11 research outputs found
The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications
Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m22). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas
Appendix A. Results of Tukey a posteriori tests for variables showing significance with the ANOVA test.
Results of Tukey a posteriori tests for variables showing significance with the ANOVA test
The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications
Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m22). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas
Examples of the major community states identified in this study: large fish biomass and non-canopy algae (‘predator-dominated’ ecosystems, i.e., the well-enforced marine reserves (A); ecosystems with lower fish biomass, but abundant algal canopies and suspension feeders (B); and ecosystems with lower fish biomass and extensive barrens (C), and areas covered by turf algae (D).
<p>(Photos: A,B: E Sala, C: Z Kizilkaya, D: A Vergés).</p
Biplot of results of redundancy analysis on biological and environmental data.
<p>Site codes as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032742#pone-0032742-g001" target="_blank">Fig. 1</a>. Green circles are well enforced no-take reserves, yellow circles are marine protected areas where some fishing is allowed or some fishing occurs due to weak enforcement, red circles are non-enforced MPAs, and white circles are unprotected, open access areas.</p
Characteristics of the marine protected areas investigated in this study.
<p>All these marine protected areas had partial protection, with areas where some types of fishing are permitted, and small no-take areas. Piperi is the no-take area of the Marine Park of Alonissos-Northern Sporades. Enforcement level <i>sensu</i> Guidetti et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032742#pone.0032742-Guidetti4" target="_blank">[48]</a>.</p
Top: Relationship between total fish biomass and biomass of apex predators.
<p>Bottom: Relationship between total biomass of algae and biomass of canopy algae (Fucales). Sites with no Fucales above 2000 g m<sup>−2</sup> are found in the NW Mediterranean.</p
Conditional effects of the Monte-Carlo permutation results on the redundancy analysis (RDA).
<p>PP: primary production, SST: surface seawater temperature.</p
Results of redundancy analysis (RDA) on log-transformed data on fish biomass, benthic biomass and cover of bare rock, and environmental and human-related variables.
<p>Results of redundancy analysis (RDA) on log-transformed data on fish biomass, benthic biomass and cover of bare rock, and environmental and human-related variables.</p