Ashley Estuary/Te Aka Aka is a large tidal lagoon in North Canterbury, that receives freshwater from the Ashley River/Rakahuri, Saltwater Creek, Taranaki Creek, and a number of small lowland streams.
The site has been monitored since 2011 because of its extensive intertidal mudflats that are under pressure from surrounding rural land use as well as run-off from urban areas. Mud content and macrofauna are monitored annually and sediment quality every 2-3 years.
The Ashley River/Rakahuri is a braided river with a dynamic channel that changes as a result of flood events. These floods can transport significant amount of gravel, sand and silt, which can dramatically alter the substrate composition of the permanent monitoring grid. If the permanent monitoring grid is unsuitable for sampling, the grid is moved to the nearest adjacent mudflat. Therefore, the results from year to year are not directly comparable.
Overall, the benthic communities in Ashley Estuary/Te Aka Aka have 'poor' health.
This dashboard shows information on the data collected by the regional councils and unitary authorities for the Estuary health scientific indicators, click the tiles for more information:
The Estuary Macrofauna Score is based on the composition of the macrofaunal community and tells us how impacted the monitored site is by mud (via a Mud Benthic Health Model). The calculated scores are continuous and represent a gradient of impact. Low scores indicate low impacts from mud (good health), whereas high scores indicate high impact (poor health). Scores are converted into one of five categories for visualisation and to easily compare sites, however the thresholds between categories do not necessarily reflect breakpoints in ecological condition. See the Estuary macrofauna factsheet for more information.
Mud content refers to the amount of fine silt and clay particles (collectively called ‘mud’) that are present in the estuary sandflats. This figure shows (mean) annual mud content measured at the monitoring site. The annual values are assessed against custom, national guidelines that indicate increasingly negative impacts on the macrofaunal community.
Ecology is not negatively impacted.
The diversity of the macrofauna community is slightly reduced.
The diversity of the macrofauna community is reduced and less resilient to disturbance.
The macrofauna community is unbalanced and dominated by a small number of tolerant species.
The macrofauna community is degraded.
View results alongside National guidelines:
View results alongside alternative guidelines:
This figure shows the (mean) annual contaminant concentration measured in the sediments of the monitored site. The annual values are assessed against the ANZG 2018 guidelines by default, and you can choose to view them assessed against several additional, more conservative guidelines. All of the guidelines show how likely it is that the contaminant is having negative ecological impacts. See the Contaminants factsheet for more information.
View results alongside National guidelines:
View results alongside alternative guidelines:
This figure shows the (mean) annual contaminant concentration measured in the sediments of the monitored site. The annual values are assessed against the ANZG 2018 guidelines by default, and you can choose to view them assessed against several additional, more conservative guidelines. All of the guidelines show how likely it is that the contaminant is having negative ecological impacts. See the Contaminants factsheet for more information.
View results alongside National guidelines:
View results alongside alternative guidelines:
This figure shows the (mean) annual contaminant concentration measured in the sediments of the monitored site. The annual values are assessed against the ANZG 2018 guidelines by default, and you can choose to view them assessed against several additional, more conservative guidelines. All of the guidelines show how likely it is that the contaminant is having negative ecological impacts. See the Contaminants factsheet for more information.