Decreased Sr/Ca ratios in the otoliths of two marine eels, Gymnothorax reticularis and Muraenesox cinereus, during metamorphosis

Abstract

Sr/Ca ratios in the otoliths of 2 marine eels, the moray eel Gymnothorax reticularis and the pike eel Muraenesox cinereus, decreased greatly when the crystal structure of otolith daily growth increments changed from concentric to radiate form. This decrease is proposed to correspond to the timing of metamorphosis from the leptocephalus to glass eel stage, similar to freshwater eels (Anguilla spp.). In freshwater eels, ontogenetic and habitat shifts might influence the decrease. However, marine eels do not migrate into freshwater after completing metamorphosis, so the decrease in these species must be the result of metamorphosis-related physiological, rather than environmental, effects. The mean age at metamorphosis of the moray eels was significantly lower than that of pike eels, and both were lower than that of freshwater eels (p < 0.05). Consequently, the spawning ground of marine eels is presumed to be closer than that of freshwater eels to the continental shelf.

Ecology of Anguilliform Leptocephali: Remarkable Transparent Fish Larvae of the Ocean Surface Layer

“…The other tropical and temperate species of glass eels that have been examined generally have larval durations within this range (see Aoyama 2009 for a recent review), but the European eel may have a longer larval duration than any other species (see Kuroki et al 2008b). The same pattern of increment widths during metamorphosis has been observed in the Atlantic species of Conger, whose ages at metamorphosis have been estimated using this method (Correia et al 2003(Correia et al , 2004 and in a species of muraenid (Ling et al 2005).…”

Femtosecond laser ablation ICP‐MS measurement of otolith Sr:Ca and Ba:Ca composition reveal differential use of freshwater habitats for three amphidromous Sicyopterus (Teleostei: Gobioidei: Sicydiinae) species

“…Indeed, for the flatfish Solea solea (L. 1758), specimens shift to a benthic life after metamorphosis and the drop in Sr:Ca that was observed during this change was attributed to a high metabolic rate rather than a shift from a marine to an estuarine location (De Pontual et al , 2003). For two marine eels [ Gymnothorax reticularis Bloch 1795 and Muraenesox cinereus (Forsskål 1775)], the Sr:Ca ratio decreases during metamorphosis although they are strictly marine species (Ling et al , 2005). In this study, however, the low Sr:Ca values observed from the metamorphosis check mark to the edge of the otolith were consistent with those attributed to a freshwater habitat occupation in Anguillidae (Tabouret et al , 2010), Rhinogobius (Tsunagawa & Arai, 2008) and Sicydiinae species (Radtke & Kinzie, 1996; Shen & Tzeng, 2002; Chang et al , 2006).…”

Phylogenetic relationships of twenty Gymnothorax species based on cytochrome b sequence data

“…For example, Gilbert et al (2005) estimated the density and biomass of moray eels (Muraenidae). In another study, Ling reported a decrease in the Sr/Ca ratios in the otoliths of Gymnothorax reticularis during metamorphosis (Ling et al, 2005). In addition, Tamburrini et al (2001) studied the structure/function relationships of the brown moray (Gymnothorax unicolor) hemoglobin system.…”