Create natural rocky reef topography on subtidal artificial structures

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

Definition: ‘Natural rocky reef topography’ refers to the full fingerprint of substrate topography found in natural rocky habitats.

Topography influences the settlement and survival of marine organisms on subtidal rocky substrates. Variation in topography generates variation in the physical environment and plays an important role in sustaining biodiversity and ecological functioning (Levin 1974). On rocky reefs, many habitat features that offer refuge from physical stressors and predation, such as bumps, crevices and holes, are generated as a function of substrate topography and geomorphology. The full fingerprint of natural rocky reef topography encompasses a variety of habitat features of different scales interacting within a mosaic.

Marine artificial structures often have much lower topographic variability than natural rocky reefs, which is thought to be a key reason for their reduced biodiversity (Wilhelmsson & Malm 2008). Natural rocky reef topography can be created on subtidal artificial structures by moulding or casting material during construction or retrospectively (see Evans et al. 2021).

^{Evans A.J., Lawrence P.J., Natanzi A.S., Moore P.J., Davies A.J., Crowe T.P., McNally C., Thompson B., Dozier A.E. & Brooks P.R. (2021) Replicating natural topography on marine artificial structures – a novel approach to eco-engineering. Ecological Engineering, 160, 106144.}

^{Levin S.A. (1974) Dispersion and population interactions. American Society of Naturalists, 108, 207–228.}

^{Wilhelmsson D. & Malm T. (2008) Fouling assemblages on offshore wind power plants and adjacent substrata. Estuarine, Coastal and Shelf Science, 79, 459–466.}

Study locations

Key messages

One study examined the effects of creating natural rocky reef topography on subtidal artificial structures on the biodiversity of those structures. The study was on an open coastline in Italy.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (1 STUDY)

Algal abundance (1 study): One replicated, randomized, controlled study in Italy found that creating natural rocky reef topography on subtidal artificial structures did not increase the abundance of juvenile canopy macroalgae that settled onto structure surfaces, regardless of the topography depth.

BEHAVIOUR (0 STUDIES)

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 2009 on a subtidal rocky reef on open coastline in the Adriatic Sea, Italy (Perkol-Finkel et al. 2012) found that creating natural rocky reef topography on settlement plates did not increase the abundance of juvenile canopy algae Cystoseira barbata that settled onto plates. After five months, there was no significant difference in the average abundance of juveniles on settlement plates with natural rocky reef topography (deep topography: 23/plate; shallow: 28/plate) and plates without (19/plate). Clay settlement plates (100 × 100 mm) were made with and without natural rocky reef topography imprinted on their surfaces using pieces of natural rock as the clay set. Six plates with each of deep (imprinted 5 mm deep) and shallow (1–2 mm) topography and six plates without were randomly arranged horizontally at 3 m depth on a rocky reef with existing adult canopy algae in March 2009. Juvenile canopy algae on plates were counted after five months.
Study and other actions tested
Referenced paper
Perkol-Finkel S., Ferrario F., Nicotera V. & Airoldi L. (2012) Conservation challenges in urban seascapes: promoting the growth of threatened species on coastal infrastructures. Journal of Applied Ecology, 49, 1457-1466.

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?

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This Action forms part of the Action Synopsis:

Biodiversity of Marine Artificial Structures

Related Actions

Actions	Effectiveness	Studies	Category
Create natural rocky reef topography on subtidal artificial structures Action Link	Awaiting assessment	1	Synopsis Link
Create large ridges or ledges (>50 mm) on subtidal artificial structures Action Link	No evidence found (no assessment)	0	Synopsis Link
Create small adjoining cavities or ‘swimthrough’ habitats (≤100 mm) on subtidal artificial structures Action Link	Awaiting assessment	4	Synopsis Link