Invasive Alga Removal Accelerates Sediment Flushing In Maubalua Bay, Oahu

Invasive species are a worldwide problem and have altered both terrestrial and marine ecosystems in Hawaii.  Avrainvillea amadelpha is one marine invader that has changed the Paiko Lagoon Peninsula (PLP) reef flat ecosystem.  PLP also has a sedimentation problem worsened by the dense presence of the alga.  Community-based groups, in partnership with governmental agencies, have attempted to restore PLP by manually removing ~3000 tons covering 26 acres of A. amadelpha.  This study investigated the effectiveness of this restoration approach in the removal of the sediment at PLP.  We collected data at least once monthly for 14 months using a sediment resuspender and turbidity meter.  Sediment concentrations were significantly less in the cleared areas of PLP.  Our data suggests that sediment retention is due to the dense presence A. amadelpha and the absence of natural flushing due to swell.  Our model found that with algal removal and swell, the flushing time of fine sediment was reduced from approximately 6.5 to 4.16 years.  Although restoration can be challenging and slow, success can still be achieved through effective community and governmental partnerships.  The removal of A. amadelpha is the first step in improving habitat quality at PLP.