Utilization of Gracilaria chilensis (Rhodophyta : Gracilariaceae) as abiofilter in the depuration of effluents from tank cultures of fish,oysters, and sea urchins

摘要

An evaluation was made on a seasonal basis of the effect of the marine macroalga culture Gracilaria chilensis on concentrations of some soluble and particulate wastes emitted during tank cultures of a fish Isacia conteptionis, an oyster Crassostrea gigas, and a sea urchin Loxechinus albus species. The animals were each cultured in separate tanks, and effluent from each was directed through separate tanks, which contained dense cultures of the Gracilaria chilensis. Inflow-outflow monitoring was conducted for the presence of nitrate, nitrite, ammonium, and phosphate. Also evaluated were particulate nitrogen and phosphate. The most significant wastes were ammonium from the fish culture and nitrate from the oyster culture. These were completely removed from the water, with minor exceptions, by the alga during all seasons of the year. Lesser amounts of soluble phosphate and nitrite, arising from the fish cultures, were also removed. Of the particulate matter, only nitrogen was in evidence from the fish cultures in the summer. It was concluded that Gracilaria chilensis culture was highly efficient at biofiltration of the soluble nutrients tested but had little effect on particulate emissions. The best growth of Gracilaria chilensis occurred in the ammonium-rich effluent from the fish culture.