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.