Page 2 - 4022883

700 BIOLOGICAL CONSERVATION 141 (2008) 699–709
particularly to avoid that positive ecological responses in properly managed reserves can be
masked by neutral/negative results in paper parks. Positive responses were observed for
large piscivores (e.g. dusky groupers) and sea urchin predators at reserves where enforce-
ment was effective. Those reserves with low or null enforcement did not differ from fished
areas.
1. Introduction
Generally speaking, marine protected areas (MPAs) refer to
portions of the coastline and/or sea where human activities,
especially fishing, are restricted or banned (Agardy et al.,
2003). As fish assemblages usually include many species tar-
geted by fishing, they are primarily expected to benefit from
protection within MPAs, especially those having no-take re-
serves (Dayton et al., 1995; Micheli et al., 2004; McClanahan
et al., 2007). The evaluation of these benefits, in terms of in-
crease in density and size of target fishes (Mosquera et al.,
2000; Coˆ te´ et al., 2001; Halpern, 2003; Micheli et al., 2004; Clau- size from 120 to more than 50,000 hectares in total surface
det et al., 2006; Guidetti and Sala, 2007), can be useful to as-
sess the ecological effectiveness of reserves. Moreover, most
target fishes are high-level predators and their functional
extinction may cause community-wide changes (Sala et al.,
1998; Jackson et al., 2001). Protection from fishing, therefore,
may directly restore populations of target fishes and indi-
rectly drive whole communities towards an unfished state
(Sala et al., 1998; Shears and Babcock, 2002; Micheli et al.,
2004; Bevilacqua et al., 2006; Guidetti, 2006). We use hereafter
the term ‘ecological effectiveness’ of marine reserves to de-
fine the responses to protection from fishing encompassing
direct and indirect effects.
Marine reserve studies have undoubtedly improved our
understanding of the unfished state of ecosystems and target
populations (Shears and Babcock, 2002; Guidetti and Sala,
2007). It is common wisdom, however, that a number of re-
serves do not meet their potential ecological objectives and
that negative/neutral results in reserve studies are mostly
underreported in the literature (Halpern and Warner, 2002).
Failing reserves are attributable to causes like inappropriate
design (Sala et al., 2002) or ineffective enforcement (Mora
et al., 2006), which may be overlooked if negative/neutral re-
sults are not taken into account.
It is becoming increasingly recognized that a large pro-
portion of marine reserves around the world receive inef-
fective enforcement. These are the so-called ‘paper parks’,
where protection occurs only in theory (Mora et al., 2006).
In such cases the use of proper sampling designs suggested
by many authors to properly investigate reserve effective-
ness (CIESM, 1999; Guidetti, 2002), e.g. by comparing
replicated ‘reserve vs fished’ sites, is useless. In fact, the
comparison ‘reserve vs fished’ sites makes sense only if
protection really occurs. The scant information in many
published studies about compliance and enforcement at
the reserves investigated makes the interpretation of
results uncertain. A major effort, therefore, is needed to
make inferences about reserve effectiveness, paying special
attention whenever data from both well-enforced and paper
Ó 2007 Elsevier Ltd. All rights reserved.
reserves are pooled to extract general patterns (e.g. in
meta-analyses). Pooling data from enforced reserves and
from paper parks carries the risk of incorrectly downplay-
ing the importance of reserves because neutral results from
paper parks could mask the positive responses of well-en-
forced reserves.
In the Mediterranean Sea there has been a rush in recent
years to establish MPAs and reserves (Juanes, 2001). In Italy
there are currently 25 MPAs formally established (with more
than 20 in the process of becoming established), ranging in
area. Italian MPAs include one or more no-take/no-access
zones (hereafter called ‘reserves’ in the text and formally de-
fined as ‘A zones’ according to Italian law), surrounded by buf-
fer zones (defined as ‘B and C zones’, where restrictions to
human uses, including fishing, become progressively more
lax) (Villa et al., 2002).
Previous studies that investigated fish response to protec-
tion within Italian marine reserves showed (1) positive effects
(Vacchi et al., 1998; Guidetti et al., 2005; Guidetti, 2006) or neu-
tral results (Tunesi et al., 2006) on fish density and size, and (2)
no obvious patterns in terms of community shifts (Sala et al.,
1998; Guidetti et al., 2005; Micheli et al., 2005; Guidetti, 2006;
Guidetti and Sala, 2007). As regards the community shift,
two target sea breams, i.e. Diplodus sargus and Diplodus vulga-
ris, have been identified as the most effective predators of sea
urchins, with the latter being the most important grazer in
rocky reefs (Sala et al., 1998). When released from predation
control, sea urchins may increase in density and overfeed
on macroalgae, which in turn may cause the transition from
macroalgal beds to barrens (Sala et al., 1998). Since the recov-
ery of sea breams (and other predator fish) was observed
within reserves, along with lower urchin density and less
extended barrens (Guidetti and Sala, 2007), Diplodus density
can be assumed to be an index of the potential of reserves
to recover from barrens to algal beds or to maintain flourish-
ing algal beds.
In spite of the increasing number of MPAs in Italy, no
general evaluations have been done to assess the ecological
responses to protection from fishing. A nation-wide project,
named ‘‘Sistema Afrodite’’, was thus started in 2002 (Greco
et al., 2004), with the aim of allowing a balanced assessment
of the actual effectiveness of marine reserves in the country
(including potential neutral/negative results).
This paper is intended to (1) assess the effects of different
levels of enforcement on the ecological effectiveness of re-
serves (i.e. direct and indirect effects), and (2) highlight the
risk of misinterpreting analyses about the effectiveness of
multiple marine reserves whenever the enforcement is not
properly taken into account.