Our beaches under pressure

One of the first things you may notice when you go to a favourite beach is that the dunes have altered and the steps leading to the beach, which were there the year before, have disappeared. Dr David Kennedy in the Melbourne School of Land and Environment explains that the beach is a dynamic system.

The sand we find at the beach has taken thousands of years to get there. Rocks and soil on land are eroded by rain, wind, frost and chemical weathering into their component parts and washed down rivers and into the sea. Once there, they combine with the broken remains of ocean organisms such as shells to form sand.

The action of the waves pushes this sand onto the shore forming beaches. Once above the water the sand then dries and then can be pushed back inland by the wind to form dunes.

“People may not realise that the dunes and the beach are a store of sand for storms. As the sand on a beach reaches deep into the ocean as well as onto the shore, storms can cause sand and the beach to move up to five metres vertically and 100 metres horizontally,” he says.

“What summer visitors don’t see is the movement which typically happens during big storms in winter. Although we don’t know how long it takes to return, the sand does come back,” he says. 

But there is more than just a natural cycle having an impact on the beach. Over the past 40 years there has been a huge influx of people to coastal areas and more people have built houses along the all-important dunes.

“Once you armour the sand and seal it off with development, the sand isn’t available but the beach still takes it from somewhere so the beaches get shorter or lower. In some cases sand may need to be brought in to replenish stocks, which is what happens on some inner Melbourne beaches.” 

Although Dr Kennedy says our coastlines are stable at the moment, this is likely to change in the future as an effect of climate change. And as materials have improved there are also more people building closer to the water and in hazard zones. 

“What might have been previously a little shack is now a million dollar development,” he says.

If you build in hazard zones, which are expected to experience more storms than other areas, the beach loses its ability to adjust. This he says was the case in New York where Hurricane Sandy pushed sand deep into residential areas. Without the dunes as a natural barrier, the storm hits whatever is in its path.

“As more people are drawn to the coast, we make a priority call. Do we want a view, or do we want to retain the beach? People wanting a view tend to win out,” he says.

Professor Ray Green from the Faculty of Architecture Building and Planning has focused his research on what characteristics coastal residents love and hate in their towns. 

“I wanted to find out how the community felt about their town, and how we can preserve the character and attributes that communities determine are of value.”

Professor Green surveyed close to 2000 people in seven Victorian coastal towns to find out what local features residents viewed were “in” and “out” of character with their local area.

What were identified as “in” character were low buildings, and houses with larger setbacks without obvious fence lines, which made them appear to blend in with bushland. What were considered “out” of character were monolithic, oversized developments lacking in vegetation that made them highly visible.

“The problem with our love of the beach is that people have been buying up old beach shacks and building McMansion type houses right to the limits of what regulations will allow,” he says.

“The results of my research allow formulation of evidence-based planning guidelines for maintaining character in coastal towns by retaining attributes which draw people to these places in the first place.” 

This is not a problem unique to Australia. In the UK there are federal laws to help maintain the identity of some of their older coastal settlements. There tranquility has been identified as a key attribute of a town’s character and the visual and audio issues that can detract from that sense of tranquility.

A tranquility mapping method has been developed which allows key attributes to be rated for their contribution to a place’s tranquility, such as being able to see the stars, or hear natural sounds like running water and birdsong.

But another challenge lies ahead. With sea levels expected to rise, and increased intensity of storms expected due to climate change, coastal settlements will be forced to adapt. This means ceasing to build on flood plains and other considerations of living close to the beach.

 “We can incorporate attributes that we know are valued characteristics of coastal towns to create innovative adaptive designs to meet the climate change challenge and at the same time preserve the amenity value in popular coastal areas,” he says.

“We need to adhere to a new way of thinking about design with regard to our coastal towns if we are going to enjoy them for the long term.”

University of Melbourne researchers are not only focused on human life beside the seashore. Many of them spend a lot of time on and in the oceans, trying to understand more about the creatures that live in them.

But the bad news is the creatures’ skeletons may be shrinking, making them vulnerable.

An international team of researchers including Professor Robert Day from the University of Melbourne’s Department of Zoology has studied shellfish and other marine animals from the tropics to polar regions and predicted their skeletons will be reduced due to ocean acidity, which is largely caused by the burning of fossil fuels.

Ocean acidity makes it harder for marine animals to make shells and skeletons, making them more vulnerable, especially as they grow. This may well reduce the food source for tropical seabirds, seals and other large aquatic animals and humans, says Professor Day.

The research was led by scientists from the British Antarctic Survey (BAS) and the National Oceanography Centre (NOC) of the UK, and looked at the natural variation in shell thickness and skeletal size in clams, sea snails, lampshells and sea urchins living in 12 different environments across the world, including many living near Melbourne, and others in tropical Queensland, to predict how they might respond to increasing human-induced ocean acidity. 

“Some of the extra carbon dioxide humans produce dissolves in the ocean and reacts with water to produce an acid. This makes it harder for shellfish to extract calcium carbonate (limestone) from the water. Many marine animals use this to make their shells or skeletons – and so the skeletons of marine animals are predicted to get lighter and less strong” Professor Day says. 

One such animal is the abalone, which is Victoria’s most valuable fishery, earning many millions in revenue for the state.

“To safeguard shellfish and other such animals, and therefore also species higher up the food chain, we need to slow the burning of fossil fuels for power, and hope that evolution allows species to adapt their shells to more acidic oceans.”

PhD student John Ford is also investigating the health of our oceans, but focused closer to home in Melbourne’s Port Phillip Bay. From Altona to Corio to Lonsdale, he has conducted 450 dives in the bay as part of his research under the supervision of Professor Steve Swearer in the Department of Zoology.

“We want to understand more about the effect of the city of Melbourne on the health of rocky reef fish sites,” says Mr Ford.

“I am examining the fish populations in 20 locations in the bay, detailing population sizes, fertility and mortality.”

The work uses a kind of forensic technique which enables the tracking of fish movement through examining the chemical makeup of their bones. 

“The ultimate aim is to identify the key rocky reefs critical to the overall health of fish populations in the Bay.”

In the little spare time he has, John Ford is also working with Melbourne chef Oliver Edwards to develop a sustainable seafood website called goodfishbadfish.com.au. 

Overfishing is an increasing issue as seafood stocks decline and demand for seafood on the plate increases. Chef Oliver Edwards created the website with his partner Beth Bicknell, and recently engaged Mr Ford to provide scientific weight and rigour to the information presented on environmental sustainability.

“The aim of the web guide is to make consumer choice easier by collating and interpreting the varied and often conflicting information about sustainable seafood from accreditation schemes, government assessments and seafood guides, providing a unique resource for shopping and recipe ideas,” says Mr Edwards.

“It provides sustainable alternatives for species with limited supply, or where fishing techniques endanger other species or habitats.

“If consumers are able to make purchasing decisions which support the development of sustainable fisheries, we can encourage changes within the industry which will lead to better environmental outcomes.” 

The website provides a simple list of species that are considered sustainable by all sources, as well as a table comparing and explaining conflicting assessments so consumers can make their own decisions.

“For example some fishing practices result in the deaths of seals and birds, which some consumers would consider unacceptable at any level, but for others if the seal population is not threatened, then it would be OK,” Mr Ford says.

The website also has seasonal recipes and seafood preparation tips from Mr Edwards and guest chefs, as well as a ‘Seafood Converter’ which provides sustainable seafood alternatives for recipes.

“Sustainable seafood is about ensuring our great-grandchildren can also enjoy the delicious abundance of fresh seafood we see at the fishmonger today,” Mr Ford says.

So when you head to your favourite coast, spare a thought for the natural cycle of the beach, marine life and the not so natural human impacts. Ideally when visiting the beach, try to leave only footprints in the sand.

www.abp.unimelb.edu.au
www.zoology.unimelb.edu.au
www.land-environment.unimelb.edu.au/