Effects of salinity gradients on larval growth and otolith asymmetry of austral hake Merluccius australis

Abstract

ABSTRACT. Austral hake Merluccius australis sustain an important demersal fishery in South Pacific and Atlantic oceans. The main spawning and nursery areas are in the Chilean Patagonia, which is characterized by large inputs of freshwater from rivers and ice melting. The spatial distribution of larval austral hake M. australis was studied during spring, and the potential effects of oceanographic conditions (temperature, salinity, vertical stability and turbidity) on early life traits, derived from sagitta otolith microstructure analysis, size-at-age (SAR), individual larval growth (IGR) and bilateral asymmetry (FA6). Larval abundance ranged between 0.86 and 41.55 ind 1000 m -3 (median: 4.08 ind 1000 m -3) and population larval growth estimated by micro-increment counts of sagitta otoliths was 0.129 ± 0.010 mm d -1 , with age varying from 4 to 24 days old. All three indicators derived from otolith analysis (SAR, IGR, and FA6) showed positive and significant correlations with vertical salinity gradients; IGR and FA6 were also positively correlated to Brunt-Väisälä frequency (vertical stability) and FA6 was correlated to turbidity. Therefore, larval M. australis were larger-at-age, grew faster and showed more asymmetry in areas with more influence of freshwater runoff in south Pacific Patagonia.

Unraveling the morphological patterns of a subantarctic eelpout: a geometric morphometric approach

“…The major content of freshwater is located off central Patagonia, where the low-salinity surface layer dominates the stratification of the upper ocean (Saldías et al 2019). This latitudinal variability has significant effects on several characteristics of marine fishes throughout the ontogeny, such as growth, survival, and bilateral symmetry (Landaeta et al 2012(Landaeta et al , 2018Molina-Valdivia et al 2021). Additionally, species with large latitudinal distribution show shallower bodies with a smaller head at higher latitudes (Riesch et al 2018), similar to our results.…”

“…This latitudinal variability has significant effects on several characteristics of marine fishes throughout the ontogeny, such as growth, survival, and bilateral symmetry (Landaeta et al. 2012, 2018; Molina‐Valdivia et al. 2021).…”

Evaluating environmental forcing on nutritional condition of Engraulis anchoita larvae in a productive area of the Southwestern Atlantic Ocean

“…Recent studies have shown that freshwater input may affect negatively early life stages of marine fishes, altering dispersion patterns, feeding habits and condition (Landaeta et al, 2012(Landaeta et al, , 2018. During 2012/2013, freshwater input was more important than during the previous sampling.…”

Positive temperature effects on the initiation and intensity of cannibalistic behaviour of larval pike, Esox lucius L. Is cannibalism reflected in otolith fluctuating asymmetry?

“…FA is reported to be a useful method to test in various fish species the environmental effects of El Nino conditions (Alados et al,1993), temperature (Lu & Bernatchez, 1999), pollution (Hardersen, 2000), parasitism (Escós et al, 1995;Loot et al, 2001), salinity (Panfili et al, 2005), and fecundity (Hechter et al, 2000). FA is also useful as an indicator of larval fish condition (Grønkjaer & Sand, 2003;Somarakis et al, 1997b) and stress (Gagliano et al, 2008;Lemberget & McCornick, 2009;Castillo-Hidalgo et al, 2018;Landaeta et al, 2018), even if the results obtained by Castillo-Hidalgo et al (2018) were inconsistent. Most recently, Fey et al (2020) showed for larval trout the significant effect of a magnetic field of 10 mT on otolith FA of larval trout.…”