Unique bryozoan reefs in Western Port, a southern temperate embayment (Australian Marine Science Association AMSA Conference 2018)

Summary

New information is presented for a unique bryozoan biogenic reef system in Western Port, Victoria, Australia.  A multispecies assemblage ofbryozoans form biogenic mounds on unconsolidated sediment in 5–8 m water depth in an area with strong tidal currents and high turbidity.  The dominant bryozoan growth form on the Western Port reefs is a rigid, foliose, densely convoluted colony forming mounds with 1–2 m of vertical relief.  Compound ascidians, hydroids and branching sponges are associated with the bryozoan colonies.  The Western Port bryozoan biotope is not known from other nearshore environments off the southern Australian mainland and is unlike those occurring on the continental shelves off southern Australian and southeastern New Zealand.  The Western Port bryozoan biotope has some similarities to those recorded from the Huon Estuary and Bathurst Channel, Tasmania and to bryozoan faunal crusts described from UK waters.  We estimate that there is potentially some 3 km² of bryozoan reef in Western Port.  The Western Port bryozoan reefs feature in recreational fisher lore and support populations of targeted fish species.  Potential anchor damage and sedimentation are key risks and we call for protection of this unique biotope, particularly in light of projected increases in recreational fishing pressure.