1 research outputs found
Do native herbivores provide resistance to Mediterranean marine bioinvasions? A seaweed example
12 páginas, 4 figuras,3 tablas.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), butC. 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.Financial support was provided by
Fundacio´n Biodiversidad and Grant CTM2005-01434/MAR
and GRACCIE project C5D2007–00067 from the Spanish
Ministry of Science and Innovation. EC was funded via a EU
Marie Curie Fellowship (MEIF-2006-041315 and ERG-2009-
248252). FT was funded by Juan de la Cierva Postdoctoral
Fellowship. CL was funded by a Spanish Postdoctoral
Fellowship.Peer reviewe