Samples were placed on ice in the field, then later frozen. In the laboratory, mussels were measured for shell total length, thawed and dissected. Adductor muscle tissue was dissected from individual animals, rinsed in deionized water (DI), and dried at 60 °C. The outermost
10 mm of mussel shells that represented the most recent growth was broken off and treated with bleach to remove Epacadostat datasheet organic matter. Shells were soaked overnight in household bleach (Chlorox, 6% sodium hypochlorite) to remove soft tissues, crushed into coarse fragments and soaked again overnight with bleach, then rinsed extensively with DI prior to drying at 60 °C. Barnacles were thawed, basal diameters were measured, and for each station approximately 50–100 animals with basal diameters of 5–20 mm were separated from their shells and combined into a composite site sample. Soft tissues were placed briefly in 1 N HCl and any carbonate shell detected by
bubble evolution was removed under a dissecting microscope. Cleaned soft tissues were then rinsed with deionized water and dried at 60 °C. Barnacle shells were treated with bleach as described above for mussels. Barnacle soft tissues MK0683 mouse were pulverized with a steel rod in glass vials. All other samples including shells and tissues of mussels were pulverized with a Wig-L-Bug automated grinder (Dentsply International). Shells and tissues were analyzed for δ13C by standard combustion methods with isotope ratio mass spectrometry (Fry, 2007), and results are reported as δ13C values using the VPDB reference (Coplen, 1994) where δ13C = (RSAMPLE/RSTANDARD − 1) * 1000 and R = 13C/12C. Samples for radiocarbon analyses were sent to the Rafter Radiocarbon Laboratory in Lower Hutt, New Zealand for measurement with accelerator mass spectrometry; results are reported as Δ14C values ( Stuiver and eltoprazine Polach, 1977). For
δ13C, both diet and inorganic carbon dynamics have been shown to affect filter feeder isotope values (Fry, 2002), with the inorganic carbon dynamics at the base of food webs leading to higher δ13C values for plants and animals in more marine portions of estuaries. To account for this basal or baseline effect which is conveniently recorded by inorganic carbon in shell carbonate, the fractionation between shells and filter feeder tissues was calculated as 13ε=(RSHELL/RTISSUE-1)*100013ε=(RSHELL/RTISSUE-1)*1000where R is the 13C/12C isotope ratio in the δ13C definition. The 13ɛ values can be thought of as the baseline-corrected fractionation through the food web leading to filter feeders, and can be compared to the fractionation expected for dietary reliance on 100% non-oil normal estuarine foods versus fractionation expected from a 100% oil-based diet.