02 December 2025 Gold clam invasion in NZ threatens drinking water for millions of people

On The Conversation, Lincoln University Adjunct Associate Professor Adam Hartland shares how, as a geochemist studying New Zealand’s freshwater systems, he's spent years tracking the subtle chemical shifts in our rivers and lakes.

But nothing prepared him for the rapid transformation unfolding in the Waikato River since the invasion of the Asian clam (Corbicula fluminea, also known as the freshwater gold clam).

First detected in May 2023 in Lake Karāpiro, a reservoir lake on the Waikato, this bivalve is now altering the river’s chemistry in ways that could jeopardise drinking water for up to two million people, disrupt hydroelectric power and undermine decades of ecosystem restoration efforts.

The Endeavour Fund research programme, Safeguarding Te Mana o te Awa o Waikato from emerging climatic pressures, has revealed how these clams are depleting essential minerals like calcium from the water, impairing arsenic removal during treatment and signalling a rapid escalation with broader impacts ahead.

Native to eastern Asia, the gold clam can self-fertilise and spreads via contaminated gear, birds or floods. Climate change will likely accelerate its invasion.

The problem is already spreading quickly beyond the Waikato River. A recent detection in a Taranaki lake has led to waterway closures. And warnings for the Whanganui River underscore the urgent need for national vigilance.

Read the full article to understand the threat of gold clam and how we must act now to safeguard our water security at The Conversation here >>

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Image credit: The Conversation