Ecosystems not as healthy as they should be
Posted on Wednesday, 14 September 2011 03:55 p.m.
Southland’s ecosystems are not as healthy as they should be and are showing signs of stress.
That is the key message from the Our Ecosystems report compiled in partnership between Environment Southland and Te Ao Marama Incorporated, released today.
The monitoring data gathered by Environment Southland scientists provides a snapshot of the wellbeing of life within Southland’s freshwater ecosystems.
Environment Southland Senior Scientist Jane Kitson said the report, that is the second instalment of four that make up Southland Water 2010: Report on the State of Southland’s Freshwater Environment, illustrate the emergence of worrying trends with regard to several parameters monitored by the Council.
Dr Kitson said Our Ecosystems provided a baseline to gauge whether standards and targets set in the Regional Water Plan, that became operative in January 2010, have been met.
One of the specified targets is a minimum 10 per cent improvement in the water quality with regard to nitrogen, phosphorus, water clarity, and faecal contamination in Southland’s hill, lowland and spring-fed water-bodies by 2020.
“The report indicates that we may not meet this target.”
Of particular concern was deteriorating water quality in Southland’s rivers and streams and low-land areas, including Waituna Lagoon and estuaries with elevated nutrient levels recorded in a number of fresh water bodies.
The nutrients measured include dissolved forms of nitrogen, phosphorus, dissolved reactive phosphorus (DRP), which can all be readily absorbed by plants, as well as nitrate–nitrite–nitrogen (NNN) and ammonia (NH3) that can be toxic to freshwater life.
But Dr Kitson said data has shown that most of the indicators suggest those concentrations had either shown no change or were deteriorating further.
Key findings include:
- More than half (53%) of the river and stream sites monitored have poor to very poor compliance with national guidelines for DRP. Sixty-seven per cent showed no change in DRP concentrations.
- Sixty-three of river and stream sites show good compliance with NNN standards, but 12 per cent have poor to very poor compliance with toxicity guidelines.
- Almost half, 48 per cent, show increasing NNN concentration trends.
- Ammonia concentrations comply with national toxicity guidelines, but 25 per cent of sites are increasing.
- Most sites showed good compliance with visual clarity standards with 86 per cent showing no change in condition.
- Sixty-one per cent of sites showed good or very good compliance with faecal bacteria standards. There was no change in faecal bacteria concentrations at 87 per cent of locations.
- Aquatic macroinvertebrate life in Southland’s rivers is showing few signs of significant deterioration but fish numbers are declining in some areas.
Dr Kitson said Environment Southland was working hard to implement changes but it was important to note that a lot of the work being done had not yet had enough time to take effect.
“But we need everyone to play their part to improve ecosystem health because of its importance socially, culturally and economically to Southland and Southlanders.”
- The first report in the series Our Health was released publicly in August 2010.
Our Ecosystems can be downloaded here
Environment Southland is the brand name of Southland Regional Council.