Artificial coastal defences could be used to enhance marine biodiversity, study shows

August 10, 2017

Future coastal defences, harbours and ports could enhance biodiversity within the marine environment through the use of cement substitutes. But the materials used need to be selected carefully in order that native and non-native species are not adversely affected, a study by the University of Plymouth suggests.

With the pressures of climate change and many of the world's population living on or near the coast, there is growing demand to increase development of the marine and coastal environment.

Many schemes already use cement replacements, but with them being introduced on a larger scale, there is a pressing need to determine their on the organisms which colonise them and the wider .

Scientists from the University conducted a series of tests over a two-month period and said some of these alternative appeared to have a negative effect on colonising native but had no effect on non-native species.

The study, published in Ecological Engineering, is one of the first to combine chemical leaching and biological data regarding the use of artificial materials within coastal and marine infrastructure.

Lecturer in Environmental Science Dr Louise Firth, the study's corresponding author, said: "As cement production is so energetically costly to produce, the construction industry is now investigating cement replacements using waste materials. Our work has shown that native and non-native species have contrasting responses to different waste material cement replacements. This highlights that much more research is needed in this area to assess the full environmental impact of such practices before adopting cement replacements in the marine ."

For the study, scientists placed tiles made using cement as well as varying quantities of two widely used substitutes – pulverised fly ash (PFA) and ground granulated blast-furnace slag (GGBS) – at waterfront locations in Plymouth.

They then monitored them for a period of seven weeks, assessing the quantity of chemicals from the tiles that leached into the marine environment but also the effects on colonising biofilms and macro-algae.

The results showed that cement replacement materials leached different metal concentrations: PFA was higher overall and GGBS was lower overall.

It also showed that there was an impact on colonising species. Whilst there was no significant difference in biofilm percentage cover or richness between treatments, it was found that treatments containing GGBS had lower native species richness than the control treatment (that had no replacements).

This study is the latest in which academics from Plymouth have explored the impact of coastal infrastructure on the marine environment. The University is also one of the partners in the World Harbour Project, which is seeking to develop resilient urban ports and harbours globally.

Dr Firth added: "The biodiversity associated with sea defences may have beneficial effects, such as habitat provision, water filtration and even strengthening the structures. However, the results presented here highlight the fact that differences in concrete composition can have significant effects on the biodiversity of subtidal fouling organisms that colonise artificial surfaces. This information could be used in future to help design features that enhance biodiversity and the ecosystem services this provides at little or no extra cost."

Explore further: Taking concrete steps toward lower carbon dioxide emissions

More information: Ryan S. McManus et al. Partial replacement of cement for waste aggregates in concrete coastal and marine infrastructure: A foundation for ecological enhancement?, Ecological Engineering (2017). DOI: 10.1016/j.ecoleng.2017.06.062

Related Stories

Taking concrete steps toward lower carbon dioxide emissions

August 2, 2017

The hardest thing about concrete just might be the problem of how to make the ubiquitous building material in an environmentally friendly manner. Recent laboratory results at Princeton University indicate that the challenge ...

Invasive plant species can enhance coastal ecosystems

July 17, 2017

Invasive plant species can be a source of valuable ecosystem functions where native coastal habitats such as salt marshes and oyster reefs have severely declined, a new study by scientists at Duke University and the University ...

A new, greener cement to meet future demand

June 3, 2014

An EPFL-led consortium is developing a new blend of cement that promises to reduce the carbon footprint of concrete by up to 40%. Now it has received financial backing from the Swiss Agency for Development and Cooperation ...

Recommended for you

Mammal long thought extinct in Australia resurfaces

December 15, 2017

A crest-tailed mulgara, a small carnivorous marsupial known only from fossilised bone fragments and presumed extinct in NSW for more than century, has been discovered in Sturt National Park north-west of Tibooburra.

Finding a lethal parasite's vulnerabilities

December 15, 2017

An estimated 100 million people around the world are infected with Strongyloides stercoralis, a parasitic nematode, yet it's likely that many don't know it. The infection can persist for years, usually only causing mild symptoms. ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.