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Ecosystems

Estuaries

Estuaries are dynamic environments where freshwater meets the sea. They support diverse habitats, native plants and animals, cultural values, recreation, and coastal resilience. Because estuaries sit downstream of entire catchments, their condition reflects what is happening across both land and freshwater systems.

Nelson’s four estuaries are:

  • Waimea Inlet – internationally significant for shorebirds
  • Nelson Haven Paruparuroa – fed by the Maitai River, important coastal habitat
  • Wakapuaka Delaware Estuary – framed by Pepin Island and Delaware Spit
  • Kokorua Estuary – accessible by boat or with permission

Nelson City Council monitors all the main estuaries across the region

View Monitoring Our Estuaries to see we reports, long-term changes, estuary condition, water quality at swimming sites and to learn more about our Estuaries.

Horoirangi Marine Reserve

Horoirangi Marine Reserve is a 904‑hectare protected area north of Nelson, extending from Glenduan to Ataata Point and one nautical mile offshore. Marked by yellow buoys, the reserve includes unique intertidal and subtidal boulder reefs that form part of the Nelson Boulder Bank — a transition zone between bedrock and boulder habitats. These rugged reefs extend up to 400 metres offshore and to depths of around 20 metres, supporting a rich diversity of shellfish, anemones, sponges, sea squirts, snails, starfish and crustaceans.

Visitors can enjoy snorkelling, diving, swimming, kayaking and boating, provided they follow marine reserve rules designed to protect the ecosystem. The soft sediments beneath the reefs also support extensive horse‑mussel beds that filter water and provide habitat for other species.

Marine Reserve rules:

  • No fishing or taking/killing marine life
  • Do not remove or disturb any natural material
  • Do not feed fish
  • Anchor with care to avoid damaging the seafloor
Map showing the boundaries of the Horoirangi Marine Reserve outlined in blue, located offshore from the coastline north of Nelson. The map includes Pepin Island, Cable Bay, Glenduan, and surrounding coastal and inland terrain

Horoirangi Marine Reserve Map - Interactive map and GPS info here.

The Boulder Bank

A long, curved gravel spit extending into calm blue water, with numerous anchored boats scattered across the bay and hills in the background under a lightly clouded sky.

Boulder Bank

The Nelson Boulder Bank is a globally rare, 13 km-long boulder spit, stretching from Mackay Bluff to "The Cut".

It supports:

  • rare native plants (including forget‑me‑nots)
  • lizard species
  • breeding sites for banded dotterels, terns, and red‑billed gull

A community group traps stoats and rats to protect these species.

Offshore Islands

Haulashore Island

A coastal inlet with a small, tree‑covered point of land, a narrow jetty, and several moored boats floating in calm turquoise water.

Haulashore Island

Once part of the Boulder Bank, Haulashore Island is now home to:

  • pied shags
  • little blue penguins (kororā)
  • a rare skink population
  • native coastal plants

NCC works with Port Nelson, Kūmānu Environmental, and the Boathouse Community Trust to restore vegetation and manage predators

*Open fires are prohibited on Haulashore Island. Gas cookers allowed only when fire conditions permit.

Saxton, Oyster, Pig and Sand Island

Calm coastal scene with a low, tree‑covered island on the horizon under a wide, partly cloudy sky

Oyster Island, Waimea Inlet. Photo: S. Butcher

Located in the Waimea Inlet these islands are important habitat for shorebirds to roost and feed.

Dunes & Sandspits

Coastal dunes protect land from erosion and storms, stabilise sand, and provide habitat for insects, lizards, and ground‑nesting birds.

Nelson’s dunes include:

  • Tāhunanui Beach
  • Kokorua Spit
  • Delaware Inlet sandspits

Native dune vegetation is now largely extinct locally due to exotic species like marram grass. However, active restoration is underway, including dune planting and sand‑trapping barriers to support species such as the back beach beetle and banded dotterel.

Community coast‑care efforts have protected dunes since 2005, using sand‑trapping and native plantings.

Coastal sand dunes covered with clumps of long, pale green grasses under a bright blue sky, with low vegetation and distant hills in the background

Tāhunanui Beach Dunes

Rocky Shores & Coastal Cliffs

Rugged rocky coasts such as Cape Soucis, Pepin Island, and areas around Atawhai support:

  • coastal herbs, succulents, and shrubs
  • lizard habitat
  • intertidal species like barnacles, crabs, snails, sea stars, and seaweeds

These ecosystems are shaped by wave action, salt spray, and exposure. They are vulnerable to weed invasion and erosion.

Aerial view of a green, hilly peninsula surrounded by calm coastal water, with winding tracks and scattered vegetation

Pepin Island. Photo: Michael Higgins

Threats to Ecosystems

Human Disturbance

  • Trampling dunes
  • Off‑track walking on sensitive vegetation
  • Anchoring on seagrass beds
  • Recreational pressure

Weeds & Invasive Species

  • Marram grass, gorse, Spanish heath
  • Marine pests in estuaries
  • Weeds altering dune stability or vegetation structure

Habitat Loss & Modification

  • Historic reclamation and earthworks
  • Loss of saltmarsh and dune vegetation
  • Coastal development

Sedimentation & Stormwater

  • Land runoff smothers estuary plants and shellfish beds
  • Pollution affecting water clarity and ecosystem health

Climate Change

  • Sea-level rise
  • Coastal inundation
  • Erosion
  • Storm surges

What Council Is Doing

Person wearing a backpack crouched on a muddy tidal flat, placing or measuring a pole, with a line of deep footprints leading across the wet surface and a tree‑lined edge and water channel in the background

NCC Estuary Monitoring team. Photo: P. Fisher

Nelson City Council, through Nelson Nature and in partnership with iwi, DOC, Tasman District Council, community groups, and landowners, works to:

  • restore dunes at Tāhunanui, Kokorua, and Delaware
  • protect and restore estuary‑edge vegetation
  • carry out weed control across priority coastal sites
  • monitor estuary health
  • reduce sediment entering waterways
  • implement the Waimea Inlet Strategy and Action Plan
  • support landowners with ecological advice and grants

This work strengthens the resilience and ecological health of coastal ecosystems.

Major NCC Programmes Supporting Coastal Ecosystems

These programmes contribute directly to marine and coastal restoration:

Council also supports the Waimea Inlet Strategy and Action Plan

What Can You Do

Sign on a wooden post reading ‘KEEP OUT OF DUNES. Walking in dunes damages the fragile environment,’ with blue sky and blurred dune vegetation in the background
  • Stay off dunes — use marked accessways
  • Join dune or estuary planting days
  • Pick up litter — keep beaches and estuaries clean
  • Report wildlife sightings on iNaturalist
  • Anchor with care — avoid seagrass meadows
  • Don’t dump garden waste in coastal areas

Even small actions protect fragile ecosystems.

Resources & Useful Links

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