The Marine and Coastal Policy states that the health of the marine and coastal environment is under threat from multiple sources, including climate change and growth in towns, cities and industries that interact with their local marine and coastal ecosystems.

These threats can lead to negative impacts on water quality and quantity, pollution and debris, invasive species, marine pests and diseases, disturbance and loss of plants and animals, and loss of access to beaches from the effects of sea walls, infrastructure and erosion. Coastal towns can also suffer loss of character from inappropriate development and poor management of visitors’ actions and impacts. Degradation occurs over time and space, and the impacts in marine and coastal areas are varied and complex.

Population growth

Victoria has experienced record population growth over the past decade with suburbs and towns around Port Phillip Bay, and within two hours’ drive of Melbourne (including on the Bellarine Peninsula, Mornington Peninsula and Bass Coast), recording big increases in population size and density. Growth in the permanent population has also been accompanied by increases in numbers of domestic, national and international visitors to coastal areas.

Growth in resident populations and visitor numbers puts pressure on the health of the coastal environment, with direct impacts including:

• Habitat loss and degradation
• Increased introduction of invasive and pest species
• Increased pollution from sources including litter,
• Stormwater runoff and wastewater discharges
• Erosion of dunes
• Loss of character of coastal towns.

Population growth also increases pressure on recreational infrastructure such as walking tracks, visitor facilities, lifesaving clubs and recreational club houses, boat ramps and marinas. This, in turn, leads to more demand for alterations to beaches, foreshores, wetlands and natural processes through groynes, sea walls and dredging to support use and development.

Climate change

Climate change is increasing the pressure on Victoria’s marine and coastal environment by exacerbating existing threats and introducing new ones, such as:

• Rising sea levels, leading to more inundation and erosion
• Increased frequency and severity of storms and other extreme weather events
• Changes in ocean temperatures, currents and acidification
• Changes to waterway flows, levels and regimes
• Changes in the range, distribution and abundance of both introduced and native plants and animals, taking advantage of a changed climate
• Coastal squeeze, which occurs when coastal ecosystems forced inland by rising sea levels run into human-made barriers such as roads and housing.

Coastal settlements, suburbs and cities including densely populated areas around Port Phillip Bay, are increasingly exposed to more severe storms, coastal flooding and erosion. Existing and severe coastal erosion will be exacerbated by climate change on the northern Western Port coast at Lang Lang and on the Mornington Peninsula-Bass Strait coast between Flinders and Point Nepean. Recreational opportunities on the coast will also change as beaches and cliffs erode.

Native vegetation loss and decline due to coastal development

Some of the native coastal vegetation is secure on public land but population growth and development will continue to create pressure for clearing at some sites.

In addition, incremental damage to native vegetation from recreation, illegal clearing, vandalism and rubbish dumping are inevitable pressures of increasing resident and visitor populations.

Invasive plants and animals

Weed invasions compete with native vegetation and damage its ability to provide habitat.  Much of the coastal zone has ongoing weed problems that are difficult to control. For example, coastal weeds such as Sea spurge invade the nesting habitats of shorebirds and seabirds.

These pressures are now well-established.  Ongoing control is critical but expensive.  It needs to be carefully targeted to maximise its benefits. Likely targets for control include:

• Known highly invasive and ecologically damaging weeds
• Emerging weeds, detected but not yet established
• Foxes and feral cats.

Ageing infrastructure

Our region has a vast inventory of coastal assets (sea walls, groynes, piers and jetties), particularly in its bays and estuaries, that have been constructed over the past 100 years. Many of these assets are ageing and, without regular maintenance or upgrading, will no longer be able to provide the services for which they were built.

However, much ageing coastal infrastructure has become integral to beach-nesting bird habitat, and provides feeding and roosting sites for migratory shorebirds. Habitat value assessments may be important before renewals are commenced.