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Do native herbivores provide resistance to Mediterranean marine bioinvasions? A seaweed example

Generalist herbivores in marine ecosystems are poorly examined for their potential to serve as a source of biotic resistance against algal invasion. We assessed how one of the main generalist herbivores in Mediterranean rocky reefs (the sea urchin Paracentrotus lividus) affects Lophocladia lallemandii and Caulerpa racemosa, two algal invaders with strong detrimental effects on native benthic communities. In a comparison of sea urchin gut contents to algal community composition, strong preferences were exhibited, leading to no relationship between consumption and availability. Both C. racemosa and L. lallemandi were abundant in algal assemblages (>60% occurrence), but C. racemosa (20% of diet) was consumed more than L. lallemandi (3.5%). Experimental enclosures of sea urchins (12 sea urchins * m−2) were carried out in locations where L. lallemandii was already established and C. racemosa was rare (new invasion) or abundant (established invasion). C. racemosa was negatively affected by sea urchins only when it was rare, and no effect was detected when the alga was already abundant. Results for L. lallemandi were exactly opposite: urchins limited seasonal increases in L. lallemandi in highly-invaded areas. Because of the small amount of direct consumption of L. lallemandi, its decrease in abundance may be related to the grazing of native algae where L. lallemandii is attached. Overall, our results show that high densities of native herbivores may reduce invasive algae at low densities, due to a combination of direct and indirect effects, but it has no significant effect in highly-invaded areas

© Biological Invasions, 2011, vol. 13, núm. 6, p. 1397-1408

Author: Cebrian Pujol, Emma
Ballesteros i Segarra, Enric
Linares, Cristina
Tomás, Fiona
Date: 2011
Abstract: Generalist herbivores in marine ecosystems are poorly examined for their potential to serve as a source of biotic resistance against algal invasion. We assessed how one of the main generalist herbivores in Mediterranean rocky reefs (the sea urchin Paracentrotus lividus) affects Lophocladia lallemandii and Caulerpa racemosa, two algal invaders with strong detrimental effects on native benthic communities. In a comparison of sea urchin gut contents to algal community composition, strong preferences were exhibited, leading to no relationship between consumption and availability. Both C. racemosa and L. lallemandi were abundant in algal assemblages (>60% occurrence), but C. racemosa (20% of diet) was consumed more than L. lallemandi (3.5%). Experimental enclosures of sea urchins (12 sea urchins * m−2) were carried out in locations where L. lallemandii was already established and C. racemosa was rare (new invasion) or abundant (established invasion). C. racemosa was negatively affected by sea urchins only when it was rare, and no effect was detected when the alga was already abundant. Results for L. lallemandi were exactly opposite: urchins limited seasonal increases in L. lallemandi in highly-invaded areas. Because of the small amount of direct consumption of L. lallemandi, its decrease in abundance may be related to the grazing of native algae where L. lallemandii is attached. Overall, our results show that high densities of native herbivores may reduce invasive algae at low densities, due to a combination of direct and indirect effects, but it has no significant effect in highly-invaded areas
Format: application/pdf
ISSN: 1387-3547 (versió paper)
1573-1464 (versió electrònica)
Document access: http://hdl.handle.net/10256/7135
Language: eng
Collection: Reproducció digital del document publicat a: http://dx.doi.org/10.1007/s10530-010-9898-1
Articles publicats (D-CCAA)
info:eu-repo/grantAgreement/EC/FP7/248252
Is part of: © Biological Invasions, 2011, vol. 13, núm. 6, p. 1397-1408
Rights: Tots els drets reservats
Subject: Invasions biològiques -- Mediterrània, Mar
Plantes invasores -- Mediterrània, Mar
Algues marines -- Mediterrània, Mar
Invasive plants -- Mediterranean Sea
Biological invasions -- Mediterranean Sea
Marine algae -- Mediterranean Sea
Title: Do native herbivores provide resistance to Mediterranean marine bioinvasions? A seaweed example
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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