“Sustainable ecosystem management” is equal to “Sustainable land management (coastal protection)” against sea level rise in small island countries.
Hajime Kayanne (Univ. Tokyo) Fongafale Is, Tuvalu Distribution of atolls
Mahe, Maldives
Majuro Funafuti,Tuvalu
Majuro, Marshall
Marshall
Maldives ■ atoll Tuvalu Global threats m IPCC AR5 (2013)
Nukutoa,Takuu Atoll, PNG
Funafuti Atoll, Tuvalu Batio, Tarawa Atoll, Kiribati Coral Gravel Ecological process in island formation
Coral reefs forms a foundation. Coral gravel constructs an ocean-side ridge. Foraminifera forms an island body.
lagoon Ocean
Coral reef
Foraminifera sand
Fongafale Is, Funafuti, Tuvalu coral gravels
foraminifer sand
Atoll islands are formed by organisms Halimeda Water pollution by sewage effluent
Reduced layer 2-3cm below bottom
H2S “Bottomless” Septic Tank tide
105 4 e-coli Aug. 7, 2010 Corals are dead and 104 concentration 3 covered by algae 103 25 times higher 2 than Japanese 102 1 (m) level Sea 101
environmental (MPN/100mL)coli E.
criteria. 100 0 6:00 9:00 12:00 15:00 18:00 Ecosystem deterioration Fongafale Is, Funafuti, Tuvalu Uliga Island
7,000 7,000
9,000 エネコ島 5,000 1,500 1,100 600600 250
Calcarina 20 Amphistegina Almost one million forams Sorites 50 in one squre meters. Foraminiferal Density 2 15 （#/100 cm ） デラップ島 Majuro Atoll, Marshall Is. Land use: expansion of residential area to vulnerable low land
Nature, 440 (2006)
Is Tuvalu sinking?
Fongafale Is, Funafuti, Tuvalu Yamano et al. (2007) 2007 Constructions against natural process Vertical sea walls prevent sand sedimentation at their foots. Tarawa, Kiribati
Causeways prevent sand transportation
Funafuti, Tuvalu Tarawa, Kiribati
from ocean to lagoon or release to deep ocean through boat channel. Geo-Ecological process is degraded by local human activities
production transportation seimentation
Ecosystem degradation by Sand drift interrupted by Beach erosion by vertical seawater pollution jetties and dredges seawalls
Dead corals covered by Vertical seawalls macro algae．
Reduced layer 2-3cm below sand
erosion
Loss of coastal vegetation Sand drift Ecosystem-based coastal protection
June 2010 12 Jan 2016 Beach nourishments (not vertical seawalls)
Fongafale Is, Funafuti, Tuvalu
JICA technical cooperation project
0 350m 0 350m (photos by Nippon Koei) Ideal design of the causeway. Open-cut to the level of reef flat. Sewage treatment by bacteria and seawater (Fujita 2016)
Organic matter Immobilization carrier of = 18gBOD/PE/d Sulfate-reducing bacteria SO 2- = 0.4gS/PE/d 2- 4 BOD + SO4 ∴ BOD : S = 45 : 1 H2S + CO2 + H2O ∴ BOD : S = 1.6 : 1
2- Soil does not have sufficient SO4 to degrade BOD. Sea water is used !! Septic Tank Tide
2- SO4 =0.9gS/L permeable 13 Production Improvement of coastal eivironment is required bofore or in parallel with any ecosystem rehabilitation challenges.
Then we can adopt ecotechnology.
Coral culture and transplantation
Okinotorishima
Foram culture
Tuvalu Sustainable ecosystem management equals sustainable land management against sea Ultimate goal level rise in small island countries.
Culturing foraminifera Open-cut causeway
and corals High
Regeneration of sandy beach
Recovery of coastal ecosystem
Waste treatment Sewage treatment challenge level challenge
Scientific and and technological Scientific Replanting coastal vegetation
Sand bypass Low Beach nourishment
Removal of jetties Backfill dredges
Decadal （10 yr） Time scale Centennial（100 yr） Present state • Only ecosystem-based management cannot save small islands from rising sea level. • However, any grey coountermeasure works must NOT coflict with, and should enhance natural ecological process which forms the island and coast. • Combined grey and green technologies are necessary. • Ecosystem-based management needs understanding by local people and governments, and socio-economical aspects of small island countries. SIDS (Small Island Developing State) Forum, UTokyo Ocean Alliance 海洋アライアンス小島嶼研究会
Global and local problems in atoll islands