209
shows a diagram of the ecosystem model in the
deep-sea hydrothermal fi eld.
These procedures follow those adopted for
terrestrial mining, but there is presently much
less scientifi c knowledge of deep-sea areas and
detailed marine investigation is much more diffi -
cult than on land.
Meanwhile, the topic of the sustainable use of
hydrothermal resources has been discussed with
regard to black ore culturing (JAMSTEC Press
Release 2012 ) and hydrothermal power generation
(JAMSTEC Press Release 2013 ), but has rarely
been discussed in terms of the sustainable use of
deep-sea ecosystems for uses such as fi sheries.
3
Bio-fl uorescence of Marine
Organisms
3.1
Biological Roles, Fluorescent
Materials
Sunlight does not reach the deep-sea fl oor, and
many deep-sea organisms use self-generated bioluminescence or detect that generated by other
organisms. In general, deep-sea organisms use
light to intimidate, dazzle, manoeuvre, etc.
The basic compounds required for luminescence are called luciferins; these are catalysed by
luciferase, resulting in luminescence. Some luciferins show fl uorescent properties in response to
UV excitation. Additionally, it is known that
some anaerobic bacteria and cnidarians show
fl uorescence under UV excitation, but the detailed
purposes are unclear.
3.2
Use of Bio-fl uorescence
Monitoring
Besides the identifi cation of fl uorescent substance, clarifi cation of fl uorescent mechanisms
and ecological understanding of deep-sea biofl uorescence, bio-fl uorescence is considered to
have important applications for monitoring deepsea ecosystem. In ordinal deep-sea investigation,
video recording of the seafl oor is conducted
using white light. However, it is not essential to
use pseudo-sunlight for deep-sea fl oor monitoring: deep-sea organisms, particularly macrobenthos, tend to have little pigmentation and it is
therefore diffi cult to identify species according to
their colours.
In this study, fl uorescence is used instead of
elastic scattering of light illumination for
deep- sea fl oor monitoring near hydrothermal
vents. It is expected to be an effective method for
monitoring deep-sea ecosystems by identifying
Bacteria
Plankton
Particulate and
Dissolved
Organic Matter
Sulfur
Bacteria
Infauna
Sediment
Sinking
Seafloor
Sinking
Feeding
Mortality Egestio
Feeding
Mortality
Outside the system
Outside the system
Dissolved
Inorganic Matter
Grazing Respiration
Epifauna
Grazing
Grazing
Outside the system
Particulate
Organic Matter
Grazing
Grazing
Grazing
Respiration
Respiration
Mortality Egestion
Feeding
Feeding
Mortality
Mortality Egestion
Feeding
Inorganic
Suspended
Particle
Discharged
Water
(Sedimentation)
Hydrogen
Sulfide(H 2 S)
DO
Diffusion
Fig. 2 Diagram of an ecosystem model in deep-sea hydrothermal fi eld
Use of Bio-fl uorescent Characteristics for Ecosystem Monitoring on Hydrothermal Deposits
shows a diagram of the ecosystem model in the
deep-sea hydrothermal fi eld.
These procedures follow those adopted for
terrestrial mining, but there is presently much
less scientifi c knowledge of deep-sea areas and
detailed marine investigation is much more diffi -
cult than on land.
Meanwhile, the topic of the sustainable use of
hydrothermal resources has been discussed with
regard to black ore culturing (JAMSTEC Press
Release 2012 ) and hydrothermal power generation
(JAMSTEC Press Release 2013 ), but has rarely
been discussed in terms of the sustainable use of
deep-sea ecosystems for uses such as fi sheries.
3
Bio-fl uorescence of Marine
Organisms
3.1
Biological Roles, Fluorescent
Materials
Sunlight does not reach the deep-sea fl oor, and
many deep-sea organisms use self-generated bioluminescence or detect that generated by other
organisms. In general, deep-sea organisms use
light to intimidate, dazzle, manoeuvre, etc.
The basic compounds required for luminescence are called luciferins; these are catalysed by
luciferase, resulting in luminescence. Some luciferins show fl uorescent properties in response to
UV excitation. Additionally, it is known that
some anaerobic bacteria and cnidarians show
fl uorescence under UV excitation, but the detailed
purposes are unclear.
3.2
Use of Bio-fl uorescence
Monitoring
Besides the identifi cation of fl uorescent substance, clarifi cation of fl uorescent mechanisms
and ecological understanding of deep-sea biofl uorescence, bio-fl uorescence is considered to
have important applications for monitoring deepsea ecosystem. In ordinal deep-sea investigation,
video recording of the seafl oor is conducted
using white light. However, it is not essential to
use pseudo-sunlight for deep-sea fl oor monitoring: deep-sea organisms, particularly macrobenthos, tend to have little pigmentation and it is
therefore diffi cult to identify species according to
their colours.
In this study, fl uorescence is used instead of
elastic scattering of light illumination for
deep- sea fl oor monitoring near hydrothermal
vents. It is expected to be an effective method for
monitoring deep-sea ecosystems by identifying
Bacteria
Plankton
Particulate and
Dissolved
Organic Matter
Sulfur
Bacteria
Infauna
Sediment
Sinking
Seafloor
Sinking
Feeding
Mortality Egestio
Feeding
Mortality
Outside the system
Outside the system
Dissolved
Inorganic Matter
Grazing Respiration
Epifauna
Grazing
Grazing
Outside the system
Particulate
Organic Matter
Grazing
Grazing
Grazing
Respiration
Respiration
Mortality Egestion
Feeding
Feeding
Mortality
Mortality Egestion
Feeding
Inorganic
Suspended
Particle
Discharged
Water
(Sedimentation)
Hydrogen
Sulfide(H 2 S)
DO
Diffusion
Fig. 2 Diagram of an ecosystem model in deep-sea hydrothermal fi eld
Use of Bio-fl uorescent Characteristics for Ecosystem Monitoring on Hydrothermal Deposits