Timor Leste

The coral reefs, seagrass meadows, mangroves, beaches and intertidal habitats support a high diversity of marine plants and animals that provide critical resources for coastal communities and also species of conservation concern, including dugongs and marine turtles.

Coral reefs (including coastal fringing and large elongate patch reefs) cover 146 km² of the Timor-Leste's nearshore area³. In Timor-Leste, most of the reefs appear to be found on the north coast, which is characterized by karst geology and uplifted ancient coral reefs^5,1 , which results in reefs with a narrow reef flat (20-100 m) and a steep drop-off (40-60 m depth). Limited information is available on the seagrass habitats in Timor-Leste. The lack of knowledge makes it difficult for stakeholders to effectively integrate seagrass protections into local, regional or national initiatives.

The earliest record of seagrass from Timor-Leste is 20 December 1953; Cymodocea rotundata and Halodule pinifolia herbaria specimens were collected from the sandy coral reef near Lore on the south coast^,67. Over the following decades, the majority of records have been ad hoc collections/observations as very few nearshore habitat surveys have been conducted. To date, no comprehensive survey has mapped the entire seagrass resources of Timor-Leste⁸. The best estimates available are from broad-scale, predominately remote assessments, conducted over the last twelve or so years.

The first broad-scale mapping of Timor Leste nearshore habitats was undertaken in 2007 along the northern coast, using Landsat TM/ETM+ imagery (imagery captured between 2003 and 2006) and field work (19-30 November 2007)⁹. Field ground-truthing of the Landsat TM imagery was undertaken in 6 locations – Metinaro, Manatuto, Baucau, Com, Jaco and Lore. From this, a broad scale (1:100k) map of the north and east coast of Timor-Leste was produced (smallest mapped element was 0.1ha). Nearshore marine habitats were delineated from the remote imagery using object based image analysis, and classified using the field ground-truthing. The marine nearshore zone was characterised by a narrow reef flat (often <60m wide, but up to almost 1km), dominated by seagrass in shallower water (approximately 2,200ha) and corals in deeper water and on the escarpment (approximately 2,000ha)⁹). A mixed-cover class, which included coral-seagrass and open reef flat, occupied 1,266 ha.

As part of the 2007 broadscale mapping⁹, a survey of Nino Konis Santana National Park confirmed the presence of Syringodium isoetifolium, Cymodocea rotundata, Halophila ovalis, and Halodule uninervis ¹⁰. Within the park, areas of seagrass habitat included: sparse patches of Thalassia hemprichii meadow (5-8% seagrass cover) on the inner reef flat on the north and east coast of Jaco Island; dense but narrow seagrass meadow on the inner reef flat at the North Coast (east of Com) where there was a 30 m wide band dominated by Halodule uninervis with some Thalassia and Syringodium isoetifolium; and a wide dense seagrass meadow with all the above species as well as Halophila ovalis on the inner reef flat at Com on the western boundary of the Marine Park¹⁰.

In 2012, a marine rapid assessment (MRAP) of coral reefs conducted between 14-23 August examined twenty-two sites, including 14 sites within Nino Konis Santana National Park (both mainland coast and Pulau Jako), as well as 4 sites on the northern mainland coast east of Dili and 4 sites on Pulau Atauro ¹¹. As shallow seagrass dominated habitats were not surveyed specifically, only seagrass presence is mentioned with no detail on species or abundance available^12,2. The authors also commented that some of the MRAP sites on the north coast suffered from sedimentation caused by erosion of watersheds and that it was highly likely that nearshore seagrass habitats present at those sites are also affected by sedimentation¹¹. It was noteworthy that some areas on Atauro Island had an extremely high cover of hard corals (and likely seagrass), compared to the mainland which was likely due to the absence of major rivers on Atauro Island.

Also in 2012, broad-scale mapping of the marine and coastal habitats of Timor-Leste was completed using Landsat satellite imagery, covering the districts of Oecussi, Bobonaro, Liquicia, Dili (Atauro Island), Kova Lima, Ainaro, Manatuto (south coast), Manufahi, and Vikeke, that were not mapped by Boggs et al. (2012)⁹,(Joyce, 2013)¹³. Five Landsat 5 TM scenes (acquired in 2008) coupled with geo-referenced aerial photographs (captured in 2002) and photographs taken during an aerial survey in November 2012 were used to guide the supervised classification. Field surveys were also undertaken to collect calibration and validation data, centred on four sites that contained a wide range of habitat-types: Beacou (Bobonaro district), Suai (Kova Lima district), Tibar (Liquicia district), and the northern coast of Atauro Island (Dili district). Beacou, Suai and Tibar were surveyed in June 2012; Atauro Island was surveyed in November 2012. Due to logistical limitations, habitats along the south coast were only assessed by aerial survey in November 2012. The total area of seagrass identified from the final classified images were 500ha of dense seagrass (30-100% cover) and 300ha of sparse seagrass (5-30% cover)¹³. If seagrass cover was less than 5%, the area was classified as bare area. Seagrass field validation points were classified correctly 67% of the time, with misclassifications occurring between classes with similar spectral reflectance signatures (e.g. coral and sparse seagrass). When combined with the 2007 mapping, this estimates the overall area of seagrass habitat in Timor Leste to be approximately 4,266 ha.

Seagrass distribution throughout Timor-Leste is most likely influenced by shelter, sediment characteristics, water clarity and tidal exposure. Eight seagrass species, with an additional two species under review for synonymy, have been confirmed from the waters of Timor-Leste: Cymodocea rotundata Ehrenb. et Hempr. ex Aschers.; Cymodocea serrulata (R. Br.) Aschers. et Magnus; Enhalus acoroides (L.f.) Royle; Halodule uninervis (Forsk.) Aschers. in Bossier; Halophila ovalis (R.Br.) Hook. f.; Syringodium isoetifolium (Ascherson) Dandy; Thalassodendron ciliatum (Forsk.) den Hartog; and,Thalassia hemprichii (Ehrenberg) Asherson. Two additional species (Halodule pinifolia and Halophila minor) are reported from Timor-Leste, but are under review for synonymy. Waycott et al. (2004)¹⁴ suggested that Halodule pinifolia and Halodule uninervis were conspecific, recognising that the plasticity of the leaf blade size can be attributed to local conditions. However, recent rbcL gene sequencing has suggested that the species may be separate¹⁵. Similarly, Halophila minor is considered synonymous with Halophila ovalis¹⁴, as it is difficult to distinguish the species visually in the field and phylogenetic studies indicate either none or some potential divergence^16,17,18.

Unconfirmed occurrences of other species (e.g. Ruppia maritima L.) appear in the literature, however no specimens confirm their presence. The occurrence of species in adjacent Indonesian waters implies presence in Timor-Leste waters, however oceanic currents may be a determining factor. For example, both Ruppia maritima and Halophila spinulosa occur in Indonesian waters, however their presence is limited; they have not been reported east of Lombok. This constrained western distribution may be a consequence of the Lombok Strait corridor of the Indonesian ThroughFlow, which could be restricting eastern dispersal. The absence of other species (e.g. Halophila decipiens) from Timor-Leste waters, may however be a consequence of limited surveys, particularly of subtidal waters deeper than 10m where some species dominate. Anecdotal reports of rarer species in Timor-Leste such as Halophila beccarii and Zostera capensis are erroneous, as these species is not reported from any adjacent areas (i.e. does not occur in Indonesia, Papua New Guinea or Australia) and the reports were from habitats where this species is not known to occur.

The seagrass species reported from Timor-Leste are not unique from those found along the coast of adjacent countries in the Arafura, Timor, Flores, Savu and Banda Seas, including: northern Australia, Papua New Guinea, and the Indonesian provinces of East Nusa Tenggara, Maluku, and Papua^19,20,21,22.

Seagrass meadows are important economic assets in Timor-Leste on both regional and local scales. Seagrass meadows represent important nursery and feeding grounds for many fish of subsistence and artisanal important in Timor-Leste, in particular Lutjanidae, Lethrinidae, and SerranidaeCTI-TLS, 2012
^23,24,26.

Seagrasses are valuable at local levels as they contribute to the provision of protein and cash income to the different human populations. In some regions, local communities engage in reef gleaning (meti fai, tono fai) of nearshore seagrass meadows during low tide targeting juvenile fishes, crabs, molluscs, and sea urchins^25,26. Apart from fisheries production, seagrasses provide a range of goods and services from attenuating wave energy and reducing coastal erosion / sedimentation to cultural importance²⁷.

The seagrass meadows of Timor-Leste also provide food and critical habitat for green sea turtle (Chelonia mydas) and dugong (Dugong dugon) which are listed as threatened or vulnerable to extinction in the IUCN Red List (www.iucnredlist.org). Considered sacred animals, dugongs are not actively hunted in Timor-Leste; however, incidentally trapped individuals are often killed and consumed. Dugong mortality has not been formally reported in Timor-Leste although the use of gillnets in nearshore waters by coastal fishers is increasing.

The distribution of dugongs in the coastal waters of Timor-Leste is largely unknown with sightings of individuals recorded on the north coast of the country and from Atauro Island. A marine megafauna survey conducted in 2008 for the whole coastline reported dugongs are rare with one individual sighted in the northwest and five individuals in the north-east²⁸. Anecdotal sightings of dugongs feeding on seagrass meadows have also been reported on the north coast by recreational divers at popular dive sites west of Dili including: Dan´s Sandy Bottom, Secret Garden, K41 and Piertamina. The most frequent sightings are of “Douglas” the resident dugong at Roda Reef, Tasi Tolu and Dili Rock East. In mid 2017 it was reported that a small juvenile dugong was accompanying “Douglas”. Dugong have also been reported from east of Dili, e.g. Dollar Beach.

In Timor-Leste, dugongs are protected under the Marine Protected Species Act, the Ministerial Diploma and Decree law, and reference to their endangered status is made in the National Biodiversity Strategy and Action Plan (NBSAP). The NBSAP describes the importance of seagrass ecosystems not only as the primary habitat for dugongs and many fish and shellfish species, but also as a protective barrier for coral reefs against sedimentation. In recognition of the significant importance of dugong to the country, Timor-Leste became the 27th Signatory to the CMS Dugong MOU on 10 September 2018, confirming its support towards the protection of dugongs and their vital seagrass habitats.

Seagrass and shallow marine habitats in Timor-Leste are susceptible to degradation through a number of anthropogenic impacts, including sedimentation, destructive aquaculture practises (e.g. intensive sea weed farming), overfishing, coastal mining (e.g. sand extraction from beaches), coastal development and land-based pollution. Unsustainable agricultural practices (e.g. traditional slash and burn) and poor land management (e.g. deforestation, forest degradation, domestic livestock grazing) combined with sloping terrain and short, intense rainfall patterns results in high levels of soil erosion which can have negative impacts on marine habitats and biodiversity. Sedimentation and elevated turbidity can cause the degradation of seagrass meadows in shallow waters. Population growth (increasing urbanisation), coastal development and inadequate wastewater disposal all contribute to an increase in nutrients and other pollutants entering the coastal environment around Timor-Leste. Impacts are currently at a relatively small scale and confined mostly to urban areas²⁹.

Research also indicates that climate change will likely affect seagrass ecosystems in Timor-Leste, through increases in sea surface temperature (expected to rise 0.5–1.1°C by 2030, and up to 4.2°C by 2090) and sea level (9 - 18cm predicted by 2030, and up to 88cm by 2090), and changes in storms/cyclone patterns, frequency and intensity³⁰. Thus, promoting and enabling an adaptive approach to seagrass management will not only maintain seagrass diversity, ecological functions and ecosystem services, but also enhance the resilience and adaptive capacity of seagrass ecosystems to cope with climate change impacts.