Singapore: Tiles that support marine biodiversity added to seawalls

While seawalls are the traditional defense for Singapore’s coasts against rising sea levels, scientists at the National University of Singapore (NUS) are re-engineering them to ensure they do not come at the cost of life underwater.

Despite the ability of the undersea parts of some man-made defenses to support coral communities, intertidal seawalls do not support biodiversity of the same richness as natural coastlines, said Associate Professor Peter Todd at NUS’ Experimental Marine Ecology Lab.

More than 65% of natural shorelines here have been transformed into hard coastal structures such as seawalls and rock slopes.

This is expected to increase in extent by the end of the century. In 2019, Prime Minister Lee Hsien Loong announced that 100 billion Singapore dollars ($72 billion) or more may be needed over the long-term to protect Singapore against rising sea levels, including plans to strengthen coastal defenses.

To reduce the impact of existing seawalls on marine creatures, NUS scientists have developed an assortment of tiles that can be retrofitted onto seawalls to mimic natural habitat features.

The concrete tiles, from wedge-shaped “rock pools” to domes depending on the surface they are placed on, act as homes that are optimized to improve the variety of marine life.

Findings from their studies show that they can double the diversity of marine organisms on grey marine infrastructure, said Prof. Todd.

He added: “The tiles can support between 20 and 25 species as compared to a traditional granite seawall, which has about 10 species. These organisms include algae, bivalves, quite a lot of marine snails and some crustaceans.”

While these organisms may not appear to be charismatic, they are important food sources to sustain larger organisms such as fish in the shoreline ecosystem, he said.