2024-03-28T14:59:27Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/640372018-07-09T07:34:32Zcom_10261_88com_10261_8col_10261_341
2013-01-11T12:56:50Z
urn:hdl:10261/64037
Indirect interactions in seagrasses: fish herbivores increase predation risk to sea urchins by modifying plant traits
Pagès, Jordi F.
Farina, Simone
Gera, Alessandro
Arthur, Rohan
Romero, Javier
Alcoverro, Teresa
Sarpa salpa
Trait-mediated
Ecosystem engineering
Environment-mediated
Interaction modifications
Paracentrotus lividus
Plant–herbivore interactions
Posidonia oceanica
9 páginas,4 figuras, 1 tabla.
1. The dominant paradigm of top-down control of ecological communities through direct consumption pathways is giving way to a more nuanced understanding of trophic interactions with
the recognition that subtler indirect effects can often play an important role in structuring communities. Direct and indirect trophic and non-trophic processes could well be acting simultaneously within the same food web, and their overall effects may even interact with each other.
2. We studied indirect interactions in a relatively simple trophic system comprising a single
producer, two herbivores and a guild of predators. In particular, we assessed whether (i) the
principal herbivore fish, Sarpa salpa, is capable of modifying a seagrass trait, canopy height,
by grazing and (ii) whether grazing-induced habitat alteration can trigger an environment-mediated modification of the interaction between herbivorous sea urchins Paracentrotus lividus and
their predators.
3. We tested these hypotheses with field experiments including fish herbivore-exclusion
experiments (to examine the ability of S. salpa to modify seagrass habitats) and predation
experiments using tethered sea urchins in a meadow with varying canopy heights (to test
whether habitat modification can mediate urchin predation risk).
4. The effect of S. salpa herbivory was highly significant. Canopy height in herbivore-excluded
plots was more than 3 5 times higher than in uncaged control plots. In addition, adult sea
urchin predation risk in the most highly grazed plots was 4–5 times higher than plots with
higher canopy heights. In contrast, predation risk on juvenile urchins was not influenced by
canopy height.
5. Our results show that predation pressure on a key herbivore can be modified both by the
environmental context within which it finds itself and by the actions of another herbivore that
modifies the plant traits that create this environmental context. These act as two discrete
pathways that interact in potentially nonlinear ways, mediating top-down control in these
ecosystems. Herbivores, particularly when acting as ecosystem engineers, may have the potential to mediate and increase predation risk, as they substantially modify habitat structure, with
consequences for refuge availability, among others. Assessing these indirect interactions is
not just important to understand the functioning of the system itself but may have important
management and conservation consequences
2013-01-11T12:56:50Z
2013-01-11T12:56:50Z
2012-10
artículo
Functional Ecology 26(5) : 1015–1023 (2012)
0269-8463
http://hdl.handle.net/10261/64037
10.1111/j.1365-2435.2012.02038.x
eng
http://dx.doi.org/10.1111/j.1365-2435.2012.02038.x
closedAccess
Wiley-Blackwell