Action Summary:
A modified artificial stepped reef structure was created with a total of 14 units (3m length × 3.5m width × 1.1m height) weighing 12.7 tonnes. These units were deployed on the bedrock of a barren ground at 7-8m depth using a barge. Ecklonia cava sporophytes were transplanted onto the artificial step seaweed reefs in February (1-2 cm), March (5-10 cm), and April (20-30 cm in length). Blade length, width and density were measured monthly from February to December 2007 by scuba divers.
Lessons Learned:
Small Ecklonia cava plants (5-10cm) grow more rapidly than large plants (20-30cm). Survival of both is similar, and much higher compared to sporophytes.
Project Outcomes:
Ecklonia cava sporophytes that were <1cm in length died within one month of being transplanted to the artificial reef. This was likely due to high numbers of sea urchins. Similarly, Laminaria species were mostly destroyed by sea urchin grazing, except blades of 5-10cm length transplanted in March survived and grew on the reef. Both the size classes of 5-10cm and 20-30cm length grew until June, and size reductions were reported from September. From October, the 5-10cm size class began to grow more rapidly than the 20-30cm size class. Survival rate was similar between both size classes.
