Distribution and dynamics of epibiota on hard structures for coastal protection

Hard structures for protection against erosion of shores are some of the most common human-made constructions in coastal areas. Nevertheless, little is known as to how marine organisms respond to their presence. The composition and distribution of intertidal epibiota at different positions around different types of defence structures (groynes and breakwaters) at three stations along the Emilia Romagna coast (Italy) were analysed. Sampling covered a range of scales: meters (distance among replicate plots), hundreds of meters (distance among replicate areas) and tens of kilometres (distance among stations). The colonisation and dynamics of conspicuous species over 1 year, following maintenance works on two structures, were also quantified. Assemblages on defence structures were characterised by a notably low richness of species, by strong spatial dominance of mussels and green ephemeral algae, and by high rates of colonisation. Abundance of mussels, Enteromorpha intestinalis and filamentous algae differed significantly among nearby areas within stations. Mussels were significantly less abundant along the landward side of breakwaters compared with all other positions on both groynes and breakwaters. Overall, however, fewer differences, than expected, were observed in the distribution of species at different positions around groynes and breakwaters, probably as a consequence of the low complexity of the colonising assemblages. Possible factors explaining the patterns of distribution observed are discussed, including the roles of harvesting of mussels and frequent maintenance works on the structures. The implications of the low richness of species observed in terms of management of defence structures and other human-made constructions are discussed.

[1]  Tim M. Glasby,et al.  Urban structures as marine habitats , 1999 .

[2]  L. Goldwasser,et al.  THE ROLE OF DISPERSAL AND DISTURBANCE IN DETERMINING SPATIAL HETEROGENEITY IN SEDENTARY ORGANISMS , 2000 .

[3]  Connell,et al.  Floating pontoons create novel habitats for subtidal epibiota. , 2000, Journal of experimental marine biology and ecology.

[4]  Tim M. Glasby,et al.  Differences Between Subtidal Epibiota on Pier Pilings and Rocky Reefs at Marinas in Sydney, Australia , 1999 .

[5]  H. Lotze,et al.  Propagule banks, herbivory and nutrient supply control population development and dominance patterns in macroalgal blooms , 2000 .

[6]  Michael B Abbott,et al.  Coastal, estuarial and harbour engineers' reference book , 1993 .

[7]  V. U. Ceccherelli,et al.  Settlement, growth and production of the mussel Mytilus galloprovincialis , 1984 .

[8]  S. Miserocchi,et al.  Breakwaters and eutrophication along the Emilia-Romagna coast , 1992 .

[9]  B. Santelices,et al.  Patterns of reproduction, dispersal and recruitment in seaweeds , 1990 .

[10]  David Whitmarsh,et al.  Artificial Reefs as a Tool to Aid Rehabilitation of Coastal Ecosystems: Investigating the Potential , 1999 .

[11]  A. Dye.  Experimental studies of succession and stability in rocky intertidal communities subject to artisanal shellfish gathering , 1992 .

[12]  L. Chou,et al.  Artificial Reefs of Southeast Asia - Do They Enhance or Degrade the Marine Environment? , 1997 .

[13]  P. Dayton,et al.  Man-made structures on marine sediments: Effects on adjacent benthic communities , 1982 .

[14]  P. Poulain.  Adriatic Sea surface circulation as derived from drifter data between 1990 and 1999 , 2001 .

[15]  C. Turner,et al.  Fish Bulletin 146. Man-Made Reef Ecology , 1969 .

[16]  V. Kourafalou.  Process studies on the Po River plume, North Adriatic Sea , 1999 .

[17]  N. Cooper,et al.  Application of Offshore Breakwaters to the UK: A Case Study at Elmer Beach , 2000 .

[18]  R. Vollenweider,et al.  Marine coastal eutrophication : the response of marine transitional systems to human impact, problems and perspectives for restoration : proceedings of an international conference, Bologna, Italy, 21-24 March 1990 , 1992 .

[19]  C. Moreno.  Community patterns generated by human harvesting on Chilean shores: a review , 2001 .

[20]  Tim M. Glasby,et al.  Do urban structures influence local abundance and diversity of subtidal epibiota? A case study from Sydney Harbour, Australia , 1999 .

[21]  J. Jackson,et al.  Modes of dispersal of clonal benthic invertebrates: consequences for species' distributions and genetic structure of local populations , 1986 .

[22]  Grazing by two species of limpets on artificial reefs in the northwest Mediterranean. , 2000, Journal of experimental marine biology and ecology.

[23]  S. Connell,et al.  Urban structures as marine habitats: an experimental comparison of the composition and abundance of subtidal epibiota among pilings, pontoons and rocky reefs. , 2001, Marine environmental research.

[24]  R. Bustamante,et al.  The dependence of intertidal consumers on kelp-derived organic matter on the west coast of South Africa , 1996 .

[25]  Tim M. Glasby,et al.  Orientation and position of substrata have large effects on epibiotic assemblages , 2001 .

[26]  Carlo Cencini,et al.  Physical Processes and Human Activities in the Evolution of the Po Delta, Italy , 1998 .

[27]  Marco Zavatarelli,et al.  Climatological biogeochemical characteristics of the Adriatic Sea , 1998 .

[28]  Underwood,et al.  Observations in ecology: you can't make progress on processes without understanding the patterns. , 2000, Journal of experimental marine biology and ecology.

[29]  L. Durán,et al.  Variation and persistence of the middle rocky intertidal community of central Chile, with and without human harvesting , 1989 .

[30]  A. Wolfson,et al.  The Marine Life of an Offshore Oil Platform , 1979 .

[31]  H. Burcharth.  Design of Breakwaters , 1994 .

[32]  T. Glasby,et al.  Surface composition and orientation interact to affect subtidal epibiota. , 2000, Journal of experimental marine biology and ecology.

[33]  A. Meijer,et al.  Active management of an artificial rocky coast , 1989, Hydrobiological Bulletin.

[34]  J. Dugan,et al.  Effects of an offshore oil platform on the distribution and abundance of commercially important crab species , 1999 .

[35]  L. Airoldi,et al.  Estimating the abundance of benthic invertebrates: a comparison of procedures and variability between observers , 1996 .