Sumatran elephants promote jumbo fish: Deduction of elephant- fish commensalism for resilient coexistence of Malay community with elephants in South Sumatra.

1.Sumatran elephants (Elephas maximus sumatranus) that are uniquely inhabiting wetlands are species critical for conservation. At the same time, Elephants are also considered problematic in some communities because of their foraging behaviour – attacking farmers’ crops and potentially causing casualties both for humans and elephants. Sumatran communities traditional knowledge holds valuable insights in coexistence with elephants. Identifying the traditional knowledge might help us understand elephant’s ecological role particularly in a tropical wetland ecosystem that remains poorly understood.2.Using semi-structured interviews, we recorded the traditional knowledge of the Perigi village communities in South Sumatra, Indonesia, a village bordering with elephant’s habitat, based on their recollection of observing and coexisting with elephants, explaining, among others, the lived experience of elephants in relatively undisturbed tropical peat swamps. 3.We find the Perigi community placed the foundation of their coexistence with elephants through elephants’ behaviour of creating lebung (ponds) and wallowing for thermoregulation purposes. The communities recorded a positive relationship between elephants’ wallowing and the enhancement of the fish population, which is attributed to their size and quantity. We deduct this as the result of the trophic cascade from elephant-fish commensalism. Further, our findings revealed the land management practices employed by the community that exchanged between mineral soils and peat swamp as a strategy for living in coexistence with elephants. This coexistence of the local communities with elephants in the peat swamp is a form of co-production on biocultural heritage, and the local communities utilise this relationship for their fisheries activities. 4.The revelation of this mechanism on the positive impact of elephants’ presence on fish and local communities contributes not only to highlighting the importance of traditional ecological knowledge in modern ecological and the elephants-humans reciprocal relationship. We provide empirical evidence that the coexistence of indigenous communities with elephants is built by placing elephants as their own agency of where their lived experience and role in the ecological system as recorded by the communities placed as a foundation for them to design sustainable, resilient coexistence mechanism.5.The way forward is to follow up on this translation by converting the deduction into evidence-based ecological traits measurement. This approach will unveil the relationship between elephants and fish and uncover other essential factors for the coexistence between elephants and humans. KEYWORDS: Sumatran elephants, fish, Traditional Ecological Knowledge, reciprocal relationship