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Manawatū Estuary

The Manawatū Estuary is a large, shallow, tidal river mouth near the coastal settlement of Foxton Beach.

Bird-watchers treasure the estuary as it boasts the most diverse range of birds to be seen in any one place in New Zealand. Its thriving mudflats, saltmarsh and dune fields support over one hundred bird species, such as the kōtuku ngutupapa (royal spoonbill) and the migratory kuaka (bar-tailed godwit). The Manawatū Estuary has been designated a wetland of international importance under the RAMSAR Convention because of its rich and varied plant and animal life.

Human activities such as vegetation clearance and land disturbance have degraded both saltmarsh and the riparian margin of the estuary where migratory galaxiids and common smelt (whitebait) release their eggs. Transformer weeds are also changing the landscape's character; these invasive plants are the most significant and immediate threat to the river mouth.

The estuary is highly-flushed because of the large freshwater inflow from the Manawatū River and the tidal movements of the Tasman Sea. Most of the nutrients and fine sediment carried downriver pass directly through to the sea. The river mouth benefits from this flushing because it is less likely to experience an increase in nutrients (eutrophication) that can lead to the harmful overgrowth of aquatic plant life.

Estuary summary

What makes my estuary unique?

Explore the characteristics of this estuary

Overview

Estuary characteristics

  • Significant features
    • The largest estuary in the Lower North Island
    • Ramsar wetland of international importance (200ha)
    • 121 bird species have been recorded in the estuary and immediately surrounding lands
    • At times, the estuary can be hosting up to 20% of the world’s wrybill population
  • Total area
    533 hectares
  • Total shoreline length
    7.5km
  • Tide
    Spring (MHWS) 2.4 m, Neap (MHWN) 1.8 m
  • Key rivers
    • Manawatū River

What's happening upstream?

See results from monitored river quality sites influencing this estuary

River quality

What's happening upstream?

The physical characteristics and health of estuaries are influenced by the rivers and streams flowing into them. For instance, when it rains the mud and contaminants generated on land can be washed into rivers and eventually flow into the estuary. The health of our rivers and streams can therefore be very important for Estuary Health, and understanding the upstream pressures can help with interpreting estuary monitoring data. Monitoring is undertaken for a range of river health indicators (e.g., water quality and ecology) in many catchments across the region. Where there are monitored river catchments that influence this estuary, these are shown below. You can click through to view monitoring results from these River Quality sites to see current state and how health has changed over time.

What surrounds my estuary?

See land cover information from monitored catchments that surround this estuary

Land cover

What surrounds my estuary?

The physical characteristics and health of estuaries are influenced by local geography and the way we use our land. This is because estuaries are the receiving environments for many of our land use activities. Land cover information can be used as an indicator of land use, therefore knowing the surrounding land cover can help us understand which pressures might be affecting Estuary Health. For example, the sandflats of estuaries surrounded by rural areas will typically contain contaminants related to rural activities (e.g., cadmium from crop fertilisers and copper from fungicides), whereas those surrounded by urban areas are more likely to contain contaminants associated with cities (e.g., zinc and lead from roads and building materials). Where there is land cover information available for nearby catchments, these are listed below. These figures show the types of vegetation and built or natural features that surround the estuary margins and the rivers that flow into this estuary. You can click through to the Land Cover topic to see these land cover classes broken down into further detail, and view changes over time.

Manawatū

What do the Broad Land Cover Classes mean?

Land cover information on LAWA is grouped into land cover classes at two levels of detail – broad and medium. For this overview we are showing the six broad-level classes for the catchment.

  • Forest

    Inclusive of; indigenous and exotic forest.

  • Scrub / shrubland

    Inclusive of; indigenous and exotic scrub / shrubland.

  • Grassland / other herbaceous vegetation

    Inclusive of; tussock and exotic grassland and other herbaceous vegetation.

  • Cropland

    Inclusive of; cropping / horticulture.

  • Urban / bare / lightly-vegetated surfaces

    Inclusive of; natural bare/lightly-vegetated and artificial bare surfaces, and urban area

  • Water bodies

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Image supplied by Arnim Littek

Monitored sites 2

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