A Shell of Its Former Self: CanOstrea luridaCarpenter 1864 Larval Shells Reveal Information About a Recruit's Birth Location?

Abstract

Despite the interest in restoring remnant populations of the Olympia oyster, Ostrea lurida Carpenter 1864, † little is known about connectivity among populations. Identifying the sources of settling larvae could broaden our understanding of the degree to which particular populations are reliant on their neighbors for their persistence. Calcified structures such as the otoliths of fish and statoliths of invertebrates are increasingly being exploited as useful ''natural tags'' that help track individual movements and, when applicable to larvae, could help to pinpoint important source populations. In controlled laboratory culturing experiments, we explored the prospects for using the chemistry of larval shells (prodissoconchs) as natural tags of larval source by examining whether larval shells record shifts in seawater element chemistry, whether larval shells undergo ontogenetic shifts in element uptake, and whether the chemistry of the shell formed during brooding is compromised by subsequent shell thickening during the planktonic phase. Results from a two-way ANOVA examining the effect of seawater element concentration and ontogeny showed that element/ Ca in the shell increased in response to increasing seawater elemental concentrations for Ba, Ce, Pb, and Mn, whereas shell Cu/Ca did not change. Ostrea lurida shell chemistry also showed strong ontogenetic shifts in element/Ca for Mg, Sr, and Cu during the transition from larva to settler. Settler shell Mg/Ca strongly increased compared with planktonic shell, whereas Sr/Ca and Cu/Ca showed the opposite pattern. Further, the chemistry of the shell formed during brooding (at the birth location) did change as a function of environmental conditions experienced during the planktonic phase for the elements Ba and Ce, but that change was limited to regions of the brooded shell just adjacent to the planktonic shell. When the brooded portions of larval shells were sampled closer to the umbo, the brooded shellsÕ chemistry remains intact. The combined results suggest that larval Ostrea lurida shells act as recorders of environmental change and show promise as tools to track larval movements.

Microchemistry of juvenile Mercenaria mercenaria shell: implications for modeling larval dispersal

“…These findings are in agreement with other investigations concerning Sr incorporation into molluscan biominerals (Lloyd et al 2008, Zumholz et al 2007, Zacherl et al 2009). Sr incorporation within abiogenic carbonate is highly influenced by precipitation rate (Lorens 1981, Morse & Bender 1990.…”

“…These authors postulate industrial and urban runoff as the primary factors influencing the availability of these elements. Laboratory experiments con ducted by Zacherl et al (2009) demonstrate a positive relationship between Pb concentrations in culture water and incorporation into juvenile and larval oyster shell and an absence of any such relationship with Cu. The well-mixed nature of our study area coupled with differential land use patterns including non-point pollution from the adjacent municipalities of Morehead City and Beaufort and extensive agricultural development suggests that anthropogenic inputs may be influencing the availability and incorporation of metals into juvenile clam shell (Swearer et al 2003).…”

“…7). Work by Zacherl et al (2009) demonstrates a positive linear relationship that acts independently of onto geny between Mn concentration in culture water and incorporation into larval and juvenile shell of the Olympic oyster Ostrea lurida. If the incorporation of Mn into hard clam carbonate also operates independently of ontogeny, the distinct Mn signal ob served in juvenile shell may also be present in the larval form.…”

“…Additional environmental factors further contribute to this process, and evidence suggests that the incorporation of some elements may be predictably influenced by the chemical and physical characteristics of the water in which they form. Laboratory experiments have demonstrated a positive linear relationship between the concentration of Mg: Ca, lead (Pb):Ca, cerium (Ce):Ca, and Ba:Ca ratios within molluscan biominerals and the concentration of these elements within culture water (Lorens & Bender 1980, Lloyd et al 2008, Zacherl et al 2009). Variation in temperature may also influence the incorporation of trace elements within biominerals.…”

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

“…Physical changes in the environment as a shell transitions from a pelagic to an infaunal lifestyle may result in different elements being available for incorporation into growing shell. It has previously been demonstrated that differences in the incorporation of elements to bivalve shell vary between larval and recruited shell (Zacherl et al 2009). It has also been found that the diet of individuals may influence the uptake of elements into bivalve shell (Thebault et al 2009 Table 2 possible that prodissoconch shell initially consists primarily of amorphous calcium carbonate (ACC), which later transitions to aragonite (Weiss et al 2002).…”