45
animals and hence, contribute signifi cantly to
coastal fi sheries (Komatsu and Tastukawa 1998 ).
Recently, it has been reported that fl oating seaweeds play a vital role as spawning and nursery
grounds of fi shes and associated animals (e.g.
Safran 1990 ; Safran and Omori 1990 ; Thiel and
Gutow 2005 ; Komatsu et al. 2009 ; Abé et al.
2013 ).
In Japan, the most important fl oating seaweeds
are Sargassum horneri (Turner) C. Agardh and
other Sargassum species (Komatsu et al. 2007 ) and
are seasonally distributed in offshore waters
(Komatsu et al. 2014 ; Mizuno et al. 2014 ) and
around the Japanese coastline (Yoshida 1963 ).
Japanese saury ( Cololabis saira ) and some fl ying
fi sh species spawn on the fl oating seaweeds, and
Japanese saury fi sheries is one of the most important fi sheries along the Sanriku Coast in autumn
because the saury migrates south from waters off
Hokkaido Island to those off the Coast. Thus, seaweed beds consisting of Sargassum species including S. horneri are highly important in supporting
fi sheries on this coast.
Zostera caulescens Miki, the world’s tallest
seagrass, reaching a length of 7 m (Aioi et al.
1996 ; 1998 ), grows extensively along the Sanriku
Coast and in Funakoshi Bay (Fig. 2 ) to a water
depth of ~ 20 m (Tastukawa et al. 1996 ; Sultana
and Komatsu 2002 ). Komatsu et al. ( 2003 ) mapped
a bed of Z. caulescens with a narrow multi-beam
sonar system in Otsuchi Bay (Fig. 2 ), where the
seagrass beds were distributed on a shallow bottom at a depth of <7 m. Furthermore, a considerable amount of data has been collected on the
seagrass and seaweed beds in Otsuchi Bay and
Funakoshi Bay because the marine research station belonging to the Atmosphere and Ocean
Research Institute of the University of Tokyo is
located in Otsuchi Bay.
On 11 March 2011, the Great East Japan
Earthquake occurred off the Sanriku Coast,
causing a massive tsunami (Department of
International Affairs of Japan Science and
Technology Agency 2011 ) that struck the coastline and caused extensive human casualties and
damage to cars, houses, ports, boats, roads and
the Fukushima fi rst nuclear power plant. The
widespread damage to fi sheries infrastructures,
such as fi shing boats, fi sh markets, freezing store
houses, fuel stands, ice-producing facilities,
Fig. 2 Map showing the Otsuchi Bay and Funakoshi Bay, Iwate prefecture and Sanriku Coast, Japan
Impact of the 2011 Tsunami on Seagrass and Seaweed Beds in Otsuchi Bay, Sanriku Coast, Japan
animals and hence, contribute signifi cantly to
coastal fi sheries (Komatsu and Tastukawa 1998 ).
Recently, it has been reported that fl oating seaweeds play a vital role as spawning and nursery
grounds of fi shes and associated animals (e.g.
Safran 1990 ; Safran and Omori 1990 ; Thiel and
Gutow 2005 ; Komatsu et al. 2009 ; Abé et al.
2013 ).
In Japan, the most important fl oating seaweeds
are Sargassum horneri (Turner) C. Agardh and
other Sargassum species (Komatsu et al. 2007 ) and
are seasonally distributed in offshore waters
(Komatsu et al. 2014 ; Mizuno et al. 2014 ) and
around the Japanese coastline (Yoshida 1963 ).
Japanese saury ( Cololabis saira ) and some fl ying
fi sh species spawn on the fl oating seaweeds, and
Japanese saury fi sheries is one of the most important fi sheries along the Sanriku Coast in autumn
because the saury migrates south from waters off
Hokkaido Island to those off the Coast. Thus, seaweed beds consisting of Sargassum species including S. horneri are highly important in supporting
fi sheries on this coast.
Zostera caulescens Miki, the world’s tallest
seagrass, reaching a length of 7 m (Aioi et al.
1996 ; 1998 ), grows extensively along the Sanriku
Coast and in Funakoshi Bay (Fig. 2 ) to a water
depth of ~ 20 m (Tastukawa et al. 1996 ; Sultana
and Komatsu 2002 ). Komatsu et al. ( 2003 ) mapped
a bed of Z. caulescens with a narrow multi-beam
sonar system in Otsuchi Bay (Fig. 2 ), where the
seagrass beds were distributed on a shallow bottom at a depth of <7 m. Furthermore, a considerable amount of data has been collected on the
seagrass and seaweed beds in Otsuchi Bay and
Funakoshi Bay because the marine research station belonging to the Atmosphere and Ocean
Research Institute of the University of Tokyo is
located in Otsuchi Bay.
On 11 March 2011, the Great East Japan
Earthquake occurred off the Sanriku Coast,
causing a massive tsunami (Department of
International Affairs of Japan Science and
Technology Agency 2011 ) that struck the coastline and caused extensive human casualties and
damage to cars, houses, ports, boats, roads and
the Fukushima fi rst nuclear power plant. The
widespread damage to fi sheries infrastructures,
such as fi shing boats, fi sh markets, freezing store
houses, fuel stands, ice-producing facilities,
Fig. 2 Map showing the Otsuchi Bay and Funakoshi Bay, Iwate prefecture and Sanriku Coast, Japan
Impact of the 2011 Tsunami on Seagrass and Seaweed Beds in Otsuchi Bay, Sanriku Coast, Japan