Community-based monitoring
toward sustainable
management of mangrove
forest in Okinawa, Japan
Shion TAKEMURA
Japan Fisheries Research & Education Agency
INTERNATIONAL SEMINAR ON MARINE TOURISM, SCIENCE AND TECHNOLOGY JAMBOREE, SAIL SABANG AND THE 4TH INTERNATIONAL WORKSHOP ON SATO UMI, Jakarta, October 5, 2017
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Mangroves are declined due to human alterations in the world.
(e.g. conversion to mariculture, agriculture, urbanization and forestry use etc)
Background:
Functions of mangrove & Recent situation
Stabilizing coast and river-mouth
-> Natural barrier
Mangrove forest
in Okinawa Island, southern Japan
Okinawa
Island
Tokyo Osaka
Okinawa
20km
Local community are going to conserve and use
mangrove ecosystem as resource of ecotourism.
Mangrove is important resource for local economy.
Okukubi River
Canoeing
Life cycle of mangrove forest
seed dispersal colonization
germination &
growth
mature gap creation
Salinity
Muddy and
soft soil
Tidal current
Disturbances
regeneration
Regeneration of mangrove community is assisted by soft soil and its condition
formed by frequent exchange of sediment at bar surface during flood.
Takemura et al., (2012)
Degradation of mangrove habitat due to
infrastructure construction in Okukubi River
1980 Before
Capacity of reservoir: 818,000m3
After April 2013
Capacity of reservoir: 8,560,000m3
These infrastructures reduce exchanges of sediment at bar surface.
Narrowed river width
(Bridge construction)
Reduction of discharge
(Dam renewal)
Mangrove habitats were changed to unsuitable for regeneration
→
Artificial forest management is needed.
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Takemura et al., (2011)
Lack of information sharing among stakeholders
SH
Local ecotourism company
Local NPO
Local government
State government
National government
Challenges
:
To share
the current situation
and
the value
of mangrove
habitat among stakeholders in order to promote consensus building toward
sustainable forest management.
Objectives:
To developed a community-based monitoring system that SH
can grasp changes occurring in mangrove forest by a simple way.
Deforestation
by national government (April 2015)
Council has been established (April 2015)
1. Development of survey system
• Web based survey system was
developed using camera and GPS function of smartphone.
2. Data collection
• We investigated monitoring surveys
using developed web based system at January and March 2016.
3. Analysis
• Photos were classified into seedlings,
saplings, dead trees or another terrestrial plants.
Osawa et al., (2013) Japanese Journal of Conservation Ecology 18:157-165
Method
(1) Smartphone Monitoring
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1. Take photo with GPS
2. Sent email attached photo
3. Store database
4. Mapping (automatically)
5. Check data (classification)
6. Publish (PC & smartphone)
Method
(2) Bed Level Change Monitoring
1. Survey sites
• 19 survey sites were established in
mangrove forest.
• The initial bed elevation of survey sites
was measured by GNSS (June 2016).
• And PVC pipes were set on the
sediment surface.
2. Data collection
• Canoe instructors measured and
recorded the length of PVC pipes
exposed from the sediment surface every month
(June 2012 ~ March 2016).
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Method
(3) Crab Distribution Monitoring
1. Sampling methods
• 5 traps were buried flush with the
sediment surface on June, October 2012 and March 2013.
• Traps were checked daily for 3 days
(only Jun 2012 was 2 days).
• At the same time, bed elevation and
substratum were measured at each survey site.
2. Analysis (Habitat suitable models)
• Distributions of crab species were
related to bed elevation and substratum using GLMM and GLM.
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Results and Discussion:
(1) Smartphone monitoring
Forest
Tree species Seeds Seedlings
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Forest situations and their locations can be identify and recorded.
Map of forest situation
Results and Discussion:
(2) Bed Level Change Monitoring
Long term patterns of river bed fluctuation can be clarified.
Outer edge area: Gradual erosion
Inner area: Dynamic equilibrium
Upper area: Erosion
Lower area: Dynamic equilibrium
Bed
Location of sandbar
B
Location of outer edge in sandbar
Imai et al., (2016) Journal of Japan Society of Civil Engineers, Ser. B1. 72(4): I_1093-I_1098
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Results and Discussion:
(3) Crab Distribution Monitoring
Crab species by pitfall traps
Habitat Suitable Models
Biological Indicators in Okukubi River
Changes of soil condition can be
Conclusion and further research
•
Our monitoring system allow for stakeholders to monitor the
mangrove forest by themselves.
•
Further research is needed to investigate continuous monitoring
and to utilize its results for policy and next actions.
(1) Smartphone Monitoring (2) Bed Level Change Monitoring (3) Crab Distribution Monitoring
