days. No other sample had losses > 10%. The benthic samples gained organic matter while sitting in the stationary water field. There was no discernible trend to the samples' potential for transport losses. However, for all replicates combined, the smaller the proportion of the lighter fraction, the greater the difference (+) in the organic matter content between the light and heavy fractions. Thus, lighter material is the last to settle and thus more prone to be transported further afield. The implications of this study include the need for model studies to examine different types of loss and also elucidation of divergent degradation properties of each component. This study also points to a functional mechanism behind greater environmental impacts associated with poorly managed farms.
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