沿岸域のストレス要因に短期的にさらされた場合のサンゴの初期生活段階への影響

The impact of short-term exposure to near shore stressors on the early life stages of the reef building coral .

• Claire V A Lager
• Mary Hagedorn
• Kuʻulei S Rodgers
• Paul L Jokiel

抄録

サンゴの繁殖と生存を成功させることは、地球規模でサンゴを存続させ、回復力を高めるために重要です。気候変動によるサンゴ礁水域の温暖化に伴い、大規模な熱帯暴風雨が頻繁に発生し、短期間に沿岸の水質を大きく変化させるようになってきています。そのため、温暖化した水域や淡水の流入、流出がサンゴの生殖に与える影響を理解することが重要です。このような沿岸域のストレス要因がハワイのサンゴに与える影響をよりよく理解するために、海洋生物学研究所の実験室で実験を行い、浮遊物濃度（100 mg l と 200 mg l）、塩分濃度（28‰）、水温（31本研究では，サンゴの初期発達段階において，3 種類の沿岸ストレス因子のいずれかに 24 時間曝露し，即効性（受精）と潜 在的影響（幼生の生存と沈降）を観察・測定した。その結果，受精成功率と沈降率はいずれの処理でも影響を受けなかったが，幼虫の生存率はすべての処理で50％以上の負の影響を受けた（>0.05）。これらのデータは、幼生の初期段階では、温暖化や暴風雨の増加に伴う沿岸域のストレス要因が影響している可能性があることを示している。

Successful reproduction and survival are crucial to the continuation and resilience of corals globally. As reef waters warm due to climate change, episodic largescale tropical storms are becoming more frequent, drastically altering the near shore water quality for short periods of time. Therefore, it is critical that we understand the effects warming waters, fresh water input, and run-off have on sexual reproduction of coral. To better understand the effects of these near shore stressors on Hawaiian coral, laboratory experiments were conducted at the Institute of Marine Biology to determine the independent effects of suspended sediment concentrations (100 mg l and 200 mg l), lowered salinity (28‰), and elevated temperature (31 °C) on the successful fertilization, larval survival, and settlement of the scleractinian coral In the present study, early developmental stages of coral were exposed to one of three near shore stressors for a period of 24 h and the immediate (fertilization) and latent effects (larval survival and settlement) were observed and measured. Fertilization success and settlement were not affected by any of the treatments; however, larval survival was negatively affected by all of the treatments by 50% or greater ( > 0.05). These data show that early life stages of may be impacted by near shore stressors associated with warming and more frequent storm events.

©2020 Lager et al.