Iron assimilation by the clam Laternula elliptica from Potter Cove, King Georg Island, Antarctica

• Main Authors: Poigner, Harald, Wilhelms-Dick, Dorothee, Abele, Doris, Staubwasser, Michael, Henkel, Susann
• Format: Dataset
• Language: English
• Published: PANGAEA 2015
• Subjects: Date/Time of event; DEPTH; sediment/rock; Elevation of event; Event label; ICP-OES after acid digestion (Poigner et al; 2013); IMCOAST/IMCONet; Impact of climate induced glacier melt on marine coastal systems; Antarctica; Iron; haemolymph fluid and hemocytes; Laternula elliptica; height of valve; length of valve; width of valve; Latitude of event; Longitude of event; MC-ICP-MS after acid digestion; anion-exchange chromatography (Schönberg; 2005); MULT; Multiple investigations; PotterCove_Laternula_STA04; PotterCove_Laternula_STA11; Potter Cove; King George Island; Antarctic Peninsula; Sample code/label; Vernier caliper; δ56Fe; Antarc*; Antarctic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.846456; https://doi.org/10.1594/PANGAEA.846456

Iron stable isotope signatures (d56Fe) in hemolymph (bivalve blood) of the Antarctic bivalve Laternula elliptica were analyzed by Multiple Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS) to test whether the isotopic fingerprint can be tracked back to the predominant sources of the assimilated Fe. An earlier investigation of Fe concentrations in L. elliptica hemolymph suggested that an assimilation of reactive and bioavailable Fe (oxyhydr)oxide particles (i.e. ferrihydrite), precipitated from pore water Fe around the benthic boundary, is responsible for the high Fe concentration in L. elliptica (Poigner et al., 2013, doi:10.1016/j.ecss.2013.10.027). At two stations in Potter Cove (King George Island, Antarctica) bivalve hemolymph showed mean d56Fe values of -1.19 ± 0.34 per mil and -1.04 ± 0.39 per mil, respectively, which is between 0.5 per mil and 0.85 per mil lighter than the pool of easily reducible Fe (oxyhydr)oxides of the surface sediments (-0.3 per mil to -0.6 per mil). This is in agreement with the enrichment of lighter Fe isotopes at higher trophic levels, resulting from the preferential assimilation of light isotopes from nutrition. Nevertheless, d56Fe hemolymph values from both stations showed a high variability, ranging between -0.21 per mil (value close to unaltered/primary Fe(oxyhydr)oxide minerals) and -1.91 per mil (typical for pore water Fe or diagenetic Fe precipitates), which we interpret as a "mixed" d56Fe signature caused by Fe assimilation from different sources with varying Fe contents and d56Fe values. Furthermore, mass dependent Fe fractionation related to physiological processes within the bivalve cannot be ruled out. This is the first study addressing the potential of Fe isotopes for tracing back food sources of bivalves.