Friedlander AM et al. (2017), Contrasts in the marine ecosystem of two Macaro...

ECB-ART-45870

PLoS One 2017 Nov 10;1211:e0187935. doi: 10.1371/journal.pone.0187935.

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Contrasts in the marine ecosystem of two Macaronesian islands: A comparison between the remote Selvagens Reserve and Madeira Island.

Friedlander AM , Ballesteros E , Clemente S , Gonçalves EJ , Estep A , Rose P , Sala E .

Abstract
The islands of Madeira and Selvagens are less than 300 km apart but offer a clear contrast between a densely populated and highly developed island (Madeira), and a largely uninhabited and remote archipelago (Selvagens) within Macaronesia in the eastern Atlantic. The Madeira Archipelago has ~260,000 inhabitants and receives over six million visitor days annually. The Selvagens Islands Reserve is one of the oldest nature reserves in Portugal and comprises two islands and several islets, including the surrounding shelf to a depth of 200 m. Only reserve rangers and a small unit of the maritime police inhabit these islands. The benthic community around Selvagens was dominated by erect and turf algae, while the community at Madeira was comprised of crustose coralline and turf algae, sessile invertebrates, and sea urchin barrens. The sea urchin Diadema africanum was 65% more abundant at Madeira than at Selvagens. Total fish biomass was 3.2 times larger at Selvagens than at Madeira, and biomass of top predators was more than 10 times larger at Selvagens. Several commercially important species (e.g., groupers, jacks), which have been overfished throughout the region, were more common and of larger size at Selvagens than at Madeira. Important sea urchin predators (e.g., hogfishes, triggerfishes) were also in higher abundance at Selvagens compared to Madeira. The effects of fishing and other anthropogenic influences are evident around Madeira. This is in stark contrast to Selvagens, which harbors healthy benthic communities with diverse algal assemblages and high fish biomass, including an abundance of large commercially important species. The clear differences between these two island groups highlights the importance of expanding and strengthening the protection around Selvagens, which harbors one of the last intact marine ecosystems in the North Atlantic, and the need to increase management and protection around Madeira.

PubMed ID: 29136657
PMC ID: PMC5685627
Article link: PLoS One

Genes referenced: fhl2 LOC100887844 LOC115925415

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References [+] :

Barrett, The origins of intensive marine fishing in medieval Europe: the English evidence. 2004, Pubmed

	Fig 1. Sampling locations around Madeira and Selvagens in the eastern Atlantic Ocean.
	Fig 2. Principal Coordinate Analysis of sessile benthic functional groups.Percent cover data were arcsine square root transformed prior to analysis.
	Fig 3. Principal Coordinate Analysis of mobile invertebrate communities between islands and depths.Top 10 species together accounted for > 90% of the individuals in each island group. Data square root transformed prior to analysis.
	Fig 4. Comparisons of fish assemblage characteristics between islands and depths.Box plots showing median (black line), mean (red dashed line), upper and lower quartiles, and 5th and 95th percentiles. A. Species richness transect, B. Number of individuals m-2, C. Grams m-2, and D. Shannon-Weiner Diversity.
	Fig 5. Principal Coordinates Analysis of fish species biomass.Square root transformation. Bray Curtis Similarity matrix.
	Fig 6. Canonical discriminate analysis of the difference in trophic group biomass between island groups and depths.Treatment (island group x depth) centroids and 95% confidence clouds are plotted together with the direction and importance of trends in trophic group.
	Fig 7. Comparisons of trophic biomass between islands and depths.Box plots showing median (black line), mean (red line), upper and lower quartiles, and 5th and 95th percentiles. A. Top predators, B. herbivores, C. secondary consumers, and D. planktivores. Values are in g m-2.

	Fig 9. Biplot of results of Principal Components Analysis with supplemental variables on dominant sessile benthic cover, mobile invertebrates, and fish biomass by trophic group.Sessile benthic cover data were arcsine square root transformed, mobile invertebrates and fish biomass were ln(x+1) transformed prior to analysis. All data were centered and standardized. Statistical results are shown in Table 6.
	Fig 10. The intertidal habitats of Ilhas Selvagens are some of the least disturbed within the region, with the highly prized sun limpet (Patella candei) common and of large size, particularly around Selvagem Pequena.