Changes in the Structural Features of Organic Matter Extracted from Compost by the Seawater during a 90-day Period under Anaerobic Conditions, and Its Effect on Oogenesis of Brown Macroalga.

Abstract

Seawater-extractable organic matter (SWEOM) has a potential to serve as an Fe complexing agent in an Fe-fertilizer intended to restore and preserve macroalgal forests. To better understand the restoration technique, structural alterations in SWEOM that occurred during a 90-day period of incubation in seawater were determined. Up to 82% of the total eluted SWEOM occurred during the initial 30 days; a small amount of SWEOM then continued to elute during the next 60 days. Spectroscopic analyses showed that the high-molecular-weight SWEOM fraction (HMW) altered in aliphatic-rich materials, while the low-molecular-weight fraction (LMW) became significantly enriched in aromatic structures. The structural alterations in the HMW and LMW could be caused by the action of anaerobic microorganisms. In addition, approximately 30 and 60% of the gametophytes were converted to eggs in the presence of HMW and LMW with Fe, respectively.