Spatial changes in trace element and strontium isotope water chemistry in a temperate river system with application to sturgeon movement

Abstract

Understanding patterns in trace element concentrations and water quality within river systems provides a foundation to evaluate retrospective movements and habitat use of fish. Because trace elements are incorporated into calcified structures of fishes relative to water concentrations, baseline maps have application for fisheries management, including for rare species such as sturgeons. Therefore, trace elements [strontium (Sr), barium (Ba), manganese (Mn), zinc (Zn), and magnesium (Mg)], strontium isotopes ( 87 Sr/ 86 Sr), dissolved oxygen and salinity were measured in the Pearl River and Lake Pontchartrain watersheds, within Mississippi and Louisiana, USA for application in assessing riverine use by Gulf Sturgeon Acipenser oxyrinchus desotoi. Water samples were collected during the summerfall period when juvenile Gulf Sturgeon were anticipated to be present and analyzed by solution and multi-collector inductively coupled plasma mass spectrometry. Trace element to calcium (Ca) ratios in Sr, Ba, Zn, and Mg were distinguishable between the upper Pearl River and the Bogue Chitto River tributary, and the upper Pearl River and lower Pearl River. For most trace elements and 87 Sr/ 86 Sr, there was a gradual increase from upper river regions to lower river regions, and large differences between freshwater and saline areas. Lake Pontchartrain watershed rivers were not easily differentiated, but regions of low dissolved oxygen concentrations in the lower reaches suggest available Gulf Sturgeon habitat may be seasonally limited. Therefore, maps of water microchemistry in the Pearl River watershed allow for retrospective analyses of fish watershed use.

A regional analysis of trace element water chemistry with applications for reconstructing environmental life history of fishes

“…Water chemistry in freshwater systems is largely influenced by bedrock composition, soil, and land use patterns (Humston and Harbor 2006). Natural weathering of rock material results in continual inputs of elements (in trace amounts) and their isotopes to water, providing unique chemical signatures for specific watersheds or locations within a watershed (Gunn et al 2019). For instance, rivers flowing through regions rich in volcanic rocks may exhibit higher concentrations of elements like arsenic, selenium, and boron, while those traversing areas with sedimentary rocks may show elevated levels of calcium, magnesium, and strontium.…”

Archaeological and modern whitemouth croaker fish (Micropogonias furnieri) of southeastern Brazil: A geochemical proxy for environmental preference

“…For example, Sr/Ca and Ba/Ca ratios have been used to assess fish movement because these elements are incorporated into the otolithic matrix in different concentrations as the fish access different environments. This relationship between elements has been efficient in tracing habitat salinity preferences between freshwater, brackish water and marine ecosystems (Avigliano and Volpedo, 2016; Brown and Severin, 2009; Elsdon and Gillanders, 2005; Gunn et al, 2019). This approach has been used to characterize the movement patterns of the whitemouth croaker in southeastern Brazil (Albuquerque et al, 2012; Pizzochero et al, 2018).…”