The Coastal Ecosystem in and Geo-ecological

Acknowledgements Management against

SATREPS ( JICA-JST), Japan Sea-Level Rise Department of Environment, Tuvalu Department of Fisheries, Tuvalu Department of Land and Survey, Tuvalu

Photos and illustration by Hajime KAYANNE, Takashi HOSONO, Akihiro KAWADA in Akihiro KAWADA Foram Sand Project Fumiko MATSUDATE (April 2009 – March 2014) Hajime KAYANNE Paeniu LOPATI Saki HARII Takashi HOSONO PART PAGE 01 Atolls and coral reefs ...... 04 02 Islands formed by the skeletons of marine animals ...... 05 03 Coral and foraminifer ...... 06 04 Marine animals and the ecosystem ...... 07 05 Big drought in 2011 and resilience of the coastal ecosystem ...... 08 06 After the collapse of the coastal ecosystem ...... 09 07 Is Tuvalu sinking? ...... 10 08 Obstacles to the island formation process ...... 11 09 Geo-Ecological management of islands ...... 13 10 Application to other atoll island countries ...... 14 11 Our island is alive ...... 15 Islands formed by Atolls and coral reefs 01 02 marine animals

Atolls are ring-shaped coral reefs tiated by deep drilling at the Eniwetak Atoll Tuvalu is a chain of atoll islands coral reef. The debris of coral skeletons standing in mid-ocean and surrounding a just after WWII, which penetrated into vol- several hundred meters wide with eleva- are tossed up to form the ocean-side storm shallow lagoon. They are the final stage canic rocks 1267 m below the sea surface tions ranging from one to four meters. The ridge. Forams are protozoa, which live on of coral reef evolution: a newly born vol- that were overlaid by coral reef limestone. islands of Tuvalu are formed on a rigid the reef flat by attaching to turf algae and canic island is first fringed with coral reefs Today, the initial volcanic island and its framework of coral reefs, which have been that precipitate calcareous shells of one to constructed by piling up the skeletons of two millimetres in size. The major part of (fringing reef). As the island subsides, the subsidence are explained by plate tectonics hermatypic corals. Corals are cnidarian an- the island body (the lagoon-side ridge and coral reef grows upward to form a barrier in which a volcanic island is formed at a imal relatives of jellyfish and sea anemone the central depression) is formed by the reef separated from the island by a shallow hot spot and then travels and subsides with that precipitate calcium carbonate skele- shells of the forams (foram sand). lagoon. Finally, the island subsides well a plate. tons. They pile up to form coral reefs that Coral and foram are the two major beneath sea level to form an atoll. This hy- Approximately 500 atolls exist in provide a foundation for the island and act players that construct the islands in con- pothesis was proposed by Charles Darwin the world, with 400 located in the Pacific as a natural breakwater. However, coral junction with several other calcifying or- in 1842 during the survey of the HMS Bea- Ocean. Tuvalu consists of 9 atolls. They are reefs never accumulate above low water ganisms, such as molluscs, calcareous red gle and then tested by deep drilling at the aligned from southeast to northwest, corre- level. and green algae, and sea urchins. There- Atoll in 1896-1898, which failed sponding to plate motion. Tuvaluan atolls Those islands above high water fore, island formation is governed by both to reach the volcanic basement but recov- have travelled from the southwest. Islands level serving as habitable land for humans physical and ecological processes. The sus- ered more than 300 m of shallow coral reef on the atolls are formed by unconsolidat- have been formed by coral debris and for- tainability of the national land of Tuvalu sediments, implying subsidence. Darwin’s ed coral gravel and foraminifera sand over aminifera (foram) sand tossed up onto the depends fully on coral and foram. subsidence theory was eventually substan- several thousand years. a b

c

a. Beach sand in FUAKEA Island. b. Coral community in the lagoon of Island. c. Foraminifer population in TENGAKO Island (TH).

04 Foram Sand Project Foram Sand Project 05 Marine animals and Corals and foraminifers 03 04 the ecosystem

Corals and foraminifers belong to a quite different phylogenetic groups. How- ever, their nutrient acquisition methods Corals and foraminifers can be are similar. Coral and foraminifer contain found in littoral and sublittoral zones symbiotic algae within their bodies. They utilize sunlight and allow their symbiotic in Tuvalu. They utilize sunlight in algae to photosynthesize. Then, they ac- shallow areas to acquire nutrients. quire nutrients from the photosynthetic products of the symbiotic algae. They also eat plankton from the water column using tentacles by the coral and pseudopods by However, they need more to sur- more than these three factors to survive. the foraminifers. vive than only sunlight and nutrients. Corals Coral easily die in polluted environments, also need a hard substrate for attachment, can become bleached or be covered with al- and foraminifers also need macroalgae for gae. Foraminifers also die and can become attachment. In addition, they still require bleached under some conditions.

b

a. Surface and inside of a foraminifer (Baculogypsina sphaerulata). . Orange color inside the foraminifer is a symbiotic diatom (TH). b. Foraminifer (Amphistegina lessonii) attached to a glass microscope slide. The arrow indicates a pseudopod (TH). c. Corals (SH) d. Tentacles and symbiotic algae (SH). c d

Coastal ecosystem in the reef of Island (TH). 06 Foram Sand Project Foram Sand Project 07 Big drought in 2011 and resilience After the collapse of the 05 of the coastal ecosystem 06 coastal ecosystem

The big drought occurred in 2011, and its negative effects have mostly subsided. The dry breadfruit trees have returned to life. Many water tanks donated from foreign coun- We can easily understand the tries will not be used until the next drought. However, that prolonged drought caused sig- damage that the coral community nificant problems that affected many lives. At experienced after the collapse of the the same time, we also recognize the degrada- coastal ecosystem and the loss of tion of the ecosystem in our sea. One example a is the black-coloured algae that were unnat- resilience when the following pictures urally overgrown in the lagoon. Coastal eco- are compared. systems that have low resilience are supposed to easily change their forms in response to small external forces. Sometime after the rain returned, the ecosystems appeared to recover their former forms, and therefore, the current a b ecosystem exhibits some resilience. However, the drastic changes in the coastal ecosystem b during the big drought clearly reflect strong a. Landing of water tanks donated as relief anthropogenic stress and weak resilience in supplies from foreign countries (TH). the coastal ecosystem. b. Lagoon beach of the island covered with spoiled algae (FM). c

c d

a. Table coral in a healthy coast of the Funafuti Atoll. b. Dead table coral in the lagoon of Island. c. Branching coral in a healthy coast of the Funafuti Atoll. c. Black cyanobacteria-covered branching coral in the lagoon of Fongafale Island during the drought (PL). d. Dead branching coral in the lagoon of Fongafale Island. (HK).

08 Foram Sand Project Foram Sand Project 09 Obstacles to the Is Tuvalu sinking? 07 08 island formation process

During the spring high tide (King The islands of Tuvalu were first The major site of foraminifera sand pro- tide), the inland areas of Fongafale Island formed by coral reefs. They still act as duction is the ocean-side reef flat, and this become inundated with seawater. Such in- a natural breakwater in front of both the sand is first delivered to the lagoon through undation has been occurring more frequent- ocean-side and lagoon-side coasts. Corals the channels between the islands and then ly. Local people argue that they have never also provide sand and gravel. However, transported along the lagoon-side coast by experienced such inundation before and coral reefs have never grown above low the longshore current. that it is therefore caused by rising sea lev- exists. The spring high tide reaches 1.2 m, water level, and the islands above high wa- A healthy ecosystem with living els induced by global warming. and thus the central depression is naturally ter level were formed by gravel and sand coral and foraminifera is fundamental to is- The landform of Fongafale Is- inundated by spring-tide water. from the calcareous skeletons of organisms. land formation, and sand production, trans- land consists of a coral reef, a storm ridge, An old geologic map revealed that The major body of the island was formed portation and sedimentation is the key pro- a central depression, and a lagoon-side the central depression was formerly cov- by the sand of foraminifera, coral, calcar- cess in island formation. Fongafale Island ridge from the ocean side to the lagoon ered by a large salty swamp fringed with eous algae and shells, with foraminifera is formed on a rigid framework of coral side, which are typical geomorphological mangrove trees. A report published as a contributing more than half and up to three- reef and located at the terminal of the sand features of atoll islands. The storm ridge companion to the map in 1896 stated that fourths of the sediment. The main contrib- transportation from the north and south. reaches 4 m in elevation above the mean “at high tide it is covered by ankle deep utor to the sediment is the foraminiferan However, this natural process is sea level (MSL), which is the highest on the with water which drains away at half ebb”, Baculogypsina sphaerulata (star sand). now inhibited by human pressure and the island, and is formed by coral debris tossed the same phenomenon observed today. The up during storm events. The habitable area natural landscape became obscured by the of the island is protected from ocean waves construction of the air strip during WWII and swells by the coral reef and storm by the US Army against the expansion of ridge. The lagoon-side ridge reaches as the Japanese occupation, which reached high as 2.5 m and provides the main human Tarawa just north of Tuvalu. The inland in- habitat. Between these two ridges, the cen- undation is the result of the expansion of tral depression, with an elevation of only 1 residential areas into the original lowland m, extends into the island, where an air strip due to the growth of the population.

Expansion of residential areas into the lowland region (Yamano et al. 2007). Combined stresses

10 Foram Sand Project Foram Sand Project 11 Geo-Ecological management of anthropogenic construction of coastal land- from all these obstacles to sand production, forms. The production of coral and for- transportation and sedimentation. The loss 09 the islands aminifera sand has been greatly reduced of the sandy beach represents the loss of by reef ecosystem deterioration as a result the island formation process, which should To protect islands against rising sea backfilling the dredges would re-open the of coastal water pollution. This pollution continue to preserve the island against in- levels, the natural island formation process transportation passage along the coast. A is caused by sewage seeping from the is- creases in sea level. needs to be rehabilitated by removing ob- vertical seawall will enhance erosion rather land accompanying the tidal cycles. Sand Local human activities have stacles. Based on the known obstacles to than sedimentation at its base. Therefore, transportation from the ocean to the la- stressed and degraded the local ecosys- sand production, transportation and sedi- beach nourishment is proposed as a short- goon is blocked by the causeway between tem and natural island formation process. mentation, we propose the feasible options er-term coastal protection and rehabilita- Fongafale and Tengako Islands. The trans- Global warming and ocean acidification herein. tion plan that enhances but does not conflict portation of sand along the lagoon coast is have also contributed to ecosystem degra- To regenerate coral and foramin- with the long-term rehabilitation of the san- interrupted by jetties and dredges. Finally, dation, and a rise in sea level would cause ifera production, ecosystem rehabilitation dy beach. sand sedimentation is prevented by revet- submergence. If the coral and foraminifera is necessary, which should be achieved These proposed plans have differ- ment and the loss of coastal vegetation. Be- are healthy, they have the potential to keep by improving the coastal environment via ent timescales and technologically chal- fore World War II, the Fongafale coast was up with the rising sea level to form a natu- sewage treatment and waste management. lenging levels. The effectiveness of beach fringed by a sandy beach, which was lost ral breakwater and island. However, local This rehabilitation would be supported by nourishment will be clearly visible, and the by a landfill during the war. Only a small stresses have increased the island nation’s foraminifera and coral culture and trans- required technology is well established. amount of sand remained along the Alapi vulnerability and damaged the natural resil- plantation and the generation of their hab- However, improvement of the coastal en- coast, and never recovered. We judge that ience against the projected rise in sea level. itats. However, the improvement of the vironment needs a longer timescale to the no recover of the sandy coast resulted coastal environment is a prerequisite. achieve. The technologies responsible for Any engineering plans for coastal foraminifera and coral culture and trans- protection must not conflict with, but rather plantation have just been established and should enhance, the natural processes. An require further challenges for adaptation to open-cut causeway will enhance sand de- the site. However, these novel technologies livery from the ocean to the lagoon, nour- should be applicable to other atoll island ishing the lagoon coast. Removal of the countries. jetties or their reconstruction with piles and

Culturing foraminifer. Re-opening the transportation passage along the coast.

12 Foram Sand Project Foram Sand Project 13 Application to other atoll Our Island is alive 10 island countries 11

Our island is alive, breathing and this mechanism. What we can do is take the ever growing. It has been entwined as a part initiative in regarding a cleaner ocean and There are approximately 500 of our cultural heritage that has been treated giving time for our island to recover. atolls around the world, mainly with care and handed down by our ances- The important thing is that we all located in the Pacific. All atolls tors. But now, our human activities have treat our ocean with care and give it the polluted the ocean and harmed our island, respect that was given by our ancestors. suffer from local and global causing its natural resilience for change to Then, coral and foraminifera will return to environmental issues. get weaker. us. Our island will regain natural resilience Construction of an artificial island and save us from ocean threat. protector may be the answer to this. It is a method that has already been used. This op- Some of these atolls form atoll would represent the first successful appli- tion however required endless maintenance island countries, such as the Marshall Is- cation in the world. If this strategy can be after construction, which causes it to be a lands, Kiribati, Tokelau, and French Poly- applied to the atolls in Tuvalu, it can also burden for generations to come. Is this ac- nesia in the Pacific Ocean and the Maldives be applied widely to other atoll island coun- ceptable? in the Indian Ocean. The establishment tries. Technologies from Tuvalu will help Islands have a natural mechanism of geo-ecological management in Tuvalu solve a central concern of island societies. against waves and rising sea level. What we have to do is to support the recovery of AK

FM FM

World distribution of atolls

AK 14 Foram Sand Project Foram Sand Project 15