Eco-engineering rock pools to a seawall in a tropical estuary: microhabitat features and fine sediment accumulation

Published source details Waltham N.J. & Sheaves M. (2018) Eco-engineering rock pools to a seawall in a tropical estuary: microhabitat features and fine sediment accumulation. Ecological Engineering, 120, 631-636.
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This study is summarised as evidence for the following.

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

Create large protrusions (>50 mm) on intertidal artificial structures

A replicated, randomized, controlled study in 2014–2016 on an intertidal seawall in a marina in the Coral Sea, Australia (Waltham & Sheaves 2018) reported that large protrusions created on the seawall supported similar macroalgae and invertebrate species richness to seawall surfaces without protrusions, but that tilted protrusions with shaded surfaces supported different community composition to horizontal ones. Over 24 months, a total of nine macroalgae and invertebrate species groups were recorded on landward-tilted protrusions, eight on seaward-tilted protrusions, eight on horizontal protrusions, and 10 on seawall surfaces without protrusions (data not statistically tested). Community composition was similar on landward- and seaward-tilted protrusions, but both differed to horizontal protrusions (data reported as statistical model results). Four species (3 mobile invertebrates, 1 non-mobile invertebrate) recorded on protrusions were absent from seawall surfaces without. Large protrusions were created by attaching concrete troughs to a boulder seawall in June 2014. Troughs contained rock pools but outside surfaces were surveyed separately and constituted protrusions lacking a top surface. Rectangular protrusions (length: 400 mm; width: 250 mm; height: 350 mm) were either horizontal or tilted 45° towards the land or sea. Underhanging surfaces of tilted protrusions were shaded. There were three of each randomly arranged at midshore along the seawall. Macroalgae and invertebrates were counted on protrusions and seawall surfaces (number/dimensions not reported) during low tide over 24 months. One horizontal protrusion was missing and no longer provided habitat.

(Summarised by: Ally Evans)
Create 'rock pools' on intertidal artificial structures

A replicated, randomized, controlled study in 2014–2016 on an intertidal seawall in a marina in the Coral Sea, Australia (Waltham & Sheaves 2018) reported that rock pools created on the seawall supported higher macroalgae and invertebrate species richness than seawall surfaces without pools, and that tilted pools supported different community composition with higher species richness than horizontal ones. Over 24 months, a total of 16 macroalgae and invertebrate species groups were recorded in both landward- and seaward-tilting pools, 11 in horizontal pools, and 10 on seawall surfaces without pools (data not statistically tested). Community composition was similar in landward- and seaward-tilted pools, but both differed to horizontal pools (data reported as statistical model results). Ten species (2 macroalgae, 5 mobile invertebrates, 3 non-mobile invertebrates) recorded in pools were absent from seawall surfaces. Sediment accumulation was similar in all pools (34–45 mm depth). Rock pools were created by attaching concrete troughs to a boulder seawall in June 2014. Rectangular pools (length: 400 mm; width: 250 mm; depth: 350 mm; volume: 35 l) were either horizontal or tilted 45° towards the land or sea, thus shaded. There were three of each randomly arranged at midshore along the seawall. Macroalgae and invertebrates were counted in pools and on seawall surfaces (details not reported) during low tide over 24 months. One horizontal pool was missing and no longer provided habitat.

(Summarised by: Ally Evans)