Utilization of Gracilaria chilensis (Rhodophyta: Gracilariaceae) as a Biofilter in the Depuration of Effluents from Tank Cultures of Fish, Oysters, and Sea Urchins

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.

Nitrate Assimilation: The Role of In Vitro Nitrate Reductase Assay as Nutritional Predictor

“…Hanisak (1983) noted that the uptake rate of ammonium generally exceeds that of nitrate. Chow et al (2001) registered the same trend for Gracilaria chilensis, with total uptake of only ammonium, when present together with nitrate and nitrite. However, very high concentrations of ammonium (> 30 -50 µM) can saturate nitrate transport, thereby inducing toxification by ammonium.…”

“…Knowledge of these responses would contribute towards a better optimization of laboratory efforts and in-field cultures for physiological studies and biomass yield, for possible economical usage. Methods for estimating in vitro NR activity have been developed by Weidner & Kiefer (1981), Chapman & Harrison (1988), Thomas & Harrison (1988), Brinkhuis et al (1989) and Chow et al (2001). Assaying procedures of NR activity are based on quantifying the reduction rate of nitrate to nitrite during the reaction catalyzed by intracellular NR enzymes.…”

Nutrient uptake efficiency of Gracilaria chilensis and Ulva lactuca in an IMTA system with the red abalone Haliotis rufescens

“…However, a lower density would permit a better operating control of the culture. This stocking density is lower than the 3000 g m -2 , reported by Abreu et al (2011) for G. vermiculophyta and the 7000 g m -2 recommended by Chow et al (2001) when using G. chilensis for the treatment of wastewater originating from fish and oysters. It is expected that the greatest uptake efficiency would be reached with the lowest water exchange rate (Chopin et al, 2001).…”

Influência da disponibilidade de nitrato sobre crescimento, atividade da nitrato redutase, composição química e captação de nitrato e fosfato em Gracilariopsis tenuifrons (Gracilariales, Rhodophyta)

“…Entretanto, a qualidade do ágar, estimada pela força do gel, foi melhor quando as algas foram cultivadas sob concentrações moderadas ou altas de nitrogênio (Bird et al, 1981 Pesquisas referentes à influência do nitrogênio sobre o metabolismo das macroalgas são importantes uma vez que este composto é essencial para a manutenção de diversas vias metabólicas do organismo e pode estar presente na água oriunda de sistemas agrícolas e nos esgotos domésticos e industriais, podendo atingir águas costeiras (Hooda et al, 2000;Hooda, 2008). Além disso, o nitrogênio também é produto da aquicultura, sendo excretado pelos invertebrados e peixes cultivados (Chopin et al, 2001;Chow et al, 2001). A extrapolação de resultados obtidos em laboratório para o ambiente natural deve ser cautelosa, porém tais estudos são relevantes para a compreensão da fisiologia de uma determinada espécie e o estabelecimento de modelos de funcionamento metabólico.…”