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

Abstract

Otolith chemistry has been widely used as a natural tag for determining environmental histories of fish that migrate across large distances and environmental gradients. However, it is not as well established as to whether otolith chemistry can be a useful tool for determining fine-scale movement and dispersal patterns of fish, particularly larvae, within estuaries. In this study, we collected water samples and otoliths from larvae of black bream, Acanthopagrus butcheri, an estuarine resident fish, and analyzed each for a suite of trace elements to determine the degree of spatio-temporal variability in elemental composition and which elements were incorporated into otoliths in relation to their associated water chemistry. We found that there were three distinct water layer signatures based on their Me : Ca water (Me 5 each element): a freshwater signature, a halocline signature, and a marine signature. There were also significant spatio-temporal patterns in Me : Ca otolith , most notably for Li : Ca, K : Ca, and Mn : Ca. This study provides encouraging evidence for the utility of intra-estuary otolith chemistry to reconstruct environmental histories during larval development. This application will enable a better understanding of the abundance, timing, and duration of residency in particular water masses and locations that are important larval nursery habitats for species that develop within estuaries.

Otolith chemistry does not just reflect environmental conditions: A meta‐analytic evaluation

“…Overall, temporal lags in element incorporation may limit the application of these elements as environmental tracers of individual movements or environment change if fish move rapidly among multiple heterogeneous environments, or if the environment fluctuates over time, thus affecting the fidelity of the spatial specificity of elemental signatures. In relation to estuarine sites where daily and seasonal changes in water chemical profiles occur (Elsdon & Gillanders, ; Walther & Nims, ), otolith chemistry has shown mixed results as a proxy of in situ water chemistry (e.g., Chittaro, Hogan, Gagnon, Fryer, & Sale, ; Dorval, Jones, Hannigan, & van Montfrans, ; Tanner et al., ; Williams, Jenkins, Hindell, & Swearer, ).…”

Discrimination of Wild and Hatchery-Reared Black Porgy <i>Acanthopagrus schlegelii</i> Using Otolith Elements Analysis of Magnesium and Manganese

“…However, the lower concentrations of Sr 2+ observed in the European hake [28] differed from those observed in black porgy in this study, potentially due to the freshwater that was added, which was groundwater containing higher concentrations of Sr 2+ . Recent studies have shown that the ratio of trace element concentration of otolith could reflect the change of elements, salinity or water temperature [41] as a tool to know about the fish migration between freshwater and sea water [42] [43], which is also a future application of this study.…”

Water and Otolith Chemistry: Implications for Discerning Estuarine Nursery Habitat Use of a Juvenile Flatfish

“…Presently, there is still some debate regarding the use of otolith chemistry to discern movements and habitat use within complex and dynamic environments such as estuaries (Elsdon and Gillanders, 2004;Reis-Santos et al, 2018;Williams et al, 2018;Walther, 2019). Several factors may contribute to variations in otolith elemental composition, particularly environmental factors such as water temperature, salinity and ambient element concentrations, which can play an important role in the control of element uptake, as well as several intrinsic factors such as the genetic background, fish diet and physiological processes (Clarke et al, 2011;Woodcock et al, 2012;Sturrock et al, 2014;Grammer et al, 2017;Izzo et al, 2018).…”