The effects of manipulating microhabitat size and variability on tropical seawall biodiversity: field and flume experiments

Published source details Loke L.H.L., Bouma T.J. & Todd P.A. (2017) The effects of manipulating microhabitat size and variability on tropical seawall biodiversity: field and flume experiments. Journal of Experimental Marine Biology and Ecology, 492, 113-120.
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This study is summarised as evidence for the following.

	Action	Category
	*Create grooves and* small protrusions, ridges or ledges (1–50 mm) on intertidal artificial structures** Action Link
	Create pit habitats (1–50 mm) on intertidal artificial structures Action Link

Create grooves and small protrusions, ridges or ledges (1–50 mm) on intertidal artificial structures

A replicated, randomized, controlled study in 2011–2012 on two intertidal seawalls on island coastlines in the Singapore Strait, Singapore (Loke et al. 2017; same experimental set-up as Loke et al. 2016) found that concrete settlement plates with groove habitats and small ridges supported higher macroalgae and invertebrate species richness and different community composition compared with granite plates without grooves or ridges. After 12 months, settlement plates with variable grooves and ridges supported a total of 49 macroalgae and invertebrate species, while plates with regular grooves and ridges supported 35 species and plates without grooves and ridges supported 22 (data not statistically tested). Average richness was higher on plates with variable grooves and ridges (18 species/plate) than regular ones (13/plate), and higher on both than on plates without (7/plate). Community composition was similar on plates with variable and regular grooves and ridges, but both differed to plates without (data reported as statistical model results). Settlement plates (400 × 400 mm) were moulded with and without groove habitats and small ridges. Plates with grooves and ridges were concrete with four-to-five concentric circular grooves and ridges/plate with either regular (32 mm width, depth/height and spacing) or variable (8–56 mm) arrangement. Plates without grooves and ridges were granite fragments set in cement. Granite may be considered an environmentally-sensitive material compared with concrete (see “Use environmentally-sensitive material on intertidal artificial structures”). Five of each design were randomly arranged at lowshore on each of two granite boulder seawalls in July 2011. Macroalgae and invertebrates on plates were counted in the laboratory after 12 months.

(Summarised by: Ally Evans)
Create pit habitats (1–50 mm) on intertidal artificial structures

A replicated, randomized, controlled study in 2011–2012 on two intertidal seawalls on island coastlines in the Singapore Strait, Singapore (Loke et al. 2017; same experimental set-up as Loke et al. 2016) found that concrete settlement plates with pit habitats supported higher macroalgae and invertebrate species richness and different community composition compared with granite plates without pits. After 12 months, settlement plates with variable pits supported a total of 49 macroalgae and invertebrate species, while plates with regular pits supported 35 species and plates without pits supported 22 (data not statistically tested). Average richness was similar on plates with variable (17 species/plate) and regular (14/plate) pits, and higher on both than on plates without pits (7/plate). Community composition was similar on plates with variable and regular pits, but both differed to plates without pits (data reported as statistical model results). Settlement plates (400 × 400 mm) were moulded with and without pit habitats. Plates with pits were concrete with 36 square pits/plate with either regular (32 mm width, depth and spacing) or variable (8–56 mm) arrangement. Plates without pits were granite fragments set in cement. Granite may be considered an environmentally-sensitive material compared with concrete (see “Use environmentally-sensitive material on intertidal artificial structures”). Five of each design were randomly arranged at lowshore on each of two granite boulder seawalls in July 2011. Macroalgae and invertebrates on plates were counted in the laboratory after 12 months.

(Summarised by: Ally Evans)