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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°C. The seaweed was grown in nine plastic mesh cages (each 1.25 m3 volume) suspended in a concrete sump tank (46 m3) 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 2.95 kg m-3 initially, increasing to 9.85 kg m-3 after a year. Specific growth rate was highest from April to June (8.0 to 9.0°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°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 38,000 m2, ten times the area required for halibut culture. Fifty percent removal of carbon from the same system requires 7,200 to 9,800 m2 cultivation area. Integration of P. palmata with Atlantic halibut is feasible below 10°C, but is impractical during summer months due to disintegration of thalli associated with reproductive maturation.

Light emitting diode (LED) technology has significant potential advantages over other light sources in algal aquaculture. This study investigated LEDs as light sources for the culture of Gracilaria tikvahiae. We cultured a wild-type and a green mutant strain of G. tikvahiae, comparing growth rate and tissue chlorophyll a, total carotenoids, and phycobiliprotein concentrations under high output cool white fluorescent, pure primary color LED, and mixed LED lighting. Under monochromatic light, the growth rates under high output cool white fluorescent lighting were significantly higher than rates under pure LED light (all three colors for wild strain and green and blue for green mutant). However, when pure color LED lighting was mixed (50%/50%), the red + green (wild-type strain and green mutant) and the green + blue LED combinations (wild-type only) showed growth rates similar to those under high output cool white fluorescent lighting. In the trichromatic experiment, growth of the wild-type strain under mixed three-color (40%/40%/20%) LED light was indistinguishable from those of the fluorescent control lighting. Chlorophyll a and carotenoid concentrations of Gracilaria grown in the dichromatic light experiment were 55% and 74% higher, respectively, under red + blue LED lighting than under the other light treatments. The wild-type strain of G. tikvahiae possessed significantly greater concentrations of chlorophyll a, and phycoerythrin than did the green mutant, while green mutant thalli had higher phycocyanin levels. With rising LED efficiency and energy savings, LEDs will be an increasingly better choice for indoor seaweed cultivation, especially if control of pigment production and morphogenesis by selective use of particular wavelengths is desirable.

Three species of marine brown macroalgae (seaweeds), Myagropsis myagroides, Sargassum henslowianum and S. siliquastrum collected from Tung Ping Chau, Hong Kong were studied for their curative effects on hepatotoxicity caused by carbon tetrachloride (CCl4) in male Sprague-Dawley rats. A single suitable oral dose of 1.25 ml kg−1 of 20% CCl4 was used as a model hepatotoxin to produce significantly elevated levels of serum glutamic pyruvic transaminase (SGPT) and glutamic oxaloacetic transaminase (SGOT). Gavage oral administration of 300 mg kg−1 of methanol crude extract from S. siliquastrum 6 h post-treatment of CCl4 significantly reduced the CCl4-induced acute elevation in the levels of SGPT and SGOT in rats. Similar results, though at a less effective level, were achieved for extracts fromS. henslowianum and M. myagroides. These results indicate that these seaweeds may contain some active principles in their methanol extracts which acted as an antidote against the hepatotoxicity induced by CCl4. Further investigation is necessary to clarify and characterize the active component(s) in the extracts.

Coastal environments are prone to nutrient contamination as a result of excessive use of fertilizers in paddy agriculture on the land. To detect nutrient increases in coastal areas, researchers have used hyperspectral reflectance response to examine some coastal plants, which have proved to be effective as bioindicators. In this study, field hyperspectral technique was evaluated as a tool to detect nutrient concentrations in two coastal plants, i.e., seagrass (Enhalus acoroides) and brown algae (Sargassum sp.), taken from Banten Bay Indonesia, at laboratory scale. Although our initial experiments are still too few in elucidating an accurate relationship of nutrients and spectral signature, we are pleased to communicate that there is scientific evidence that hyperspectral measurement can be used to detect nutrient concentrations in coastal vegetation. Two types of fertilizers—urea, which contains 46% nitrogen, and triple super phosphate (TSP), which contains 14–20% soluble P2O5, commonly used by the local paddy farmers—were applied to both coastal plants in the aquarium experiment. The results of factorial analysis of variance (ANOVA) tests and pigmentrelated indices have proved that some significant differences exist in several wavelengths in response to the fertilizer treatments. This study revealed that brown algae were more sensitive to the same amount of fertilizer applied than seagrass.