Algal cover and sea urchin spatial distribution at Madeira Island (NE Atlantic)

Authors

  • Filipe M. A. Alves Centro de Ciências do Mar, Universidade do Algarve, Faculdade de Ciências do Mar e do Ambiente
  • Luís M. Chícharo Centro de Ciências do Mar, Universidade do Algarve, Faculdade de Ciências do Mar e do Ambiente
  • Ester Serrao Centro de Ciências do Mar, Universidade do Algarve, Faculdade de Ciências do Mar e do Ambiente
  • Antonio D. Abreu Estação de Biologia Marinha do Funchal, Cais do Carvão, Promenade da Orla Marítima do Funchal

DOI:

https://doi.org/10.3989/scimar.2001.65n4383

Keywords:

sea urchins, Madeira Island, algae, Diadema antillarum, distribution

Abstract


This study describes sea urchin spatial distribution in relation to environmental factors, and the relationship between Diadema antillarum density and algal abundance. Twenty-three transects around Madeira Island were surveyed by scuba divers, and sea urchin density and algal cover were determined in situ. Sampling sites along these transects were characterised in terms of distance from the tide line, water depth, substratum type, bottom declivity and water turbulence. Diadema antillarum was the dominant sea urchin species. Paracentrotus lividus and Arbacia lixula occurred at shallower depths (2-6 m), contrasting with the distribution of Sphaerechinus granularis, which occurs among D. antillarum (4-20 m). Surveys found two alternative types of communities on rocky shores: 1) a community with high algal cover and low numbers of sea urchins, along the north and south-west coasts and; 2) a community with little algal cover and high densities of sea urchins, along the south-east coast. Macroalgal cover and D. antillarum densities were inversely correlated (adjusted R2=75.6%; n = 429; p< 0.05). The results showed that water turbulence was the most important factor limiting the distribution of D. antillarum on rocky substrates. We propose a multiple non-linear regression model (using backward stepwise analysis) to explain D. antillarum abundance on the rocky shores: D. antillarum/m2 (??)= 0.121 - 0.209 distance from shore (in m) (??) + 2.052 water depth (in m) (??) - 1.778 water turbulence level (??) - 0.007 water turbulence level4 (??); where ?? indicates data are square-root transformed (adjusted R2 = 60.99%; n = 454; p< 0.05).

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Published

2001-12-30

How to Cite

1.
Alves FMA, Chícharo LM, Serrao E, Abreu AD. Algal cover and sea urchin spatial distribution at Madeira Island (NE Atlantic). scimar [Internet]. 2001Dec.30 [cited 2022Oct.2];65(4):383-92. Available from: https://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/670

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