Create short flexible habitats (1–50 mm) on intertidal artificial structures

Overall effectiveness category Awaiting assessment
Number of studies: 1
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Background information and definitions

Definition: ‘Short flexible habitats’ are flexible protruding materials such as rope, ribbon or twine 1–50 mm in length (modified from “Soft structures” in Strain et al. 2018).

Short flexible habitats, such as understory macroalgal blades, turfs and soft-bodied invertebrates, provide other organisms refuge from desiccation and temperature fluctuations during low tide in intertidal rocky habitats (Kim 2002). They can support high biodiversity (Thrush et al. 2011) but can also dominate space and have negative effects on other species (O’Brien & Scheibling 2018). The size, density and material properties of flexible habitats are likely to affect the size, abundance and variety of organisms that can use them and the spaces they create.

Some organisms that form flexible habitats tend to be absent or sparse on intertidal artificial structures (Firth et al. 2016), although some readily colonize in suitable conditions. Artificial flexible habitats such as ropes or nets can be present on some structures, but are likely to be temporary and regularly disturbed (e.g. moved and replaced) when present. Short flexible habitats can be created on intertidal artificial structures by adding material, either during construction or retrospectively. In addition to potential biodiversity benefits, flexible habitats may offer some bioprotection for the underlying substrate, with potential to reduce weathering and enhance the durability of engineering materials (Coombes et al. 2013). Material choice is important for creating flexible habitats, since some flexible materials are unlikely to persist in the marine environment, while those that do may become entanglement hazards or contribute to pollution if dislodged. Studies that investigate the effects of transplanting live soft-bodied organisms onto structures are not included here, but are considered under the action “Transplant or seed organisms onto intertidal artificial structures”.

There is a body of literature describing the use of artificial turfs as collectors to measure larval supply and settlement in rocky intertidal habitats and to investigate the effects of structural complexity on ecological interactions (e.g. Kelaher 2003; Morris et al. 2018; von der Meden et al. 2015). These studies are not included in this synopsis, which focusses on in situ conservation actions to enhance the biodiversity of marine artificial structures.

^{Coombes M.A., Naylor L.A., Viles H.A. & Thompson R.C. (2013) Bioprotection and disturbance: seaweed, microclimatic stability and conditions for mechanical weathering in the intertidal zone. Geomorphology, 202, 4–14.}

^{Firth L.B., White F.J., Schofield M., Hanley M.E., Burrows M.T., Thompson R.C., Skov M.W., Evans A.J., Moore P.J. & Hawkins S.J. (2016) Facing the future: the importance of substratum features for ecological engineering of artificial habitats in the rocky intertidal. Marine and Freshwater Research, 67, 131–143.}

^{Kelaher B.P. (2003) Changes in habitat complexity negatively affect diverse gastropod assemblages in coralline algal turf. Oecologia, 135, 431–441.}

^{Kim J.H. (2002) Patterns of interactions among neighbour species in a high intertidal algal community. Algae, 17, 41–51.}

^{Morris R.L., Martinez A.S., Firth L.B. & Coleman R.A. (2018) Can transplanting enhance mobile marine invertebrates in ecologically engineered rock pools? Marine Environmental Research, 141, 119–127.}

^{O’Brien J.M. & Scheibling R.E. (2018) Turf wars: competition between foundation and turf-forming species on temperate and tropical reefs and its role in regime shifts. Marine Ecology Progress Series, 590, 1–17.}

^{Strain E.M.A., Olabarria C., Mayer-Pinto M., Cumbo V., Morris R.L., Bugnot A.B., Dafforn K.A., Heery E., Firth L.B., Brooks P.R. & Bishop M.J. (2018) Eco-engineering urban infrastructure for marine and coastal biodiversity: which interventions have the greatest ecological benefit? Journal of Applied Ecology, 55, 426–441.}

^{Thrush S.F., Chiantore M., Asnaghi V., Hewitt J., Fiorentino D. & Cattaneo-Vietti R. (2011) Habitat-diversity relationships in rocky shore algal turf infaunal communities. Marine Ecology Progress Series, 424, 119–132.}

^{von der Meden C.E.O., Cole V.J. & McQuaid C.D. (2015) Do the threats of predation and competition alter larval behaviour and selectivity at settlement under field conditions? Journal of Experimental Marine Biology and Ecology, 471, 240–246.}

Study locations

Key messages

One study examined the effects of creating short flexible habitats on intertidal artificial structures on the biodiversity of those structures. The study was in an estuary in southeast Australia.

COMMUNITY RESPONSE (1 STUDY)

Overall community composition (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures altered the combined macroalgae and non-mobile invertebrate community composition on structure surfaces, and had mixed effects on the combined mobile invertebrate and fish community composition on and around structure surfaces during low tide, depending on the site.
Invertebrate community composition (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures did not alter the mobile invertebrate community composition on and around structure surfaces during high tide.
Fish community composition (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures did not alter the fish community composition on and around structure surfaces during high tide.
Overall richness/diversity (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures decreased the combined macroalgae, invertebrate and fish species richness on and around structure surfaces during low tide.
Invertebrate richness/diversity (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures had mixed effects on the mobile invertebrate species richness on and around structure surfaces during high tide, depending on the site.
Fish richness/diversity (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures did not increase the fish species richness on and around structure surfaces during high tide.

POPULATION RESPONSE (1 STUDY)

Overall abundance (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures did not increase the combined mobile invertebrate and fish abundance on and around structure surfaces during low tide.
Algal abundance (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures had mixed effects on the macroalgal abundance on structure surfaces, depending on the species group and site.
Invertebrate abundance (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures had mixed effects on the abundance of non-mobile invertebrates on structure surfaces, and of mobile invertebrates during high tide, depending on the species group and site.
Fish abundance (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures did not increase the fish abundance on and around structure surfaces during high tide.

BEHAVIOUR (1 STUDY)

Fish behaviour change (1 study): One replicated, randomized, controlled study in Australia found that creating short flexible habitats on intertidal artificial structures did not increase the number of bites fishes took of structure surfaces.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, randomized, controlled study in 2016 on two intertidal seawalls in Sydney Harbour estuary, Australia (Morris et al. 2018) found that adding short flexible habitats (coir panels) to rock pools created on the seawalls had mixed effects on macroalgae, invertebrate and fish community composition, species richness and abundances, depending on the species group and site. Over eight months, during low tide, a total of 44 macroalgae, invertebrate and fish species groups were recorded in pools with coir and 57 in pools without (data not statistically tested). Average macroalgae and non-mobile invertebrate species richness was lower in pools with coir (9 species/pool) than without (12/pool) and the community composition differed (data reported as statistical model results), while abundances varied depending on the species group and site (data not reported). Mobile invertebrate and fish species richness was also lower in pools with coir (2 species/pool) than without (3/pool), but their abundance was similar (data not reported), while effects on their community composition varied by site. During high tide, a total of 13 fish species were recorded in and around pools with coir and 14 in and around pools without, while 49 mobile invertebrate species groups were recorded in each. Average fish species richness, abundance, community composition, and the number of bites they took, were all similar in and around pools with and without coir (data not reported). Mobile invertebrate species richness in pools with coir (8–11 species/pool) and without (9–16/pool) varied by site, as did their abundances (data not reported), but the community composition was similar. Short flexible habitats (coir panels: 734 cm², 15 mm fibre length, 168 fibres/cm²) were created on the inside vertical surfaces of concrete rock pools created on two vertical sandstone seawalls in January–February 2016. Five pools with coir and five without were randomly arranged at midshore in each of two sites along each seawall. Macroalgae, invertebrates and fishes were counted in pools during low tide over eight months. Mobile invertebrates and fishes were also surveyed during two high tides using a suction pump and videos, respectively. Three pools were missing and no longer provided habitat.
Study and other actions tested
Referenced paper
Morris R.L., Golding S., Dafforn K.A. & Coleman R.A. (2018) Can coir increase native biodiversity and reduce colonisation of non-indigenous species in eco-engineered rock pools? Ecological Engineering, 120, 622-630.

Please cite as:

Evans, A.J., Moore, P.J., Firth, L.B., Smith, R.K., and Sutherland, W.J. (2021) Enhancing the Biodiversity of Marine Artificial Structures: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Biodiversity of Marine Artificial Structures

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Create long flexible habitats (>50 mm) on intertidal artificial structures Action Link	Awaiting assessment	1	Synopsis Link
Create pit habitats (1–50 mm) on intertidal artificial structures Action Link	Awaiting assessment	22	Synopsis Link