Community Change within a Caribbean Coral Reef Marine Protected Area following Two Decades of Local Management

Structural change in both the habitat and reef-associated fish assemblages within spatially managed coral reefs can provide key insights into the benefits and limitations of Marine Protected Areas (MPAs). While MPA zoning effects on particular target species are well reported, we are yet to fully resolve the various affects of spatial management on the structure of coral reef communities over decadal time scales. Here, we document mixed affects of MPA zoning on fish density, biomass and species richness over the 21 years since establishment of the Saba Marine Park (SMP). Although we found significantly greater biomass and species richness of reef-associated fishes within shallow habitats (5 meters depth) closed to fishing, this did not hold for deeper (15 m) habitats, and there was a widespread decline (38% decrease) in live hard coral cover and a 68% loss of carnivorous reef fishes across all zones of the SMP from the 1990s to 2008. Given the importance of live coral for the maintenance and replenishment of reef fishes, and the likely role of chronic disturbance in driving coral decline across the region, we explore how local spatial management can help protect coral reef ecosystems within the context of large-scale environmental pressures and disturbances outside the purview of local MPA management.Funding was provided by the Saba Conservation Foundation ((SCF), King Abdullah University of Science and Technology, The Australian National University and Australian Research Council. The funders had no role in study design and analysis, decision to publish, or preparation of the manuscript. Staff of the SCF were involved in data collection

Community change within a Caribbean coral reef Marine Protected Area following two decades of local management

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS ONE 8 (2013): e54069, doi:10.1371/journal.pone.0054069.Structural change in both the habitat and reef-associated fish assemblages within spatially managed coral reefs can provide key insights into the benefits and limitations of Marine Protected Areas (MPAs). While MPA zoning effects on particular target species are well reported, we are yet to fully resolve the various affects of spatial management on the structure of coral reef communities over decadal time scales. Here, we document mixed affects of MPA zoning on fish density, biomass and species richness over the 21 years since establishment of the Saba Marine Park (SMP). Although we found significantly greater biomass and species richness of reef-associated fishes within shallow habitats (5 meters depth) closed to fishing, this did not hold for deeper (15 m) habitats, and there was a widespread decline (38% decrease) in live hard coral cover and a 68% loss of carnivorous reef fishes across all zones of the SMP from the 1990s to 2008. Given the importance of live coral for the maintenance and replenishment of reef fishes, and the likely role of chronic disturbance in driving coral decline across the region, we explore how local spatial management can help protect coral reef ecosystems within the context of large-scale environmental pressures and disturbances outside the purview of local MPA management.Funding was provided by the Saba Conservation Foundation ((SCF), King Abdullah University of Science and Technology, The Australian National University and Australian Research Council

Summary of three-way MANOVA comparing biomass of reef-associated fishes across the Saba Marine Park.

<p>Zone (closed and open to fishing), depth (5 m and 15 m) and site (two per zone) were fixed factors in a fully orthogonal design comprising a total of 48 point-count censuses of 27 fish species in 2008. Significant <i>p</i>-values (df = 26, 15, α = 0.05) are indicated in bold.</p

Mean difference in fish density, biomass, species richness and habitat structure among zones of the Saba Marine Park.

<p>(A) Schematic of point-census surveys conducted in shallow (5 m) and deep (15 m) habitats within a 329 m³ cylinder (10 m diameter at base). Mean difference (closed: open zones, ±95% confidence limits) for each of the five surveys (grey bars) and across all years (“overall”, black bar) in both shallow and deep habitats (left and right columns, respectively) for (B, C) fish density, (D, E) fish biomass, (F, G) fish species richness, (H, I) percent live hard coral cover and (J, K) benthic structural complexity index. Asterisks indicate a significant overall effect (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone-0054069-t001" target="_blank">Table 1</a>). Data for years prior to 2008 sourced from Polunin and Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Polunin1" target="_blank">[22]</a>, Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts1" target="_blank">[23]</a> and Roberts and Hawkins <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts2" target="_blank">[24]</a>.</p

Overall effects and heterogeneity in the mean difference of reef-associated fishes and habitat structure among zones of the Saba Marine Park.

<p>Spanning five surveys (1991, 1993, 1994, 1995, 2008) at two depths (5 and 15 meters) among zones closed and open to fishing, the significant <i>p</i>-values for overall effect of zoning (Z, df = 4, α = 0.0125, after Bonferroni correction for multiple comparisons, k = 5) and variability across survey years (<b>χ</b>², df = 4, α = 0.10, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Higgins2" target="_blank">[40]</a>) are indicated in bold. Underlying data for 1991–95 sourced from Polunin and Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Polunin1" target="_blank">[22]</a>, Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts1" target="_blank">[23]</a> and Roberts and Hawkins <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts2" target="_blank">[24]</a>.</p

Biomass of reef-associated fish species among zones of the Saba Marine Park.

<p>Distribution of mean biomass (±95% confidence limits) of herbivorous (A–D) and carnivorous (E–J) fishes in 2008 across shallow (5 m) and deep (15 m) habitats in zones closed (grey bars) and open (white bars) to fishing. Species (functional role and trophic level indicated in parentheses <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Froese1" target="_blank">[38]</a>) are arranged in ascending trophic level: (A) <i>Acanthurus bahianus</i> (grazer, 2.0), (B) <i>Acanthurus chirurgus</i> (grazer, 2.0), (C) <i>Sparisoma viride</i> (excavator, 2.0), (D) <i>Sparisoma aurofrenatum</i> (scraper, 2.0), (E) <i>Haemulon carbonarium</i> (invertivore, 3.3), (F) <i>Haemulon flavolineatum</i> (invertivore, 3.3), (G) <i>Cephalopholis fulva</i> (carnivore, 4.1), (H) <i>Cephalopholis cruentata</i> (carnivore, 4.2.), (I) <i>Lutjanus apodus</i> (carnivore, 4.2) and (J) <i>Lutjanus mahogoni</i> (piscivore, 4.5).</p

Summary of overall effects and temporal heterogeneity in the mean difference of fish biomass among zones of the Saba Marine Park.

<p>Spanning five surveys (1991, 1993, 1994, 1995, 2008) of herbivorous and carnivorous fish families at depths (5 and 15 meters) among zones closed and open to fishing, the significant <i>p</i>-values for overall effect of zoning (Z, df = 4, α = 0.0125, after Bonferroni correction for multiple comparisons, k = 5) and variability across survey years (<b>χ</b>², df = 4, α = 0.05, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Higgins2" target="_blank">[40]</a>) are indicated in bold. Underlying data for 1991–95 sourced from Polunin and Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Polunin1" target="_blank">[22]</a>, Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts1" target="_blank">[23]</a> and Roberts and Hawkins <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts2" target="_blank">[24]</a>.</p

Temporal change in fish trophic guilds, species richness and habitat structure among zones of the Saba Marine Park.

<p>Comparison between closed (grey bars) and open (white bars) zones of the Saba Marine Park in terms of mean (±95% confidence limits) density and biomass (respectively) of (A, B) carnivorous and (C, D) herbivorous reef-associated fishes, alongside mean (E) percent cover of live hard coral, (F) species richness and (G) benthic structural complexity in shallow habitats (5 m depth) during 1991–1995 as compared to most recent (to right of dotted line) 2008 survey. Data for years prior to 2008 sourced from Polunin and Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Polunin1" target="_blank">[22]</a>, Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts1" target="_blank">[23]</a> and Roberts and Hawkins <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts2" target="_blank">[24]</a>.</p

Map of Saba.

<p>(A) Location of Saba, Netherlands Antilles in the Caribbean Sea. (B) Study sites within the Saba Marine Park, Saba. All circles indicate study sites for the 1991–1995 censuses, with closed circles sites being those resurveyed in 2008. Dotted enclosure indicates the no-take zone “closed” to fishing.</p

Mean difference in biomass of herbivorous and carnivorous fish families among zones of the Saba Marine Park.

<p>Mean difference (closed : open zones, ±95% confidence limits) is presented for each of the five surveys (grey bars) and across all years (“overall”, black bars) for both shallow (5 m) and deep (15 m) habitats (left and right columns, respectively) for the herbivorous fish families (A, B) Acanthuridae and (C, D) Scaridae, and the carnivorous fish families (E, F) Haemulidae, (G, H) Serranidae and (I, J) Lutjanidae. Asterisks indicate a significant overall effect (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone-0054069-t002" target="_blank">Table 2</a>). Data for years prior to 2008 sourced from Polunin and Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Polunin1" target="_blank">[22]</a>, Roberts <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts1" target="_blank">[23]</a> and Roberts and Hawkins <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054069#pone.0054069-Roberts2" target="_blank">[24]</a>.</p