Penguins, plovers, people and weeds…

Researchers from the University of Melbourne and Birds Australia are investigating the full impact coastal weeds have on seaside environments in Australia.

After a long day of hunting fish, little penguins head back to their nests in the sand dunes for a much-needed rest. But introduced coastal weeds could be cutting off the exhausted penguins from their nests, Professor Roger Cousens from the Melbourne School of Land and Environment explains.

“Marram Grass is a widespread introduced species of weed that can radically alter coastal landforms. By holding sand together, the weed can cause mini cliffs to form after storms, and these steep cliffs would be very difficult for little penguins to climb to get up to their nests,” Professor Cousens says.

 “Little penguins rely heavily on their nesting areas for both shelter and breeding, and therefore restricted access to these sites would mean huge problems for the species.”

And it is not just little penguins that might be threatened by invasive weeds, other shorebirds could also be vulnerable, Professor Cousens explains.

“For example dense areas of sea spurge, another species of weed, might make it impossible for nesting Hooded Plovers to see predators coming, causing the birds to nest in more exposed places where they are at increased risk of trampling or being washed away.

“Invasive weeds might also push out native food plants for certain species, thus creating areas of unsuitable habitat.”

Professor Cousens says that weeds might also have social impacts on human visitors to the coast if clumps of weeds affect their experience at the beach.

“People might avoid going to certain beaches because of dense weed cover; it is also known that some individuals have allergic reactions to certain weeds, such as sea spurge,” he says.

But the problem is, the environmental and social impacts of weeds in Australia have never been measured.

“We know that invasive weeds in coastal regions are likely to have a wide variety of complex impacts, but we just don’t know the significance of them” he says.

“For example, it might be the case that removal of weeds in well-intended attempts to clean up a beach may actually increase erosion and even exacerbate enviornmental problems when storms hit coastal towns.

“With no solid research, we are unable to make informed and appropriate management decisions in relation to how to control coastal weed cover.”

Determined to solve this problem, Professor Cousens will lead a team of interdisciplinary researchers, including a plant ecologist, a social scientist, a coastal geographer, a zoologist and an economist to fully assess the impacts of coastal plant invaders.

“This is urgently required so that guidance can be given to develop more strategic approaches to the management of coastal weeds,” he says.

The project, supported by a research grant provided by the Australian Government’s Rural Industries Research and Development Corporation, will involve researchers working closely with state government, local community groups, catchment management authorities, and will also enlist the help of ‘citizen scientists’.

“We want to observe how native and exotic animals associate with weeds on a large scale, and therefore we will be calling on help from local volunteers in certain areas to make observations of animals interacting with the weeds,” Professor Cousens says.

“This is a great feature of the project as local people can help us provide valuable data which in turn will help manage their local environment.”

Other aspects of the project include mapping structural changes in dunes, collating data from herbaria to determine dates of appearance of exotic beach species, and interviewing people to learn about their attitudes, feelings and knowledge of weeds along sandy beaches.

Professor Cousens explains that the output of the project will include a document and a website summarising the impacts of coastal invaders which can be used to inform managers at all levels.

“The project will result in a far better knowledge of weed impacts, which will ultimately help us protect our valuable native wildlife and Australia’s iconic coastal environment.”

http://land-environment.unimelb.edu.au/