Journal archives for October 2021

October 13, 2021

Coastal Dunes - Species that Matter - Sea Spurge

While not intending to focus on the dramatic, this month I once again divert from the focus on some of the amazing and wonderful native and endemic species that we have on this coast in our dune wilderness, to focus on a different kind of problem to last month's highlighted weed [1].

Two years ago I learned about sea spurge via

https://inaturalist.nz/observations/34943019

It took my iNaturalist colleagues some weeks to settle on the identification, since at the time, this species was only known in NZ from an initial invasion in the Waikato. A DoC lady woke us up to MPI's position on this species. The participants in this process celebrated finding this plant early, before the problem became serious. If only it remained so simple. MPI's management of this species stands in stark contrast to the sorry state of our coastal dunes ecology due to coastal wattle [1] which is a far more advanced problem, in terms of destroying the native coastal dunes ecosystems. So, what's the big deal?

https://research.csiro.au/nswweeds/wp-content/uploads/sites/174/2018/11/Darby-River-landscape-14.jpg

a) Euphorbia paralias, as it is formally named, is a significant problem in Australia, where it is soaking up large sums of money to manage it.

b) Not only is the illustrated beach effectively overgrown, sea spurge can cause skin and eye irritation from the sap. This is a real deterrent for beach-oriented tourism. New South Wales is not the worst hit problem, but over 60% of beaches in NSW are affected already.

c) MPI regards this as an early-stage problem that needs to be beaten, before it starts to affect the New Zealand economy.

https://www.mpi.govt.nz/dmsdocument/3554-sea-spurge-a-serious-threat-to-new-zealands-beaches

This reflected initially in the early finds with rapid, comprehensive reactions, an ecological parallel to the government's proactive stance on Covid-19.

From the single find on the lower North Island two years ago, a recent coastal dunes survey by Kelsi Hoggard of Horizons Regional Council, had over the past month, highlighted a further three instances in our region, which were mature enough to have spawned several generations of plants, at sites west of Moana Roa Scenic Reserve south of Scott's Ferry, half way between Waitarere Beach and Hokio Beach, and half way between Kuku Beach and Waikawa Beach.[2] There has recently also been a site highlighted south of Paraparaumu Beach, as well as one on the West Coast of the South Island.

To drive the situation home, recently I came across another patch, 4km north of the Foxton Beach Surf Club, ie. right in our back yard [3].

Once again, reporting this on a Sunday caused a furore, with multiple persons from MPI chasing details, as well as our local Council and DoC contacts. This is taken seriously.

Maybe you can use this material as a guide to recognising this problem when you happen to walk in the dunes. I certainly hope so! As a starting point, if you download and read the URL on the MPI website, it will give you the necessary details to report any find of this species. That's my bottom line message - how you can help. These are our New Zealand beaches that we're working to preserve.

Consider the larger context. This is broached nicely in my article from last month[1] for coastal wattle, or you can see another 'fine' example at the well managed estuary of the Waikanae River, which at the dune front, turns into a wall of tree lupin [4]. These problems are past an easy solution, so let's not let sea spurge get like that too.

Enough banging of the drum. Start with the URL from MPI, and let's work together on this.

[1] https://inaturalist.nz/journal/arnim/55596-coastal-dunes-species-that-matter-coastal-wattle

[2a] https://inaturalist.nz/observations/93765978

[2b] https://inaturalist.nz/observations/94880736

[2c] https://inaturalist.nz/observations/94880602

[3] https://inaturalist.nz/observations/96144946

[4] https://inaturalist.nz/observations/32318247

Posted on October 13, 2021 07:37 AM by arnim arnim | 0 comments | Leave a comment

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