Restoring
kelp beds

Restoring kelp to Tikapa Moana – the Hauraki Gulf

While the Hauraki Gulf is beautiful from the surface, below the waterline the ecosystem is in crisis. A key tohu or indicator is the kina (sea urchin) barrens that have taken over many reefs in the Hauraki Gulf where kelp used to flourish, a vital part of a healthy ecosystem. These ‘trees of the sea’ are also hugely efficient at fixing and storing carbon and are increasingly being identified as a critical part of a healthy climate.

In the Hauraki Gulf, scientists say the loss of large snapper and crayfish through over-fishing means kina are now grazing down the kelp beds at an alarming pace, without their natural predators to keep them in check. Areas that were previously dense in kelp are now barren. Currently, it’s estimated about 50% of the shallow reefs around Hauturu-o-Toi (Little Barrier Island) and Otata (part of the Noises Islands) are kina barren. However, kelp beds can be restored and the flourishing beds within the Goat Island marine reserve are a shining local example.

Live Ocean is supporting work by Dr Nick Shears from the University of Auckland to understand both the scale of the problem and what happens when the kina are removed from barrens. Does ‘resetting’ the system accelerate the restoration of kelp on a large scale?

These findings could be very significant for new areas of marine protection, where kina removal could significantly accelerate habitat restoration. This work also investigates how kelp forests contribute to coastal carbon cycles. “Kelps are extremely efficient at fixing carbon, but our research has demonstrated that only a small proportion of this carbon is stored in kelp forests, with much of it being released back into the ocean.  This research will help us understand the long-term fate of this “lost” carbon and the role of kelp forests in climate change mitigation”. This topic is an emerging area and provides an exciting potential opportunity to quantify blue carbon. This is vital in order to understand the importance of ocean restoration.

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