Mangaonuku Dashboard

KEY:

>= 120

< 120

Checked Data

Unchecked Data

Rolling average: 95.467

Aquatic macroinvertebrate communities are at the centre of aquatic food webs, and link the energy of the sun to fish and birds. They respond to a combination of water quality, habitat (including river flow), and climate.

We report upon macroinvertebrates by calculating the Macroinvertebrate Community Index (MCI). The MCI assigns a score to each species or taxon (1 to 10), based on its tolerance or sensitivity to organic pollution, and then calculates the average score of all taxa present at a site. Increases in MCI are generally considered to be good.

What's going on here!

Macroinvertebrate communities of the Mangaonuku are considered 'fair', and reflect moderately degraded habitat and instream conditions. Improving riparian protection, planting trees to shade waterways and reducing erosion will usually help MCI the most.

KEY:

< 260

>= 260

Checked Data

Unchecked Data

Rolling median: 80 E. coli/100ml

We use E. coli as an indicator of faecal contamination from warm blooded animals. Not all strains of E. coli are hazardous; however, high concentrations suggest that other pathogens maybe present.

River flow has a strong influence on water quality and ecology. High flows are associated with increased sediment loading and associated contaminants.

What's going on here!

E. coli levels are typically moderate to low in the Mangaonuku , although some spikes still occur. Ensuring waterways are protected from stock will help reduce spikes in E. coli.

KEY:

< 0.8mg/L

>= 0.8mg/L

Checked Data

Unchecked Data

Rolling average: 2.037mg/L

An essential element for plant growth but elevated levels can lead to excessive plant and algal growth with associated problems. It is readily transformed between soluble and insoluble forms. The graph represents changes in Dissolved Inorganic Nitrogen (DIN) which is the form of nitrogen available for aquatic plant and algae growth. The Tukituki Catchment Plan has set a limit of 0.8 mg/L for the Mangaonuku Catchment.

What's going on here!

The concentrations of DIN in the Mangaonuku are amongst the highest in the Tukituki, and all of Hawke's Bay. Mitigations to reduce nitrogen levels are a very high priority for this subcatchment. Constructed wetlands may be an effective approach if other on-farm approaches are insufficient.

KEY:

< 0.010mg/L

>= 0.010mg/L

Checked Data

Unchecked Data

Rolling average: 0.02mg/L

We measure a particular form of phosphorous - Dissolved Reactive Phosphorous (DRP) because this is the only form available for aquatic plant and algae growth. Phosphorous is an essential element for plant growth but elevated levels can led to excessive plant or algal growth with associated problems. Over time, phosphate bound to sediment (soil particles in the water) dissolves and becomes DRP.

What's going on here!

The Mangaonuku is not meeting the relevant plan target for DRP (0.010mg/L). Elevated phosphorus can be due to a variety of sources, but often relates to erosion and overland flow from critical source areas. Protecting wide buffers around riparian areas can help prevent phosphorus entering waterways.

KEY:

<= 4.1NTU

> 4.1NTU

Checked Data

Unchecked Data

Rolling median: 0.545mg/L - NB the calculated median is calculated from both FNU and NTU data, so should be treated with caution.

Increases in turbidity are associated with elevated sediment loading which is often caused by erosion. River flow has a strong influence on turbidity and other aspects of water quality. High flows are associated with increased sediment loading and associated contaminants. The relationship between turbidity and rainfall/river flow is a complex one. During heavy rain solids are washed into the stream but there is also more dilution. Compared to large powerful rivers like the Tukituki, the fine sediment and organic matter is more likely to settle on the bed of the Mangaonuku. Sedimentation reduces habitat quality, and limits the type of animals that can live in the waterways.

What's going on here!

Extremely high turbidity occurs on high flows in the Mangaonukuand represents the large sediment load being transported downstream by waterways in the Tukituki. Reducing hill country erosion, and protecting and stabilising stream banks, should be a priority for landowners in this catchment.