Long hot summer may wipe out birds, fish
Waikato’s conservation groups are preparing for what could be a ‘‘worrying trend’’, wiping out large numbers of wildlife in the Hauraki Plains.
Earlier this year two internationally significant Ramsar wetlands – Kopuatai Peat Wetland and the Firth of Thames mudflats – were under threat, became killing fields for populations of wildlife as the summer heat exacerbated existing habitat problems.
Botulism turned waterways into ‘‘pea soup’’ killing ducks, unshaded drains reached 29 deg C frying eels and endangered shorebirds died from a suspected toxic algae bloom.
With this season predicted to be just as long and hot, Mailee Stanbury from Department of Conservation says organisations are gearing up for another ‘‘triple threat’’ summer.
‘‘Botulism outbreaks often happen on the Hauraki Plains during warm summers stagnantly, but what happened last year was a bad year,’’ the senior ranger biodiversity for the Hauraki said.
‘‘Fish and Game picked up over 3500 dead ducks. At the same time there was die-off in eels that were trapped in heated waterways that led mainly into the Piako River.
‘‘Compounding that as well, there was a sudden die-off in some shorebirds.’’
As one of many on the frontline, Stanbury said it was ‘‘heart wenching’’ to witness people carrying thousands of dead wildlife out of the waterways. They aim to be more prepared this year.
‘‘There were a lot of tears. It was hard to see their little bodies brought in and get placed in your hands.
‘‘Eels are also quite a robust species so when they’re being badly affected like that you know other species are suffering too.’’
Pu¯ korokoro Miranda Shorebird Centre manager Keith Woodley, who has dedicated 20 years of his life educating people on shorebirds also witnessed the ‘‘significant’’ outbreak.
In March, he noticed a number of birds struggling to fly in the Firth of Thames and immediately contacted DOC.
‘‘We found some dead birds and the 80 odd birds that went into rehabilitation at various rescue operations, we lost eight of those birds, but the rest were subsequentially released,’’ Woodley said.
The 8000 hectares of inter-tidal flats that sees around 100,000 birds flock to the flats had had a few botulism outbreaks over the years, but this year was different.
‘‘They didn’t have symptoms they’d normally exhibit if they had botulism — such as drooping necks — and 90 per cent of those birds we found were affected were red knots.’’
Red knot birds are an endangered arctic breeding species that travel from Russia and migrate to New Zealand. They are a specialist feeder on bivalve shellfish, eating them whole and crunching them in their stomach.
This led experts to believe the sickness was due to a toxic algae bloom found in their feeding ground.
‘‘Unfortunately we weren’t able to get anything from testing those birds. I understand from the experts that to test for algae bloom you’ve got to actually test for every possible bloom.
‘‘The other strand that we were $ concerned about is that if there is something affecting those bivalve shellfish we didn’t know where these birds are feeding. They could be feeding anywhere on the mudflap between Miranda and Thames.’’
Agencies are now worried this coming season will see another ‘‘perfect storm of conditions’’.
While both botulism and algae bloom
SAVE $20 are caused from various stressors, warmer temperatures are a key factor.
‘‘There is certainly a worrying trend particularly with climate change and extreme weather on the rise,’’ Stanbury said.
‘‘We know that this year will see warmer temperatures but there’s also the potential for cyclones. So there will be dry periods and sudden downpours of rain that
pcould lead to flooding particularly after a dry period. We’re not sure what the effects of that will have on the environment.
Agencies, such as DOC, Fish and Game and Waikato Regional Council, are in discussions, creating am emergency plan in the event of another drought.
The long term resolution, however, will take some time.
One of the major restoration projects, Piako River Green Corridor, will see $3.2 million spent over five years to restore the Piako River.
In 2016 the river’s quality was considered generally poor, being somewhat oxygen depleted and murky and with particularly high concentrations of nitrogen and phosphorus.
The Piako River Green Corridor will include restoration, such as planting to increase biodiversity and create shade for wildlife and improving drainage systems from Kopu Bridge, Waihou River, to Waitakaruru, Piako River.
‘‘We know hotspots now and where there’s likely to be congregations of wildlife. We can also monitor water temperatures and oxygen levels. In the plan we will see how to safely move eels, and prepare for our next steps.
‘‘It’s one thing to be ready for an emergency, but making substantial change will take years. While I know it’s hard for the farmers about the new reforms that have come through nationally, farming, drainage and planting — those are the things that are going to help prevent events like this.’’