Population

Australia is an urban coastal nation. In 2001, 85% of Australia’s population lived within 50 kilometres (km) of the coast, but by 2019, that proportion had risen to 87% (ABS 2020b). This equates to over 22 million Australians now calling the coast home. While coastal population growth has previously been concentrated in urban centres, it is now spreading to coastal townships and villages (Infrastructure Australia 2020). Regional coastal development as a result of migration out of the cities caused by the COVID-19 pandemic may increase this trend (see the Urban chapter).

Pressures associated with population include the direct footprint of land use on coastal habitat, consequences of urban infrastructure (e.g. artificial light pollution) and the impact of human activities (e.g. tourism, recreation, recreational fishing and littering) on the coastal environment.

Assessment Pressures associated with population density

2021

Somewhat adequate confidence

Indigenous assessment

Most population-driven pressures are considered to be high or very high impact, and increasing. This reflects the growth of Australia’s coastal population and failure to decouple population density from per-person environmental footprint.
The Indigenous assessments for the state of population pressures found 1 pressure has a high impact and 1 has a very high impact, and the trends for 2 pressures are unclear.
Local government area (LGA) assessments (see Approach) showed that population density, coastal development and land use concern almost all LGAs Australia-wide. Other population pressures are felt most in the south, near major cities.
Related to United Nations Sustainable Development Goal targets 8.9, 11.6, 14.1, 14.4

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Assessment Coastal development and land use

2021

Adequate confidence

Coastal development is increasing. There is an immediate need for coastal planning to better manage the impacts of urban growth.
The Indigenous assessment for some regional areas was low, with a stable trend.

Assessment Tourism and recreation

2021

Somewhat adequate confidence

2016

Pressures are expected to shift more in line with domestic travel patterns, while ecosystem resilience is evident when pressures are absent.
The Indigenous assessment for some regional areas was low, with a stable trend.

Assessment Customary fishing

2021

Limited confidence

There is a general lack of understanding about customary fishing. A range of management arrangements have been developed to support customary fishing, but the various laws are not always supportive for all communities.
The Indigenous assessment for some regional areas was low, with a stable trend.

Assessment Marine plastics and debris

2021

Limited confidence

2016

Marine debris is widespread around Australia and there is increasing evidence of its impacts on coastal species and habitats.
The Indigenous assessment for some regional areas was low, with a stable trend.

Assessment Microplastics

2021

Low confidence

There is growing concern but large uncertainty about ecological impacts of microplastics.
The Indigenous assessment for some regional areas was low, with a stable trend.

Assessment Light pollution

2021

Somewhat adequate confidence

Coastal artificial light pollution is increasing annually, but its impacts are poorly understood. Research into community-level and long-term effects is required.
The Indigenous assessment for some regional areas was low, with a stable trend.

Coastal development and land use

Coastal development is a continuing pressure on coastal environments throughout Australia. A 2009 federal House of Representatives Inquiry into climate change and environmental impacts on coastal communities recognised the impact of urban development on the Australian coastline and called for a ‘national coastal policy and strategy’ (SCCCWEA 2009).

Pressures on coastal environments are increasing with the spread of coastal development beyond capital cities (see the Urban chapter). Development carries a suite of impacts, including direct habitat destruction as well as most other pressures (besides climate-driven pressures) covered in this chapter.

The management of coastal development in Australia involves all levels of government and multiple stakeholders. The federal government has at various times undertaken an active role in data collection, coastal science, and funding programs for coastal adaptation to major risks and regional development. The state governments each have coastal laws for managing land use. Most of the responsibility for coastal planning and development controls is delegated to local government. Regional development as a response to the COVID-19 pandemic will potentially add to the current strain on coastal communities, and will need to be supported by smart infrastructure and sensitive urban management.

The potential (very significant) environmental impact of dense urban development on the eastern seaboard contrasts with the sea Country management plans in north-eastern Arnhem Land (which have minimal impact). But all areas require an integrated approach to land use and development, from catchment to coastal to marine environments (Future Earth Australia 2021). The Australian Coastal Councils Association, comprising representatives of coastal councils, has reiterated its call for a ‘national coastal policy, and restoration of national funding for coastal planning and management research so that coastal communities and assets are adequately prepared to address the adverse effects of climate change impacts’ (ACCA 2019).

Tourism and recreation

Tourism is a recognised driver of growth within the Australian economy (Tourism Research Australia 2020). The industry boasts an average contribution to annual gross domestic product (GDP) of $46.9 billion since 2008–09 (ABS 2020a). In 2018–19, GDP from tourism was reported as $61.2 billion, with expenditure from domestic travel surpassing $100 billion (Tourism Research Australia 2020). Australia is ranked as the seventh largest national tourism market globally (based on international tourism receipts).

Our coasts are the focus of much of Australia’s tourism, and as an island continent, it is not surprising that coastal tourism dominates the Australian tourism market. Australian coastal locations (particularly beaches and the Great Barrier Reef) have been identified as the most attractive destinations, with aquatic and coastal experiences among the greatest drivers.

Coastal areas are also important places for domestic recreation and sport, with over 500 million individual visitations by adults (people over 16 years old) in 2019–20 (SLSA 2020).

Tourism pressures and impacts

Negative environmental impacts can be linked to increased visitor numbers. Environmental pressures associated with tourism include trampling, pollution, degradation, natural habitat loss, erosion, disturbance of wildlife, and increased demands on local resources and infrastructure (Sun & Walsh 1998, Canteiro et al. 2018). However, low-impact ecotourism that aligns tourism with conservation objectives has become an increasingly favoured tourism model (Knox et al. 2020).

Popular coastal attractions for residents and tourists are recreational activities such as walking, sunbathing, swimming, boating, fishing (land-based and rock), surfing, snorkelling, scuba diving, whale watching and nonpowered watercraft (e.g. kayaking, canoeing, paddle boarding, wind surfing) (SLSA 2020, Turnbull et al. 2020). Participation levels for Australian adults in these activities have remained consistent (Figure 28), which could suggest a similar pattern for associated pressures on the environment due to these activities.

Recent research evaluated the environmental response to the sudden reduction in anthropogenic (human-caused) stressors (i.e. pollution, noise, activities) at urban coastal beaches during a COVID-19 lockdown (Soto et al. 2021). Positive ecosystem changes were reported, with increased dune vegetation, higher densities of flora and fauna, and reductions in pollution and noise (Soto et al. 2021). These results highlight the resilience of coastal ecosystems, and suggest that with careful management and increased awareness, coastal environments can be restored relatively quickly.

Changes in tourism

Because Australia is an island destination geographically distanced from most international markets, Australian markets reliant on tourism trends can change significantly due to external impacts. Recently, Australia has faced an unprecedented combination of geopolitical and environmental challenges (i.e. 2019–20 bushfires and the COVID-19 pandemic) that have had dramatic impacts on tourism, and altered the tourism and recreation profile in Australia (Folinas & Metaxas 2020, Lawes et al. 2021).

Australian tourism has historically been led by international visitations, but recently has been driven by strong domestic visitor numbers (Figure 28). International and domestic mobility came to a standstill due to the COVID-19 pandemic, and while domestic tourism is improving, international travel may be affected for years to come.

Anecdotally, altered working arrangements and various restrictions placed on many Australian communities are thought to have substantially altered behaviour and coastal participation (Lawes et al. 2021). Behavioural changes may include how coastal environments are used (e.g. increased fishing for food, or more time spent at the beach in response to changed employment circumstances), or which locations are visited (i.e. alternate locations being visited due to social distancing or beach closures).

How these challenges will influence pressures placed on coastal environments remains to be seen, and will depend on the severity and longevity of their impacts.

Customary fishing

Customary fishing is hunting, gathering and fishing of marine and coastal species for personal, subsistence, communal, ceremonial, spiritual or trade purposes. Customary fishing is also known as traditional use, cultural harvest or cultural fishing. Various target species are included within customary fishing activities, including finfish, dugong, turtles, crocodiles, shellfish, molluscs, crustaceans, polychaetes (marine worms) and pyurans (cunjevoi), along with various species of algae and marine plants (Schnierer & Egan 2015, Schnierer & Egan 2016). The time spent on customary fishing differs between locations, and depends on local customs, social needs and access to Country since colonisation. Customary fishing methods are often low-impact activities carried out from shore or from small boats. Customary catch is expected to be relatively small for most stocks (Productivity Commission 2016). Due to its low impact, customary fishing is unlikely to compromise sustainability objectives.

The quantity, composition and local status of the catch across Indigenous communities are mostly unknown. Customary fishing practices vary significantly between communities. Publicly available information on customary fishing practices, including information on the current state and trend of customary fishing across Australia, is poor (Productivity Commission 2016). There is often a complex process of gaining resources and community support for any data collection programs that occur within Indigenous communities. Upholding sustainability objectives requires more than just quantifying the amount of used resource. With Indigenous-led management, monitoring a range of important species can be made a priority to ensure consideration of all threats to ecosystem health rather than investing time and capacity into recording just cultural catch.

A lack of understanding by the public and policy-makers about the established cultural rights to customary fishing builds distrust and undermines the collection and sharing of harvest information with broader stakeholders. While catch information may not be reported publicly, information on customary fishing may be retained in the community or shared in confidence with agencies. This means community discussions about sustainability could be unfolding without the public knowing.

Various initiatives have been developed to support the management of customary fishing (Table 4). The management of cultural harvest is often not static, and can involve multiple threads of information gathering and discussion within the community. The management of controls over customary fishing activities need to be culturally sensitive and not infringe on the rights and interests of native title holders. Importantly, they should be developed in collaboration with Indigenous communities (Productivity Commission 2016). The intersection of native title and fisheries laws is not fully settled across Australia; this means some customary fishing is not afforded the appropriate rights by Australian fisheries law.

Marine plastics and debris

Marine (and coastal) debris is identified as a key threatening process for threatened and endangered vertebrate fauna. Addressing the challenge of coastal debris is complex, and requires coordination between many stakeholders, from the manufacturer to consumer, to stop coastal debris increasing into the future.

Anthropogenic debris is human-made items that have been discarded, either accidentally or intentionally, into the aquatic environment. Much of the world’s debris is estimated to be from land-based sources, ‘leaking’ into waterways because of inadequate waste management, failed design, dumping or littering (Galgani et al. 2015). As Australia’s population grows along the coast, the escape of solid waste, such as plastic, into coastal habitats may increase. The expanding stock of debris along Australia’s coasts increases the risks to habitats and fauna, posing a range of threats to organism and ecosystem health. For example, among 1,733 seabirds of 51 species, a significant dose-response relationship was found between ingested marine debris and death (based on mortality data) (Roman et al. 2019).

Debris is composed of different materials and items, such as glass and plastic bottles, metal cans, cigarettes, plastic bags, balloons, rubber and fishing line, which affect the environment in different ways (Wilcox et al. 2016). The items’ characteristics, such as shape, density and composition, define their interactions with habitats and species, posing risks such as entanglement or ingestion, or facilitating bioinvasion (where debris provides somewhere for invasive diseases and species to travel) and bioaccumulation (where debris such as plastics accumulate through the food web) (Kühn et al. 2015). While these threats are understood in theory, their ecological impacts (to individuals, species or assemblages) are still unclear (Rochman et al. 2016).

Marine debris also has impacts on human wellbeing, including economic (tourism, fishing industry) impacts, impacts on navigation, human ingestion of plastics, and social and cultural impacts.

An essential step to understanding ecological risks of debris is quantifying debris composition and abundance across Australia, over time. Several studies have shown plastics to be the main debris material found across the Australian coastline, although there are clear differences in debris composition across marine bioregions (Figure 29) (Hardesty et al. 2017). Specific items also vary between regions (Figure 30). For example, Cape York and other remote areas experience high loads of fishing floats and drink bottles, while debris in Port Phillip Bay (Victoria) and other urban beaches is characterised by litter such as straws, food packaging and cigarette butts. Research is required into how debris items move through and interact with the environment; from source to ecological and socio-economic impacts.

Regional differences in composition and abundance suggest differing pathways and sources of debris. For example, Willis et al. (2017) differentiated between littering, urban run-off and marine transport within Tasmania. In Western Australia, plastic pollution is an ongoing issue, with a 2017 study conducted in Perth metropolitan waters finding levels of plastic pollution ranging from 950 to 60,000 pieces per square kilometre (Hajbane & Pattiaratchi 2017). Identification of regional debris pathways will improve the efficacy of management strategies.

Legislation and policies targeting littering and debris items have been enacted, particularly circular economy initiatives (e.g. plastic bag bans, container deposit schemes; see the Urban chapter), but the impact on levels of coastal debris is yet to be seen. Management plans also require timeseries to evaluate progress. Monitoring efforts can be supported by citizen scientists, who have already contributed millions of entries across Australia into initiatives such as the Australian Marine Debris Database. These citizen science initiatives are increasingly training volunteers in the use of scientific methods to increase data accuracy and reliability (e.g. the Australian Marine Debris Initiative and the ReefClean project funded by the Reef Trust and AUSMAP).

Microplastics

Microplastic pollution in the marine environment has been identified as one of the main areas of concern for ecosystems and human health. Over the past 2 decades, ecological, medical, social science and human behaviour research has resulted in greater public awareness and policy responses by governments around the world to address this problem (Andrady 2011, Boucher & Friot 2017).

Microplastics are particles less than 5 millimetres in size and can be of primary or secondary origin (Eriksen et al. 2014, Boucher & Friot 2017). Primary origin means they were created for production purposes, either as a ‘raw’ material (e.g. pellets) or to be added to other materials to enhance their properties (e.g. microbeads in cosmetics or cleaning agents) (Napper & Thompson 2016, Boucher & Friot 2017, Guerranti et al. 2019). Secondary origin means they resulted from degradation of larger plastic items (Boucher & Friot 2017). Microplastics can enter the marine environment via many pathways, including wastewater treatment plants, rain water and stormwater run-off, and wind (Browne 2015, Komyakova et al. 2020). Most of these pathways have been poorly studied, with limited reliable quantitative data available (Komyakova et al. 2020).

Due to their microscopic size, microplastics can be absorbed or consumed by many organisms, including commercially important fish species (Browne et al. 2008, Watts et al. 2014, Fossi et al. 2016, Herrera et al. 2017, Santillo et al. 2017, Nelms et al. 2018, Herrera et al. 2019). Several studies have demonstrated that consumption of high concentrations of microplastics can lead to serious health impacts in several marine organisms (Browne et al. 2013, Rochman et al. 2016, Mattsson et al. 2017, Prinz & Korez 2020), although other studies did not detect substantial impacts (Browne et al. 2008, Van Cauwenberghe et al. 2015, Ašmonaitė et al. 2018).

Microplastics are thought to contribute to approximately 90% of floating marine litter (Eriksen et al. 2014). They have been found in a wide variety of aquatic habitats, from tropics to the Arctic and Antarctic, on remote islands, and at the great depth of the Japanese and Mariana Trenches (Browne et al. 2011, Baztan et al. 2014, Auta et al. 2017, Waller et al. 2017, Chiba et al. 2018, Peng et al. 2018, Jamieson et al. 2019).

It has been estimated that sediment in south-eastern Australia contains an average of 3.4 microplastics per millilitre (mL) (Ling et al. 2017). Some microplastic particles are more prevalent in nature than others. Microfibres are one of the most common types (Browne et al. 2011, Ling et al. 2017, Barrows et al. 2018), and some sites in Western Australia are reported to have up to 30 microfibres per 250 mL of sediment (Browne et al. 2011). Comparison of the microplastic concentrations between habitats and regions has been hindered by a lack of standardised methods for microplastics quantification and identification (Song et al. 2015, Lares et al. 2019, Cashman et al. 2020).

Overall, there is limited understanding of the effect of microplastic pollution on the health of marine ecosystems, as well as on human health, leading to substantial scientific debates on the topic (Backhaus & Wagner 2018, Karbalaei et al. 2018, Rist et al. 2018, Oliveira et al. 2019). One of the reasons for limited understanding is poor applicability of currently available research to real-life situations, with over 80% of concentrations used in studies examining environmental impacts of microplastic pollution not being detected in nature (Bucci et al. 2020).

Despite limited data on the impact of microplastics, there have been substantial management and policy efforts targeting microplastics pollution. Several countries, including Australia and New Zealand, have introduced microbead bans and phasing-out in personal care and cosmetic products, largely due to the 2012 international Beat the Microbead campaign (Rochman et al. 2015, Dauvergne 2018, Guerranti et al. 2019, Miraj et al. 2019, DAWE 2020e). However, most of the efforts have been limited to a single industry (beauty) or to the management of large waste in general (Vince & Hardesty 2018, DAWE 2020e).

Light pollution

Over the past 200 years, natural systems have been challenged by increasing urbanisation and the expanded presence of artificial light at night (ALAN) in the form of streetlights, industrial or residential facilities, and vehicles. ALAN can hide or distort the natural day–night and seasonal patterns of light, causing various ecological changes (Hopkins et al. 2018).

Negative impacts of ALAN on the marine environment include decreased reproductive success of fish (Fobert et al. 2019), shifts in predatory behaviour of invertebrates (Underwood et al. 2017) and fish (Bolton et al. 2017), and changes to the physiology and biochemistry of reef-building corals (Levy et al. 2020) and fish (O'Connor et al. 2019).

ALAN in the marine environment is forecast to significantly increase in response to coastal population growth. Worldwide, more than 1 billion people live within 100 km of a coastline, and approximately 22% of coastlines are affected by ALAN (Davies et al. 2014). The impact of ALAN can be detected in all ecosystems, but its effect on coastal and marine environments remains understudied. A recent United Kingdom study of an urbanised estuary found more than 76% of the sea floor was exposed to biologically disruptive levels of ALAN (Davies et al. 2020).

We do not have such assessments in Australia, but coastal environments near major Australian cities are likely to be affected by ALAN given the ubiquity of global coastal light pollution (Davies et al. 2014). Intertidal and shallow subtidal habitats are among the most affected by ALAN, as artificial lighting is commonplace along beaches, coastal streets and promenades, or within harbours and marinas.

The global transition to LED lighting may exacerbate coastal impacts of light pollution. LEDs emit a higher proportion of blue light, which promotes significant shifts in physiology of all species and the movement and behaviour of animals. Moreover, as blue light typically travels further through water, light spill into nontarget areas is more likely. This is particularly relevant for the marine environment, as blue light penetrates deeper in the water column than other colours, and marine organisms are evolutionarily adapted to respond to even the lowest levels of natural light (Shima et al. 2021).

Any effect of light pollution on the health of our coastal regions and oceans will have direct impacts for human health and wellbeing. More than 80% of Australians live near coastlines, many of which are already light polluted (Kamrowski et al. 2012). As human expansion further threatens the integrity of our coastlines, the associated increase in light pollution threatens the potential health and wellbeing benefits that living on the coast may yield.

We lack direct evidence for much of the impact of light pollution on coastal systems. Most studies of ALAN have focused on its effect on ecological and evolutionary responses of individuals or populations, and are typically focused on ALAN as a single stressor (Sanders et al. 2021). To improve our understanding of the community- and ecosystem-level responses to ALAN, we need to move beyond assessing species-specific impacts. To address the effects of ALAN in ecologically relevant settings, we need to study longer-term impacts and how ALAN interacts with other anthropogenic stressors.

Managing lighting is challenging: it requires balancing environmental versus human needs and perceptions of safety. Urban developments do not require in-depth environmental light assessments and thus these assessments are often cursory. The recently published National light pollution guidelines for wildlife (DAWE 2020f) will assist, but the implementation of these guidelines remains nonmandatory.