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 report_green_no_change.png   NO SIGNIFICANT CHANGE

This indicator shows that most of the monitored sites are moderately healthy and there were no consistent trends in estuarine ecosystem health between 2012 and 2017.

Why is this indicator important?

This indicator describes the diversity of animals that live in our estuaries. Estuaries are an important part of our coastal marine area. They are productive ecosystems, but are also one of the most sensitive coastal areas, and are at risk from human activities.

Waikato Regional Council currently monitors the sediment-dwelling animal communities in three estuaries: the southern Firth of Thames, Whaingaroa (Raglan) Harbour, and Tairua Harbour. Sediment-dwelling animals (such as shellfish, crustaceans and marine worms) are important in estuaries because they cycle nutrients between the sediment and water, stabilise and rework sediments, and are an important food resource for birds, fish, and crabs. The animal community characteristics are summarised by a Traits Based Index that makes use of the animals’ biological traits. Biological traits are the physical and behavioural characteristics that define a particular species (e.g. body size, mobility, feeding behaviour).

The Traits Based Index (TBI) tells us about the health of our estuaries. It ranges between zero and one, with one being most healthy and zero being least healthy. We can use the TBI to track the health of our estuary sites over time, and to compare the health of different estuaries.

Ecosystem health at sites in monitored estuaries

TBI scores range between zero and one, with one being most healthy and zero being least healthy.


    TBI score (a measure of ecosystem health)
Estuary Site 2012 2013 2014 2015 2016 2017
Firth of Thames Gun Club 0.380 0.310 0.420 0.344 0.344 0.306
Kaiaua 0.340 0.330 0.410 0.381 0.395 0.362
Kuranui Bay 0.350 0.270 0.360 0.301 0.268 0.414
Miranda 0.420 0.340 0.370 0.334 0.348 0.419
Te Puru 0.300 0.310 0.260 0.301 0.452 0.424
Whaingaroa (Raglan) Harbour Haroto Bay 0.260 0.350 0.330 0.320 0.287 0.278
Okete Bay 0.570 0.450 0.450 0.456 0.508 0.400
Ponganui Creek NA NA NA NA 0.541 0.584
Te Puna Point NA NA NA NA 0.485 0.414
Whatitirinui Island 0.490 0.590 0.590 0.565 0.621 0.513
Tairua Harbour Gumdigger Gully 0.350 0.380 0.290 0.344 0.296 0.339
Manaia Road 0.470 0.470 0.340 0.386 0.419 0.409
Oturu Sream 0.340 0.360 0.370 0.447 0.334 0.358
Pauanui 0.570 0.440 0.410 0.438 0.532 0.386
Pepe Inlet 0.400 0.370 0.330 0.381 0.353 0.353

TBI scores

To provide an indication of overall regional coastal ecosystem health, the average of the results from each site are shown below.

Average Traits Based Index (TBI) scores for monitored sites

Coastal graph 2019



Regional index

(average of all sites)

2012 0.40
2013 0.38
2014 0.38
2015 0.38
2016 0.41
2017 0.40

What is this indicator telling us? 

  • Most of the sites are moderately healthy (having a TBI score between 0.3 and 0.4).
  • There were only slight changes in the TBI (and therefore in estuarine health) between 2012 and 2017 at the monitored sites. We expect the TBI score to vary slightly from year-to-year due to natural variability. There were no consistent increasing or decreasing trends in TBI scores at any of the monitored sites.

Check out related information on our website and other organisations’ websites listed on our Waikato Progress Indicators’ Useful Links page.

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Data sourced from Waikato Regional Council’s Regional Estuary Monitoring Programme:

Update details: is carried out on an annual basis.

Customised data request requirements: Request is for the Traits Based Index calculated for sites in the Regional Estuary Monitoring Programme.


Territorial Authority (TA) disaggregation: No

Other regions: No

New Zealand: No

Other countries/ Organisation for Economic Co-operation and Development (OECD): No