Utilization of Gracilaria chilensis (Rhodophyta : Gracilariaceae) as a
biofilter in the depuration of effluents from tank cultures of fish,
oysters, and sea urchins
F.Y.
Chow, J. Macchiavello, S.S. Cruz, E. Fonck, J. Olivares-2001
Journal
of the World Aquaculture Society, 32(2): 215-220 (from Current Contents)
Abstract :
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.
(Univ
Catolica Norte, Fac Ciencias Mar, Casilla 117, Coquimbo, Chile)