Investigating the kinetics of Cd transport between internal organs of the freshwater decapod Macrobrachium australiense

Cresswell, T; Simpson, SL; Mazumder, D; Callaghan, PD; Nguyen, AP; Corry, M

Investigating the kinetics of Cd transport between internal organs of the freshwater decapod Macrobrachium australiense

Date

2014-09-14

Authors

Publisher

SETAC

Abstract

The bioaccumulation of metals by aquatic organisms can be studied in great detail using radiotracers, allowing insights into rates of uptake and fate of the metals accumulated in tissues. While there have been numerous studies on the whole-body bioaccumulation of metals by organisms, little is known about the kinetics of organ-specific bioaccumulation. This study used the radioisotope 109Cd to explore the internal uptake kinetics of this non-essential metal following accumulation from solution by the freshwater decapod crustacean Macrobrachium australiense. The first stage of the study involved exposing 24 organisms for up to 2 weeks to 0.55 µg Cd/L in synthetic river water with three individuals being removed at pre-defined time points. Following exposure, animals were rinsed in a 0.1 mM EDTA solution to remove any loosely-bound metal, rapidly frozen and the anatomical distribution of the radionuclide visualised from fresh frozen sections (20 um) using autoradiography. The second phase of the study consisted of exposing organisms to the same radiotracer solution for a short period (6 h) and long period (7 d), followed by depuration in metal- and isotope-free water for up to 3 weeks. Organisms were removed from depuration at pre-defined time points, rapidly frozen, the anatomical distribution of the radionuclide determined as above. Preliminary results suggest that the gills appeared to saturate after 7 d exposure, with negligible increase over another 7 d of exposure. However, the ratio of Cd between the hepatopancreas and gills increased over time, suggesting the organism was actively processing accumulated metal. Rates of accumulation into different internal compartments in response to changes in uptake and depuration durations will be discussed. The findings of the study provide new information on the processing of a non-essential metal by M. australiense and could potentially be used to estimate the exposure history of field-caught organisms.

Keywords

Biological accumulation, Metals, Australia, Rivers, Radioisotopes, Kinetics

Citation

Cresswell, T., Simpson, S.L., Mazumder, D., Callaghan, P., Nguyen, A.P., Corry, M. 2014. Investigating the kinetics of Cd transport between internal organs of the freshwater decapod Macrobrachium australiense. Abstract presented to the SETAC-AP/AU Adelaide Conference. 14-17 September; Adelaide, Australia.