Spatial and temporal variability in the otolith chemistry of the Brazilian snapper Lutjanus alexandrei from estuarine and coastal environments

Abstract

Otolith chemistry of juvenile and adult individuals of the Brazilian snapper Lutjanus alexandrei was measured to assess the utility of natural markers for investigating individual movements. Individuals were collected over a 3-year period (2010-2012) along the north-eastern coast of Brazil from both estuarine (juvenile to sub-adult stages) and coastal (sub-adult to adult stages) areas. Six elements ((7) Li, (24) Mg, (55) Mn, (59) Co, (88) Sr and (137) Ba) were measured in sectioned otoliths of L. alexandrei using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Edge composition analysis indicated that element:Ca ratios in the otoliths of juvenile and sub-adult L. alexandrei from estuaries were not significantly different among the three consecutive years (2010, 2011 and 2012), suggesting that physicochemical conditions within the nursery area investigated were temporally stable. Similarly, apart from two elements (Ba and Co), element:Ca ratios for larger L. alexandrei inhabiting coastal waters were also similar. In contrast, otolith chemistry of similar sized L. alexandrei from estuarine and coastal areas was significantly different (based on recently accreted material). Otolith Mn:Ca and Ba:Ca were both significantly higher for L. alexandrei collected in estuaries compared to fish from adjacent coastal reefs, while the opposite trend was observed for Sr:Ca. Given the pronounced differences in otolith chemistry between estuarine and coastal areas, element:Ca transects were constructed from the core to margin of the otoliths for adults (age 7+ years) collected on reefs to determine the timing of movement (ontogenetic migration) from estuarine to coastal areas. Based on observed patterns of decline for both Mn:Ca and Ba:Ca, it appears that L. alexandrei begin the move to more coastal habitats (i.e. lower element:Ca ratios) after age 2 years. The patterns observed for this species highlight the importance of conserving connectivity between coastal habitats to maintain sustainable fish stocks exploited by artisanal fisheries.

Spatial and temporal variation in otolith chemistry and its relationship with water chemistry: Stock discrimination of Sperata aor

“…Water Sr:Ca ratios showed significant seasonal differences with lower values during the rainy season that could be due to proportionately lower contribution of Sr from silicate weathering during monsoon (Tripathy et al, 2010). Sr:Ca ratios may also be influenced by endogenous factors such as ontogeny and growth rate or both when stronger salinity gradient between habitats is lacking (Aschenbrenner, Ferreira, & Rooker, 2016;Walther, Kingsford, O'Callaghan, & McCulloch, 2010). Therefore, further studies are needed to elucidate the importance of these factors on Sr incorporation in the otoliths.…”

“…These elements in the otoliths show low enrichment; therefore, the utility of these elements in stock discrimination is limited (Thomas et al, 2017). Thus, further studies are warranted to fully understand the physiological processes governing incorporation of these elements within the otoliths and their use as an environmental marker (Aschenbrenner et al, 2016).…”

“…The elements such as Na, K, Mg and Mn have a physiological role and are essential for several cellular functions, thereby suggesting a high physiological response in their regulation (Barnes & Gillanders, 2013;Hamer & Jenkins, 2007). Thus, further studies are warranted to fully understand the physiological processes governing incorporation of these elements within the otoliths and their use as an environmental marker (Aschenbrenner et al, 2016). Thus, further studies are warranted to fully understand the physiological processes governing incorporation of these elements within the otoliths and their use as an environmental marker (Aschenbrenner et al, 2016).…”

Fine‐scale variability in elemental composition of estuarine water and otoliths: Developing environmental markers for determining larval fish dispersal histories within estuaries

“…Traditional methods using artificial physical (Thorrold et al ) or chemical (Thorrold et al ) tags, and mark recapture experiments (Warren and Pardew ), are not feasible given the constraints on animal size, tag reliability, and recovery rates. Over the past three decades, there has been growing awareness of the utility of using the chemistry of otoliths (ear bones) as natural tags to investigate movement and habitat usage in fish (Kalish ; Secor et al ; Gillanders and Kingsford ; Campana ; Swearer and Caselle ; Vasconcelos et al ; Walther and Thorrold ; Aschenbrenner et al ; Fraile et al ; Rooker et al ).…”

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

“…Diverse ecological tools may help to examine the way G. genidens uses freshwater habitats. For example, the chemical analysis of otoliths has been successfully applied to evaluate displacement patterns in migratory fishes (Thorrold et al ., 2001; Wells et al ., 2012; Aschenbrenner et al ., 2016) and to distinguish fish stocks (Campana et al ., 2000; Tabouret et al ., 2010; Fortunato et al ., 2017). This technique allows reconstruction of the chemical conditions experienced by migratory teleost fishes during their development (Campana, 1999; Elsdon et al ., 2008; Avigliano & Volpedo, 2016) and has been increasingly used over the past 20 years (Secor et al ., 1995; Patterson et al ., 2005; Albuquerque et al ., 2010; Arai et al ., 2019).…”