Ecological consequences of the type of rock used in the construction of artificial boulder-fields

Published source details Green D.S., Chapman M.G. & Blockley D.J. (2012) Ecological consequences of the type of rock used in the construction of artificial boulder-fields. Ecological Engineering, 46, 1-10.
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This study is summarised as evidence for the following.

	Action	Category
	Use environmentally-sensitive material on intertidal artificial structures Action Link

Use environmentally-sensitive material on intertidal artificial structures

A replicated, randomized, controlled study in 2007–2008 in four intertidal boulder-fields in Sydney Harbour estuary, Australia (Green et al. 2012) found that using sandstone boulders in place of basalt boulders altered the macroalgae and non-mobile invertebrate community composition in two of four sites, and that abundances varied depending on the species group and site. After 10 months, macroalgae and non-mobile invertebrate community composition differed on sandstone and basalt boulders in two of four sites, but was similar in the other two sites (data reported as statistical model results). Sandstone boulders supported higher non-turf macroalgal abundance (0–17% cover) than basalt boulders (0–10%), and higher turf macroalgal abundance at one site (sandstone: 48%; basalt: 1%), but similar turf abundance at the other three sites (14–31 vs 9–25%). Sandstone boulders supported similar abundances of tubeworms (Serpulidae) and oysters (Ostreidae) to basalt boulders (tubeworms: 7–24 vs 8–27%; oysters: 0–9 vs 1–9%), but fewer barnacles (Cirripedia) (0 vs 1–2%). Five sandstone and five basalt oval quarried boulders (diameter: 350 mm) were randomly arranged at lowshore in each of two basalt (artificial) and two sandstone (unspecified) boulder-fields in June 2007. Macroalgae and non-mobile invertebrates were counted on boulders over 10 months.

(Summarised by: Ally Evans)