Influence of trophic pathways on daily growth patterns of western Mediterranean anchovy Engraulis encrasicolus larvae

Abstract

Late larval stages of anchovy Engraulis encrasicolus ranging from 10 to 20 mm standard length were sampled in the 2009 Mediterranean Acoustic Surveys project carried out during the spawning season off the Ebro River plume (NW Mediterranean [NWM] population) and the Bay of Málaga (SW Mediterranean [SWM] population). A combined study of environmental variables, daily growth, otolith biometry and stable isotope analysis (SIA) was undertaken to differentiate the trophic influence on larval growth rates. An inter-population comparative analysis determined trophic-based differences in their growth patterns. The NWM population showed a specialized prey selectivity associated with a low productive ecosystem in contrast to the SWM population, which showed a more generalist feeding behavior associated with an ecosystem of higher food resources. Moreover, δ 13 C values were significantly different between populations, indicating the different origin of carbon sources. The intra-population analysis, differentiating between an optimum and deficient growth group as defined by a prior residual analysis, showed a direct relationship between growth potential and feeding behavior. Higher growth rates registered significantly greater δ 15 N values and thereby showed a higher trophic position, indicating a greater feeding specialization in larvae originating from less productive regions. Such was not the case in the area of higher productivity. Furthermore, both populations showed that carbon sources were decisive in defining better growth potential. Finally, otolith biometry clearly differentiated between growth rates in the optimum and deficient larval growth groups.

Anchovy (<em>Engraulis encrasicolus</em>) otoliths reveal growth differences between two areas of the Spanish Mediterranean Sea

“…Similar results have been reported in genetic studies (Sanz et al 2008, Zarraonaindia et al 2012, Viñas et al 2013) and in studies on larval growth (Quintanilla et al 2015). Moreover, similar differences in growth by area have also been observed for sardine (Sardina pilchardus) in the Spanish Mediterranean Sea (Alemany and Álvarez 1993).…”

Isotopic discrimination factors and nitrogen turnover rates in reared Atlantic bluefin tuna larvae (<em>Thunnus thynnus</em>): effects of maternal transmission

“…Nevertheless, a posterior correction of the δ 13 C values for lipid content in ABFT larvae and preys was estimated using the model proposed by Logan et al (2008). This empirical lipid correction has been previously used in fish larvae (Laiz-Carrión et al 2013, Quintanilla et al 2015.…”

“…Maternal qualities related to condition may be relevant to growth potential of larvae (Marteinsdottir and Steinarsson 1998, Green and McCormick 2005, Swain and Nayak 2009, Perez and Fuiman 2015. Under natural conditions, higher values of δ 15 N have shown greater growth potential in bullet tuna larvae (Auxis rochei) and in the Mediterranean anchovy (Engraulis encrasicolus) (Laiz-Carrión et al 2011, Quintanilla et al 2015. Thus, it is reasonable to assume that isotopic values of mother-offspring provide relevant information on the trophic position of the broodstock and may reflect larval growth characteristics as well as migratory patterns between populations (Hoffman et al 2011, Le Bourg et al 2014).…”

“…An alternative approach to understanding early life trophodynamics of larvae without examining gut contents is to estimate the natural content of the stable isotopes of nitrogen and carbon. Stable isotopes can elucidate the feeding niches of a particular species, detect their ontogenetic trophic shifts (Pepin and Dower 2007, Laiz-Carrión et al 2013, Quintanilla et al 2015, estimate the relative diet breadth (Sweeting et al 2007a, 2007b, Tanaka et al 2014) and analyse migration patterns (Rooker et al 2007). This technique is increasingly being applied in the study of trophic food web dynamics of marine ecosystems (Bode et al 2007, Logan et al 2010, Costalago et al 2012, Quintanilla et al 2015.…”

“…SIA has proven to be a potential tool to study trophic ecology of wild-caught fish larvae (Laiz-Carrión et al 2011, Quintanilla et al 2015. But field research still needs experimental proof to understand the patterns of ontogenic-related feeding shifts and isotopic variations (Gamboa-Delgado et al 2008, Varela et al 2011, Tanaka et al 2014.…”