Coastal marine habitats are extremely important to ocean health, but researchers at New Zealand’s Cawthron Institute are
warning that the global phenomenon of ‘coastal hardening’, caused by urbanisation and industry in coastal areas, is
putting them under threat.
Cawthron marine scientist Oliver Floerl lead authored a new paper published in the prestigious scientific journal ‘Nature Sustainability’, which outlines the threat coastal hardening poses.
“We mapped coastal infrastructure like ports, wharves, marinas and seawalls in 30 urban centres around the world, from
Cardiff (UK), to Portland (Maine, USA) to Bluff (NZ),” Floerl said.
“When we replace natural habitats with artificial ones, we impact the species that live there, damage the ecosystem and
make our shores vulnerable to invasive marine pest species.”
“Our international research team, which included scientists from Australia and the US, found that coastal infrastructure
has already replaced more than half of the coastline in the areas we studied.”
“This is a very big impact on the natural environment, and the research conducted on this problem around the world
suggests that further increases in ‘coastal hardening’ are likely to deplete important resources for coastal marine
ecosystems already under pressure from processes such as pollution and harvesting,” Floerl said.
“Already today, there is a strong relationship between the extent of coastal hardening and the number of pest species
detected in New Zealand’s coastal areas.”
“All of these issues impact us because we depend on fisheries and harvesting food in these areas, they are habitats for
native animals and plants, and we also want to reduce coastal erosion and increase resilience against storms.”
In order to better predict increases in coastal hardening, and assist in mitigating and managing its negative effects,
the research team drew on a wide range of economic, social and environmental factors to develop a statistical model for
predicting future increases in coastal hardening at regional scales and applied it to New Zealand as a case study,
examining the expansion of coastal infrastructure in different economic and population growth scenarios.
The model’s forecasts can be used by land managers, regulators and industry for developing strategies to mitigate the
risks and impacts associated with the expansion of coastal hardening.
“Using our model, the various stakeholders involved in Marine Spatial Planning (MSP) are able to estimate the potential
for increases in coastal hardening based on eight key variables relating to shipping, boating, regional economies,
populations and coastline length,” said co-author Dr Katherine Dafforn of Macquarie University in New South Wales.
Going forward, Dafforn and Floerl would like to see the risks of coastal hardening recognised and integrated into Marine
Spatial Planning (MSP) to balance and reconcile socio-economic and ecological objectives.
“We think the model we have developed provides an important tool for coastal managers that, combined with innovations in
ecological engineering, biofouling control and species monitoring tools, could support improved conservation and
biosecurity risk management in New Zealand and around the world,” said Dafforn.