World Harbour Project (Penang): Does structural complexity hold the key to enhancing biodiversity on artificial structures?

Extensive development in coastal and marine environments is occurring worldwide. This phenomenon has led to the growing number of artificial structures including seawalls, breakwaters, and rock armour which are design to... [ view full abstract ]

Extensive development in coastal and marine environments is occurring worldwide. This phenomenon has led to the growing number of artificial structures including seawalls, breakwaters, and rock armour which are design to protect against sea level rise and coastal erosion (termed as ocean sprawl). While development offers economic growth, it is often built at the expense of natural coastal habitats. As concerns continue to grow, we embark on the World Harbour Project to test the efficacy of retro-fitting complex habitats to coastal protection infrastructure in Penang using green engineering approach. The experiment was set up on artificial structures at two locations. Three different treatments of flat, 2.5 cm and 5.0 cm height enhancement settlement plates with five replicates each were installed at mid-water level. Trimonthly monitoring for one year beginning in September 2016. We calculated multi-trophic richness and relative abundance correlated with net primary and secondary productivity. Although increasing primary producer abundances show a proportional increase in net primary production, there were no detectable differences between the 5.0 cm and the flat, 2.5 cm plates. There were also no differences in the number of species or abundances of key functional groups: algae and bivalve communities across all three settlement plates suggesting that the organisms were indifferent to the degree of complexity of the plates. Our results suggest increasing habitat complexity is not sufficient to enhance diversity and productivity of coastal infrastructure. These results differ from other locations and could be driven by the increased wave action or temperatures in the region.