SEANA Autumn Camp 2023, Port Campbell – Deborah Evans

The Timboon Field Naturalists Club organised this year’s SEANA autumn camp, choosing sites along the coastal strip in the Bay of Islands Coastal Park to the west of Port Campbell and the Port Campbell National Park and Twelve Apostles Marine National Park to the east. We had plenty of opportunities to view the magnificent coastal scenery that includes London Bridge, Loch Ard Gorge and The Twelve Apostles for which the area is internationally famous. However, it was what was up on the tops of the cliffs that was of special interest for us.

The geological processes that produce the ‘wrinkled’ coastline and the spectacular rock stacks are evident on the cliff tops, with depressions developing where water seeps through cracks in the overlying clay down to the limestone, producing solution caves which eventually collapse to form narrow bays with the familiar steep-sided cliffs. [photos, inc. loch ard stalactites, Muttonbird Island] These depressions have resulted in numerous small wetlands along the coast, including the ones near Peterborough which are important Latham’s Snipe habitat. It was these wetlands that particularly drew the attention of the birders and the botanists at the camp. A local endemic plant noted by a number of GFNC members was the endemic Port Campbell Guinea-flower Hibbertia truncata. [photo from Ellinor]

Giant Kelp, Wild Dog Bay
Hibbertia truncata

For me, it was of course the rocks and beaches that were the drawcard. Of special interest was Two Mile Bay just west of Port Campbell, the one place where a remnant of the Pleistocene glacial maximum and lower-sea-level coastline has been preserved, possibly by offshore reefs which have broken the powerful swell that has carved the other cliffs and stacks. (There’s nothing but ocean between here and the Antarctic, so it’s not surprising that this is known as the Shipwreck Coast!) Here the cliff had been weathered to a vegetated sloping bluff, with a relic coastal terrace, now including a swamp, and a vegetated foredune with a new rock platform emerging.

Further west, down on the beach at Wild Dog Cove, a highlight was the marine algae, including Giant Kelp Macrocystis pyrifera which had been the subject of our Friday evening talk. The forests of kelp have been disappearing along the coast but have recently started to reappear around Port Campbell. (Look for the ‘Mission Macrocystis’ project on iNaturalist.) [Photo Ellinor]

Also down on the beach in the Bay of Martyrs and a threat to the Little Penguin colony further east at London Bridge were two notorious weeds, Sea Spurge and, more recently, the South African Coast Daisy Arctotheca populifolia which flourishes on sand. A recently released virus for Sea Spurge seems to be starting to have an effect. The local Bay of Islands Friends group have achieved much success in both planting and weed removal along the cliff tops and beaches here, resulting in much suitable habitat for Rufous Bristlebirds, which called frustratingly all along the coast, including in Port Campbell itself.

Thanks and congratulations to the Timboon Field Naturalists Club for a wonderful weekend.

Deborah’s photos

Bay of Martyrs
Loch Ard Gorge
Loch Ard stalactites in the now collapsed caves
Two-mile Bay relic coastline
Muttonbird Island, an important Short-tailed Shearwater nesting area. Note the vertical joints along which rock stack collapses can occur.
Fossiliferous layer in the Port Campbell Limestone, Wild Dog Bay