Taxonomic and geographic influences on fish otolith microchemistry

Abstract

Fish otoliths are comprised primarily of CaCO3 and grow throughout an individual's lifetime. The chemical composition of otoliths is often a distinctive characteristic of the populations that live in discrete areas, and as a result, it has been used for population classification studies, supporting ecological and fisheries research. However, the deposition of chemical elements in the otolith is influenced by both physiological and environmental factors. We review observed trends in otolith elemental composition and then test the taxonomic and geographical patterns, using marine species in European waters. anova comparisons and multivariate analyses revealed strong taxonomic signals in species inhabiting the same region. Variations in Sr, Mg, Mn and Ba concentrations were most often species specific; for example, multivariate analyses showed separation of cod (Gadus morhua) and herring (Clupea harengus) based primarily on Mg and Sr concentrations, while Mn and Ba concentrations separated bluemouth (Helicolenus dactylopterus) and sole (Solea solea). The relative contributions of taxonomic and regional factors varied between elements. For cod and herring, for example, species‐specific differences explain 75% of the variation for Mn, but only 50% of the variation in Sr. Although there are significant regional differences within a single species on both a restricted and extensive geographic scale, these regional patterns are not the same for each species. As the amount of otolith composition data increases, representing more species and regions, as well as longer time series, further analyses can provide a deeper insight into the predictability of using otolith data in fisheries ecology.

Daily otolith growth and ontogenetic geochemical signatures of age-0 anchovy (Engraulis encrasicolus) in the Gulf of Cádiz (SW Spain).

“…The usefulness of detecting changes in salinity through the analysis of Sr, Ba and Mg in otoliths has been highlighted in general terms, but data interpretation must account for multiple sources of variation including speciesspecificity, temperature and growth effects (reviewed in Campana, 1999;Elsdon et al, 2008;Sturrock et al, 2012;Chang & Geffen, 2013). One concern in the use of otolith geotags to track changes in water characteristics is linked to the effect of physiology in ion incorporation (e.g.…”

Interspecific variation in juvenile snapper otolith chemical signatures in the northern Gulf of Mexico

“…Normalizing the data also had no effect on Authors of other studies have reported significant differences in otolith chemical signatures among species sampled from the same nursery habitats or systems (Gillanders & Kingsford 2003, Hamer & Jenkins 2007, Reis-Santos et al 2008. Typically, co-located species which are more closely related phylogenetically and ecologically tend to have more similar otolith chemical signatures (reviewed in Chang & Geffen 2013). For example, Brown (2006) reported otolith elemental composition was similar between juvenile flatfishes English sole Pleuronectes vetulus and speckled sanddab Citharichthys stigmaeus co-located among 3 regions along the coast of California, and that mean regionspecific LDF classification accuracies differed little when species were modeled separately (78 and 79%, respectively) versus jointly (77%).…”

“…Otolith chemical signatures have been shown to be effective natural tags in fishes, and examining population connectivity and estimating nursery sources with otolith chemical signatures has become widespread in fish ecology (reviewed in Campana & Thorrold 2001, Elsdon et al 2008, Chang & Geffen 2013. Employing otolith chemical signatures has been particularly effective for examining recruitment dynamics and population connectivity in estuarinedependent and diadromous fishes.…”

“…Juveniles typically spend at least their first year of life associated with these habitats prior to recruiting to reefs later in their second year of life, and their feeding ecologies overlap as well, with juvenile diets consisting principally of zooplankton, benthic invertebrates, squids, and transitioning to greater piscivory with ontogeny (Franks & VanderKooy 2000, W. F. Patterson et al 2005, McCawley & Cowan 2007, Mikulas & Rooker 2008. Therefore, few species are as similar phylogenetically and ecologically in the northern GOM as red and lane snappers, factors that Swearer et al (2003) and Chang & Geffen (2013) concluded had great influence on the similarity of otolith chemical signatures between species. A variety of factors, such as salinity, temperature, growth, or food, can affect the incorporation of constituents examined in red and lane snapper otoliths (Elsdon et al 2008, Chang & Geffen 2013.…”

“…Therefore, few species are as similar phylogenetically and ecologically in the northern GOM as red and lane snappers, factors that Swearer et al (2003) and Chang & Geffen (2013) concluded had great influence on the similarity of otolith chemical signatures between species. A variety of factors, such as salinity, temperature, growth, or food, can affect the incorporation of constituents examined in red and lane snapper otoliths (Elsdon et al 2008, Chang & Geffen 2013. For example, Sr and Ba concentrations in otoliths of several species, including gray snapper Lutjanus griseus, have been shown to reflect ambient concentrations in water, although their incorporation into otoliths may be affected to a lesser extent by water temperature and growth rate (Bath et al 2000, Elsdon & Gillanders 2002, Martin & Wuenschel 2006, Walther & Thorrold 2006.…”