CO2-driven ocean acidification reduces larval feeding efficiency and changes food selectivity in the mollusk Concholepas concholepas

fromthe atmosphere into the oceans through a process knownas ocean acidiﬁcation (OA) (Feely et al., 2004). Theimpact of this process on marine ecosystems has only re-cently been recognized as a human-induced stressor,with potentially serious impacts for the sustainability andmanagement of many economically important marineresources (Miller et al., 2009). Within the various phylaparticularly vulnerable to OA, calcifying organisms, suchas marine mollusks, are exceptionally vulnerable (Byrne,2011). They have been recognized for their great eco-nomic value and as a food source for humans (Leiva andCastilla, 2001). Therefore, any impacts of OA on sensi-tive life-history traits of these organisms will potentiallylead to adverse ecological and economic impacts.In recent years, numerous studies have demonstratedthe negative effects of OA on marine mollusks, includingreduced growth and calciﬁcation rates (Gazeau et al.,2007; Miller et al., 2009), reduced fertilization success(Byrne et al., 2010), compromised induced defenses(Bibby et al., 2007) and impairment of immune function(Bibby et al., 2008). Although feeding could be one of thekey physiological processes affected by OA, there havebeen few reports of the effect on feeding behavior in bothadult and/or larval stages of marine mollusks (Stumppet al., 2011;Barton et al., 2012). Feeding processes duringearly life stages of marine invertebrates are likely to bemore sensitive to OA than in adults (Findlay et al., 2008,2010). Moreover, OA has been shown to induce morpho-logical changes in larval invertebrates with signiﬁcantimplications for feeding performance and food selectivity(Chan et al., 2011). In consequence, since it is well knownthat food quantity and quality greatly inﬂuences larvalsurvival, development and growth (Boidron-Me´tairon,1995), the inﬂuence of OA on feeding may explainobserved impacts on these physiological traits and onotherenergydependent processes including calciﬁcation. Here, we selected an important species of the rockyintertidal and sub-tidal communities of the Chileancoast, in the Southern Paciﬁc Ocean, the carnivorousgastropod known as “loco” (Chilean abalone), Concholepasconcholepas (Brugie`re, 1789) (Castilla, 1999). Concholepasconcholepas is an economically and ecologically importantcomponent of the rocky intertidal and sub -tidal commu-nities along the Chilean coast (Castilla, 1999). After 1 to2 months of intra-capsular development, the veligerlarvae hatch from clumps of benthic egg capsules atabout 240–260 mm protoconch length (DiSalvo, 1988). The competent larval stage (i.e. larvae ready to settle) isreached after about 3 months at a protoconch sizebetween 1600 and 1900 mm(DiSalvo, 1988), which cor-responds to the time lapse between maximal abundanceof egg capsules and peak abundance of competent larvaein the water (Manri´quez and Castilla, 2001). Then, theyrequire from 3 to 12 months of planktonic life to reachcompetence and settling on the rocky shore (Gallardo,1973). We conducted incubation experiments to investi-gate the effect of CO