[A-OS16] Coastal ocean circulation and material cycle

[AOS16-05] Numerical study on multigenerational connectivity of eelgrass habitats in the Seto Inland Sea based on Lagrangian probability density functions and a Markov chain model

*Yusuke Uchiyama¹, Motoki Ubara², Taichi Kosako³, Shinya Hosokawa³ (1.Graduate School of Engineering, Kobe University, 2.Tajima Prefectural Government, Hyogo Prefecture, 3.Port and Airport Research Institute)

Keywords:eelgrass, buoyant reproductive shoot, Lagrangian transport, JCOPE2-ROMS ocean circulation model

Towards sustainable conservation of eelgrass (Zostera marina) habitats in the Seto Inland Sea (SIS), a long-term numerical reanalysis was conducted with a high-resolution ocean circulation model coupled with a floating buoyant eelgrass shoot (viz., seed) transport model. A Lagrangian analysis quantitatively evaluated the population connectivity among eelgrass habitats considering their overgrown areas. A multigenerational connectivity evaluation model was then formulated based on Markov chains to investigate extensive, interbasin shoot exchange among perennial eelgrass in the SIS over a period of nine years (nine generations). Although self-recruitment within the interior of the subbasins (bay and sea/nada) is predominant in a single year (one generation) connectivity, eelgrass shoots were found to pass over the straits and to expand their habitats to remote areas across generations. On the other hand, the Kurushima Strait plays a pivotal role in lateral shoot transport, segmenting the eelgrass habitats in the SIS zonally into two parts.