• Fisheries and Aquatic Sciences
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• 제12권1호
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• pp.70-77
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• 2009

Porphyra yezoensis is known to act as a biofilter against nutrient-rich effluent in seaweed-based integrated aquaculture systems. However, few studies have examined its physiological status under such conditions. In this study, we estimated the photosynthetic activity of P. yezoensis by chlorophyll fluorescence of PSII (${\Delta}F/F'm$ and relative $ETR_{max}$) using the Diving-PAM fluorometer (Walz, Germany). In addition, bioremediation capacity, tissue nutrients, and C:N ratio of P. yezoensis were investigated. The ammonium concentration in seawater of seaweed tank 4 decreased from $72.1{\pm}2.2$ to $33.8{\pm}0.4{\mu}M$ after 24 hours. This indicates the potential role of P. yezoensis in removing around 43% of ammonium from the effluents. Tissue carbon contents in P. yezoensis were constant during the experimental period, while nitrogen contents had increased slightly by 24 hours. In comparison with the initial values, the ${\Delta}F/F'm$ and $rETR_{max}$ of P. yezoensis had increased by about 20 and 40%, respectively, after 24 hours. This indicates that P. yezoensis condition improved or remained constant. These results suggest that chlorophyll fluorescence is a powerful tool in evaluating the physiological status of seaweeds in a seaweed-based integrated aquaculture system.

• ALGAE
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• 제17권3호
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• pp.187-194
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• 2002

A seaweed biofilter/production system of being developed to reduce the environmental impact of marine fish farm effluent in coastal ecosystems as a part of an integrated aquaculture system. Several known seaweed taxa and their cultivars have been considered as candidate biofilter organisms based on their species-specific physiological properties such as nutrient uptake kinetics and their economic value. Porphyra is an excellent cadidate and shows efficient nutrient extraction properties. Rates of ammonium uptake were maintained at around 3 ${\mu}moles{\cdot}g{\cdot}dw^{-1}{\cdot}min^{-1}$ at 150 ${\mu}M$ inorganic nitrogen at $10^{\circ}C$. Ulva is another possible biofilter candidate with an uptake rate of 1.9 ${\mu}moles{\cdot}g{\cdot}dw^{-1}{\cdot}min^{-1}$ under same conditions. A simple uptake/growth and harvest model was applied to estimate the efficiency of the biofilter/production system. The model was deterministic and used a compartment model structure based on difference equations. The efficiency of Porpyra filter was estimated over 17% of ${NH_4}^+$ removal from the contimuous supply of 100 ${\mu}mole{\cdot}l^{-1}\;{NH_4}^+\;at\;100l{\cdot}sec^{-1}$ flow rate.

• 한국수산과학회지
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• 제45권4호
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• pp.351-357
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• 2012

To determine whether the seaweed Saccharina japonica can effectively utilize dissolved nutrients from Sebastes schlegeli fish cultures, a laboratory experiment was conducted in a static system for 7 days at ESFRI, NFRDI in Korea. The experiment included an S. schlegeli monoculture system and an S. schlegeli-S. japonica IMTA system. Saccharina schlegeli density ($415{\pm}24g$; mean${\pm}$SE) remained the same in all treatments, whereas seaweed density varied across treatments of 0, 0.5, 1, 2, and 3 kg (control and T1-T4, respectively). During the experiment, nutrient ($NH_4^+$ and $PO_4^{3-}$) concentrations were measured at 24-h intervals. $NH_4^+$ concentration of the control group increased from $0.117{\pm}0.021mg/L$ at the start of experiment to $5.836{\pm}0.904mg/L$ at the end of experiment. $NH_4^+$ concentrations of each treatment were $3.004{\pm}0.040$, $2.086{\pm}0.133$, $1.642{\pm}0.121$ and $0.775{\pm}0.007mg/L$ in T1, T2, T3, and T4, respectively, at the end of experiment. The concentration of $PO_4^{3-}$ exhibited a similar trend to $NH_4^+$ concentration. $NH_4^+$ and $PO_4^{3-}$ concentrations significantly decreased with increased S. japonica thallus density each day (P<0.05). The nutrient removal efficiency (NRE) and nutrient uptake rate (NUR) showed different relationships with changes in thallus density; NRE increased but NUR decreased as thallus density increased. Based on measured concentrations of $NH_4^+$ and S. japonica weight, regression analysis defined the relationship between as an exponential function, $Y=3.8165e^{-0.505X}$ ($R^2$ = 0.9552). Our results demonstrated that S. japonica can function as an efficient component in IMTA with environmental and potentially economic benefits for fish hatcheries.

• ALGAE
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• 제29권1호
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• pp.35-45
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• 2014

Palmaria palmata was integrated with Atlantic halibut Hippoglossus hippoglossus on a commercial farm for one year starting in November, with a temperature range of 0.4 to $19.1^{\circ}C$. The seaweed was grown in nine plastic mesh cages (each $1.25m^3$ volume) suspended in a concrete sump tank ($46m^3$) in each of three recirculating systems. Two tanks received effluent water from tanks stocked with halibut, and the third received ambient seawater serving as a control. Thalli were tumbled by continuous aeration, and held under a constant photoperiod of 16 : 8 (L : D). Palmaria stocking density was $2.95kg\;m^{-3}$ initially, increasing to $9.85kg\;m^{-3}$ after a year. Specific growth rate was highest from April to June (8.0 to $9.0^{\circ}C$), 1.1% $d^{-1}$ in the halibut effluent and 0.8% $d^{-1}$ in the control, but declined to zero or less than zero above $14^{\circ}C$. Total tissue nitrogen of Palmaria in effluent water was 4.2 to 4.4% DW from January to October, whereas tissue N in the control system declined to 3.0-3.6% DW from April to October. Tissue carbon was independent of seawater source at 39.9% DW. Estimated tank space required by Palmaria for 50% removal of the nitrogen excreted by 100 t of halibut during winter is about 29,000 to $38,000m^2$, ten times the area required for halibut culture. Fifty percent removal of carbon from the same system requires 7,200 to $9,800m^2$ cultivation area. Integration of P. palmata with Atlantic halibut is feasible below $10^{\circ}C$, but is impractical during summer months due to disintegration of thalli associated with reproductive maturation.