Worse than an oil spill
New exhibition raises questions about Clovelly Beach concreting “Worse than an oil spill” This is how Professor Gee Chapman describes the impact of armouring Australia’s coastline. Prof Chapman is a global expert on the environmental impact of artificial shorelines. She opened my exhibition The Dying Bay at GalleryEast, Clovelly on August 24, 2017.
“Hundreds of species may have disappeared from the intertidal shores by covering the habitat with concrete,” Professor Chapman says. “An oil spill is a transient event. An oil spill looks terrible, but the number of animals killed is not usually excessive and populations can soon recover. When you remove habitat, including intertidal rocky shores, habitat for many species has gone and it has gone forever.”
Australia’s rocky coastline hosts a large diversity of animals and seaweeds, some of them very ancient. But it does not get the same publicity as coral reefs. Professor Chapman believes animals and plants living on our rocky shores are just as deserving of protection as are kangaroos or koalas.
In Clovelly the lost species are not extinct, Professor Chapman stresses. They live on other shores in Clovelly, in NSW and elsewhere. Increasing concreting, however, will remove more and more habitat for these species. I've been photographing above and underwater at Clovelly Beach for a year leading up to my exhibition.
The idea came from a visit to the Torres Strait in 2015. I was on a shoot documenting how climate change and rising seas was threatening local communities But at low tide I noted the seabed behind the seawall helping keep the ocean at bay was stripped of any marine life.
A local scientist told me this was the flip side of seawalls. So when I came back home and observed how Clovelly had changed I began to question the wisdom of concreting the bay. Could the backwash created by raising the concrete in 2005 be impacting on marine life? Could we lose the abundance of fish and fauna in the bay over the coming decades? What is behind the invasion of green algae in recent summers? KILLER ALGAE
I invited Professor Chapman, to inspect Clovelly Beach and examine archival images of the bay. “While the concrete is unlikely to have directly caused the infestation of green algae, which I have been told has happened in recent summers, it could, indirectly, be a factor,” says Professor Chapman. “If the walls increase action and water movement, this could disturb the bottom of the bay. These fast-growing, short-lived algae really do well in disturbed conditions. The waves will also rip it up from the bottom, so it floats about. And that will help it spread and when it dies, it will become slimy.
“If, in summer, the algae starts growing thicker and thicker or persists for longer, it may kill the underlying algae, barnacles and other animals that filter the water and help to keep it clean because when it grows over them they may be unable to feed,” she added. Professor Chapman recommends that the council, as a first step, commission a study into the prevalence and temporal patterns in the algae. In addition, it is important that a comparative scientific study is done to find out what impact the walls at Clovelly bay may be having on the adjacent sub-tidal habitats (inside the bay).
2021 STUDY FINDINGS
In 2021 Randwick Council commissioned biodiversity studies from the Sydney Institute of Marine Studies into the impact the concreting of the northern bay may have had on marine fauna and flora. The study found the marine life on the northern seawall had changed compared to the rocky foreshores, rather than declined.
"Overall the results show that, although the communities living on the seawall at Clovelly Bay are generally different than those found on the natural rocky shores at Clovelly or adjacent bays, the seawall supports a diverse community of fish, seaweed and invertebrates."
Most of the concrete was a Depression era construction and over the past century it has become pockmarked and cracked, providing crevices and homes for intertidal species. SIMS recommended no repairs or cleaning of the surface. If structural repairs are needed in future, it recommends complex surfaces or living seawalls. Council is now to commission a further study into the green algae outbreaks in the bay and whether they may impact on water quality. Or what other factors lead to poor water quality in the bay during the summer.
Award winning photographer Greg Weight supported my exhibition with images of the algae bloom that turned Clovelly Beach the colour of blood in 2012. “The ocean has had a natural interactive relationship with the coastline for millions of years,” he said. “Concrete slabs made purely for human convenience that inhibit that delicate balance cannot and obviously do not preserve the marine ecology. During the 20 years I have lived here and snorkelled here I have witnessed algae blooms, blocked drainage and heavy swell. Let’s correct the problem.” Locals have also complained about the embankments amplifying the swell as it bounces off the concrete creating a washing machine effect and making swimming hazardous.
Professor Chapman estimates that 80% of the money spent on protecting coastlines from rising seas, is spent on either new seawalls or strengthening existing ones. She has worked with other scientists on eco-engineering seawalls and embankments, in order to make them more ecologically friendly. This is an increasingly important field of research in Sydney and in many places abroad. “Just making a few changes to a the structure of a seawall can more than double the diversity of marine life that can live on it,” she says, “Although the worst damage is often done by embankments on beaches, where entire beaches can be lost. There is enough data already available to show that walls on certain types of beaches cause loss of some habitat and the species that live in it.”
Gee Chapman is an Honorary Professor of Marine Ecology, School of Biological Sciences, Centre for Research on Ecological Impacts of Coastal Cities at the Marine Ecology Laboratories, School of Biological Sciences,
University of Sydney, Australia
She has written 28 publications for academic journals on armouring seashores, including Paucity of mobile species on constructed seawalls and Ecologically-informed engineering reduces loss of intertidal biodiversity on artificial shorelines,
In The Dying Bay I explored the stark beauty and abstractions created by the collision of water and concrete, the impact on beach goers driven from the crashing waves like climate refugees and, below the surface, the green algae that could smother other marine life. It opened at Gallery East, 21 Burnie St, Clovelly on Thursday evening at 6pm, August 24th and ran (Thursdays to Sundays, 11-6) until September 3rd.
This was a crowdfunded project to raise awareness of how artificial shorelines can destroy marine life. We hope our images will help mobilise the community during the upcoming local government elections to push for the comprehensive scientific studies recommended by Prof Chapman in the hope the concrete can be removed or modified and the north shore restored to its natural state (see below).
The Last Beach | Duke University Press
"The Last Beach is a must-read for anyone interested in the plight of the world's beaches. This brave confrontation with coastal engineers, coastal planners, developers, politicians, and beachfront property owners lays bare their adverse impact on the world's beaches." — Andrew Short, School of Geosciences, University of Sydney
Habitat Development Along a Highly Urbanised Foreshore
Dover Park East Environmentally Friendly Seawall
Tom Heath, marine biologist and catchment officer Georges River Council
Environmentally Friendly Seawalls: A Guide to Improving the Environmental Value of Seawalls and Seawall-lined Foreshores in Estuaries
Artificial marine structures facilitate the spread of non indigenous green algae
FABIO BULLERI* and LAURA AIROLDI
FROM SEA WALL TO SEA LIFE: IMPLEMENTING SEAWALLS THAT
SUPPORT INTERTIDAL BIODIVERSITY
C Covich1, P Makim
Mosman Council, Sydney, NSW
Catalyst: Sea Walls - ABC TV Science
Bureau of Meteorology , 2016