Integrating western science with Māori knowledge to understand changes in sedimentation and water quality in Ōhiwa Harbour

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Humans are impacting the natural world around us at an unprecedented scale. Land use changes, a growing population, and anthropogenic-linked climate change are altering river discharge patterns, coastal geomorphology, and with them marine ecosystems and the sustainability of the ocean as a breadbasket. One of the major variables that connects human impact on land with the coastal oceans is the sediment flux through rivers and estuaries.

In Aotearoa New Zealand, sediment yield from rivers to the ocean is large, controlled in part by a young, erodible underlying geology, which is dominated by steep mountainous rivers with small drainage basins. Notwithstanding the natural controls on sediment yield, studies have shown that New Zealand estuaries are being infilled with river-derived sediment at increasing rates since the arrival of Polynesians and even more profoundly in the post-European era. Such increased sedimentation has had marked negative consequences for estuarine and coastal biodiversity and productivity which has disproportionately affected first nation Māori communities who live on the coast.