Study

Ecological enhancement techniques to improve habitat heterogeneity on coastal defence structures

  • Published source details Hall A.E., Herbert R.J.H., Britton J.R. & Hull S.L. (2018) Ecological enhancement techniques to improve habitat heterogeneity on coastal defence structures. Estuarine, Coastal and Shelf Science, 210, 68-78.

Actions

This study is summarised as evidence for the following.

Action Category

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

Action Link
Biodiversity of Marine Artificial Structures

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

Action Link
Biodiversity of Marine Artificial Structures

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

Action Link
Biodiversity of Marine Artificial Structures

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

Action Link
Biodiversity of Marine Artificial Structures
  1. Create groove habitats (1–50 mm) on intertidal artificial structures

    A replicated, controlled, before-and-after study in 2014–2015 on an intertidal seawall on open coastline in the North Sea, UK (Hall et al. 2018a) found that creating groove habitats on the seawall altered the macroalgae and invertebrate community composition and increased their species diversity, richness and abundance on seawall surfaces. After 12 months, the macroalgae and invertebrate species diversity (data reported as Shannon index) was similar on seawall surfaces with and without grooves, but higher than on surfaces before grooves were created. Species richness and abundance were higher on surfaces with grooves (5 species/surface, 183 individuals/surface) than without (2 species/surface, 12 individuals/surface), and also compared with before grooves were created (0 species and individuals/surface). Community composition differed on surfaces with and without grooves (data reported as statistical model results). Groove habitats were created by cutting into vertical surfaces of a granite boulder seawall. Arrays of nine horizontal grooves (length: 600 mm; width: 3–20 mm; depth: 10 mm) were irregularly-spaced on 600 × 600 mm seawall surfaces. There were seven surfaces with grooves and seven without at mid-lowshore. Organisms were removed from surfaces when grooves were created in October 2014, then macroalgae and invertebrates were counted on surfaces with and without grooves during low tide over 12 months.

    (Summarised by: Ally Evans)

  2. Create groove habitats (1–50 mm) on intertidal artificial structures

    A replicated, controlled, before-and-after study in 2015–2016 on two intertidal groynes on open coastline in the English Channel, UK (Hall et al. 2018b) found that creating groove habitats on the groynes increased the macroalgae and invertebrate species diversity and richness on groyne surfaces, but did not increase their abundance or alter the community composition. After 12 months, the macroalgae and invertebrate species diversity (data reported as Shannon index) was similar on groyne surfaces with and without grooves, but higher than on surfaces before grooves were created. Species richness was higher on surfaces with grooves (5 species/surface) than without (2/surface), and also compared with before grooves were created (1/surface). Abundances were similar on surfaces with grooves (55 individuals/surface) and without (75/surface) to surfaces before grooves were created (71/surface). Twelve species (5 macroalgae, 4 mobile invertebrates, 3 non-mobile invertebrates) recorded on surfaces with grooves were absent from those without, but the community composition was similar (data reported as statistical model results). Groove habitats were created by cutting into vertical surfaces of two limestone boulder groynes. Arrays of nine horizontal grooves (length: 600 mm; width: 3–20 mm; depth: 10 mm) were irregularly-spaced on 600 × 600 mm groyne surfaces. There were 24 surfaces with grooves and 24 without at lowshore. Organisms were removed from surfaces when grooves were created in March 2015, then macroalgae and invertebrates were counted on surfaces with and without grooves during low tide over 12 months.

    (Summarised by: Ally Evans)

  3. Create pit habitats (1–50 mm) on intertidal artificial structures

    A replicated, controlled, before-and-after study in 2014–2015 on an intertidal seawall on open coastline in the North Sea, UK (Hall et al. 2018a) found that creating pit habitats on the seawall altered the macroalgae and invertebrate community composition and increased their species diversity, richness and abundance on seawall surfaces. After 12 months, the macroalgae and invertebrate species diversity (data reported as Shannon index), richness and abundance were higher on surfaces with pits (3 species/surface, 99 individuals/surface) than without (1 species/surface, 26 individuals/surface), and also compared with surfaces before pits were created (0 species and individuals/surface). Community composition differed on surfaces with and without pits (data reported as statistical model results). One macroalgal species recorded on surfaces with pits was absent from those without. Pit habitats were created by drilling into vertical surfaces of a granite boulder seawall. Round pits were in arrays of four (diameter: 16 mm; depth: 20 mm; 70 mm apart) on 200 × 200 mm seawall surfaces. There were 16 surfaces with pits and 16 without at mid-lowshore. Pits were angled to retain water. Organisms were removed from surfaces when pits were created in October 2014, then macroalgae and invertebrates were counted on surfaces with and without pits during low tide over 12 months.

    (Summarised by: Ally Evans)

  4. Create pit habitats (1–50 mm) on intertidal artificial structures

    A replicated, controlled, before-and-after study in 2015–2016 on two intertidal groynes on open coastline in the English Channel, UK (Hall et al. 2018b) found that creating pit habitats on the groynes altered the macroalgae, invertebrate and fish community composition and increased their species diversity and richness but not abundance on groyne surfaces. After 12 months, macroalgae, invertebrate and fish species diversity (data reported as Shannon index) was higher on surfaces with pits than without, and also compared with surfaces before pits were created. Species richness on surfaces with pits (2 species/surface) was statistically similar to surfaces without (1/surface), but higher than before pits were created (1/surface). Abundances were lower on surfaces with pits (7 individuals/surface) than without (65/surface), and statistically similar to before pits were created (33/surface). Community composition differed on surfaces with and without pits (data reported as statistical model results). Five species (2 mobile invertebrates, 2 non-mobile invertebrates, 1 fish) recorded on surfaces with pits were absent from those without. Pit habitats were created by drilling into vertical surfaces of two limestone boulder groynes. Round pits were in arrays of four (diameter: 16 mm; depth: 20 mm; 70 mm apart) on 200 × 200 mm groyne surfaces. There were 48 surfaces with pits and 48 without at lowshore. Pits were angled to retain water. Organisms were removed from surfaces when pits were created in March 2015, then macroalgae, invertebrates and fishes were counted on surfaces with and without pits during low tide over 12 months.

    (Summarised by: Ally Evans)

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