Use of fresh water by an estuarine-resident marine catfish: evidence from gonadal and otolith chemistry analyses

Abstract

In this study, we examine how the Guri catfish Genidens genidens uses estuarine and freshwater habitats along the largest South American coastal lagoon, through the chemical analysis of otoliths and microscopic analysis of gonads. Chemical composition (Sr:Ca) of otolith edges allowed distinguishing between individuals who used the estuarine or freshwater compartments of the lagoon. The analysis of core-to-edge chemical profiles of each individual otolith revealed that the population may present two different patterns of habitat use along the lagoon. The ‘type 1’ pattern (89.5%) includes fish who appear to have been born in estuarine waters, whereas ‘type 2’ (9.5%) includes those fish born in fresh water. Nevertheless, juveniles from both patterns appear to migrate to estuarine waters. The gonad analysis shows G. genidens may reproduce in fresh water, as nearly 57% of all sampled fish were found to spawn in the freshwater portion of the lagoon. Also, the otolith core of many adult fish presented freshwater signatures, thus suggesting consistent fresh water use during early life. Our findings based on otolith and gonadal analyses challenge the previous classification of G. genidens as an estuarine resident. Rather, our results allow the suggestion that this species should be placed in the ‘estuarine and fresh water’ guild, which includes both fish completing their life cycles within the estuary and fish who consistently use freshwater habitats.

Fish otoliths from the middle Miocene Pebas Formation of the Peruvian Amazon

“…The catfishes of the family Ariidae are primarily marine and brackish water fishes; however, many of them also occur in estuaries, and some migrate upstream in rivers. Chemical analyses of otolith and tissues of modern species support extensive movement of ariids throughout freshwater, estuarine, and marine habits (Avigliano et al, 2017;Condini et al, 2019;Pusey et al, 2020). In North, Central, and South America, five extant ariids species are found, primarily in fresh water (Betancur-R & Willink, 2007;Hubbs & Miller, 1960;Marceniuk & Menezes, 2007;Marceniuk et al, 2019).…”

Morphometric analysis of lapillus otoliths in two estuarine bioindicator catfish (Siluriformes, Ariidae) from a marine protected area in Brazil

“…In this context, some authors have used lapillus otoliths to determine age and growth in populations of ariids that inhabit the Brazilian coast, such as Genidens genidens, Genidens barbus, Netuma barba, and Sciades proops (Reis, 1986;Oliveira and Novelli, 2005;Carvalho, et al, 2014;Freire et al, 2017;Maciel et al, 2018Maciel et al, , 2019. Some studies on otolith morphometrics in ariids have also been performed to aid in species identification (Chen et al, 2008;Vaz-dos-Santos, 2015), differentiation of sexual dimorphism (Maciel et al, 2019), and as an indication of habit use and movement between regions of the species by chemical evaluation (i.e., Ca/Sr, Ca/Ba) in lapillus otoliths (Avigliano et al, 2015(Avigliano et al, , 2020(Avigliano et al, , 2021Fortunato et al, 2017;Condini et al, 2019;Maciel et al, 2020). Finally, lapillus otoliths of C. spixii have been used to compare with those of the species G. genidens (Carvalho et al, 2014), and these structures have been used in assessments of the somatic growth-otolith growth relationship (Azevedo et al, 2019).…”