Opportunistic predation by small fishes on epibiota of jetty pilings in urban waterways

Epibiota were sampled on nine small jetties in the tidal, urban canals of south-east Queensland, Australia, to determine if the small fishes that are associated with these jetties prey on the epibiota on the pilings of the jetties and whether these fishes depend on the epibiota as a source of food. Epibiota was dominated by barnacles, filamentous and foliose algae and ranged in thickness from 4 to 11 mm. The two species of fishes that associated most closely with jetty pilings, Pandaka lidwilli (Gobiidae) and Monodactylus argenteus (Monodactylidae), were sampled twice during the day and twice during the night for analysis of stomach contents. During the day, the diet of P. lidwilli was dominated by amphipods (c. 70%, by mass of organic content), with copepods, bivalves and bryozoans each contributing