When natural ocean shoreline is replaced by an artificial seawall, a lot of precious intertidal habitat is lost. A new study, however, indicates that by covering those walls with specially designed tiles, a substitute habitat can be created.
Small creatures that live in the intertidal zone tend to like nooks and crannies where they can gain a secure foothold, hide from predators, and take shelter from the sun when the tide is out. Unfortunately, sea walls are typically just flat, barren, vertical concrete expanses, devoid of any such features.
An international team of researchers recently experimented with adding nooks and crannies to those walls, in the form of 3D-printed creviced concrete tiles. For a period of one year, these were left attached to harbor walls in 14 locations around the world, including Hong Kong, Sydney, San Francisco and London.
When subsequently compared to completely flat tiles that were deployed in the same areas, it was found that the creviced tiles contained 19 to 51 percent more species, and 59 to 416 percent more animals. Not surprisingly, most of the creatures – such as barnacles, snails and limpets – preferred to inhabit the bottom of the crevices, where they were most sheltered.
The effectiveness of the tiles was improved when they were "seeded" with oysters before being applied to the walls. Not only did the oysters themselves proceed to grow well over the testing period, but they also served as food for predators, plus the wrinkled surfaces of their shells provided more of a habitat for small organisms.
The study is part of the larger Australian-led World Harbour Project, and is described in a paper that was recently published in the journal Global Ecology and Biogeography.
Sources: World Harbour Project, City University of Hong Kong