Here’s a neat tool that could be of use to urban planners and restoration ecologists – CASU, the “Complexity for Artificial Substrates” program. CASU is open source software developed by Lynette Loke at the National University of Singapore and colleagues in Singapore, the Netherlands, Brazil, and the United Kingdom. The program allows users to design and visualize artificial substrates for urban waterfronts that are more complex than traditional, uniform surfaces we currently see on most bulkheads and seawalls. Since substrate complexity is tied to biodiversity of intertidal ecosystems, more complex substrates like those generated by CASU may serve as “ecological enhancements” for urban waterfronts.
Loke and colleagues originally developed CASU as part of a project aimed at increasing biodiversity on seawalls in Singapore using molded concrete tiles. By manipulating the topographic complexity of the tiles and deploying them in the field, they wanted to test whether more complex tile designs would increase the diversity of intertidal organisms. The problem is that you can define complexity in number of different ways. What specific aspects of habitat complexity actually affect intertidal diversity most and which are most important to include in your design?
CASU allows the user to modify 5 variables that affect complexity: (1) the number of object types, (2) relative abundance of object types, (3) density of objects, (4) variability and range in the objects’ dimensions, and (5) their spatial arrangement. In the case of their molded tiles, these 5 variables altered the arrangement and configuration of depressions in the tiles’ exposed surface (which are the “objects” that alter habitat complexity in their study).
Loke and colleagues describe CASU in further detail in a recent article in PLoS One. Indeed, after deploying their tiles in the field for 13 months, they did find that tiles with more complex surfaces supported greater diversity of intertidal organisms. Their subsequent work teasing apart which components of complexity are most influential for intertidal diversity on Singapore’s seawalls appears to be in press at the moment, so stay tuned for that. In the meantime though, you can download CASU using the links at the bottom of this page.