Synergistic effects of reserves and connectivity on
Andrew D. Olds*, Kylie A. Pitt, Paul S. Maxwell and Rod M. Connolly
Australian Rivers Institute – Coast and Estuaries and School of Environment, Grifﬁth University, Gold Coast, Qld,
In light of the global extent and cascading effect of our impact on the environment, we
design and manage reserves to restore biodiversity and the functioning of ecosystems. Mobile
organisms link important processes across ecosystems, however, their roles in providing these
services are often overlooked and we need to know how they inﬂuence ecosystem functions in
reserves. Herbivorous ﬁsh play a key role in coral reef seascapes. By removing algae, they
promote coral growth and recruitment, and help to increase resilience.
We examined how connectivity with mangroves affected herbivore populations and ben-
thic succession on reefs in eastern Australia. We surveyed ﬁsh assemblages, examined reef
composition and characterised benthic recruitment on reefs at multiple levels of connectivity
with mangroves, in a no-take reserve and areas open to ﬁshing.
Our results show that connectivity enhanced herbivore biomass and richness in reserves,
and that these connectivity and reserve effects interacted to promote herbivory on protected
reefs near mangroves.
Connectivity and reserve protection combined to double the biomass of roving herbivo-
rous ﬁsh on protected reefs near mangroves. The increase in grazing intensity drove a trophic
cascade that reduced algal cover and enhanced coral recruitment and reef resilience.
Synthesis and applications. Our ﬁndings demonstrate that ecosystem resilience can be
improved by managing both reefs and adjacent habitats together as functional seascape units.
By understanding how landscapes inﬂuence resilience, and explicitly incorporating these
effects into conservation decision-making, we may have greater success with environmental
restoration and preservation actions.
Key-words: Australia, coral reef, ﬁsh, herbivory, landscape ecology, mangroves, marine re-
serve, trophic cascade
Conservation and restoration activities are focussed on
the maintenance or creation of resilient, functioning eco-
systems (Cadotte, Carscadden & Mirotchnick 2011).
Mobile organisms enhance ecological resilience by linking
ecosystem functions across landscapes (Nystro
m & Folke
2001; Lundberg & Moberg 2003). These species connect
ecological processes (e.g. Mumby & Hastings 2008) and
food webs (e.g. Polis, Anderson & Holt 1997) through
space. Until recently, however, their role in providing
these ecosystem services has received little consideration
(Massol et al. 2011). Spatial ecology and ecosystem
functioning are now integrated into conservation through
ecosystem-based management (e.g. Foley et al. 2010),
which is focussed on the protection of multiple species,
ecosystem processes and values, and may improve our
ability to manage processes across whole ecosystems
(Massol et al. 2011). Several recent studies have explored
incorporating connectivity into conservation planning (e.g.
Beger et al. 2010; Edwards et al. 2010), but to better
inform decision-making, we now require evaluation of its
effects on ecosystem functioning in reserves.
The movement of organisms and materials across land-
scapes is commonly called connectivity and is important
for maintaining ecological processes. Broadly speaking,
connectivity is a function of habitat area, quality and
arrangement, and the dispersal capabilities of individual
species (Hodgson et al. 2009). We deﬁne habitat as units
*Correspondence author. E-mail: a.olds@grifﬁth.edu.au
© 2012 The Authors. Journal of Applied Ecology © 2012 British Ecological Society
Journal of Applied Ecology 2012, 49, 1195–1203 doi: 10.1111/jpe.12002