Transplant or seed organisms onto subtidal artificial structures

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

Study locations

Key messages

  • Eleven studies examined the effects of transplanting or seeding species onto subtidal artificial structures on the biodiversity of those structures. Eight studies were on open coastlines in Japan, Italy and Croatia, and one of each was in an inland bay in eastern USA, an estuary in southeast Australia, and on an island coastline in the Singapore Strait.

COMMUNITY RESPONSE (2 STUDIES)

  • Overall community composition (1 study): One replicated, paired sites, controlled study in the USA found that transplanting oysters onto subtidal artificial structures altered the combined invertebrate and fish community composition on and around structure surfaces.
  • Overall richness/diversity (1 study): One replicated, paired sites, controlled study in the USA found that transplanting oysters onto subtidal artificial structures increased the combined invertebrate and fish species richness and diversity on and around structure surfaces.
  • Invertebrate richness/diversity (1 study): One randomized, before-and-after study in Singapore reported that transplanting corals onto a subtidal artificial structure increased the coral species richness on structure surfaces.

POPULATION RESPONSE (11 STUDIES)

  • Overall abundance (1 study): One replicated, paired sites, controlled study in the USA found that transplanting oysters onto subtidal artificial structures did not increase the combined invertebrate and fish abundance on and around structure surfaces, but that the effects varied for different species.
  • Algal abundance (3 studies): Two replicated, randomized, controlled studies in Italy and Croatia found that the cover of canopy algae transplanted onto subtidal artificial structures increased and/or was higher when transplanted under cages but decreased and/or was lower when left uncaged. One study in Japan reported that the abundance of kelp recruits on a subtidal artificial structure varied depending on the distance from transplanted kelp individuals and the surface orientation.
  • Invertebrate abundance (2 studies): One replicated, randomized, controlled and site comparison study in Australia found that transplanting sea urchins onto a subtidal artificial structure reduced the cover of non-native sea mat on kelps growing on the structure. One randomized, before-and-after study in Singapore reported that transplanting corals increased the coral cover on structure surfaces.
  • Algal reproductive success (1 study): One study in Japan reported that kelp transplanted onto a subtidal artificial structure appeared to reproduce.
  • Invertebrate reproductive success (1 study): One replicated, paired sites, controlled study in the USA reported that oysters transplanted onto subtidal artificial structures appeared to reproduce.
  • Algal survival (5 studies): Three of five replicated studies (including two randomized, controlled studies) in Italy found that the survival of canopy algae transplanted onto subtidal artificial structures varied depending on the wave-exposure and surrounding habitat or the presence and/or mesh size of cages around transplants, while in one the surface orientation had no effect. Two studies reported that no canopy algae transplants survived, and in one this was regardless of the presence of cages.
  • Invertebrate survival (3 studies): One randomized, before-and-after study in Singapore found that the survival of corals transplanted onto a subtidal artificial structure varied depending on the species. One replicated, paired sites, controlled study in the USA found that cleaning activities did not affect survival of transplanted oysters. One replicated, randomized, controlled and site comparison study in Australia simply reported that transplanted sea urchins survived.
  • Algal condition (3 studies): Two replicated studies (including one randomized, controlled study) in Italy found that the growth of canopy algae transplanted onto subtidal artificial structures varied depending on the wave-exposure and surface orientation or the presence of cages around transplants, while in one the mesh size of cages had no effect. One study in Japan simply reported that transplanted kelp grew.
  • Invertebrate condition (2 studies): One randomized, before-and-after study in Singapore reported that the growth of corals transplanted onto a subtidal artificial structure varied depending on the species. One replicated, paired sites, controlled study in the USA reported that cleaning activities did not affect the growth of transplanted oysters.

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

  1. A study in 2003–2005 on a subtidal breakwater on open coastline in Tosa Bay, Japan (Serisawa et al. 2007) reported that kelp Ecklonia cava transplanted onto concrete blocks placed on the breakwater grew and appeared to reproduce. Over 22 months, transplanted kelp grew to reproductive size (data not reported) and new recruits appeared on the surrounding breakwater surfaces. After 22 months, there were 0–53 kelp recruits/m2 within 10 m of the transplants, depending on the distance from transplants and the orientation of the surface (data reported from Figure 4 in original paper). Recruits grew to 260–360 mm length. Kelp seedlings (100 mm length) were attached to ropes fixed on two concrete blocks and transplanted onto a concrete breakwater at 4 m depth in April 2003. Other details were reported in Japanese. Transplanted kelp were monitored and new recruits were counted on breakwater surfaces over 22 months.

    Study and other actions tested
  2.  A replicated, paired sites, controlled study in 2008 on eight subtidal pontoons in the Delaware Inland Bays, USA (Marenghi & Ozbay 2010) found that 29–89% of oysters Crassostrea virginica transplanted onto floats attached to the pontoons survived and grew, regardless of cleaning frequency, and that transplanting oysters increased the invertebrate and fish species richness and diversity on and around floats, but had mixed effects on abundances, depending on the species. Over four months, transplanted oyster survival (29–89%) and growth (5–25 mm) was similar on floats cleaned every two or four weeks. In total, 23 mobile invertebrate and fish species were recorded on and around floats with transplanted oysters and 17 on and around floats without, while 11 non-mobile invertebrate species were recorded on transplanted oyster shells. Average mobile invertebrate and fish species diversity (reported as Simpson’s and Evenness indices) and richness was higher on and around floats with transplanted oysters (8–10 species/float) than without (4–7/float), and their combined abundance was similar (data not reported), although abundances varied by species (see paper for results). Oysters supported on average seven non-mobile invertebrate species/float. Mobile invertebrate and fish community composition differed on and around floats with and without oysters (data reported as statistical model results). Oyster recruits were seen on transplanted oysters. Hatchery-reared oysters (61 mm average length) were transplanted into wire baskets (25 mm mesh size) submerged 0.2 m beneath plastic floats (1.0 × 0.7 × 0.3 m) and attached to pontoons. One float with oysters (6 l) and one without were attached to each of eight pontoons in June 2008. Floats were cleaned every two weeks on four pontoons and every four weeks on four. Oyster survival and growth was monitored, non-mobile invertebrates on oyster shells were counted, and mobile invertebrates and fishes on and around floats were netted (3 mm mesh size) and counted over four months.

    Study and other actions tested
  3.  A replicated, randomized, controlled and site comparison study in 2006–2007 on 20 subtidal jetty pilings in Sydney Harbour estuary, Australia (Marzinelli et al. 2011) reported that 100% of sea urchins Holopneustes purpurascens transplanted onto pilings survived, and found that transplanting urchins reduced the non-native sea mat cover (mostly Membranipora membranacea) on kelp Ecklonia cava growing on the pilings. After one month, all transplanted sea urchins remained on pilings. Non-native sea mat cover on kelp was lower on pilings with transplanted urchins (0–19% cover) than on pilings without (29–89%), and similar to kelp on natural reefs in one of two trials (pilings with urchins: 0–6%; natural reefs: 1%), but higher on pilings in the second trial (pilings with urchins: 17–19%; natural reefs: 2–3%). Sea urchins (>50 mm diameter) were collected from natural reefs and transplanted onto kelp growing on wooden jetty pilings (1.5 × 1.5 m surfaces) at 0–3 m depth, with five urchins/piling. Five pilings with urchins and five without were randomly arranged in each of two sites on a jetty in November 2006. Transplanted urchins were counted and non-native sea mat cover on kelp blades was measured from photographs after one month. Sea mat cover was also measured on kelp on nearby natural reefs. The experiment was repeated in April 2007.

    Study and other actions tested
  4. A replicated study in 2008–2009 on four subtidal breakwaters on open coastline in the Adriatic Sea, Italy (Perkol-Finkel et al. 2012a) reported that 0–33% of canopy algae Cystoseira barbata transplanted onto the breakwaters survived, depending on the wave-exposure and surrounding habitat, and that survivors grew. Data were not statistically tested. After one week, no transplanted canopy algae survived on breakwaters on sandy shorelines. On rocky shorelines, after eight months, average survival was 33% on wave-sheltered sides of breakwaters and 9% on wave-exposed sides. Survival was 3–44% on horizontal surfaces and 9–27% on vertical surfaces. On average, wave-sheltered transplants grew to 120 mm and wave-exposed transplants to 90 mm. Average length was 130 mm on horizontal and 60 mm on vertical surfaces. Some transplants survived 12 months and appeared to reproduce (no data reported). Boulders with attached juvenile canopy algae (50 mm length) were collected from natural reefs, fragmented and transplanted onto boulder breakwaters using epoxy putty. Fragments were attached in 12 patches, with five individuals/patch, on both the wave-sheltered and wave-exposed sides of each of four breakwaters in June 2008 (depth not reported). Of the 12 patches in each setting, four were on each of: horizontal surfaces with adult canopy algae, horizontal surfaces without, and vertical surfaces without. Two of the breakwaters were on rocky shorelines and two were on sandy shorelines. Transplants were monitored over eight months.

    Study and other actions tested
  5. A replicated study in 2009 on two subtidal breakwaters on open coastline in the Adriatic Sea, Italy (Perkol-Finkel et al. 2012b) reported that juvenile canopy algae Cystoseira barbata transplanted onto breakwaters did not survive. After three days, no transplants remained on either breakwater. Boulders (100 mm diameter) with attached juvenile canopy algae were collected from a natural reef and transplanted onto boulder breakwaters using epoxy putty. Four boulders with canopy algae (numbers not reported) were attached on horizontal surfaces on the wave-sheltered side of each of two breakwaters on sandy shoreline in June 2009 (depth not reported). Transplants were monitored over three days.

    Study and other actions tested
  6. A replicated, randomized, controlled study in 2009 on two subtidal breakwaters on open coastline in the Adriatic Sea, Italy (Perkol-Finkel et al. 2012c) reported that juvenile canopy algae Cystoseira barbata transplanted onto breakwaters did not survive, regardless of whether they were transplanted under cages or left uncaged. After two days, no transplants remained on either breakwater. Boulders (100 mm diameter) with attached juvenile canopy algae were collected from a natural reef and transplanted onto boulder breakwaters using epoxy putty. Eight boulders with canopy algae were attached on horizontal surfaces on the wave-sheltered side of each of two breakwaters on sandy shoreline in June 2009 (depth not reported). Four randomly-selected boulders on each breakwater were protected from grazers by plastic cages (10 mm mesh size) and four were left uncaged. Transplants were monitored over two days.

    Study and other actions tested
  7. A replicated, randomized, controlled study in 2009 on two subtidal breakwaters on open coastline in the Adriatic Sea, Italy (Perkol-Finkel et al. 2012d) reported that 50–100% of juvenile canopy algae Cystoseira barbata transplanted onto the breakwaters survived, and found that survival and cover was higher when algae was transplanted under cages than when left uncaged. After eight days, average survival and remaining cover of transplanted canopy algae was higher under cages (100% survival, 88% of original cover) compared with uncaged transplants (50% survival, 24% cover). Limestone settlement plates (100 × 100 mm) were attached to rocky seabed at 3 m depth in March 2009 and were colonized by juvenile canopy algae. In June 2009, plates were removed and transplanted onto boulder breakwaters using epoxy putty. Eight plates were attached on horizontal surfaces on the wave-sheltered side of each of two breakwaters on sandy shoreline (depth not reported). Four randomly-selected plates on each breakwater were protected from grazers by plastic cages (1 mm mesh size) and four were left uncaged. Transplants were monitored over eight days.

    Study and other actions tested
  8. A replicated, randomized, controlled study in 2010 on a subtidal breakwater on open coastline in the Adriatic Sea, Italy (Ferrario et al. 2016a) reported that canopy algae Cystoseira barbata transplanted onto the breakwater under cages grew, but decreased in length when left uncaged. Over 13 days, canopy algae transplant growth was similar under large-mesh cages (131% of original length) and small-mesh cages (115%), but uncaged transplants decreased in length (18% of original length). Boulders with attached juvenile canopy algae were collected from natural reefs, fragmented and attached to limestone plates (100 × 100 mm) using epoxy putty, then transplanted onto a boulder breakwater. Fifteen plates with 5–6 individuals/plate were attached to horizontal surfaces on the wave-sheltered side of a breakwater on sandy shoreline in July 2010 (depth not reported). Five randomly-selected plates were protected from grazers by large-mesh plastic-coated wire cages (10 mm mesh size), five by small-mesh cages (1 mm) and five were left uncaged. Transplants were monitored over 13 days. Three caged plates were missing and no longer retained transplants on the breakwater.

    Study and other actions tested
  9. A replicated, randomized, controlled study in 2010 on three subtidal breakwaters on open coastline in the Adriatic Sea, Italy (Ferrario et al. 2016b) reported that 67–100% of canopy algae Cystoseira barbata transplanted onto the breakwaters survived, depending on the presence and mesh-size of cages around them. After 15 days, canopy algae transplant survival was higher under small-mesh cages (100%) than large-mesh cages (75%) and for uncaged transplants (67%), which were similar. Boulders with attached juvenile canopy algae were collected from natural reefs, fragmented and attached to limestone plates (100 × 100 mm) using epoxy putty, then transplanted onto boulder breakwaters. Fifteen plates with 5–6 individuals/plate were attached to horizontal surfaces on the wave-sheltered side of each of three breakwaters on sandy shorelines in August 2010 (depth not reported). On each breakwater, five randomly-selected plates were protected from grazers by large-mesh plastic-coated wire cages (10 mm mesh size with 60 × 70 mm openings), five by small-mesh cages (1 mm) and five were left uncaged. Transplants were monitored over 15 days. Four caged plates were missing and no longer retained transplants on the breakwater.

    Study and other actions tested
  10. A replicated, randomized, controlled study in 2010–2011 on three subtidal breakwaters on open coastline in the Adriatic Sea, Croatia (Ferrario et al. 2016c) reported that the cover of canopy algae transplanted onto breakwaters under cages increased, but decreased when left uncaged, and found that cover of caged transplants was higher than uncaged transplants. After 12 months, canopy algae transplant cover was higher under cages than when left uncaged for both Cystoseira barbata (caged: 72%; uncaged: 8%) and Cystoseira compressa (caged: 79%; uncaged: 13%) canopy algae. Cover increased by 7–31% under cages, but decreased by 40–55% when left uncaged. Limestone settlement plates (100 × 100 mm) were attached to rocky seabed at 3–4 m depth in May 2010 and were colonized by two species of juvenile canopy algae (40–70% cover). In October 2010, plates were removed and transplanted onto boulder breakwaters using epoxy putty. Eight plates of each species were attached to horizontal surfaces on the wave-sheltered side of each of three breakwaters on rocky shorelines (depth not reported). On each breakwater, four randomly-selected plates of each species were protected from grazers by plastic-coated wire cages (10 mm mesh size) and four were left uncaged. Transplants were monitored from photographs over 12 months.

    Study and other actions tested
  11. A randomized, before-and-after study in 2015–2016 on a subtidal seawall on an island coastline in the Singapore Strait, Singapore (Toh et al. 2017) reported that 58–100% of corals transplanted onto the seawall survived, depending on the species, that most survivors grew, and that transplanting corals increased the coral species richness and cover on the seawall. After six months, average transplant survival was lower for Pocillopora damicornis (58%) than for all other hard coral species (Echinopora lamellosa: 100%; Hydnophora rigida: 100%; Merulina ampliata: 91%; Platygyra sinensis: 97%; Podabacia crustacea: 92%). Surviving M. ampliata transplants had negative growth rates (-1 cm2/month), while all other species had positive growth rates (E. lamellosa: 11 cm2/month; H. rigida: 14 cm2/month; P. sinensis: 4 cm2/month; P. damicornis: 26 cm2/month; P. crustacea: 4 cm2/month). Coral species richness and cover on the seawall was higher (8 species, 21% cover) than before corals were transplanted (2 species, 3% cover). Corals were collected from natural reefs, fragmented and reared on nursery tables adjacent to a granite boulder seawall at 4 m depth for nine months, before being transplanted onto the seawall using epoxy putty. Fragments (diameter: 9–16 cm; area: 48–160 cm2) of six hard coral species (36 fragments/species) were randomly arranged in four patches on the seawall at 3m depth during April–August 2015. Corals were counted on the seawall (20 × 3 m section) before and six months after transplants were attached. Transplants were monitored from photographs over six 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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