Intraspecific variability of the saccular and utricular otoliths of the hatchetfish Argyropelecus hemigymnus (Cocco, 1829) from the Strait of Messina (Central Mediterranean Sea)

Abstract

Mesopelagic species are enjoining increasing attention due to the growing impact of fisheries activities on deep marine biocenosis. Improving the knowledge base on mesopelagic species is required to enhance their conservation due to the knowledge gaps regarding many species and families. In this context, otoliths can be fundamental to assessing their life history, ecomorphological adaptation to the deep environment and stock composition. The present paper aims to explore the saccular and utricular otoliths morphology and intra-specific variability of the hatchetfish, Argyropelecus hemigymnus, from the Strait of Messina. Lapilli and sagittae were collected from 70 specimens and separated into four size classes. Morphometric, shape and SEM investigations were performed to describe their morphology, contours, and external structural organization, also studying their intraspecific variability related to sample sizes and differences between otolith pairs. Results showed an otolith morphology different from those reported in the literature with fluctuating asymmetry in sagittae and lapilli belonging to Class IV, and a high otolith variability between all the size classes. Data herein described confirm the otoliths singularity of the population from the Strait of Messina, shaped by a unique marine environment for oceanographic and ecological features.

Asymmetry of Sagittal Otolith Shape Based on Inner Ear Side Tested on Mediterranean Red Mullet (Mullus barbatus Linnaeus, 1758): Comparative Analysis of 2D and 3D Otolith Shape Data

“…The projection described by Gonçalves et al [110] was mainly used in 2D shape analysis to identify stocks, but it cannot be used to analyse the sulcus acusticus. Previous studies have attempted to examine the size and shape of this part of the otolith using 2D shape analysis [111][112][113]. However, these approaches have limitations, as they do not take into account the depth of this structure.…”

Geographic Variation in Opisthonema oglinum (Lesueur, 1818) in the Southeastern Brazilian Bight Inferred from Otolith Shape and Chemical Signatures

“…Sixteen minor and trace elements ( 137 Ba, 111 Cd, 52 Cr, 59 Co, 65 Cu, 7 Li, 25 Mg, 55 Mn, 23 Na 60 Ni, 208 Pb, 85 Rb, 121 Sb, 82 Se, 88 Sr, and 66 Zn), plus the calcium ( 44 Ca), were analyzed with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) using an iCAP 227 TM Q 228 (Thermo Fisher Scientific, Bremen, Germany) instrument equipped with a concentric glass nebulizer, a Peltier-cooled baffled cyclonic spray chamber, a standard quartz torch, and a two-cone interface design (nickel sample and skimmer cones). Argon of high purity (99.9997%, Gasin II, Leça da Palmeira, Portugal) was used as the nebulizer and plasma gas.…”

“…Thus, otoliths are suitable tools to evaluate individual phenotypic geographic variations at the stock, population, or subpopulation level, which requires appropriate sampling designs, methodological approaches, and study goals [9,10,12]. The sagitta is usually the largest and thus the most used in previous studies, although the other otoliths are also useful and informative for these purposes [21][22][23][24][25].…”

Discriminant inter and intrapopulation variation in sagittal otolith shape and morphometry in Chelon ramada (Actinopterygii, Mugilidae) from the Boughrara and El Bibane lagoons in Tunisian waters

“…species-specific features (Callicó Fortunato et al ., 2014; Avigliano et al ., 2016; Ferri et al ., 2018; Mejri et al ., 2022b). In addition, these otoliths have been documented to show variations in morphologies (shape and morphometry) at both the inter and intraspecific levels (Ferri et al ., 2018; Tuset et al ., 2018; Ben Labidi et al ., 2020b; Mejri et al ., 2020, 2022b; Khedher et al ., 2021; D'Iglio et al ., 2023) and their morphometry, in particular, has a close relationship to fish body size (Martucci et al ., 1993). In addition, it has been shown that these variations are influenced by several factors, including genetic (Vignon and Morat, 2010; Berg et al ., 2018), ontogenetic (Hüssy, 2008; Capoccioni et al ., 2011), physiological (Lombarte and Cruz, 2007; Schulz-Mirbach et al ., 2019), phylogeny (Campana and Neilson, 1985; Torres et al ., 2000), and exogenous factors, such as living depth (Wilson, 1985; Lombarte and Lleonart, 1993), temperature (Lombarte and Lleonart, 1993) and salinity of the water (Capoccioni et al ., 2011), and food supplies (Gagliano and McCormick, 2004; Hüssy, 2008; Bremm and Schulz, 2014).…”