Nature NSW – Autumn 2021

Spiralling away, local losses in a global crisis

Gary Dunnett, Executive Officer

The more familiar you become with a park the more it divides a series of connected places, all with their own special characteristics.  Royal is my local national park – in fact the suburb I live in was originally part of the park before it was excised in a land swap in the late 1800s.  One of my favourite places in Royal is the Basin, an area of roughly sixty hectares of mangrove forest, sandflats and tidal creek.  I have a deep personal attachment to the Basin, built on childhood camping holidays, family picnics and days spent exploring the sandy swimming holes and oyster encrusted mangroves.  It was the natural choice when it came time to introduce my own kids to the joys of mask and snorkel. 

I few years ago I did a photographic project documenting the amazing diversity of wildlife that lives in the Basin.  I saw all the estuary staples like whiting, bream, flathead, blue swimmer and fiddler crabs, but the more I looked the more wildlife came to light.  My two favourites were the Southern Dumpling Squid, a tiny predator that roams the submerged mangrove roots at night hunting for shrimp and unwary fish, and the Sea Hare, a strangely charismatic ‘sea slug’ that emits a cloud of purple dye if disturbed.  

The project can be viewed (I’d suggest as a slideshow, look for the ‘triangle in a box’ symbol) at https://www.flickr.com/photos/garydunnett/albums/72157633102297178

It is against this somewhat less than objective backdrop that I’ve been watching with increasing horror as the once magnificent mangroves of the Basin have turned into stark white skeletons over the last year.  It is hard to tell from water level, but I’d estimate that as much as 40% of the mangrove forest has died over this time.  It’s not just the young or old trees, with individuals of all sizes going and both of the local mangrove species.  When I put on a mask, the scale of the problem simply increases, with once extensive seagrass beds smothered by mobile sands along with the muddy banks that attracted blennies, gobies and even the occasional mud crab. 

The thing that shocks me most about the apparent collapse of this once productive system is that it has happened so quickly.  NPA has contacted NPWS and the wetland scientists in the Department of Planning, Industry and Environment asking for an urgent investigation.  There are a few obvious candidates for the massive dieback, including browsing of mangrove foliage by the feral Rusa Deer that infest the park, the change in channel patterns that was triggered by the major storms earlier in 2020, or excessive heating of the shallow waters during last summer’s record-breaking heatwaves.  I suspect that the heat waves basically cooked the forest, with the others acting as contributing factors, but the issue clearly warrants careful investigation.

It is entirely possible that the ecosystem collapse that is happening at the Basin is purely a matter of local factors that have little or no implications for the rest of our protected areas.  I genuinely hope that such proves to be the case.  Unfortunately, if there is anything the last summer told us, it is that the world is changing, and we cannot assume our climate, weather and environment will remain stable. 

This suggests a new type of vigilance by NPA members.  We need to be alert for more than the development proposals, poor practices or outright vandalism that degrades our parks and reserves, and keep an eye out for the ‘intact’ places that are showing signs of ecological damage or even collapse.  It is not a joyful task, yet identifying the local manifestations of climate change is incredibly important.  It helps to reinforce the momentum towards global action, and also offers the opportunity to enact local actions to mitigate or adapt to the emerging problems.  Adaptation is not an excuse for global inaction, but it will prove essential for the survival of many precious places. 

Nature NSW Online  –Autumn 2021

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