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precedente: PM.8
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livello superiore: PM
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seguente: PM.10
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PM.9 - Spatial scale of variability of sea urchins and algal communities in the
Dubrovnik area
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Privitera Davide (1)*,
Chiantore Mariachiara (1),
Mangialajo Luisa (1),
Glavic Niksa (2),
Kozul Valter (2),
Cattaneo-Vietti Riccardo (1)
| (1) |
Dipart. per lo Studio del Territorio e delle Sue Risorse,
Università degli Studi di Genova, Corso Europa 26, 16132 Genova, Italia |
| (2) |
Institute of Aquaculture and Mariculture of Dubrovnik, Damjana
Jude 12, PoBox 83 Dubrovnik, Croatia |
| * |
dazpriv@hotmail.com |
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The grazing activity of the sea urchins Paracentrotus lividus and
Arbacia lixula n may produce and maintain barren grounds. This study is
addressed to analyse the spatial scale of variability (Locations: thousands of
meters apart; sites: hundreds of meters apart) of the population structure of
the two species and of the algal communities they live on, in the Dubrovnik
area (Croatia). Sea urchins were counted and measured along three transect for
each Site. Samples of algae (20x20 cm quadrates) were collected for each Site
and sea urchin specimens were collected to evaluate gonad (GSI, lipids) and
gut conditions (RI, gut content, lipids and chlorophyll a). Sea urchins show
significant variability only at the Site level, both in terms of population
structure (density and mean size), gonad and gut conditions. In fact, at the
Site scale, P. lividus density varies from 0.3 to 9.2 ind/m2 and
A. lixula from 1.2 to 12.4 ind/m2. The same pattern of variability is
found for the algal community composition (two-way nested Permanova and ANOSIM
significant at the Site level), although a large variability occurs at the
smaller scale (replicates). Yet, the total algal biomass (except ECR), the
total cover and the percent cover of most abundant species, with few
exceptions, do not show significant variability at any of the investigated
scales. These results suggest that algal communities show a small scale
patchiness and the total algal cover and biomass do not affect the sea urchin
populations.
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The following is the established format for referencing this article:
Privitera (2006). Spatial scale of variability of sea urchins and algal communities in the Dubrovnik area. In
Ecologia. Atti del XV Congresso Nazionale della Società Italiana di Ecologia
(Torino, 12-14 settembre 2005) a cura di Claudio Comoglio, Elena Comino,
e Francesca Bona
[online] URL: http://www.xvcongresso.societaitalianaecologia.org/articles/Privitera.pdf |
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consulta l' Indice analitico (alfabetico per autore) |
sfoglia l' Indice delle sessioni del Congresso |
a cura di Comoglio, Comino, e Bona
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