- New research on slugs has found two types of mangrove forests in the Indo-West Pacific region, highlighting their much-needed protection against deforestation and rising sea levels.
- The Indo-West Pacific is known to have the highest diversity of mangrove plants in the world, but it wasn’t previously clear which parts of the region had peak diversity.
- The latest research found the mangrove forests of the archipelagic region that spans from Papua New Guinea to Malaysia differ in numerous characteristics, including sediment size, freshwater input and plant species.
JAKARTA — New research on slugs has found two types of mangrove forests in the Indo-West Pacific region, highlighting their much-needed protection against deforestation and rising sea levels.
The study said the Indo-West Pacific had two mangrove hotspots with distinct habitat types: fringe mangroves in the Coral Triangle (encompassing central and eastern Indonesia, the Philippines, Papua New Guinea and Melanesia) and riverine mangroves in the Strait of Malacca, between the west coast of Peninsular Malaysia and Indonesia’s Sumatra. The finding was apparent after a research duo from the U.S. had investigated slug species abundance of the family Onchidiidae, which are gastropods that have evolved and adapted to mangroves.
“The existence of two peaks of onchidiid diversity in the Indo-West Pacific reflects the fact that not all mangrove forests are the same,” read the paper published Sep. 22 in the journal Scientific Reports.
The scientific article said Onchidiidae were ideal as a case study for looking into patterns of species diversity and their home range outside coral reefs, as the family has genetically changed in mangroves and rocky coasts. Scientists have also revised its classification and evolutionary development in recent years, the paper noted.
“We recognized the significant implications of this finding for both mangrove conservation and also the broader field of marine biogeography, which led us to write a paper focused on highlighting the biogeography of mangrove gastropods,” Tricia Goulding, research associate at the Smithsonian National Museum of Natural History, who is the lead author of the study, told Mongabay in an email interview.
Additionally, rising sea levels and extensive deforestation have affected the mangrove distributions, including the species in the Indo-West Pacific, such as Sonneratia griffithii, a species isolated to parts of India and Southeast Asia where 80% of mangrove area has been lost and is listed as critically endangered by the IUCN.
The Indo-West Pacific is known to have the highest diversity of mangrove plants in the world, but it wasn’t clear which parts of the region that spans from Papua New Guinea to Malaysia had peak diversity. The latest research found the mangrove forests of the archipelagic region differ in numerous characteristics, including sediment size, freshwater input and plant species.
The study noted that mangroves growing upstream, along rivers and shores at high tide were typically more threatened by habitat loss than fringe mangroves, as the former were often in close proximity to human settlements and the first to be cleared for timber and oil palm plantations, as well as the construction of aquaculture ponds.
Goulding said her team’s study highlighted a hotspot of mangrove biodiversity in the Strait of Malacca with unique classification diversity from the Coral Triangle, and it indicated that further studies of invertebrate diversity were needed to preserve the diversity that maintained functioning mangrove ecosystems into the future.
“Planning of mangrove conservation has largely focused on reducing the decline in mangrove forest area, although it has been advised that more focus should be placed on conserving areas [to] protect the diversity of mangrove plants and species considered at risk based on the IUCN Red List and maintaining the ecosystem services provided by mangroves,” she said.
Mangrove restoration is another popular strategy for conservation, like the plan by the Indonesian government to replant 600,000 hectares, or nearly 1.5 million acres, of mangrove ecosystems by 2024. However, previous reports and scientific studies have indicated that restored mangroves were less biodiverse and stable, and had lower ecosystem function compared with natural mangrove stands. While restoration is much needed and can be effective, many have noted that the strategy could be rendered useless when destruction of natural mangroves occurred in other areas.
“Given how large the region is, I don’t feel that I have enough data to broadly comment on current efforts by stakeholders to manage mangroves in the Indo-West Pacific,” Goulding said.
“What I can say is that efforts to promote sustainable use of mangroves, such as methods of aquaculture that do not clear cut mangrove forests should be further developed with stakeholders, as this could lead to an improved balance between extracting resources by local communities and minimizing damage to natural ecosystems,” she added.
Basten Gokkon is a senior staff writer for Indonesia at Mongabay. Find him on 𝕏 @bgokkon.
Goulding, T. C. & Dayrat, B. (2023). The Coral Triangle and Strait of Malacca are two distinct hotspots of mangrove biodiversity. Scientific Reports, 13, 15793. doi:10.1038/s41598-023-42057-6
Carugati, L., Gatto, B., Rastelli, E., Lo Martire, M., Coral, C., Greco, S., & Danovaro, R. (2018). Impact of mangrove forests degradation on biodiversity and ecosystem functioning. Scientific Reports, 8(1). doi:10.1038/s41598-018-31683-0
Su, J., Friess, D. A., & Gasparatos, A. (2021). A meta-analysis of the ecological and economic outcomes of mangrove restoration. Nature Communications, 12(1). doi:10.1038/s41467-021-25349-1
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