Local-scale variation in trace elemental fingerprints of the estuarine bivalve Austrovenus stutchburyi within and between estuaries

Abstract

Trace elemental fingerprinting has been used to estimate population connectivity of marine species by using variations in the chemistry of shell produced in different water masses to determine the natal location of settlers. This method has been successfully used to differentiate between estuaries and coasts at spatial scales of 10s to 100s of km. Here, we investigated the suitability of trace elemental fingerprinting to distinguish subpopulation connectivity at management scales suitable for local fishery or conservation management. The trace element chemistry of Austrovenus stutchburyi shells was used to distinguish between intra-and inter-estuary subpopulations at local (~1 to 10 km) scales, with ~99% success. Differences between 8 locations within a large harbour and 4 smaller neighbouring estuaries were detected. Sr:Ca, Zn:Ca and Mn:Ca elemental ratios were the primary drivers of inter-site trace elemental fingerprint differences. Intra-shell variation in elemental fingerprints was used to examine temporal stability and demonstrated that, although intra-shell differences were present, site-specific differences in elemental fingerprints were maintained. The results of this study suggest trace elemental fingerprinting can be a viable method to estimate population connectivity over small inter-and intra-estuary spatial scales.

Ocean acidification can interact with ontogeny to determine the trace element composition of bivalve shell

“…Methods used were adapted from Norrie et al (2016). Mussels were defrosted, the shells were split open, and the flesh was removed using stainless steel forceps.…”

“…The possibility also exists for these largely separate applications of CaCO 3 trace elemental composition to be combined. The suite of trace elements used in trace elemental fingerprinting studies does not frequently overlap with the elements used in climate reconstructions (Dunphy et al 2011;Hahn et al 2012;Poulain et al 2015;Norrie et al 2016). If changes in pH influence elements, which are not generally used in trace elemental fingerprinting, it may be possible to use trace elemental fingerprinting techniques to determine the location at which a CaCO 3 structure formed and simultaneously infer the environmental conditions at this location using a complementary suite of elements.…”

Use of settlement patterns and geochemical tagging to test population connectivity of eastern oysters Crassostrea virginica

“…Estuaries are ideal areas to study variation in TE ratios because they have high spatiotemporal environmental variability due to different geomorphologies, pollution sources, and freshwater inputs (Swearer et al 2003, Thorrold et al 2007). Previous estuarinebased studies have found spatial variation in TE ratios in bivalve shells across 1−10s of km (Norrie et al 2016) and temporal variation on a scale of weeks to months in bivalve shells (Becker et al 2005) and years in gastropod shells (Zacherl 2005). These findings suggest that spatiotemporal variation within estuaries should be adequate to distinguish larvae among natal sites using TE ratios.…”

Comparative influence of genetics, ontogeny and the environment on elemental fingerprints in the shell of Perna canaliculus

“…To determine how overall trace elemental fingerprints varied between sites and between families, as well as to determine if genetic variation prevented classification of individuals to their growth site, a quadratic discriminant function analysis (QDFA) was performed 20,41 . This was done stepwise by removing the least significant TE :Ca ratio whilst still maintaining site classification success rates of >90%.…”

“…It is important that any ontogenetic influences are known before inferences on changes in the environment as an animal grows can be determined. If this is the case, it is important that differences in trace elemental fingerprints between locations are greater than any ontogenetic differences to avoid complications in the development of reference fingerprints 20 .…”