The physiological effects of polyethylene microbeads ingestion in juvenile orange-spotted grouper (Epinephelus coioides)

• Main Authors: Chung, Pei-Chi, 鐘珮綺
• Other Authors: Shao, Yi-Ta
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/2x4aba

碩士 === 國立臺灣海洋大學 === 海洋生物研究所 === 106 === Plastic particle in the ocean is an emerging pollutant that may affect aquatic habitats globally. Some of them are very small that can be eaten by marine animals and accumulate via trophic structure. However, the physiological influences of the plastic microbeads ingestion of high level predator was still unclear. This study aimed to investigate the physiological impacts of polyethylene (PE 10-125um) microbeads that were ingested by juvenile orange-spotted groupers (Epinephelus coioides). To this end, fish were fed with the diet including 10^2 (low concentration group, L.C.) or 10^5 (high concentration group, H.C.) fluorescent microbeads per gram for two weeks, and the tissue samples were collected at 3hr, 24hr and 48hr after the last feeding. The fluorescent microbeads were detected in pyloric caeca and intestine of H.C. group at 3hr, but not found at other time points or L.C. group. The results suggested that the groupers could remove those particles from the digestive tract rapidly. However, in H.C. group, the microbeads were detected in the gill filaments as well, especially, which were found at all time points. The possible stress responses were evaluated by the plasma cortisol levels and head kidney cytochrome-P450-11A1 (cyp11a1) gene expression. Nevertheless, there was no significant effect found in both L.C. and H.C. treatment. Furthermore, the fish under H.C. treatment had higher hepatic leptin A (lepa) and head kidney leptin receptor (lepr) mRNA level at 3hr. Those results indicated that PE beads ingestion may influence energy metabolism by endocrine manipulation in the head kidney. Furthermore, the expressions of interleukin- 6 (il6) gene, which indicated the inflammatory response, were up-regulated in the tissues of head kidney, gut, liver and gills 3hr when the microbeads remained in the digestive tract under H.C. treatment. Present study concluded that the H.C. microbeads from ingestion may not remain in the digestive tract more than 1 day, even if the fish exposed to the microbeads that was far higher than normal environment. However, the beads were possible to attach on the gill membrane for longer time. Moreover, the ingestion of H.C. microbeads may cause immune responses and disrupt the energy metabolism in the short period as the beads were residue in the body. While, there is no impact in L.C. group.