Macrofouling assemblages in coastal waters adjacent to the Port of Colombo, Sri Lanka

Abstract

Sri Lanka was an important node and a major centre of international trade in the ancient maritime silk route, and still serves a significant role in present global maritime trade. The critical role played by the country’s ports on economic development has come at the cost of compromising the ecological health of the environment. The present study was to assess the status of biofouling assemblages in coastal waters impacted by the Port of Colombo. Sampling was conducted from February to December 2018 in the Dikkowita Fisheries Harbour, Kirulapone canal opening, and Panadura Fisheries Harbour. The fouling assemblages in the rocky intertidal zone were studied using photo-quadrats and environmental surveys. Photo-quadrats were obtained monthly following a protocol developed by the Marine Biological Association of the United Kingdom and modified to suit the local environments, whilst area surveys were conducted at two-month intervals. In addition, artificial settlement structures were deployed to assess subtidal fouling communities. Species abundance was estimated by individual counts, and percentage cover was determined using CPCe software. A total of 47 macrofouling taxa were recorded. High numbers were recorded from the phyla Mollusca (20), Arthropoda (06), and Porifera (4). Saccostrea cuccullata (Bivalvia), Cellana radiata (Gastropoda), Clypidina notata (Gastropoda), and Balanus reticulatus (Crustacea) were some of the common species found in all three study sites. Oysters were the dominant macrofouling organisms in terms of percentage cover in Dikkowita Fisheries Harbour and Kirulapone canal opening. Our study also recorded three globally invasive species, B. reticulatus, Amphibalanus amphitrite and Perna viridis, alerting us to the need for long-term monitoring.