Antifouling biocides such as organotin compounds and their alternatives are potent toxicants in marine ecosystems. In this study, we employed several molecular and biochemical response systems of the Pacific oyster Crassostrea gigas to understand a potential mode of action of antifouling biocides (i.e. tributyltin (TBT), diuron and irgarol) after exposure to different concentrations (0.01, 0.1, and 1 μg L^-1) for 96 h. As a result, all the three antifouling biocides strongly induced the antioxidant defense system. TBT reduced both enzymatic activity and mRNA expression of Na⁺/K⁺-ATPase and acetylcholinesterase (AChE). Lower levels of both Na⁺/K⁺-ATPase activity and AChE mRNA expression were observed in the diuron-exposed oysters compared to the control, while the irgarol treatment reduced only the transcriptional expression of AChE gene. We also analyzed transcript profile of heat shock protein (Hsp) superfamily in same experimental conditions. All antifouling biocides tested in this study significantly modulated mRNA expression of Hsp superfamily with strong induction of Hsp70 family. Taken together, overall results indicate that representative organotin TBT and alternatives have potential hazardous effects on the gill of C. gigas within relatively short time period. Our results also suggest that analyzing a series of molecular and biochemical parameters can be a way of understanding and uncovering the mode of action of emerging antifouling biocides. In particular, it was revealed that Pacific oysters have different sensitivities depend on the antifouling biocides.

Korea has a long history of utilizing seaweeds, as the country has a high biodiversity of seaweeds. The abundance and composition of seaweed species have changed over the past decades due to climate change and anthropogenic influences. Some species showed a significant extension of their distribution range to the north while some species declined. Some areas have even become barren ground. Korea has put extensive effort into restoring the seaweed resources in these deforested areas. Korea is one of the most advanced countries in the World in terms of seaweed aquaculture. However, the aquacultured species are mostly limited to three genera, Saccharina , Undaria and Pyropia/Porphyra , which represent 96% of the entire seaweed production in the country. Korea has developed highly advanced cultivation technologies as well as various cultivars using breeding and hybridization technologies for these species. There has also been considerable effort in developing environmentally sustainable aquaculture systems using seaweed cultivation (e. g. integrated multi-trophic aquaculture, nutrient bioextraction and biofloc). This study discusses the current status and challenges of the above mentioned topics in detail. In addition, the present study encourages South and North Korean scientists to collaborate in the study of seaweed resources at the border of these two countries.

Physiological responses to the hypo-osmotic and temperature stresses of an invasive species, Gracilaria vermiculophylla, were compared to those of the native Atlantic species, G. tikvahiae and G. c...