Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 


Study into Didymo’s impact on 55 South Island waterways

Major study into Didymo’s impact on 55 South Island rivers and streams

August 10, 2014

In one of the largest field studies of its kind to examine Didymo, or rock snot, a University of Canterbury project has sampled 55 rivers and streams across the South Island in every major region, to establish its niche and effects on ecosystems.

One of the university’s freshwater ecology PhD student researchers, Jon Bray, says their investigations found that Didymo presents a catch 22 scenario. The Didymo spread seems to have slowed substantially in recent years so for the moment the situation is not getting better or worse, he says.

The 'check, clean, dry' biosecurity campaign may be regarded as successful. It has ensured that over the last 10 years Didymo has still not invaded the North Island despite the presence of suitable habitat.

``Didymo is a lover of clean water and it blooms in response to low levels of water nutrients which is the opposite of what we may expect. Thus its impact is greatest in some of our lowest nutrient or pristine waterways.

``Didymo is then also absent from waterways that are suffering the effects of agricultural practices, but these practices are considered the single biggest issue facing New Zealand freshwater ecosystems.

``Invasive organisms, such as Didymo, are recognised as a major threat to biodiversity globally. New Zealand's ecosystems provide an example of significant documented losses to biodiversity due to invasives. However, globally, freshwater ecosystems are now considered some of the most impacted from the effects of invasives.

``The arrival of Didymo as an invasive freshwater organism within New Zealand garnered significant attention from the media, biosecurity and research scientists. It is a species of algae native to the northern hemisphere and was originally considered rare.

``Now it is rapidly spreading in many temperate regions and forms large cotton wool like masses smothering river and stream bottoms. However, its effects on ecosystems are only noted where it blooms. These habitats are low nutrient, dam and lake-fed rivers where lakes and dams reduce the effect of floods, which removes Didymo.’’

Bray, whose thesis is being supervised by Professor Jon Harding, says while tools to eradicate and manage Didymo have been investigated, prevention of spread is the regarded as the only viable long term policy.

However, Didymo is impacting the South Island’s rivers and streams. Aside from the pervasive effects of agricultural impacts, a number of other freshwater invasives such as the brown trout are thought to have significantly impacted New Zealand's freshwater ecosystems with ongoing effects.

``Generally there is an unfortunate and growing consensus among invasion scientists that within what may be termed the human era, invasion events will continue unabated. Therefore, changes associated with invasives are expected to continue to impact biodiversity and ecosystems,’’ Bray says.

The university’s Freshwater Ecology Research Group is a large research unit within the School of Biological Sciences which is seeking to help protect New Zealand’s freshwater systems. About 95 percent of New Zealand’s natural wetland ecosystems have been destroyed, while a significant number of our indigenous freshwater fish species are under threat.

Many lowland streams, rivers and lakes are not clean. One of our largest lowland rivers, the Manawatu River, was recently described as one of the most polluted rivers in the world. Lake Ellesmere, or Te Waihora, is the largest lowland lake in New Zealand and it has been described as dead, Professor Harding says.

ends

© Scoop Media

 
 
 
 
 
Business Headlines | Sci-Tech Headlines

 

Economic Update: RBNZ Says Rate Cut Seems Likely

The Reserve Bank will likely cut interest rates further as a persistently strong kiwi dollar makes it difficult for the bank to meet its inflation target, it said. The local currency fell. More>>

ALSO:

House Price Action Plan: RBNZ Signals National Lending Restrictions

The central bank wants to cap bank lending to property investors with a deposit of less than 40 percent at 5 percent and restore the 10 percent limit for owner-occupiers wanting to take out a mortgage with a deposit of less than 20 percent, according to a consultation paper released today. More>>

ALSO:

Sparks Fly: Gordon Campbell On China Steel Dumping Allegations

No doubt, officials on the China desk at MFAT have prided themselves on fashioning a niche position for New Zealand right in between the US and China – and leveraging off both of them! Well, as the Aussies would say, of MFAT: tell ‘em they’re dreaming. More>>

ALSO:

Loan Sharks: Finance Companies Found Guilty Of Breaching Fair Trading Act

Finance companies Budget Loans and Evolution Finance, run by former 1980s corporate high-flyer Allan Hawkins, have been found guilty of 106 charges of breaching the Fair Trading Act for misleading 21 borrowers while enforcing loan contracts. More>>

ALSO:

Post Panama Papers: Govt To Adopt Shewan's Foreign Trust Recommendations

The government will adopt all of the recommendations from former PwC chairman John Shewan to increase disclosure and introduce a register for foreign trusts with new legislation to be introduced next month. More>>

ALSO:

The Price Of Cheese: Cheddar At Eight-Year Low

Food prices decreased 0.5 percent in the year to June 2016, influenced by lower grocery food prices (down 2.3 percent), Statistics New Zealand said today. Compared with June 2015, cheese prices were down 9.5 percent, fresh milk was down 3.9 percent, and yoghurt was down 9.2 percent. More>>

ALSO:

Financial Advisers: New 'Customer-First' Obligations

Goldsmith plans to do away with the current adviser designations which he says have been "unsatisfactory" in that some advisers are obliged to disclose potential conflicts of interest and act in their customers' best interests, but others are not. More>>

ALSO:

Get More From Scoop

 
 
 
 
 
 
 
 
 
Sci-Tech
Search Scoop  
 
 
Powered by Vodafone
NZ independent news