Asymmetric competition prevents the outbreak of an opportunistic species after coral reef degradation
Authored by Peter J Mumby, Manuel Gonzalez-Rivero, Yves-Marie Bozec, Iliana Chollett, Renata Ferrari, Christine H L Schoenberg
Date Published: 2016
DOI: 10.1007/s00442-015-3541-x
Sponsors:
United Kingdom Natural Environment Research Council (NERC)
Wildlife Conservation Society
Platforms:
No platforms listed
Model Documentation:
ODD
Flow charts
Mathematical description
Model Code URLs:
Model code not found
Abstract
Disturbance releases space and allows the growth of opportunistic
species, excluded by the old stands, with a potential to alter community
dynamics. In coral reefs, abundances of fast-growing, and
disturbance-tolerant sponges are expected to increase and dominate as
space becomes available following acute coral mortality events. Yet, an
increase in abundance of these opportunistic species has been reported
in only a few studies, suggesting certain mechanisms may be acting to
regulate sponge populations. To gain insights into mechanisms of
population control, we simulated the dynamics of the common
reef-excavating sponge Cliona tenuis in the Caribbean using an
individual-based model. An orthogonal hypothesis testing approach was
used, where four candidate mechanisms-algal competition, stock-recruitment limitation, whole and partial mortality-were
incorporated sequentially into the model and the results were tested
against independent field observations taken over a decade in Belize, Central America. We found that releasing space after coral mortality can
promote C. tenuis outbreaks, but such outbreaks can be curtailed by
macroalgal competition. The asymmetrical competitive superiority of
macroalgae, given by their capacity to pre-empt space and outcompete
with the sponge in a size-dependant fashion, supports their capacity to
steal the opportunity from other opportunists. While multiple system
stages can be expected in coral reefs following intense perturbation
macroalgae may prevent the growth of other space-occupiers, such as
bioeroding sponges, under low grazing pressure.
Tags
long-term
growth
Field experiments
Population-dynamics
Phase-shifts
Life-history
Interspecific competition
Scleractinian corals
Excavating sponge
Caribbean
corals