Transplant or seed organisms onto intertidal artificial structures

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

Study locations

Key messages

  • Ten studies examined the effects of transplanting or seeding species onto intertidal artificial structures on the biodiversity of those structures. Seven studies were in estuaries in southeast Australia and Hong Kong, two were on island coastlines in the Singapore Strait and one was in a port and on an open coastline in southeast Spain.

COMMUNITY RESPONSE (5 STUDIES)

  • Overall community composition (3 studies): Three replicated, randomized, controlled studies in Hong Kong and Australia reported that oysters transplanted onto intertidal artificial structures supported macroalgae, mobile invertebrate, non-mobile invertebrate and fish species that were absent from on and around structure surfaces without transplanted oysters.
  • Overall richness/diversity (3 studies): Three replicated, randomized, controlled studies in Hong Kong and Australia found that transplanting oysters onto intertidal artificial structures had mixed effects on the combined macroalgae and invertebrate species richness and/or diversity on structure surfaces, depending on the site and/or the presence and size of grooves and small ridges or ledges on surfaces.
  • Invertebrate richness/diversity (1 study): One replicated, randomized, controlled study in Australia found that transplanting oysters onto intertidal artificial structures increased the mobile invertebrate species richness on structure surfaces.
  • Fish richness/diversity (3 studies): Two of three replicated, randomized studies (including two controlled studies) in Australia found that transplanting oysters and/or coralline algae onto intertidal artificial structures did not increase the fish species richness on and around structure surfaces. One found mixed effects of transplanting oysters, depending on the presence and size of grooves and small ridges on surfaces and the site.

POPULATION RESPONSE (10 STUDIES)

  • Overall abundance (2 studies): One of two replicated, randomized, controlled studies in Australia found that transplanting oysters onto intertidal artificial structures did not increase the combined macroalgae and invertebrate abundance on structure surfaces. One study found mixed effects depending on the presence and size of grooves and small ridges/ledges on structure surfaces.
  • Invertebrate abundance (3 studies): Two of three replicated, randomized, controlled studies in Hong Kong and Australia found that transplanting oysters onto intertidal artificial structures had mixed effects on the mobile invertebrate abundance on structure surfaces, depending on the presence of grooves and small ridges or ledges on surfaces and/or the site. One of the studies also found that transplanting oysters increased the non-mobile invertebrate and oyster recruit abundance and decreased barnacle abundance. One found increased oyster and mobile invertebrate abundance.
  • Fish abundance (3 studies): Two of three replicated, randomized studies (including two controlled studies) in Australia found that transplanting oysters and/or coralline algae onto intertidal artificial structures did not increase the fish abundance on and around structure surfaces. One found that fish abundance around transplanted oysters was similar regardless of the presence and size of grooves and small ridges on structure surfaces.
  • Algal survival (1 study): One replicated study in Singapore found that macroalgae transplanted onto an intertidal artificial structure were more likely to survive at mid- and highshore than at lowshore.
  • Invertebrate survival (8 studies): Six of eight studies (including six replicated, three randomized and two controlled studies) in Australia, Spain, Singapore and Hong Kong reported that the survival of mobile invertebrates (seasnails, starfish and/or urchins and anemones) or non-mobile invertebrates (limpets, corals and sponges or oysters) transplanted onto intertidal artificial structures varied depending on the species, site, and/or the presence and size of grooves and small ridges or ledges on structure surfaces. One of the studies found that oyster survival was higher when transplanted into grooves compared with on ridges, while one found that survival in grooves and on ledges varied depending on the site. Two studies simply reported that a proportion of transplanted oysters survived.
  • Algal condition (1 study): One replicated study in Singapore found that the growth of macroalgae transplanted onto an intertidal artificial structure was similar at lowshore, midshore and highshore.
  • Invertebrate condition (2 studies): One study in Singapore reported that the growth of corals and sponges transplanted onto an intertidal artificial structure varied depending on the species. One replicated study in Spain simply reported that transplanted limpets grew.

BEHAVIOUR (1 STUDY)

  • Fish behaviour change (1 study): One replicated, randomized, controlled study in Australia found that transplanting oysters and/or coralline algae onto intertidal artificial structures did not increase the time fishes spent interacting with structure surfaces or the number of bites they took, but that benthic fishes took more bites from surfaces with transplanted oysters than from those with transplanted algae and oysters together. These results were true regardless of whether there were grooves and small ridges on 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

  1. A replicated study in 2003–2005 on four intertidal breakwaters in Ceuta Port and on open coastline in the Alboran Sea, Spain (Espinosa et al. 2008) reported that 0–17% of limpets Patella ferruginea transplanted onto breakwaters survived, but that most survivors grew. Data were not statistically tested. After 28 months, 2–17% of transplanted limpets survived on the wave-sheltered inaccessible breakwater, 15% on the wave-exposed inaccessible breakwater, 8% on the wave-sheltered accessible breakwater, and 0% on the wave-exposed accessible breakwater. Growth rates ranged from 0–4 mm/month with no clear differences between sites. Limpets were collected from a boulder breakwater during reconstruction, marked and then transplanted onto four nearby boulder breakwaters. Twenty limpets were transplanted onto boulder surfaces in each of three patches (10 m long) on each of four breakwaters during spring 2003 (shore level/month and other transplantation details not reported). Breakwaters were either inside the port (wave-sheltered) or outside (wave-exposed) and either accessible to people or inaccessible, with one breakwater/exposure-accessibility combination. Transplants were monitored over 28 months.

    Study and other actions tested
  2. A study in 2010 on two intertidal seawalls in Sydney Harbour estuary, Australia (Browne & Chapman 2014) reported that the survival of mobile invertebrates transplanted into rock pools created on the seawalls varied depending on the species. After 10 days, transplanted turban snails Turbo undulatus, keyhole limpets Scutus antipodes and sea anemones Actinia tenebrosa survived in midshore pools on both seawalls (data not reported). All transplanted sea urchins Heliocidaris erythrogramma and starfish Patiriella calcar had died and no transplanted nerite snails Nerita atramentosa remained in pools. Six species of mobile invertebrates were collected from natural reefs and transplanted into rock pools created on two vertical sandstone seawalls at highshore and midshore in 2010. No other details were reported. Transplanted animals were surveyed during low tide after 10 days.

    Study and other actions tested
  3. A study in 2010–2012 on an intertidal seawall on an island coastline in the Singapore Strait, Singapore (Ng et al. 2015) found that 0–90% of coral and sponge fragments transplanted onto the seawall survived, depending on the species, and that most survivors grew. After 24 months, hard coral transplant survival was higher for Porites lobata (47%) than Pocillopora damicornis and Hydnophora rigida (both 0%). Soft coral survival was higher for Lobophytum sp. (88%) than Cladiella sp. (37%) and Sinularia sp. (13%). Sponge survival was higher for Lendenfeldia chondrodes (68%) than Spongia ceylonensis (14%) and Rhabdastrella globostellata (0%). In hard corals transplanted for 13 months, survival was higher for Goniastrea minuta (90%) than Diploastrea heliopora (10%). Diploastrea heliopora fragments had negative growth rates (-1.2 cm2/month), while the other seven surviving species had positive growth rates (0.3–19.7 cm2/month). Corals and sponges were collected from natural reefs, reared in a nursery, then fragmented and transplanted onto a granite boulder seawall at lowshore. Fragments (≥30 mm) of three hard coral species (18–38 fragments/species), three soft coral species (30–40/species) and three sponge species (44–49/species) were transplanted in May 2010. Fragments of two additional hard coral species (30 fragments/species) were transplanted in April 2011. Hard corals were transplanted directly onto seawall surfaces using epoxy putty, while soft corals and sponges were grown onto concrete plates (50 mm diameter, 5 mm thick) first. Transplants were monitored during low tide until May 2012.

    Study and other actions tested
  4. A replicated study in 2016 on an intertidal seawall in Sydney Harbour estuary, Australia (Morris et al. 2018) reported that 18–79% of mobile invertebrates transplanted into rock pools created on the seawall remained in and around the pools, depending on the species. After one day, on average, 60% of transplanted topshells Austrocochlea porcata remained in pools (30%) and on seawall surfaces around pools (30%). Between 73–79% of transplanted periwinkles Bembicium nanum remained in (23–29%) and around (50%) pools. Only 18% of transplanted starfish Parvulastra exigua remained in pools and none around pools. Topshells, periwinkles and starfish were collected from natural rock pools and transplanted into artificial pools created at midshore on a vertical sandstone seawall. Ten individuals of each species were transplanted into each of three pools on each of two occasions during January–February 2016. Transplanted animals remaining in and around pools on the seawall were counted during low tide after one day.

    Study and other actions tested
  5. A replicated, randomized study in 2015–2016 on two intertidal seawalls in Sydney Harbour estuary, Australia (Strain et al. 2018) found that 28–94% of oysters Saccostrea glomerata transplanted onto settlement plates survived, and that oyster survival and fish species richness around plates, but not fish abundance, varied depending on the presence and size of grooves and small ridges on plates and the site. Over six months, at one of two sites, transplanted oyster survival was higher on settlement plates with deep/tall grooves and ridges (52%) than on plates without (28%), and both were similar to plates with shallow/short grooves and ridges (43%). Survival was higher in grooves (85–95%) than on ridges (30–35%). Fish species richness was higher on and around oyster plates with deep/tall grooves and ridges (7 species/plate) than without (4/plate), while maximum fish abundance was similar (5 vs 4 individuals/plate) (not reported for shallow/short grooves and ridges). At the second site, no significant differences were found for oyster survival (deep/tall grooves and ridges: 94%; shallow/short: 80%; none: 91%; grooves: 96–98%; ridges: 95–98%), fish species richness (3 species/plate with and without grooves and ridges) or fish abundance (2 vs 3 individuals/plate). Dead oysters were either cracked (0–60%), intact (0–5%) or missing (0–8%). Hatchery-reared juvenile oysters were attached to concrete settlement plates (250 × 250 mm) using epoxy glue and transplanted onto vertical sandstone seawalls. There were 52 oysters/plate (24 mm average length) in patches of 4–5 individuals covering ~220 cm2. Plates had textured surfaces with or without deep/tall (50 mm) or shallow/short (25 mm) grooves and small ridges. Five of each were randomly arranged at midshore on each of two seawalls in November 2015. Transplanted oysters were monitored during low tide over six months. Fishes were counted on and around plates from time-lapsed photographs during two high tides after one month.

    Study and other actions tested
  6. A replicated, randomized, controlled study in 2016–2017 on three intertidal seawalls in Sydney Harbour estuary, Australia (Ushiama et al. 2019) found that transplanting oysters Saccostrea glomerata, coralline algae Corallina officinalis, or both onto settlement plates did not increase the fish species richness or abundance or alter fish behaviour on and around plates, but benthic fish behaviour varied depending on the species transplanted. After 8–12 months, fish species richness and abundance were similar on and around settlement plates with and without transplanted coralline algae, oysters or both (data not reported). The same was true for the time fishes spent interacting with plates (with coralline algae: 1–21 minutes/60-minute survey; with oysters: 2–30 minutes/survey; both: 1–18/survey; neither: 1–27/survey). Benthic fishes took more bites from plates with oysters (10 bites/survey) than plates with both algae and oysters (2/survey), while both were similar to plates with algae only (6 bites/survey) and with neither (4/survey). There were no significant differences for pelagic fishes (with algae: 8 bites/survey; oysters: 21/survey; both: 5/survey; neither: 8/survey). Coralline algae collected from natural reefs and hatchery-reared juvenile oysters were attached to concrete settlement plates (250 × 250 mm) using epoxy glue and transplanted onto vertical sandstone seawalls. Algae, oysters (46 mm average length), both or neither were attached in eight patches/plate covering 125 cm2. Plates had textured surfaces with or without grooves and small ledges (50 mm). Nine of each transplant-grooves/ledges combination were randomly arranged at midshore on each of three seawalls in March 2016. Fishes were counted on and around one of each plate design from 60-minute videos during each of three high tides after 8–12 months. The time fishes spent within 50 mm of plates and the number of bites they took was recorded.

    Study and other actions tested
  7. A replicated, randomized, controlled study in 2016–2017 on two intertidal seawalls in the Pearl River estuary, Hong Kong (Bradford et al. 2020) found that 36% of oysters Saccostrea cuccullata transplanted onto settlement plates survived, and that transplanting oysters increased non-mobile invertebrate and oyster abundance on plates, decreased barnacle abundance, and had mixed effects on mobile invertebrate abundance and macroalgae and invertebrate species richness, depending on the presence of grooves and small ridges on plates and the site. After 12 months, 36% of transplanted oysters survived. At one of two sites, settlement plates with transplanted oysters supported higher macroalgae and invertebrate species richness (14–17 species/plate) and mobile invertebrate abundance (51–106 individuals/plate) than plates without oysters (9–12 species/plate, 15–81 individuals/plate). At the second site, the same was true for flat plates (with oysters: 16 species/plate, 65 individuals/plate; without: 9 species/plate, 19 individuals/plate) but no significant differences were found for plates with grooves and ridges (12–13 species/plate with and without oysters, 43–49 vs 31–45 individuals/plate). At both sites, plates with transplanted oysters supported higher abundance of non-mobile invertebrates (48–58% cover) and new oyster recruits (1–4 g/plate) but fewer barnacles (Cirripedia) (0–4 g/plate) than plates without (non-mobile invertebrates: 13–42%; oyster recruits: 0–2 g/plate; barnacles: 1–13 g/plate). Three mobile invertebrate species recorded on plates with transplanted oysters were absent from those without. Oysters collected locally were attached to concrete settlement plates (250 × 250 mm) using epoxy glue and transplanted onto vertical concrete seawalls. Plates had oyster patches covering 225 cm2/plate or no oysters, and textured surfaces with or without deep/tall (50 mm) or shallow/short (25 mm) grooves and small ridges. Five of each transplant-grooves/ridges combination were randomly arranged at midshore on each of two seawalls in November 2016 (month/year: M. Perkins pers. comms.). Macroalgae and invertebrates on plates were counted from photographs and in the laboratory, and barnacle and oyster recruit biomass (dry weight) was measured after 12 months. One plate was missing and no longer provided habitat.

    Study and other actions tested
  8. A replicated study in 2019 on an intertidal seawall on an island coastline in the Singapore Strait, Singapore (Heery et al. 2020) found that red macroalgae Hydropuntia edulis transplanted onto the seawall grew at similar rates at all shore levels, but was more likely to be dislodged at lowshore than at mid- and highshore. Over one month, the biomass of transplanted macroalgae increased by 2 g/individual on average. The average growth rate was 3%/day and average biomass yield was 2 kg/m2 of seawall. Growth rates were similar at lowshore (3%/day), midshore (2%/day) and highshore (2%/day), but the probability of dislodgement was higher at lowshore (58%) than midshore (8%) and highshore (17%). Red macroalgae collected from natural reefs were woven into nylon ropes and transplanted into water-retaining plastic troughs (1.0 × 0.1 m) attached to a seawall. Six individuals were transplanted into each of four troughs at each of lowshore, midshore and highshore in January 2019. Growth rates (% change in wet weight/day) and biomass yield (change in wet weight/m2) were measured during low tide after one month.

    Study and other actions tested
  9. A replicated, randomized, controlled study in 2015–2016 on two intertidal seawalls in Sydney Harbour estuary, Australia (Strain et al. 2020) reported that 17–52% of oysters Saccostrea glomerata transplanted onto settlement plates survived, and found that oyster survival, macroalgae, invertebrate and fish species richness and abundances varied depending on the presence of grooves and small ledges on plates, the species group and site. Over 12 months, at one of two sites, transplanted oyster survival was higher on settlement plates with grooves and ledges (52%) than without (17%), and higher in grooves (92%) than on ledges (23%). At the second site, no significant differences were found (69% with and without grooves and ledges; grooves: 77%; ledges: 85%). Macroalgae and non-mobile invertebrate abundance was similar on plates with transplanted oysters (24–39% cover) and without (31–46%). Their species richness was higher on flat plates with oysters (5 species/plate) than those without (2/plate), but no significant difference was found when grooves and ledges were present on plates (6/plate with and without oysters). Mobile invertebrate species richness was higher on plates with oysters (10–12 species/plate) than without (4–7/plate). Their abundance was higher on plates with oysters (38 individuals/plate) than without (20/plate) when grooves and ledges were present, but did not differ on flat plates (16/plate with and without oysters). Fish species richness and abundance were similar on and around plates with and without oysters (3 vs 2 species/plate, both 1 individual/plate). Twenty-two species (3 macroalgae, 2 non-mobile invertebrates, 14 mobile invertebrates, 3 fishes) recorded on and around plates with transplanted oysters were absent from those without. Hatchery-reared juvenile oysters were attached to concrete settlement plates (250 × 250 mm) using epoxy glue and transplanted onto vertical sandstone seawalls. Plates had 52 oysters/plate in patches of 4–5 individuals or no oysters, and textured surfaces with or without grooves and small ledges (50 mm). Five of each transplant-grooves/ledges combination were randomly arranged at midshore on each of two seawalls in November 2015. Macroalgae and invertebrates were counted on plates during low tide, from photographs and in the laboratory over 12 months. Fishes were counted on and around plates from time-lapsed photographs during two high tides.

    Study and other actions tested
  10. A replicated, randomized, controlled study in 2015–2016 on two intertidal seawalls in Sydney Harbour estuary, Australia (Vozzo et al. 2021) reported that 60% of oysters Saccostrea glomerata transplanted onto settlement plates survived, and found that macroalgae and invertebrate species richness, diversity and abundances varied depending on the presence and depth/height of grooves and ridges or ledges on plates, the species group and site. After 12 months, 60% of transplanted oysters survived. The macroalgae and invertebrate species richness was higher on settlement plates with transplanted oysters (18–19 species/plate) than without (8–10/plate) when there were no or shallow/short grooves and ridges or ledges on plates. When deep/tall grooves and ridges or ledges were present, richness was similar on plates with and without transplanted oysters (17 vs 15/plate). The same was true for species diversity (data reported as Shannon index) and at one site for macroalgae and non-mobile invertebrate abundance (no or short/shallow grooves and ridges: 102–128% cover with oysters vs 30% without; deep/tall grooves and ridges: 98–108% with oysters vs 77–99% without). At the second site, no significant differences were found (with oysters: 126–150%; without: 87–121%). Oyster (Ostreidae) and mobile invertebrate abundances were higher on plates with transplanted oysters (oysters: 101–152 individuals/plate; mobiles: 83–156/plate) than without (oysters: 15–91/plate; mobiles: 12–38/plate). Eighteen species (2 macroalgae, 15 mobile invertebrates, 1 non-mobile invertebrate) recorded on plates with transplanted oysters were absent from those without. See paper for full results. Juvenile oysters were attached to concrete settlement plates (250 × 250 mm) using epoxy glue and transplanted onto vertical sandstone seawalls. Plates had 52 oysters/plate in patches of 4–5 individuals or no oysters, and textured surfaces with or without deep/tall (50 mm) or shallow/short (25 mm) grooves and small ridges or ledges. Five of each transplant-grooves/ridges combination were randomly arranged at midshore on each of two seawalls in November 2015. Macroalgae and invertebrates on plates were counted in the laboratory after 12 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?

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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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