|Available online at https://bit.ly/MarlboroughBeachReport|
This new report covers some of our ongoing disaster recovery work on the Kaikōura and Marlborough coasts.
The report responds to a request from Marlborough District Council (MDC) for information on the coastal environment, with a particular focus on supporting the development of a bylaw to address changes in recreational use patterns that have occurred since the Kaikōura earthquake. We present a selection of information from our earthquake recovery research that has a focus on understanding the impacts and ongoing processes of change. Major impacts of the natural disaster are associated with vertical uplift of the coastal environment, although ongoing erosion and deposition processes are also important.
Interactions with human activities are also important because they can exert strong influences on the reassembly of ecosystems which is a critical aspect of outcomes over the longer-term. Earthquake uplift caused widespread mortality of many coastal habitats and species (e.g., algal assemblages) that are adapted to a relatively specific set of conditions, often associated with characteristic locations in relation to the tidal range. In uplifted areas the intertidal zone has moved seaward leading to a physical widening of many beaches. This has provided greater opportunity for off-road vehicle access to the coast and has become particularly noticeable at headlands and other natural barriers that were previously impassable at high tide. Off-road vehicles pose threats to sensitive vegetation and wildlife unless appropriately managed. Achieving this is assisted by an understanding of the specific impacts of vehicle use, which in turn requires information on the location of sensitive areas.
To ensure the best outcomes for earthquake recovery there is an urgent need to assess and respond to the new spatial patterns, and to make plans to avoid conflicts where possible. In our RECOVER (Reef Ecology and Coastal Values, Earthquake Recovery) project funded by the Ministry of Business, Innovation and Employment (MBIE) and supported by the Ministry for Primary Industries (MPI) we are collecting information on important conservation values and activities. Although research is continuing, this report provides findings that include mapping of indigenous dune system remnants, recruitment of the indigenous sand-binders spinifex (Spinifex sericeus) and pīngao (Ficinia spiralis) on uplifted beaches, distribution of red katipō (Latrodectus katipo) within earthquake-affected dune systems, distribution of banded dotterel / pohowera (Charadrius bicinctus bicinctus) nesting pairs to determine important areas, and spatial overlaps with vehicle tracking measurements along the coast.
Based on the information collected to date, key findings include:I. There is strong evidence for the recent decline of pīngao in this area that should be of concern to coastal managers given its conservation status as an ‘at risk – declining’ species and as a Ngāi Tahu taonga species. The overall pattern includes an apparent lack of recruitment to replace old-dune pīngao remnants that are under threat from ongoing environmental change.
II. There is a unique opportunity to help re-establish pīngao and spinifex dune ecosystems through a strategic restoration approach that takes advantage of the uplifted beaches.
III. To assist recovery processes and opportunities, there is a need to avoid vehicle damage to existing dune faces and new dune establishment zones (which are close to the new high tide mark), particularly where spinifex and/or pīngao are present. Similarly, there is a need to avoid disturbance to reef platforms which are only slowly recovering and are highly fragile in their current condition.
IV. On this coastline, the fore-dune face is an important area for katipō and should be a focus for conservation efforts, especially where sparse vegetation types such as pīngao and spinifex are present. This creates an additional reason for protecting newly developing fore-dunes and assisting the re-establishment of indigenous dune systems. There are also major differences in katipō densities along the coast in similar habitats due to unknown factors which require further research.
V. The distribution of banded dotterel nesting sites includes several well-defined hotspots (clusters of nesting sites in close proximity) that are priority areas for protection. The specific impacts of vehicle use in these areas require further work to determine, but there is considerable overlap with the current pattern of vehicle tracking. Effective measures are needed to control threats from vehicle movements through techniques such as spatial planning to ensure a separation between vehicles and nesting areas during the breeding season.
VI. Bringing together information from studies at a variety of scales is needed for a comprehensive understanding of earthquake change and to assess the merits of new management proposals. These needs will continue beyond the life of the RECOVER project since many important recovery processes are only just beginning (e.g., new dune establishment and algal assemblage recovery). At the same time, ongoing disturbances, including natural disasters and climate change, will continue to affect the coast and are important aspects for longer term monitoring.