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Helgol Mar Res (2013) 67:535543 DOI 10.1007/s10152-012-0341-0
ORIGINAL ARTICLE
Intertidal rocky shore seaweed communities subjectto the inuence of shallow water hydrothermal activity in So Miguel (Azores, Portugal)
Francisco M. Wallenstein Ruben P. Couto
Daniel F. Torro Ana I. Neto
Armindo S. Rodrigues Martin Wilkinson
Received: 26 September 2012 / Revised: 7 November 2012 / Accepted: 9 November 2012 / Published online: 24 November 2012 Springer-Verlag Berlin Heidelberg and AWI 2012
Abstract The volcanic origin of the Azores archipelago (Portugal) gives rise to active deep sea and shallow water hydrothermal activity that affects benthic communities. Intertidal seaweed surveys were conducted at two shores affected by intense shallow water hydrothermal vents. Water temperature, acidity and salinity were monitored. Seaweed communities were found to be species poor and have a disproportionally larger number of lamentous early
successional species on shores that are subject to the effect of hot and acidic freshwater of volcanic origin. There is an ecological resemblance between hydrothermally affected seaweed communities in the Azores and those affected by acid mine drainage in the UK, thus indicating that hydrothermalism can be a useful scenario for pollution studies under conditions of ocean warming and acidication.
Keywords Intertidal Macroalgae Hydrothermal
activity Pollution
Introduction
The Azores islands are located in the northern Atlantic Ocean (36N/31W and 43N/25W), and their recent volcanic origin is indicated by active deep sea and shallow water hydro-thermal activity. Such habitats are naturally enriched in heavy metals (see Von Damm 1990; Carvalho et al. 2011) and thus provide examples of naturally polluted sites to compare with those that are affected by human pollution. They also provide unusual ecological situations of increased temperature and acidity due to the input of hot hydrothermal water springs and the diffusion of acidic volcanic gases (mainly CO2; Cruz and
Frana 2006; Carvalho et al. 2011). Organisms that live in such environments are therefore chronically exposed to thermal pollution and chemical pollution as well as to acidication that can affect biotic communities at various levels (e.g., productivity, species diversity, abundance and composition, and the bioaccumulation of contaminants), consequently affecting overall ecosystem health (Elliott and Cutts 2004).
There have been studies on the effects of shallow water hydrothermal activity on subtidal marine organisms in the Mediterranean (e.g., Dando et al. 1991; Sartoni...