The unseen transboundary commons that matter for Cambodia's inland fisheries: Changing sediment flows in the Mekong hydrological flood pulse.

This paper focuses on the 'the unseen transboundary commons' of residues, nutrients and mobile matter associated with the annual flood pulse that support Cambodia's inland fisheries. We develop the idea of biophysical geopolitics concentrating on political‐socio‐natures rather than the purely biophysical. In the context of multiple mega‐projects in the Basin, we argue the flood pulse has become increasingly compromised, which is an urgent socio‐ecological security issue facing the Mekong region. Scores of livelihoods are dependent on the hydrological flood pulse via the reproduction of the inland fisheries, and a diversity of wetlands resources. Our paper builds on cross‐comparative research focusing on a geo‐strategic mouth of the Tonle Sap (Chhnok Tru) and a transborder area along the Mekong main‐stream (Stung Treng, Cambodia – Champasak, Laos area). By viewing biophysical matter as becoming trans‐border geopolitical matter, we wish to emphasise the critical socio‐ecological character of the hydrological flood pulse, and the urgency of cumulative spatial and temporal changes affecting diverse wetlands communities. Loss of wild capture fisheries and the more unpredictable flows of the Mekong are signs of an emergent and dangerous era of increasing environmental insecurity. [ABSTRACT FROM AUTHOR]