Action Summary:
A 2.0 hectare rocky beach was constructed between -2.5 and +2.5m within a marine in late 1990 and early 1991 (Area N). In late 1990, a 3.0ha rocky beach and kelp habitat was created between 0 and -2.5m on the east side of the marina (Area B). In early 1990, an 0.2ha shallow rocky subtidal habitat was created between 0 and -2.5m on the west side of the marina (Area C). A control site was established west of the marina. The rocky habitats for Areas B and C were constructed by spreading approximately 5,400m of 10 to 20cm diameter, pit-run aggregate on an existing mud-sand bottom. The artificial beach (Area A) was constructed by layering 3,060m3 of 10 to 15cm diameter aggregate over a linear distance of 450 m of fill, then covering this material with a thin layer of 3 to 6cm diameter beach gravel.
Lessons Learned:
Notes a range of percent covers for the different tide heights of the reef, but these are estimated.
Project Outcomes:
There were substantial differences in benthic composition between the control and mitigation sites, with various kelp species (mainly Nereocystis, Laminaria and Sargassum) colonising the mitigation rock in all areas. Sand substrates were not utilised by attached micro-algae, but they were often covered either totally or partially with benthic diatoms and drift algae. The distribution and density of macroalgae generally increased between subsequent sampling periods in areas where suitable uncolonized substrates were available.
