Kazuhiro OSHIMA’s scientific contributions

Using projected monthly mean sea surface tem-perature (SST) in the 21st century obtained by multiple climate models and SST-based indices for the poleward range expansions of three types of coral habitats, we quantitatively evaluated the effects of SST warming on potential northern limit of coral habitats in seas close to Japan and their uncertainty in the global warming pro-jections. The uncertainty in the timing of temperate coral community formation due to global warming was no less than 30 years, with a modulation of ±10 years due to decadal climate variability. Tropical-subtropical and tem-perate coral communities and coral occurrence in seas close to Japan were predicted to shift poleward by a few hundred kilometers by the end of the 21st century. The average estimated speeds of the shifts were 1, 2, and 4 km/year for the tropical-subtropical coral community, temper-ate coral community, and coral occurrence, respectively. The simulated speeds were relatively slower than those previously observed (up to 14 km/year; Yamano et al. 2011), indicating that there are time lags between the new recruitment of coral colonies and the establishment of coral communities. Hence, monitoring of coral dynamics in response to SST warming is required. Collaboration between monitoring and modeling would enhance the reliability of future projections of changes in coral ha-bitats. Such projections are important for conserving marine biodiversity and developing plans for human societies to adapt to global warming.

地球温暖化に伴う海水温上昇は，造礁サンゴ（以下，サンゴ）の生息域を高緯度側に移動（北半球においては北上）させる，或いは白化の規模・頻度・強度を増大させることで，将来のサンゴの分布や健全度に多大な影響を及ぼすと考えられる。本研究では，高解像度気候予測シミュレーションで得られた月平均海面水温（SST; Sea Surface Temperature）から見積もられた簡易指標を用いて，日本近海を対象に温暖化に伴うSST上昇が日本近海の潜在的なサンゴの分布および健全度に及ぼす影響を評価した。その結果，現在は南九州沿岸に存在する主なサンゴ礁の形成北限と新潟・千葉沿岸にある高緯度サンゴの分布北限が，21世紀末にはそれぞれ北部九州沿岸と青森・岩手沿岸に至る可能性が示された。また，南西諸島ではサンゴの白化や大量死をもたらす深刻な白化を誘発するような高水温が出現する頻度が増え，現在では単発的に報告されているサンゴの白化が，21世紀半ば以降にはより通常の現象として認識される可能性があることが示唆された。