Three species have disappeared entirely from the Marlborough Sounds, a new report has revealed, in a major blow to biodiversity in the region.
By Kira Carrington, Local Democracy Reporter
Of the four ecologically significant species monitored at 16 sites in Queen Charlotte Sound/Tōtaranui, only one remained.
That lone survivor was being threatened by an invasive species, according to the Ecologically Significant Marine Sites programme report.
Marlborough District Council principal coastal scientist Oliver Wade presented the report to the council’s Environment and Planning committee on November 20.
The Sounds faced a biodiversity crisis, Wade said.
“This is the last bits that we're losing, of what [biodiversity] we have in the Sounds,” Wade said.
“These are generally small animals living on the sea floor, and they’re the foundation of the ecosystem, but we are losing these, wherever we go and look, we are losing [them].”
The report found that red algae, gore tubeworms, and the unique and ancient brachiopods had all disappeared from Queen Charlotte Sound/Tōtaranui.
The gore tubeworm were small filter-feeders that created tubes from surrounding sand, a source of food and habitat for many other species, Wade said.
“Sadly to say … this tubeworm has totally disappeared,” he said.
Red algae beds were also a key source of food and habitat within the Sounds ecosystem. Wade said its disappearance would have "major implications for biodiversity on the sea floor".
Brachiopods were a key part of the Sounds’ unique biodiversity. The ancient species usually lived in deep cold waters, making the Sounds one of the only places they were easily accessible to humans.
“The wider Marlborough Sounds was considered to be one of the best places in the world to come and study these species,” Wade said.
“They've been around on the planet for about 500 million years, you think, the dinosaurs were here about 250 million years ago. These guys are a survivor.”
But brachiopod numbers had been declining for the past five years, Wade said.
“[This year], we couldn't find one.
“Which, considering they've been around for hundreds of millions of years, is quite disturbing.”
The last man standing appeared to be the Galeolaria tubeworm. They were usually not found in large groups but, in the Sounds, they had formed large reef systems, such as the Perano Shoal.
“Thankfully, I will confirm that the Galeolaria are still here,” Wade said.
But the Galeolaria’s survival was being threatened by the invasion of parchment worm, believed to have come from Auckland, Wade said.
"This parchment worm is actually replacing the Galeolaria and out-competing it. So we're seeing some of these reef systems are actually in really poor condition now."
Environmental advocacy group Guardians of the Sounds chairperson Tim Healy told Local Democracy Reporting that a lack of biosecurity measures for boats meant more invasive species in the Sounds, such as the "catastrophic" exotic caulerpa, Healy said.
“You might as well save the country some money and sack everybody in biosecurity because they can't do anything anyway,” Healy said.
“They're underfunded and they can't do anything.
“So we've just got our fingers crossed that every time something appears, that the natural environment will be stronger than the invader.”
Biosecurity New Zealand director of pest management John Walsh said boats that did not dock at the marina were still required to have clean hulls before entering the Sounds under the South Marine Biosecurity Partnership.
“The rules are backed up by the Marlborough District Council’s regional pest management plan which makes non-compliance an offence,” Walsh said.
“The rules are mainly enforced through summer surveillance of vessels in the region.”
Walsh said exotic caulerpa was highly unlikely to establish itself in the Sounds, as the water temperature in winter would be too cold for it to survive.
Local Democracy Reporting is local-body journalism co-funded by RNZ and NZ On Air.
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