A method for screening antifouling paints using the CIELAB coordinates of Ectocarpus sp. under a flow-through condition.

A laboratory test with a flow-through system was designed and its applicability to testing antifouling paints of varying efficacies was investigated. Six different formulations of antifouling paints were prepared to have increased contents (0 to 40 wt%) of Cu2O. The test plates were initially aged for 45 days by rotating them at a speed of 10 knots inside a cylinder drum. A bioassay was then conducted using the alga, Ectocarpus sp., as the test species. The new bioassay for screening antifouling paints under a flow-through system was successfully established using algae affixed on substrata. The correlation between the mean values of CIELAB parameters (L*, a* and b*), the total colour difference (ΔE*), and the cell survival rate of the algae was investigated. The paint performance estimated from the bioassay was confirmed using correlation patterns between colour parameters and the algal cell survival rate.

Phosphate Enrichment Hampers Development of Juvenile Acropora digitifera Coral by Inhibiting Skeleton Formation.

Coral reef degradation due to various local stresses, such as nutrient enrichment and terrestrial run-off into coastal waters, is an increasing global concern. Inorganic phosphates have been considered to possibly inhibit skeleton formation in corals. Despite many studies available on the effects of nutrients on corals, a clear consensus on how nutrients exert deteriorative effects on corals has not been established satisfactorily. In this study, we examined the effects of phosphates and nitrates on in vitro aragonite CaCO3 formation by using biogenic polyamines and in vivo aragonite formation in the skeleton of juvenile Acropora digitifera corals. We showed that the phosphates at similar concentrations clearly inhibited both in vitro and in vivo CaCO3 formation. In contrast, nitrates inhibited neither in vitro aragonite CaCO3 formation nor in vivo aragonite formation in juvenile coral skeleton. Furthermore, our findings showed that inhibition of coral skeleton formation was due to absorption of phosphate on the skeleton, which inorganically inhibited normal development of juvenile coral skeleton.