Can otolith elemental chemistry retrospectively track migrations in fully marine fishes?

Abstract

Otolith microchemistry can provide valuable information about stock structure and mixing patterns when the magnitude of environmental differences among areas is greater than the cumulative influence of any vital effects. Here, the current understanding of the underlying mechanisms governing element incorporation into the otolith is reviewed. Hard and soft acid and base (HSAB) theory is employed to explore the differences in chemical behaviours, distributions and affinities between elements. Hard acid cations (e.g. Mg(2+) , Li(+) and Ba(2+) ) tend to be less physiologically influenced and accepted more readily into the otolith crystal lattice but are relatively homogeneous in seawater. Soft acid cations (e.g. Zn(2+) and Cu(2+) ) on the other hand, exhibit more varied distributions in seawater, but are more likely to be bound to blood proteins and less available for uptake into the otolith. The factors influencing the geographical distribution of elements in the sea, and their incorporation into the otoliths of marine fishes are reviewed. Particular emphasis is placed on examining physiological processes, including gonad development, on the uptake of elements commonly used in population studies, notably Sr. Finally, case studies are presented that either directly or indirectly compare population structuring or movements inferred by otolith elemental fingerprints with the patterns indicated by additional, alternative proxies. The main obstacle currently limiting the application of otolith elemental microchemistry to infer movements of marine fishes appears to lie in the largely homogeneous distribution of those elements most reliably measured in the otolith. Evolving technologies will improve the discriminatory power of otolith chemistry by allowing measurement of spatially explicit, low level elements; however, for the time being, the combination of otolith minor and trace element fingerprints with alternative proxies and stable isotopic ratios can greatly extend the scope of migration studies. Among the otolith elements that routinely occur above instrument detection limits, Ba, Mn and Li were deemed the most likely to prove reliable geographic markers in marine species.

Otolith Sr:Ca ratio and morphometry as indicators of habitat of a euryhaline species: The case of the silverside Odontesthes bonariensis

“…La concentración de los elementos depositados en los otolitos puede ser afectada en gran medida por la composición química del agua y en menor medida por la temperatura y la dieta (Campana 1999, Wells et al 2003, Ranaldi y Gagnon 2008, Brown y Severin 2009, Sturrock et al 2012. En general, la concentración de Sr en los otolitos de especies de agua dulce, estuarinas y anádromas se correlaciona positivamente con la salinidad del agua (e.g., Kraus y Secor 2004, Sturrock et al 2012; sin embargo, esta relación depende de la especie y debe ser evaluada previamente a la aplicación en estudios de identificación de poblaciones pesqueras, conectividad o migración.…”

“…En general, la concentración de Sr en los otolitos de especies de agua dulce, estuarinas y anádromas se correlaciona positivamente con la salinidad del agua (e.g., Kraus y Secor 2004, Sturrock et al 2012; sin embargo, esta relación depende de la especie y debe ser evaluada previamente a la aplicación en estudios de identificación de poblaciones pesqueras, conectividad o migración. Particularmente para las especies marinas, la relación entre el Sr del otolito y la salinidad tiende a ser débil (Brown y Severin 2009, Sturrock et al 2012. Brown y Severin (2009) indicaron que la relación Sr:Ca del agua es más homogénea en ambientes marinos que en ambientes de agua dulce o ambientes salobres.…”

“…It has a mean depth of between 5 and 25 m (Guerrero et al 2010) and the electrical conductivity ranges from 67 to 30,300 S cm -1 (Avigliano and Volpedo 2013[a?]). Chascomús Lagoon is located 10 m above sea level and forms part of the lower relacionada con la concentración de los mismos en el agua (Campana 1999, Sturrock et al 2012, Avigliano 2014. Estas características, sumadas al hecho de que son estructuras metabólicamente inertes y acelulares que incorporan elementos químicos en forma constante del agua, hacen que los otolitos sean una herramienta muy útil para estudios de poblaciones pesqueras e historia de vida de los peces (Campana 1999;Avigliano y Volpedo 2013b;Avigliano et al 2014Avigliano et al , 2015aAvigliano et al , 2015bAvigliano et al , 2015c.…”

“…Cabra water and to a lesser extent by the temperature and diet (Campana 1999, Wells et al 2003, Ranaldi and Gagnon 2008, Brown and Severin 2009, Sturrock et al 2012. In general, the Sr concentration in otoliths of freshwater, estuarine, and anadromous fish species correlates positively with the salinity (e.g., Kraus andSecor 2004, Sturrock et al 2012); however, this relationship depends on the species and should be analyzed before being used in fish stock identification, connectivity, and migration studies.…”

“…The otoliths of teleost fish, located in the vestibular system, are complex polycrystalline structures composed mainly of calcium carbonate and small amounts of other minerals (trace elements) immersed in an organic matrix (Campana 1999). In certain species, the concentration of some of these elements, like strontium, barium, zinc, and magnesium, among others, is related to the their concentration in water (Campana 1999, Sturrock et al 2012, Avigliano 2014. These characteristics, coupled with the fact that they are inert and acellular metabolic structures that constantly incorporate chemical elements from water, make otoliths a useful tool for fish stock assessments and life history studies (Campana 1999; durante el estadio larval y juvenil, esta especie se alimenta principalmente de plancton, mientras que en el estadio adulto, incorpora además otros organismos como moluscos gasterópodos y crustáceos (Escalante y Grosman 2001).…”