Create large adjoining cavities or ‘swimthrough’ habitats (>100 mm) on subtidal artificial structures

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Two studies examined the effects of creating large adjoining cavities or ‘swimthrough’ habitats on subtidal artificial structures on the biodiversity of those structures. One study was in a lagoon in Mayotte and one was in a marina in southeast USA.

COMMUNITY RESPONSE (1 STUDY)

  • Fish community composition (1 study): One replicated, paired sites, controlled study in the USA reported that large swimthrough habitats created in front of a subtidal artificial structure supported fish species that were absent from structure surfaces without swimthroughs.
  • Fish richness/diversity (1 study): One replicated, paired sites, controlled study in the USA found that creating large swimthrough habitats in front of a subtidal artificial structure increased the overall fish species richness on and around structure surfaces, but that effects varied depending on the fish size class.

POPULATION RESPONSE (1 STUDY)

  • Fish abundance (1 study): One replicated, paired sites, controlled study in the USA found that creating large swimthrough habitats in front of a subtidal artificial structure increased the overall fish abundance on and around structure surfaces, but that individual species abundances varied depending on the species, size class and survey month.

BEHAVIOUR (1 STUDY)

  • Use (1 study): One study in Mayotte reported that large swimthrough habitats created on a subtidal artificial structure, along with small swimthroughs and environmentally-sensitive material, were used by juvenile spiny lobsters and groupers, sea firs, and adult fishes from five families.

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

  1. A study in 2009–2010 on a subtidal pipeline in a lagoon in the Mozambique Channel, Mayotte (Pioch et al. 2011) reported that large swimthrough habitats created on pipeline anchor-weights, along with small swimthroughs and environmentally-sensitive material, were used by juvenile spiny lobster Panulirus versicolor, juvenile blue-and-yellow grouper Epinephelus flavocaeruleus, sea firs (Hydrozoa), and adult fishes from five families. After one month, juvenile spiny lobsters and blue-and-yellow groupers, sea firs, and adult damselfish/clownfish (Pomacentridae), wrasse (Labridae), butterflyfish (Chaetodontidae), squirrelfish/soldierfish (Holocentridae) and surgeonfish (Acanthuridae) were recorded on and around anchor-weights with swimthroughs and environmentally-sensitive material. Large swimthrough habitats were created by leaving gaps between concrete anchor-weights placed over a seabed pipeline (400 mm diameter). Anchor-weights also had basalt rocks or semi-cylindrical tiles attached to the top, creating small swimthrough habitats. Basalt may be considered an environmentally-sensitive material compared with concrete. Habitat dimensions/numbers were not reported. A total of 260 anchor-weights were placed with one every 10 m along the pipeline at 0–26 m depth during December 2009–March 2010. Fishes were counted on and around the pipeline from videos after 1 month.

    Study and other actions tested
  2. A replicated, paired sites, controlled study in 2015–2016 on a seawall in a marina in Port Everglades, USA (Patranella et al. 2017) found that creating large swimthrough habitats in front of the seawall increased the fish species richness and abundance on and around seawall surfaces, but that effects varied depending on the species, size class and survey month. Over 14 months, total fish abundance was higher on and around seawall surfaces with swimthroughs (1,614 individuals) than those without (655 individuals). Fish species richness and average abundance (all size classes combined) was also higher (swimthroughs: 4 species and 10 individuals/survey; no swimthroughs: 2 species and 4 individuals/survey). This was also true for fishes in 20–300 mm size classes (swimthroughs: 0–2 species and 1–3 individuals/survey; no swimthroughs: 0–1 species and individuals/survey), but not for smaller or larger groups (both 0 species/survey; swimthroughs: 0–1 individuals/survey; no swimthroughs: 0 individuals/survey). Species abundances around seawall surfaces with and without swimthroughs varied depending on the species, size class and survey month (see paper for results). Sixteen species recorded on and around swimthroughs were absent from seawall surfaces without. Large swimthrough habitats (length: ~510 mm; width: ~250 mm; height: ~100 mm) were created by placing concrete bricks as spacers between four horizontally-stacked concrete paving slabs (510 × 510 mm). Twelve stacks of pavers with three swimthroughs/stack were placed at 1–3 m depth on silty seabed 0.5 m in front of a seawall in February 2015. Fishes were counted on and around sections of the seawall (1.5 × 1.5 m) with and without swimthroughs over 14 months.

    Study and other actions tested
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

Biodiversity of Marine Artificial Structures

This Action forms part of the Action Synopsis:

Biodiversity of Marine Artificial Structures
Biodiversity of Marine Artificial Structures

Biodiversity of Marine Artificial Structures - Published 2021

Enhancing biodiversity of marine artificial structures synopsis

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