Solutions

1. The 'A-Rest System' – operational methods to assiduously restore coastal margins
2. Wider beaches and lower water tables
3. Wider dunes & beaches for increasing property protection and tourism potential.
4. Species biodiversity (flora, fauna, fisheries)

Species biodiversity (flora, fauna, fisheries)

This nation possesses more than 50 perfectly adapted plant species capable of contributory habitation in coastal dune sands. These naturally evolved species (frequently endemic) once existed in natural successional zones - from foredunes through mid-dunes and on to increasingly complex and species-diverse back-dune climax-forests. Each landward succession revealed enhanced biodiversity gains as humus and nutrients, plus shelter and forage supplies were added by the pioneer inhabitants of the previous more-seaward zone. These three distinct zones also had their own attendant and often similarly endemic faunal inhabitants; many now endangered or lost from this environment, including the distinctive and poisonous NZ katipo spiders (Latrodectus katipo), the helpful indigenous solitary sand-dwelling bees (Leioproctus metallicus) and the iconic flightless kiwi (Apteryx spp.). Coastal dune ecosystems form the extreme seaward margin of all terrestrial existence.

But currently 99% of these ecosystems have been destroyed by anthropogenic impact (Williams 2010), starting with influence of NZ’s first inhabitants - the 14th Century arrival of the initial Polynesian settlers – the last great global migration. The exceptional impact from these early peoples plus their later and damaging European counterparts has collectively been both extensive and uncompromising. This is now recorded as a sequence of unnatural mammalian impacts in this land formerly occupied almost solely by plants, birds, reptiles and invertebrates.

However not all news is bad news – we now have the ability to restore these damaged ecosystems, and for many sensible motives, including mitigation of SLR while also enhancing coastal biodiversity. Numerous areas of substantial biodiversity gains can be readily generated through restoration of these severely degraded coastal environments – ‘our’ beaches and dunes.

These gains generally involve improving outcomes for coastal flora and their highly dependent fauna – in this case through discussion about indigenous wading birds and reptiles. The current scarcity of dependable, secure habitat and the foraging opportunities provided by indigenous flora in this zone has generated heavy impacts on the dependent fauna. Many species have consequently been absent for such a lengthy period that they are currently poorly recognised in the coastal zone, e.g. NZ geckos. Many others are still being impacted presently - their decline over time is still occurring but at a slower rate. Some of these latter types are discussed below.

1. Coastal wading birds – e.g. Variable oystercatcher, NZ dotterel, Banded dotterel, NZ fairy tern, Caspian tern, Godwit etc.

   • The first species above has “a declining or fluctuating range size, habitat extent and quality” (BirdLife International), while the NZ Dotterel is listed as endangered (DOC)
   • The NZ fairy tern is an endangered species, and carries a 'Category A' priority for conservation action, and a Department of Conservation Recovery Plan is currently in action.
   • These bird species commonly nest in sand at the upper reaches of beach berms, above the strand-line.
   • They require a naturally rising sandy slope that can only occur on beaches/dunes in a natural and porous condition, which enables these birds to nest successfully, and further enable successful hatching and fledging of their offspring – PETER - do you wish to have the attachments too - Especially the caption for the first plate – “Note: The surface disturbance of sand invertebrates and dark-brown stain of their exudates surrounding the now-buried seaweed.”) These colonising invertebrates (often sand hoppers) are exponentially more numerous where dunes have been restored, and conditions for seaweed deposition are more favourable.
   • Storm surges on eroding beaches (plus predation - both aerial and ground based) often have severe impacts on their breeding success, and can be a severely-limiting factor in many seasons, to the point where people today exclaim at “the stupidity of the birds nesting in these exposed places – no wonder their success is declining!” Common and ill-informed comments such as these are indicative more of the length of time these degradations have been present, rather than “stupidity” of the birds nesting where their far-older and naturally-evolved behavioural instinct still dictates is favourable (when these sites were formerly and essentially ‘safe and successful’.)
   • Restoration of dunes naturally raises the profile of the swash-zone of beach berms and ensures better survival rates and opportunities for juveniles - in association with increased foraging opportunities for adults.
   • Protection from aerial predators is provided by the evolved and naturally-cryptic shelter of the indigenous dune plants (especially pingao), plus by virtue of having local community groups involved with active trapping and control of ground-based predators.
   • NOTE – during the 2011 grounding of the container-ship Rena, and the resultant environmental impacts of many tonnes of leaked oil and the resultant, amplified human clean-up activity on BOP beaches, one pair of variable oystercatchers did nest successfully, and in full view of thousands of holiday makers at Mt. Maunganui (adjacent to the Mount Maunganui Domain Motor Camp.) This pair independently determined that the safest opportunity for them to nest and successfully raise & fledge their chick that year (under the prevailing and difficult conditions) was within a coastal dune restoration area, protected only by a flimsy tape barrier. Photos are available – Mount oystercatchers
   • This same pair of variable oystercatcher’s returned to successfully nest and fledge a subsequent chick the following year. This happy ‘coincidence’ is a feature at many restored beach sites. The opposite is regrettably true for many relict dune sites.

2. Lizards – e.g. NZ skinks, geckos

   • There are over 80 species of lizards in NZ – but over 40 are now considered rare, threatened, or endangered.
   • Most of the many NZ lizard species have evolved over centuries to be responsible for zoophily – pollination of flowers by vertebrates. And most often, coastal forest-margin mid-dune plants like cabbage tree (ti kouka), Coprosma spp, kanuka and manuka, coastal fuchsia, and flaxes (both harakeke, wharariki) are the plant species most commonly pollinated by these lizards. The fruits that follow their pollination are also frequently foraged by these indigenous vertebrate species, and whose seeds are probably distributed following ingestion.
   • It is apparent that the margins of coastal forest probably would have been a favoured habitat for lizard species, due to the high prevalence of these low-stature and heavily-fruiting shrubs and small trees.
   • These natural coastal-margin plant species (the low-stature and heavy-fruiting shrubs and small trees) are logically constrained by the severe environmental conditions existing on all dunes. They grow where other taller (and poorer-fruiting) species fail to survive – in this very poor moisture retaining and nutrient containing substrate (sand), with severe and damaging salt-laden winds, hot & dry conditions in summer, and with quite minute organic matter content.
   • The coastal-margin plant species perform an important role – they form a buffer for the taller climax forest species occurring landward, and so form (or more aptly formed) a succinct and critical sub-zone – often referred to as a ‘vegetation wedge’, progressively raising and slowing wind velocity with each landward succession and so protecting the final climax-forest. In function, the original foredune vegetation protected the seaward edge of this ‘vegetation wedge’, and so each successional sequence had its own clique of indigenous dependants.
   • However, centuries of human-impact has resulted in these dune forests being now largely absent (less than 1% remaining), with the subsequent detrimental effects on indigenous lizard (and avifauna) populations, in conjunction with other factors, like predation by introduced mammals.

3. Fisheries

   • Due to the considerable length and scale of the anthropogenic impacts, little is known about the effects of coastal degradation on fisheries.
   • However, one interesting new finding was uncovered recently regarding the effects of plant types on dune formation, coastal resilience, and local mollusc fisheries.
   • This work was conducted in preparation for university thesis by Josh Müller on Matakana Island, a 22km long sand-barrier island on the ocean margin of Tauranga harbour.
   • Müller (2011) found that juveniles of the bivalve mollusc, Toheroa (Paphies ventricosa), were more prevalent on dunes dominated by indigenous Spinifex plants. This was due to the ability of Spinifex to maintain lower water tables within the dune formation, which results in the sand being more porous. This attribute favours both Toheroa presence (especially juveniles) AND dune resilience during storms, and is the mechanism that creates wider dunes and beaches.

As detailed previously, NZ coastal margins have been affected by a tranche of impacts for centuries, so long now that many people are not truly aware of the scale, severity or pervasive nature of these countless deleterious effects.

Similar biodiversity impacts are known, or at least likely, in most other global nations bearing analogous detrimental influences. And now remediation of these universal impacts is not only possible, such action is highly desirable from many viewpoints.

• Müller, J. 2011. Influence of vegetation cover on coastal aquifer fluctuations and sand transport on Matakana Island. The University of Waikato, Hamilton.