Report Number: 144
Year: 2013

Utility of the Brown Alga, Padina boryana as a Biomonitor of Polychlorinated Biphenyls (PCBs) in Tropical Marine Waters: A Preliminary Investigation

A feasibility study was conducted to determine if Padina boyana, a pan-tropical brown seaweed, could be cultured and transplanted into areas where it does not normally occur, for pollution monitoring and assessment purposes. To this end, P. boryana propagules were successfully recruited on newly commissioned polypropylene ropes and allowed to grow in situ for 80 days before translocation to a PCB contaminated site for 13 days. Representative plants were subsequently harvested from the ropes at 2-3 day intervals for PCB analysis. Nine PCB congeners were consistently detected in all samples and were accumulated at rates that generally increased with decreasing chlorine content. PCB uptake in the alga was clearly biphasic and believed to reflect two passive processes: a) the rapid adsorption of chlorobiphenyls on external components of P. boryana cell walls, and b) the much slower absorption of congeners across cellular membranes into the plant’s cytoplasmic interior. The equilibration time and mean steady state PCB (Σ9PCBs) concentration in the ‘fast compartment’ was estimated at 4 days and ~11 ng/g dry weight (ppb) respectively. Uptake in the ‘slow compartment’ was assumed to follow first order kinetics with equilibration time and steady state estimates of >150 days and >200 ppb respectively. The implications of these and other findings of the study are discussed from a biomonitoring perspective. Recommendations for future studies are also presented.

Gary R.W. Denton
Brian C. Schaible