The Flower Pot Fix

Engineering, it has been said, is that art of taking ideas out of thin air and expressing them in steel and concrete. Now, some engineers are demonstrating how to incorporate ecological concepts into heavy-duty coastal building projects, using items as simple as concrete flower pots to create more habitat for algae, shellfish and starfish.

Thick seawalls, lengthy jetties and other forms of protective coastal “armoring” are “getting taller and spreading,” Mark A. Browne and Maura Gee Chapman of the University of Sydney write in Environmental Science & Technology. Often, the structures “may be the only ‘rocky’ habitat for kilometers in major ports and estuaries in and around cities.” But studies have shown that “many intertidal species, particularly larger mobile animals such as starfish, urchins and large gastropods, do not live on seawalls, whilst those that do may be genetically less diverse, grow or reproduce slowly… Thus expanding urbanization has potentially serious implications for intertidal assemblages from rocky shores.”

But “ecologically-informed engineering” could offer some hope. In Australia’s Sydney Harbor, for example, builders have intentionally introduced critter-friendly nooks, crannies and pool-like structures into seawalls and other structures to create new habitat. Although some early efforts to create small niches enhanced “the number of species living on the walls in the short term, [in the] longer term they were less successful as they filled with sessile animals, so the available habitat was lost.” Efforts to create larger cavities and pools – by leaving out blocks, for example, or attaching large concrete flower pots – were more successful, more than doubling species diversity of algae and marine organisms within just a few months.

“Our work shows that collaboration between experimental ecologists and engineers… can lead to a range of cheap and easy engineering techniques that can be applied to new and existing coastal infrastructure,” the authors conclude. Although it remains to be seen how durable the flower pots and other new habitat will be, it does represent a “useful approach to try to sustain, rather than erode, levels of intertidal biodiversity in and around cities.”David Malakoff | August 31, 2011

Source: Browne, M., & Chapman, M. (2011). Ecologically-informed engineering reduces loss of intertidal biodiversity on artificial shorelines. Environmental Science & Technology DOI: 10.1021/es201924b

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