253
H.-J. Ceccaldi et al. (eds.), Marine Productivity: Perturbations and Resilience of Socio-ecosystems,
DOI 10.1007/978-3-319-13878-7_27, © Springer International Publishing Switzerland 2015
Abstract
A boat-based coral observation system was developed using lidar (light
detection and ranging) technique for large-area coral monitoring. The system comprises an ultraviolet (UV) pulsed laser and a gated imageintensifi ed CCD (ICCD) camera to obtain fl uorescent images of the
seafl oor. Coral observations were conducted using a glass- bottom boat at
Taketomi Island, Okinawa, Japan, and the distributions of live corals along
the boat tracks were obtained.
M. Sasano (*) • M. Imasato
National Maritime Research Institute ,
Mitaka , Tokyo , Japan
e-mail: sasano@nmri.go.jp; imasato@nmri.go.jp
H. Yamano • H. Oguma
National Institute for Environmental Studies ,
Tsukuba , Ibaraki , Japan
e-mail: hyamano@nies.go.jp; oguma@nies.go.jp
Coral Observation by the BoatBased Fluorescence Imaging Lidar
Masahiko Sasano , Motonobu Imasato ,
Hiroya Yamano , and Hiroyuki Oguma
1
Introduction
Reef-building corals (hereafter corals) are at risk
from global climate change and other threats. In
particular, the Japanese marine area forms the
northern limit of global coral distribution, and
previous studies have confi rmed that corals are
rapidly decreasing (Okamoto et al. 2000 ) and
moving northward (Yamano et al. 2011 ). Such
changes emphasise the increasing importance of
monitoring regional coral distribution. Most
reef- building corals have fl uorescent proteins
that emit blue-green fl uorescence on UV excitation (Hedley and Mumby 2002 ). Therefore, the
spatial distributions of live coral can be obtained
from observations made using fl uorescence
imaging lidar (Fig. 1 ).
2
Lidar Technique
2.1
Observation Method
Lidar is an active remote sensing system that
emits pulsed laser to a target and receives scattered light from it. The distance r from the system to the target is expressed via the time
difference Δ t between emitting the laser pulse
and receiving the scattered light,
r
c
n
t
=
2
Δ
( 1 )
Here, c is the speed of light in vacuum and n is
the absolute refractive index, which is 1.0003 in
air and ranges from 1.33 to 1.34 in seawater.
H.-J. Ceccaldi et al. (eds.), Marine Productivity: Perturbations and Resilience of Socio-ecosystems,
DOI 10.1007/978-3-319-13878-7_27, © Springer International Publishing Switzerland 2015
Abstract
A boat-based coral observation system was developed using lidar (light
detection and ranging) technique for large-area coral monitoring. The system comprises an ultraviolet (UV) pulsed laser and a gated imageintensifi ed CCD (ICCD) camera to obtain fl uorescent images of the
seafl oor. Coral observations were conducted using a glass- bottom boat at
Taketomi Island, Okinawa, Japan, and the distributions of live corals along
the boat tracks were obtained.
M. Sasano (*) • M. Imasato
National Maritime Research Institute ,
Mitaka , Tokyo , Japan
e-mail: sasano@nmri.go.jp; imasato@nmri.go.jp
H. Yamano • H. Oguma
National Institute for Environmental Studies ,
Tsukuba , Ibaraki , Japan
e-mail: hyamano@nies.go.jp; oguma@nies.go.jp
Coral Observation by the BoatBased Fluorescence Imaging Lidar
Masahiko Sasano , Motonobu Imasato ,
Hiroya Yamano , and Hiroyuki Oguma
1
Introduction
Reef-building corals (hereafter corals) are at risk
from global climate change and other threats. In
particular, the Japanese marine area forms the
northern limit of global coral distribution, and
previous studies have confi rmed that corals are
rapidly decreasing (Okamoto et al. 2000 ) and
moving northward (Yamano et al. 2011 ). Such
changes emphasise the increasing importance of
monitoring regional coral distribution. Most
reef- building corals have fl uorescent proteins
that emit blue-green fl uorescence on UV excitation (Hedley and Mumby 2002 ). Therefore, the
spatial distributions of live coral can be obtained
from observations made using fl uorescence
imaging lidar (Fig. 1 ).
2
Lidar Technique
2.1
Observation Method
Lidar is an active remote sensing system that
emits pulsed laser to a target and receives scattered light from it. The distance r from the system to the target is expressed via the time
difference Δ t between emitting the laser pulse
and receiving the scattered light,
r
c
n
t
=
2
Δ
( 1 )
Here, c is the speed of light in vacuum and n is
the absolute refractive index, which is 1.0003 in
air and ranges from 1.33 to 1.34 in seawater.