Enhancing alpha and beta diversity on vertical seawalls by retrofitting eco-engineered panels

The effect of surface heterogeneity of manmade substrate on alpha diversity of intertidal epibiota is well-studied, but its influence on beta diversity remains largely unexplored. Herein, two designs of eco-engineered panels were retrofitted onto existing vertical seawalls in three regions of Hong Kong Special Administrative Region, China, and were compared with scraped seawall plots for two years. Panels and controls were surveyed quarterly for epibiotic alpha diversity, followed by a survey for beta diversity after two years of deployment. Over 30 % of taxa were unique to either or both panel designs, compared to only about 5 % of unique taxa on the control plots. Within-site beta diversity was approximately 10-40 % higher than that of two nearby unmodified seawalls across all three regions. Also, filter feeding and habitat forming taxa were more abundant on the panels. Evidently, eco-engineered panels can enhance alpha and beta diversity, and enrich the biological community therein.