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

Abstract

ABSTRACT. The silverside Odontesthes bonariensis is a euryhaline species native of South America and represents a very important fishing resource for the Plata Basin (Argentina and Uruguay). This study compares the Sr:Ca ratio of water as well as the Sr:Ca ratio and morphometry of the sagittal otolith of the silverside present in different environments (one salt lake, two freshwater dams, one lagoon, and one estuary) in order to evaluate the use of these variables as markers of habitat. The pattern of the Sr:Ca ratio in the water agrees with the one found in the otoliths, showing a positive relationship with the conductivity of the water. Univariate and multivariate analyses of variance indicated significant differences (P < 0.05) among the localities studied for the morphometric indices. The discriminant function analysis provided a high percentage of correctly classified individuals for the saltwater environment (100%) and the lentic water bodies and estuary (60-80%), circularity and form factor being the most relevant morphometric variables. These results indicate that the Sr:Ca ratio and otolith morphometry are good markers of habitat for this important resource.Key words: morphometry, Sr:Ca, otolith, Odontesthes bonariensis, Argentina. RESUMEN. El pejerreyOdontesthes bonariensis es una especie eurihalina nativa de Sudamérica y representa un importante recurso pesquero para la cuenca del Plata (Argentina y Uruguay). En este estudio se comparó la relación Sr:Ca del agua y la relación Sr.:Ca y morfometría de los otolitos sagittae de pejerreyes presentes en diferentes ambientes (un lago de agua salada, dos embalses de agua dulce, una laguna y un estuario) con el objetivo de evaluar el uso de estas variables como marcadores de hábitat. El patrón de la relación Sr:Ca del agua concuerda con la hallada en los otolitos, mostrando una relación positiva con la conductividad del agua. Los análisis univariados y multivariados indicaron diferencias (P < 0.05) entre las localidades estudiadas para los índices morfométricos. El análisis discriminante mostró un elevado porcentaje de individuos correctamente clasificados para el ambiente de agua salada (100%), los cuerpos de agua lenticos y el estuario (60-80%), siendo la circularidad y el factor de forma los índices morfométricos de mayor relevancia para esta clasificación. Estos resultados indican que la relación Sr:Ca y la morfometría del otolito son buenos marcadores de hábitat para este importante recurso.

Assessment of the morphometry of saccular otoliths as a tool to identify triplefin species (Tripterygiidae)

“…Campana & Casselman, 1993;Burke et al, 2008;Cañas et al, 2012;Avigliano et al, 2014), to differentiate species (e.g. Few studies use relationships based on the sulcus such as SS/OS (Gauldie, 1988, Lombarte, 1992Avigliano et al, 2014Avigliano et al, , 2015cJaramilo et al, 2014;Zhuang et al, 2014) Commonly used indexes in this paper such as OL/SuL, circularity and rectangularity were not efficient to characterize the studied species (see PCA, Figure 3). Platt & Popper, 1981;Gauldie, 1988;Lombarte et al, 2003;Volpedo & Echeverría, 2003; Volpedo & Fuchs, 2010;Jaramilo et al, 2014;Avigliano et al, 2015c), as an environmental indicator (Nelson et al, 1994;Avigliano et al, 2012Avigliano et al, , 2015c and to determine fossilized specimens (e.g.…”

“…Therefore, the taxonomic value of otoliths is well established (e.g. Platt & Popper, 1981;Gauldie, 1988;Lombarte et al, 2003;Volpedo & Echeverría, 2003; Volpedo & Fuchs, 2010;Jaramilo et al, 2014;Avigliano et al, 2015c), as an environmental indicator (Nelson et al, 1994;Avigliano et al, 2012Avigliano et al, , 2015c and to determine fossilized specimens (e.g. Because of these characteristics, otolith morphometry has been widely used to identify fish stocks (e.g.…”

Migration and brackish environment use of Prochilodus lineatus (Characiformes: Prochilodontidae) inferred by Sr:Ca ratio transects of otolith

“…For this reason, the Sr:Ca ratio of otolith has been widely used to infer migratory and population aspects of several species (Avigliano, Volpedo, 2016); for example Genidens barbus (Avigliano et al, 2015a(Avigliano et al, ,b, 2016a(Avigliano et al, , 2017b, Odontesthes bonariensis (Valenciennes, 1835) (Avigliano, Volpedo, 2013;Avigliano et al, 2014Avigliano et al, , 2015c, Mugil liza Valenciennes, 1836 7 e170055 [7] (Callicó Fortunato et al, 2017), Lycengraulis grossidens (Spix & Agassiz, 1829) (Mai et al, 2014), Micropogonias furnieri (Desmarest, 1823) (Albuquerque et al, 2012) and P. lineatus (Avigliano et al, 2016b(Avigliano et al, , 2017a. Particularly in P. lineatus it has been used the otolith microchemistry (Sr:Ca, Ba:Ca and Zn:Ca ratios) as well as otolith and scales morphometry in order to identify different nursery areas (Avigliano et al, 2016b(Avigliano et al, , 2017a.…”

Identification of nurseries areas of juvenile Prochilodus lineatus (Valenciennes, 1836) (Characiformes: Prochilodontidae) by scale and otolith morphometry and microchemistry

“…On the other hand, form factor did not showed to be a good indicator for the streaked prochilod, as well as for other species like C. rupestris (Longmore et al, 2010). However, form factor index along with ellipticity index, led to the identification of populations of O. bonariensis (Avigliano et al, 2015e). These discrepancies among different species show that the use of morphologic indices to separate breeding areas or populations is species and/or environmentally dependent, and should be correctly evaluated before their use for monitoring or population studies.…”

“…These indices showed to be a good tool as habitat indicators for other species of the same basin, like pejerrey O. bonariensis (Avigliano et al, 2015e) and river croaker Plagioscion ternetzi (Avigliano et al, 2015a). The DA classification percentages are similar to those reported by other authors (Tuset et al, 2003a;Avigliano et al, 2015e), who have indicated that the otolith shape indices can be used as natural markers, not only to separate the species, but also to identify populations or nurseries. Circularity was also a good habitat indicator for other species like Coryphaenoides rupestris (Longmore et al, 2010) and Lophius piscatorius (Cañás et al, 2012).…”