Day 6 – March focus on Norfolk Island’s reef
The creek laden with silt and water-borne nutrients overflowing into Emily Bay and directly onto the inshore reef after heavy rain
It seems appropriate as we celebrate Foundation Day here on Norfolk Island, that today’s March focus post looks at how man has modified Emily and Slaughter Bays and the surrounding environs over the last couple of hundred years.
Foundation Day celebrates the day Lieutenant Philip Gidley King first arrived on Norfolk Island on 6 March 1788, not quite six weeks after the First Fleet arrived at Port Jackson (Sydney) in New South Wales. It entwines our history inextricably to the colonial history of Australia.
When King arrived, much of the area we now know as Kingston was a swamp entangled in almost impenetrable vegetation. Chimney Hill created a natural stone barrier preventing water from draining into Emily Bay (see Bradley’s map below). Instead, water would collect and then seep gradually from the swamp out through the water table into the bays. Inundations of fresh water would have been rare because the water and silt were held back by the natural landscape and vegetation.
In 1789, one of the first engineering works to be undertaken in the colony – indeed, in either of the new colonies of Norfolk Island and Port Jackson – was done under the auspices of King, so that this low-lying, relatively flat and easily accessible land (a rarity on the island) could be used to grow much-needed crops. He had a channel cut through the swamp. It was taken on a course to the north of Chimney Hill, before making a sharp turn south into Emily Bay (see Wakefield’s plan, below), thereby creating a stream that drained the swamp.
From this moment on the coral reef was compromised. Corals hate fresh water. We now understand that the constant, and proximate, inundations of fresh water draining into Emily Bay create problems for the coral reef habitat; therefore, the aim is to slow the water flows by recreating the pre-settlement swamp (this plan can be traced back to at least 2003 under the old Norfolk Island Administration). However, with the recent record rainfalls the island has experienced, this has not been an easy task.
I know people will say, why hasn’t the reef been this bad before? Well, I liken it to compound interest. Coral reefs are reasonably resilient but gradually, over time, the health of the reef has deteriorated, the damage compounding to the point where the system becomes unstable and a tipping point is reached.
Have we reached our tipping point? The researchers think we could be close.
It has also been likened to a death by a thousand cuts, where multiple stressors accrue, each one itself not necessarily important but grouped together they can become deadly (Great Barrier Reef Science Commentary).
You can read more about the drainage channels (as well as other interesting stuff) on the signs affixed to the barbeque at Chimney Hill in the Kingston site.
1788 map by William Bradley showing the coastline of Kingston and Chimney Hill before it was quarried.
*Norfolk Island ; S. end of Norfolk Island / W. Bradley delin. 1788 ; W. Harrison & J. Reid sc
King’s channel became silted up after the settlement closed in 1814. When it was reopened in 1825, the original channel was restored and further drainage works were undertaken. Wakefield’s 1829 plan shows the now-restored first channel as it passes to the north of Chimney Hill before emptying into Emily Bay.
*Plan of the settlement and Garrison Farm & Co., Norfolk Island / surveyed by Capt. Wakefield, 39th Regt., May 1829