12, Dec, 2014

New Zealand’s disappearing kelp forests

Category: News

A newly published scientific paper reveals widespread collapse and destruction of kelp forest around New Zealand’s coast. Noted ecologist, diver and film maker, Wade Doak, of Northland, New Zealand, says the paper, in the international Royal Society’s Philosophical Transactions, charts the widespread collapse and destruction of marine algal forests, the kelp beds, around New Zealand's and other countries' coasts. Auckland University marine scientist Dr Nick Shears worked on the paper. Research from New Zealand reefs in this global study includes data from reefs throughout New Zealand, which found urchin barrens to occur at various locations from Cape Karikari in the north, to Patterson Inlet in the south. According to Dr Shears, the ecological balance has been lost with the widespread decline of sea urchin predators from over fishing. The loss of predators, such as snapper and large crayfish, that eat sea urchins (kina), has resulted in many coastal reefs suffering an explosion of kina populations and subsequent loss of the ecologically rich kelp beds. The result: underwater reefs dominated by sea urchins, but barren of the ecologically vital kelp beds which nourish and provide habitat for a wide variety of species. The twenty ecologists and other coastal scientists from several different countries and research organisations, show that this ecosystem phase shift has occurred on many coastal reefs around New Zealand and also on the reefs of those other countries. Wade Doak describes this change as "a slow-motion train wreck; as destructive as an asteroid hit; longer lasting than an oil spill.”He blames over-exploitation of inshore waters by modern fishing techniques. Large scale removal of sea urchin (kina) predators such as snapper and crayfish produces a trophic cascade where sea urchins thrive, but little else. According to Wade Doak, many barrens are in top tourism areas such as the world rated Tutukaka Coast. Divers are sending him their observations and pictures from all over the country. Scientists can now also discern barren reefs from satellite images and Google maps. Marine specialist Vince Kerr urges action to halt the decline of kelp beds. This means allowing kina predators to return. “Once the kelp forest community has been replaced by an urchin/kina regime, it is very hard to restore the former, age old, rich undersea vistas. Marine ecologist Roger Grace warns that kina barrens have a diminished value for coastal fishing and kaimoana gathering, (barrens’ kina are unpalatable) The also reduce the carbon-fixing ability of the sea with implications for global warming and climate change - consequences that parallel large scale felling of forests. All three specialists agree that thriving marine reserves offer insights into how much is at stake and how these trends can be reversed through protection.” Images and credits as below. Map of NZ kina barrens (supplied by Dr Nick Shears , In Shears and Babcock 2007). Underwater image kina barrens (supplied by Dr Nick Shears) Underwater image of normal kelp forested reef (Supplied by Dr Roger Grace) "The point in the middle of Matai Bay. Cape Karikari extremity, is surrounded by rocky reef which drops to sand. On the left side there is a fringe of dark seaweed along the rocky shore, changing quickly to pale-coloured rock which lacks seaweed and is the kina barren. The rock then drops to pale sand, in places with a narrow fringe of dark kelp forest just before the sand." (Photo: Roger Grace). Further information - the Scientific Paper and a Youtube of the launch: Link to the paper just out on the urchin barren problem globally, published in the prestigious international journal, Philosophical Transactions B of the Royal Society: Cover of Ling et al 2014 paper:

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