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Patterns of spatial variability in epiphytes of Posidonia oceanica: differences between a disturbed and two reference locations
Piazzi, L.; Balata, D.; Cinelli, F.; Benedetti-Cecchi, L. (2004). Patterns of spatial variability in epiphytes of Posidonia oceanica: differences between a disturbed and two reference locations. Aquat. Bot. 79(4): 345-356.
In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770, more
Peer reviewed article  

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    Mediterranean Sea; Mediterranean sea; Posidonia oceanica (Linnaeus) Delile, 1813 [WoRMS]; MED, Italy, Tuscany [Marine Regions]; Marine
Author keywords
    seagrasses anthropogenic disturbance Mediterranean Sea

Authors  Top 
  • Piazzi, L.
  • Balata, D.
  • Cinelli, F.
  • Benedetti-Cecchi, L., more

    The proposition that epiphytes of the seagrass Posidonia oceanica are sensitive to anthropogenic disturbance was tested by comparing assemblages between disturbed and control meadows in the northwest Mediterranean. We examined effects of urban and industrial sewage on the structure of assemblages, on the mean abundance of common taxa and on their patterns of variation at a hierarchy of spatial scales. This was accomplished through a nested sampling design that enabled comparisons at scales ranging from centimetres to kilometres. Spatial heterogeneity at the scale of shoot (10 s of cm apart), measured in terms of variance in abundance of single taxa, was significantly enhanced close to the point of discharge compared to controls for encrusting algae, filamentous algae and bryozoans. Only foraminifers displaced a reduced amount of variation close to the outfall at this spatial scale. A similar reduction occurred for encrusting algae at the quadrat scale (100 s of cm apart). The study also revealed that epiphytes of P. oceanica were most variable at the extremes of the range of scales investigated (among locations 1000 s of m apart and among shoots and quadrats), whereas variation at the intermediate scale (among sites 10 s of m apart) was negligible. In contrast to patterns in spatial variance, no effects related to anthropogenic disturbance were observed on mean percentage cover of targeted organisms, nor on the structure of assemblages.

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