Population dynamics and feeding ecology of pipefish (Syngnathidae) associated with eelgrass beds of Western Port, Victoria

Abstract

Three species of pipefish, Urocarnpus carinirostris Castelnau, Vanacarnpus phillipi (Lucus) and Mitotichthys semistriatus (Kaup), occurred regularly in collections from eelgrass beds of Western Port. A fourth species, Stigmatopora nigra Kaup, was rare. U. carinirostris and V. philippi dominated catches. Brooding males were present for 6-9 months of the year, juveniles were recruited in summer and early autumn, and both species were annual. The pipefish fauna included two main behavioural types. V. phillipi and M. sernistriatus oriented themselves horizontally and were relatively strong swimmers. U. carinirostris and S. nigra were more sedentary, attaching themselves to benthic vegetation by means of a prehensile tail. The latter two species closely mimicked eelgrass leaves in movements, orientation and colour. All inhabited the eelgrass leaf canopy except V. phillipi, which occupied the sediment-water interface. The pipefish were visually orienting, sit-and-wait predators. Pelagic or epibenthic copepods and small epibenthic amphipods comprised the bulk of diets; only V. phillipi ingested polychaetes and plant detritus.