Action

Designate a Marine Protected Area and prohibit/limit recreational activities (including anchoring)

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

Study locations

Key messages

COMMUNITY RESPONSE (2 STUDIES)

  • Richness/diversity (2 studies): One site comparison study in Mexico and Cuba found similar coral species richness in a site closed to diving/snorkelling and a site with no diving/snorkelling restrictions. One replicated, site comparison study in Egypt found that in protected areas that limited anchoring by using mooring buoys (and prohibited some fishing), a biodiversity index (which included corals) was higher or similar compared to unprotected areas.

POPULATION RESPONSE (4 STUDIES)

  • Abundance/Cover (4 studies): Three site comparison studies (incluinding one replicated, before-and-after study) in Mexico and Cuba, Bonaire and the US Virgin Islands found that prohibiting diving/snorkelling or prohibiting anchoring (and some fishing) had mixed effects on coral cover or densities when compared to unprotected areas or protected areas with no diving/snorkelling restirctions. One study in Egypt found that in protected areas that limited anchoring by using mooring buoys (and prohibited some fishing) one species group of corals increased in one of three protected areas, but other species showed no change.
  • Condition (1 study): One site comparison study in Spain found that in protected areas that prohibited diving (and fishing) fewer coral Paramuricea clavata colonies had other organisms growing on them compared to areas where diving and/or fishing was permitted. The study also reported that colonies with organisms growing on them had fewer reproductive cells than those without.

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, site comparison study in 2003–2008 at two coral reef sites off St John, US Virgin Islands (Monaco et al. 2009) found that in protected areas where anchoring was prohibited and some fishing and collection was also prohibited, hard coral cover was lower in the protected areas compared to outside, and soft coral cover was higher in one area compared to outside but similar in a second. Hard coral cover was lower in the protected areas (4% and 4%) compared to the unprotected areas (15% and 8%) and soft coral cover was higher in the protected areas in one comparison (inside: 22%, outside: 13%) and similar in a second (inside: 12%, outside: 11%). In one case, coral cover declined in the protected area (2003: 7%, 2008: 3%), but declined more dramatically in the unprotected area (2003: 26%, 2008: 6%), and in a second case, cover in the protected area was 4% in 2003 and 2% in 2008, and in the unprotected area cover was 10% in 2003 and 6% in 2008 (results were not tested for statistical significance). Two protected areas were selected, one on the mid-shelf reef and one in a bay. Anchoring was prohibited, alongside fishing and collection of all species except the blue runner Caranx crysos. Sites in the protected areas (18–30 sites/year) and in adjacent unprotected areas (15–25 sites/year) were surveyed annually from 2003–2008. Coral cover was assessed at one location/site within a 15 m diameter area.

    Study and other actions tested
  2. A site comparison study in 2010–2011 at nine coral reef sites in Cap de Creus and Medes Islands, off Spain in the northern Mediterranean (Tsounis et al. 2012) found that in a protected area that prohibited diving, and also prohibited all fishing, fewer coral Paramuricea clavata colonies had other organisms growing on them (likely due to injury/damage) than in areas where diving and/or fishing was permitted. In the protected area, 4–10% of colonies had other organisms growing on them, compared to 10–33% in unprotected areas. Colonies with organisms growing on them had fewer reproductive cells (5–13 gonads/coral polyp) than those without (10–25 gonads/coral polyp), and authors also reported on differences in concentrations of lipids, carbohydrates and proteins in coral branches (see paper for details). One area of a marine park (established in 1996) where both diving and fishing was prohibited was selected, along with six other sites in the same area (with a mix of diving and recreational fishing) and two sites in a different area (with some diving permitted but no fishing). In June 2010 and January 2011, a total of 15 surveys across the nine locations were carried out (4 in the fully protected area) by divers along transects (6–20 m long, 16–38 m deep).

    Study and other actions tested
  3. A replicated, site comparison study in 2007–2010 in five coral reef sites in the Red Sea off Egypt (Branchini et al. 2015) found that in protected areas that introduced mooring buoys for dive boats and also prohibited some fishing and collection, a biodiversity index (which included corals) was higher in two of three protected areas compared to one of two unprotected areas. There was no difference between sites in other comparisons (data reported as statistical model results). For fire corals Millepora sp., frequency of sightings increased over time in one of three protected areas (2007: 85% of surveys, 2010: 90%), but did not increase in the two unprotected areas. Other coral species did not show trends over time (data reported as statistical model results). Three protected areas in Sharm el-Sheikh where commercial and sport fishing were prohibited and two unprotected areas were selected. In 2007–2010, over 7,000 volunteer divers carried out surveys at 100 locations across the five sites (17,900 surveys, 14,500 hours of survey time). Divers completed a questionnaire where they recorded species that they had seen (14 named coral species and option to report other corals) and estimated the number of individuals. Volunteer surveys were validated against surveys carried out by experts.

    Study and other actions tested
  4. A site comparison study in 2014–2015 at four coral reef sites in Mexico and Cuba (Perera-Valderrama et al. 2017) found that in protected areas that limited numbers of snorkellers or divers, there were not clear differences in coral richness and abundance compared to areas with no restrictions, though there were some differences in community composition. In Mexico, a site with no divers/snorkellers had 23 species and a site with high diver/snorkeller numbers had 20 species, whereas two sites in Cuba with low diver/snorkeller numbers had 35 and 36 species. In Mexico, the no divers/snorkellers site had greater coral density (20–23 colonies/m2) in two of four comparisons than the site with high diver/snorkeller numbers (17–19 colonies/m2), but lower coral cover in three of four comparisons (no divers/snorkellers: 27–44 cm2/m2, high divers/snorkellers: 46–53 cm2/m2). Coral communities varied between sites in terms of relative abundance, and differences in species density and live coral cover were larger between the sites with no divers/snorkellers and high diver/snorkeller numbers in Mexico than between the two sites with low diver/snorkeller numbers in Cuba (data reported as graphical analysis). Two sites were selected in protected areas in both Mexico and Cuba. One Mexican site was closed to all divers/snorkellers, and the other received around 100 divers or snorkellers/day. Both Cuban sites received around 15 divers or snorkellers/day. Each site was sampled four times over two years, with eight transects (1 x 10 m) established in each site, and five 1 m2 quadrates sampled/transect (40 samples/site).

    Study and other actions tested
  5. A replicated, before-and-after, site comparison study in the early 1980s–2009 in four coral reef sites in Bonaire (Relles et al. 2019) found that one of two protected areas that prohibited diving/snorkelling showed an increase in hard coral cover, while the other, and two unprotected sites, showed declines. Results were not tested for statistical significance. The sheltered, protected area had higher hard coral cover and lower number of coral patches after protection (cover: 83%, patches: 3) than before (cover: 66%, patches: 7), but the exposed protected area and both unprotected areas (sheltered and exposed) had lower cover (after: 41–54%, before: 79–90%) and more patches (after: 3–9, before: 0–7) after protection. Authors also reported on other metrics including patch size and connectivity. Two marine reserves were established in 1991 that excluded divers and other underwater visitors. One was exposed to storms and the other was sheltered. Adjacent unprotected sites were also selected, one exposed and one sheltered. In the early 1980s, maps of coral cover were created through aerial photographs and scuba diving surveys. In 2008–2009, satellite images were acquired for the same locations, along with 17 underwater video transects. Habitat was classed as coral (live hard coral cover >20%), or sand (>50% sand) or sand-coral mixture (< 20% hard coral and < 50% sand, where additional cover could include octocorals).

    Study and other actions tested
Please cite as:

Thornton A., Morgan, W.H., Bladon E.K., Smith R.K. & Sutherland W.J. (2024) Coral Conservation: Global evidence for the effects of actions. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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Coral Conservation

This Action forms part of the Action Synopsis:

Coral Conservation
Coral Conservation

Coral Conservation - Published 2024

Coral synopsis

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