SPATIAL DIFFERENCES IN SUBTIDAL EPIBIOTIC COMMUNITY STRUCTURE IN MARINA AT KEPPEL BAY, SINGAPORE

Urban structures in marine environments represent novel habitats for numerous species. Marinas are one such modified environment, exemplified by pontoons that can act as surrogate habitats for sessile epibiotic organisms. Because they float, pontoons are rather special structures where epibiota are not influenced by changes in depth associated with tidal variations. Baseline data for pontoon communities in Singapore are deficient, hence the present study surveyed subtidal epibiota growing on pontoons at Marina at Keppel Bay. Differences in community structure among three locations and between the interior and exterior of berths within the marina were investigated (six stations in total). It was hypothesised that dissimilarities in physicochemical parameters among survey stations could influence the composition of epibiotic assemblages. Forty-nine taxa were identified and these were generally similar to those found on local coral reefs. Dissimilarities in community structure were significant among locations but not between the interior and exterior of berths. Three major distinguishing taxa contributed to among-location differences (i.e., Stereonephthya sp., Padina sp., and Halimeda sp.). Light intensity and hydrodynamic conditions were identified as factors most likely influencing variation in taxa composition. This study shows how pontoons can support the settlement and growth of subtidal organisms, to some extent mitigating the negative impact associated with urbanisation and coastal modification.