Marine Succession Rates on Intertidal and Subtidal New Armor Rock in Chiniak Bay, Kodiak, Alaska

Alaska has 33,904 miles of coastline and most coastal infrastructure in the state is armored for erosion protection, yet little is known about colonization or recolonization rates post-disturbance in high northern latitudes. This study quantifies the recruitment and colonization of new armor rock at the Kodiak Airport and documents algal and sessile invertebrate species abundance and assemblage (percent cover) at the airport study sites compared to reference sites with similar substrates, salinity, wave exposure, and depth. Over four years of annual intertidal and subtidal monitoring, average percent cover by algae and invertebrates at study sites ranged from 13% to 100%. Study sites showed extensive cover by early colonizing algae and invertebrates in both the intertidal and subtidal substrates at 15 months post-construction silt curtain removal (Year 1). Prominent biobands of monospecies (e.g., bay mussels [Mytilus trossulus]) observed in Year 1 largely changed to barnacles (Balanus sp.) and algal species by Year 4. Both algal cover and number of species increased over time at airport study sites; total cover and number of species at these study sites were similar to reference sites by Year 4. The colonization rate of armor rock and the successional timeframe to develop full ecological functions are important because of the potential effects of armor rock on aquatic habitats at both local and landscape scales. This study illustrates that colonization of new armor rock in southcentral Alaska can be rapid (average 80.8% cover of intertidal and subtidal substrates after one year) and that interannual variability of species abundance may occur throughout the successional cycle.