A preliminary study of the bioremediation potential of Codium fragile applied to seaweed integrated multi-trophic aquaculture (IMTA) during the summer

In integrated multi-trophic aquaculture (IMTA), seaweeds have the capacity to reduce the environmental impact of nitrogen-rich effluents in coastal ecosystems. To establish such bioremediation systems, selection of suitable seaweed species is important. The distribution and productivity of seaweeds vary seasonally based on water temperature and photoperiod. In Korea, candidate genera such as Pophyra, Laminaria, and Undaria grow from autumn to spring. In contrast, Codium grows well at relatively high water temperatures in summer. Thus, aquaculture systems potentially could capitalize on Codium's capacity for rapid growth in the warm temperatures of late summer and early fall. In this study, we investigated ammonium uptake and removal efficiency by Codium fragile. In laboratory experiments, we grew C. fragile under various water temperatures (10, 15, 20, and 25 degrees C), irradiances (dark, 10, and 100 mu mol photons m(-2) s(-1)), and initial ammonium concentrations (150 and 300 mu M); in all cases, C. fragile exhausted the ammonium supply for 6 h. At 150 mu M of NH4+, ammonium removal efficiency was greatest (99.5 +/- 2.6%) when C. fragile was incubated at 20 degrees C under 100 mu mol photons m(-2) s(-1). At 300 mu M of NH4+, removal efficiency was greatest (86.3 +/- 2.1%) at 25 degrees C under 100 mu mol photons m(-2) s(-1). Ammonium removal efficiency was significantly greater at 20 and 25 degrees C under irradiance of 100 mu mol photons m(-2) s(-1) than under other conditions tested.