Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

Published source details Chapman M.G. & Blockley D.J. (2009) Engineering novel habitats on urban infrastructure to increase intertidal biodiversity. Oecologia, 161, 625-635.
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This study is summarised as evidence for the following.

	Action	Category
	Create 'rock pools' on intertidal artificial structures Action Link
	Create hole habitats (>50 mm) on intertidal artificial structures Action Link

Create 'rock pools' on intertidal artificial structures

A replicated, controlled study in 2006–2007 on an intertidal seawall in Sydney Harbour estuary, Australia (Chapman & Blockley 2009) reported that rock pools created on the seawall, along with holes, supported higher macroalgae and non-mobile invertebrate species richness than seawall surfaces without pools or holes, and found that limpet Siphonaria denticulata abundance was higher in pools than on surfaces at highshore, but lower at mid and lowshore. After 12–14 months, pools supported 15–37 macroalgae and non-mobile invertebrate species groups/site (highshore: 15–21/site; midshore: 24–36/site; lowshore: 30–37/site), while seawall surfaces without pools or holes supported 2–21/site (highshore: 2–3/site; midshore: 7–11/site; lowshore: 19–21/site) (data not statistically tested). At least 22 species (≥12 macroalgae, ≥10 non-mobile invertebrates) recorded in pools were absent from surfaces without. At highshore, limpets were more abundant in pools (3–59 limpets/pool) than on seawall surfaces (0–8/surface), but the opposite was true at midshore (1–2/pool vs 78–214/surface) and lowshore (0/pool vs 4–10/surface). It is not clear whether these effects were the direct result of creating rock pools or holes. Rock pools were created during July–September 2006 by replacing seawall blocks with water-retaining troughs during construction of a vertical sandstone seawall. Six rectangular pools (length: 600 mm; width: 300 mm; depth: 50 mm; volume: 9 l) were created at highshore, midshore and lowshore in each of three sites along the seawall. Pools were shaded. Pools were compared with six seawall surfaces (length: 600 mm; width: 300 mm) at each shore level and site. Macroalgae and invertebrates were counted in pools and on seawall surfaces during low tide in September 2007.

(Summarised by: Ally Evans)
Create hole habitats (>50 mm) on intertidal artificial structures

A replicated, controlled study in 2006–2007 on an intertidal seawall in Sydney Harbour estuary, Australia (Chapman & Blockley 2009) reported that hole habitats created on the seawall, along with rock pools, supported higher macroalgae and non-mobile invertebrate species richness than seawall surfaces without holes or pools, and found that limpet Siphonaria denticulata abundance varied depending on the shore level and site. After 12–14 months, holes supported 2–31 macroalgae and non-mobile invertebrate species groups/site (highshore: 2–10/site; midshore: 16–18/site; lowshore: 27–31/site), while seawall surfaces without holes or pools supported 2–21/site (highshore: 2–3/site; midshore: 7–11/site; lowshore: 19–21/site) (data not statistically tested). At least 14 species (≥5 macroalgae, ≥9 non-mobile invertebrates) recorded in holes were absent from surfaces without. Limpet abundances varied by shore level and site (see paper for results). It is not clear whether these effects were the direct result of creating holes or rock pools. Hole habitats were created during July–September 2006 by replacing seawall blocks with water-retaining troughs during construction of a vertical sandstone seawall. Six cuboidal holes (length: 600 mm; height/depth: 300 mm) were created at highshore, midshore, and lowshore in each of three sites along the seawall. Hole surfaces were sandstone and concrete. Water pooled to 50 mm in the base of holes but wet surfaces were not surveyed. Holes were compared with six seawall surfaces (length: 600 mm; height: 300 mm) at each shore level and site. Macroalgae and invertebrates were counted in holes and on seawall surfaces during low tide in September 2007.

(Summarised by: Ally Evans)