Turning riprap into reefs: Integrating oyster shells into shoreline armouring.

Boulder seawalls constructed with granite riprap for shoreline armouring lack habitat complexity, leading to lower marine biodiversity than natural rocky shores. Baskets of live oysters and cured oyster shells, and strings of cured shells laid on concrete blocks were installed on ripraps in Hong Kong, China with an aim to enhance biodiversity and ecosystem functioning towards that of a natural rocky shore. Inhabiting taxa were monitored for at least 18 months and biofiltration capacity of the emerging community was determined ex-situ.

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.

Provision of refugia and seeding with native bivalves can enhance biodiversity on vertical seawalls.

Recent studies have suggested that increasing habitat complexity of artificial seawalls by modifying surface heterogeneity could enhance exploitable habitat and therefore species richness and abundance. We tested the effects of adding complex tiles (with crevices/ledges) of different heterogeneity (i.e.