2017-2018 Seagrass Surveys, Efate, Vanuatu

Commonwealth Marine Economies Programme

Enabling safe and sustainable marine economies across Commonwealth Funded by Small Island Developing States UK Government www.gov.uk/guidance/commonwealth-marine-economies-programme [email protected] Seagrass Surveys Efate, Vanuatu (2017-2018)

BACKGROUND SEAGRASS IN VANUATU During 2017 and 2018, a team of This loss is mainly due to the Seagrass beds are common in marine scientists from Cefas worked impact of encroaching urban the islands of Vanuatu, with the in the island of Efate, Vanuatu, developments and activities like largest and denser meadows found studying seagrasses. Seagrasses are fishing, dredging, anchoring and in sheltered shallow lagoons and underwater plants that evolved from poor land management causing bays with sandy sediments. There land plants. Seagrass meadows are turbidity and siltation in coastal globally important for a number of waters. In addition, changing climatic have been two assessments of reasons: they are highly productive conditions like like warming seas, seagrasses in Vanuatu as part ecosystems and provide many rising sea level, and cyclone damage of wider biodiversity surveys ecological services as well as acting are aggravating widespread habitat published in 1990 and 20112, and as a natural carbon sink, absorbing degradation. nine species have been identified, large amounts of carbon dioxide and Shallow intertidal seagrasses are but a complete scientific evaluation storing it as organic carbon for long likely to be more vulnerable to of seagrasses in Vanuatu has not periods of time. climate impacts, particularly those been conducted. Therefore, the Disturbance and loss of these nearer to populated areas, while total area of seagrass beds and the deeper and more remote subtidal habitats can result in large emissions level of threat to both dugongs and of carbon dioxide back into the seagrasses will be more resilient seagrasses remain unknown. atmosphere. Seagrass meadows are although they may experience rapidly decreasing in number and changes in distribution and 2. http://www. dugongconservation.org extent across the globe, and Vanuatu composition of species in the is no exception. future as sea level rises.

Common tropical Indo-Pacific seagrass species categorised according to life history traits based on their ability to resist or recover from disturbance 1 — persistent (P) or colonising (C), or a mix of these: opportunistic (O). Species observed in the 2017-18 surveys are shown in bold.

1. After Kilminster et al. (2015). https://www.sciencedirect.com/science/article/pii/S0048969715005124. Symbols courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/symbols/).

ea serrulata (O) Halophila ovalis (C) dule uninervis (C/O) Enhalus acoroides (P) Halophila decipiensHalophila (C) tricostata (C) Halophila spinulosa (C) Zostera muelleri (C/O) Thalassia hemprichii (P) Halo Cymodoc Cymodocea rotundata (O) Syringodium isoetifolium (O)

Photo: Ethan Daniels | Alamy Enhalus acoroides www.gov.uk/guidance/commonwealth-marine-economies-programme

Funded by Importance of seagrass UK Government

Seagrass meadows are globally Photo: Dieter Tracey important for a number of reasons. They provide habitat for many fish as well as molluscs and sea cucumbers that are vital to the food security and the economy of coastal communities across Pacific island countries like Vanuatu. Seagrasses contribute to maintain good water quality by trapping sediments and pollutants. Seagrass meadows provide grazing and shelter for sea turtles and dugongs; the protection and conservation of seagrasses is crucial to the survival of these Seagrass meadows provide valuable nursery habitat to many fish species. vulnerable species. Finally, seagrasses are one of the main “blue carbon” habitats, together with mangroves and saltmarshes, so called because they sequester carbon dioxide from the atmosphere and store it in its organic form for very long periods of time unless disturbed. Disturbance and loss of these habitats can result in the remineralisation of the stored organic carbon and the emission of potentially very large amounts of carbon dioxide back into the atmosphere. Seagrass meadows are important for their ability to sequester and store carbon from the atmosphere.

Photo: Louise Murray | Alamy

Seagrass meadows provide food for dugongs, so the protection and conservation of seagrasses is crucial to the survival of this vulnerable species. www.gov.uk/guidance/commonwealth-marine-economies-programme

Funded by Partners in seagrass mapping UK Government This work would not have been validate our remote sensing satellite possible without the enthusiastic mapping of intertidal seagrasses support of many Vanuatu in Efate and other islands. C2O 6 collaborators. marine champions associated to the C2O RESCCUE project are currently SPREP 1 provided invaluable working to support adaptation to assistance with logistics, regional climate change through integrated networking and data collection. coastal management and sustainable Through the kindness of our contacts fisheries; they accompanied us during 2 at the USP Emalus campus in Port our surveys in the northern, more Vila, Efate, Cefas had access to remote seagrass sites. dedicated laboratory and storage areas, as well as the support of Finally, we are grateful for the students and staff who provided support of the Government of essential assistance during field Vanuatu as co-leaders with the UK and laboratory activities. We worked of the Commonwealth Clean Oceans closely with DoWR 3 building capacity Alliance. The Vanuatu Department and skills in aspects of water quality, of Environmental Protection and Conservation has kindly approved a Cefas scientists with collaborators from the and officers from DoWR were DoWR and USP carrying out field work on research permit for Cefas to collect instrumental to our research, acted the seagrass meadows Paoganisu (top) and seagrass to carry out this study. as local guides and helped in the Pango Vale Vale (bottom) in, Efate, Vanuatu. field and in the laboratory throughout the project. Colleagues form VESS 4 1. The Secretariat of the Pacific Regional Environment Programme http://www.sprep.org/( ) carrying out SeagrassWatch 5 2. University of the South Pacific https://www.usp.ac.fj/?id=7158( ) 3. Vanuatu Department of Water Resources (https://mol.gov.vu/index.php/en/water/226-water) monitoring surveys in various 4. Vanuatu Environmental Science Society (https://www.vanuatuconservation.org/about-vess/) islands in Vanuatu were happy to 5. SeagrassWatch (http://www.seagrasswatch.org/home.html) share knowledge and data to help 6. Coasts Climate Oceans Consulting (https://www.c2o.net.au/people) Survey results (2017-2018) Our results suggest that the health Further research is needed to The proportion of organic carbon and diversity of seagrasses, as well understand to what extent these to total carbon was 1.68%, only as their capacity to store carbon, are differences are influenced by slightly lower than the global linked to the water quality. Higher environmental factors such as average. To our knowledge these are values of carbon storage resulted nutrient load in the water or sediment the first measurements of carbon from samples from seagrass type. From the 2017 samples we stored by seagrass in Vanuatu. growing in shallow, calm lagoon calculated the average carbon stocks While we continue to analyse the areas where the sandy sediment is to be 107 tonnes of carbon per 2018 seagrass data, overall they deeper. Near Port Vila the seagrass hectare, lower than the current global confirm that the type of sediment, appeared covered by epiphytes and average (140 tonnes per hectare). the morphology of the coast, and the carbon content of the seagrass This may be due to the fact that in the relative distance to the island’s plants was lower. Epiphytes are Efate the seagrass generally grows urban areas, has an effect on the bacteria and algae growing on the on a shallow layer of sediment (less seagrass and its capacity for surface of the seagrass leaves. than 50 cm deep) over a base of rock carbon storage. An excess of epiphytes suggests and coral, which limits the storage of eutrophication. carbon below-ground.

Cefas scientists and collaborators carrying out quadrat observations of intertidal seagrass in Efate, Vanuatu. www.gov.uk/guidance/commonwealth-marine-economies-programme

Funded by UK Government % COVER AND SPECIES (2017) (2017) AND SPECIES % COVER

Seagrass cover (%) and species composition in intertidal locations in Efate, Vanuatu during the 2017 surveys. Seagrass species ID key: Th — Thalassia hemprichii; Cr — Cymodocea rotundata; Ea — Enhalus acoroides; Hu — Halodule uninervis; Ho — Halophila ovalis. www.gov.uk/guidance/commonwealth-marine-economies-programme

Funded by UK Government HEIGHT AND HEALTH (2017) (2017) HEIGHT AND HEALTH

Seagrass plant height (cm), health and species composition in intertidal locations in Efate, Vanuatu during the 2017 surveys. Seagrass species ID key: Th — Thalassia hemprichii; Cr — Cymodocea rotundata; Ea — Enhalus acoroides; Hu — Halodule uninervis; Ho — Halophila ovalis. www.gov.uk/guidance/commonwealth-marine-economies-programme

Funded by UK Government % COVER AND SPECIES (2018) (2018) AND SPECIES % COVER

Seagrass cover (%) and species composition in intertidal locations in Efate, Vanuatu during August 2018. Seagrass species ID key: Th — Thalassia hemprichii; Cr — Cymodocea rotundata; Ea — Enhalus acoroides; Hu — Halodule uninervis; Ho — Halophila ovalis. www.gov.uk/guidance/commonwealth-marine-economies-programme

Funded by UK Government HEIGHT AND HEALTH (2018) (2018) HEIGHT AND HEALTH

Seagrass plant height (cm), health and species composition in intertidal locations in Efate, Vanuatu during August 2018. Seagrass species ID key: Th — Thalassia hemprichii; Cr — Cymodocea rotundata; Ea — Enhalus acoroides; Hu — Halodule uninervis; Ho — Halophila ovalis. Commonwealth Marine Economies Programme

Enabling safe and sustainable marine economies across Commonwealth Funded by Small Island Developing States UK Government www.gov.uk/guidance/commonwealth-marine-economies-programme [email protected]

Conclusions The Commonwealth Marine Data collected from 2016 to 2018 modelling provides key information Economies (CME) Programme offer an insight into the status of to policy makers on how cumulative in the Pacific has worked across the marine environment and will be pressures of a changing climate, several Pacific countries, with Cefas used in mapping the resilience of and coastal water quality issues, can contributing or leading work in the marine ecosystems to climate impact the valuable marine services in Vanuatu, Solomon Islands, Fiji change and coastal pollution. The Pacific, whilst information on carbon and Kiribati. combination of coastal water quality storage and seagrass habitats can assessments, climate reporting and help mitigate these impacts. The CME Programme supports small island developing states by building the capacity of the INTEGRATION WITH WIDER RESILIENCE FRAMEWORK islands to manage their marine resources and develop their national c maritime economies. It is also Local to national scale – helping to address climate change, Hydrodynamic modelling including the UN Sustainable Development Goal 14 (to conserve and sustainably use the oceans, Regional to national scale – Remote sensing seas and marine resources for sustainable development). The CME Programme in Vanuatu b focused on the collection of water a quality, human health, seagrass and blue carbon data to inform Local scale – In situ an ongoing risk assessment monitoring programme and identify key issues facing Vanuatu’s communities and marine ecosystems. The full work package in Vanuatu includes assessments of coastal water quality, human health, seagrass habitat mapping and carbon measurements with the aim of to providing a holistic Seagrass mapping is part of a broader CME programme integrating multiple sources of information, assessment of environmental including (a) water quality data collected in the in-situ monitoring programme, (b) hydrodynamic quality for Vanuatu. modelling to further understanding the transport and extend of pollutants, and (c) extended observations of some water quality parameters (e.g. Chl-a) through the analysis of remote-sensing data.

Produced by the Centre for Environment, Fisheries and Aquaculture Science (Cefas) funded under the Commonwealth Marine Economies (CME) Programme¹ Cefas contact: Dr Michelle Devlin [email protected] We would like to thank those who helped facilitate this work programme including Mr Toney Tevi, Head of Maritime & Ocean Affairs Division, Ministry of Foreign Affairs, Vanuatu Government; Dr David Loubser, Vanuatu Country Manager (PEBACC); Secretariat of the Pacific Regional Environment Programme (SPREP) and Dr Krishna Kotra of The University of the South Pacific. All photos by the Cefas team except where indicated otherwise. ¹https://www.gov.uk/guidance/commonwealth-marine-economies-programme For more information about the CME Programme contact: [email protected] / @CME_Prog