Ecology

The different environments around the edges of the Regeneration Strategy project area provide important habitats for a diverse range of plants and animals. The area has three main habitats: the coastal sand dunes and south end of the Spit; the intertidal areas adjacent to the Estuary/Ihutai; and areas of open space and reserves.


What we know

Range of habitats

The coastal sand dunes habitat comprises a wide and sandy beach, foredunes, and backdunes. This habitat supports several birds, shellfish and sand-binding plants. Most of these plants are exotic species such as marram grass, although native species have been planted in a number of areas, including the Southshore Spit Reserve.

The intertidal areas of saltmarsh are mostly located north of Bridge Street, and in patches on several parts of the estuary edge in Southshore. Indigenous species include marsh ribbonwood (Plaginathus divaricatus), sea rush (Juncus krausii) and jointed rush/oioi (Apodasmia similis).

Some of the saltmarsh is suffering die-back because of increased tidal flooding and bed erosion following the earthquakes, particularly around Bridge Street. However, in other areas where improved habitat condition and new habitat where areas experienced some uplift, small patches of saltmarsh have expanded (for example, around Tern Street and Penguin Street).

The Estuary/Ihutai itself supports an abundant and diverse ecosystem. The importance of the Estuary/Ihutai as a bird habitat for roosting and feeding is nationally and internationally recognised.

It provides a rich food source and is a strategic location for migratory birds. The variety and abundance of migratory waders and wetland birds located in one place is particularly significant, with up to 144 bird species recorded .

Adjoining the Estuary/Ihutai is the residential red zone, now cleared of buildings and grassed, and a number of recreation and scenic reserves. These areas are a mixture of exotic tree species, open grassed areas, and native regeneration planting.

Some areas, such as the area near the river mouth north of Bridge Street, have seen an increase in bird populations and the diversity of species over the last 30 years . In other areas the existing vegetation has become increasingly stressed by the change in salinity and water levels due to subsidence as a consequence of the 2010-2011 Canterbury earthquakes, and further slight subsidence that occurred during the 2016 Kaikōura-Hurunui earthquake .

These ecosystems, including those on the edge of the Estuary/Ihutai adjacent to the Regeneration Strategy project area, are highly sensitive to changes in salinity, water level, moisture, sedimentation, the concentration of contaminants, temperature, and sunlight.


Why this is important

International, national, regional and district significance

The coastal margin of the Regeneration Strategy project area and the Estuary/Ihutai are recognised either nationally, regionally or at a district level for their unique ecosystems, and the amenity values. These areas are listed in the table below.


Climate change will exacerbate sensitivities

Increases in sea level and storms as a result of climate change will cause changes in salinity, water depth, and wave-affected areas, impacting the Estuary/Ihutai habitats adjacent to the Regeneration Strategy project area .


Opportunity to maintain and enhance values and natural protection

The habitats in the Regeneration Strategy project area provide an important buffer between the natural and built environment on both the open coast and estuary edge. For example, saltmarshes increase accretion rates by providing an erosion buffer, increasing or stabilising the marsh surface through its network of plant roots .


What we don’t know

It is not clear whether there will be long term or irreversible impacts of climate change on the natural habitats and ecosystems, and if so what these are and when they will become apparent.


The different environments around the edges of the Regeneration Strategy project area provide important habitats for a diverse range of plants and animals. The area has three main habitats: the coastal sand dunes and south end of the Spit; the intertidal areas adjacent to the Estuary/Ihutai; and areas of open space and reserves.


What we know

Range of habitats

The coastal sand dunes habitat comprises a wide and sandy beach, foredunes, and backdunes. This habitat supports several birds, shellfish and sand-binding plants. Most of these plants are exotic species such as marram grass, although native species have been planted in a number of areas, including the Southshore Spit Reserve.

The intertidal areas of saltmarsh are mostly located north of Bridge Street, and in patches on several parts of the estuary edge in Southshore. Indigenous species include marsh ribbonwood (Plaginathus divaricatus), sea rush (Juncus krausii) and jointed rush/oioi (Apodasmia similis).

Some of the saltmarsh is suffering die-back because of increased tidal flooding and bed erosion following the earthquakes, particularly around Bridge Street. However, in other areas where improved habitat condition and new habitat where areas experienced some uplift, small patches of saltmarsh have expanded (for example, around Tern Street and Penguin Street).

The Estuary/Ihutai itself supports an abundant and diverse ecosystem. The importance of the Estuary/Ihutai as a bird habitat for roosting and feeding is nationally and internationally recognised.

It provides a rich food source and is a strategic location for migratory birds. The variety and abundance of migratory waders and wetland birds located in one place is particularly significant, with up to 144 bird species recorded .

Adjoining the Estuary/Ihutai is the residential red zone, now cleared of buildings and grassed, and a number of recreation and scenic reserves. These areas are a mixture of exotic tree species, open grassed areas, and native regeneration planting.

Some areas, such as the area near the river mouth north of Bridge Street, have seen an increase in bird populations and the diversity of species over the last 30 years . In other areas the existing vegetation has become increasingly stressed by the change in salinity and water levels due to subsidence as a consequence of the 2010-2011 Canterbury earthquakes, and further slight subsidence that occurred during the 2016 Kaikōura-Hurunui earthquake .

These ecosystems, including those on the edge of the Estuary/Ihutai adjacent to the Regeneration Strategy project area, are highly sensitive to changes in salinity, water level, moisture, sedimentation, the concentration of contaminants, temperature, and sunlight.


Why this is important

International, national, regional and district significance

The coastal margin of the Regeneration Strategy project area and the Estuary/Ihutai are recognised either nationally, regionally or at a district level for their unique ecosystems, and the amenity values. These areas are listed in the table below.


Climate change will exacerbate sensitivities

Increases in sea level and storms as a result of climate change will cause changes in salinity, water depth, and wave-affected areas, impacting the Estuary/Ihutai habitats adjacent to the Regeneration Strategy project area .


Opportunity to maintain and enhance values and natural protection

The habitats in the Regeneration Strategy project area provide an important buffer between the natural and built environment on both the open coast and estuary edge. For example, saltmarshes increase accretion rates by providing an erosion buffer, increasing or stabilising the marsh surface through its network of plant roots .


What we don’t know

It is not clear whether there will be long term or irreversible impacts of climate change on the natural habitats and ecosystems, and if so what these are and when they will become apparent.