Invertebrate Biodiversity Associated With a Unique Bryozoan Biogenic Reef Complex (Western Port, Victoria, Australia)

ABSTRACT A unique biogenic bryozoan reef has been recently discovered in Western Port (a temperate embayment), Victoria, Australia. This reef is significant owing to its contiguous, regular, linear rows of densely stacked bryozoan colonies with large vertical relief. We aimed to (1) document the biodiversity of the macroinvertebrate epifauna associated with this unique linear bryozoan reef, and (2) to determine if there were differences in invertebrate matrix epifauna associated with each of the three bryozoan species which differ in structural complexity. This was achieved by collecting samples from colonies of the three dominant bryozoan species that make up the reef: Triphyllozoon munitum , Triphyllozoon moniliferum and Celleporaria foliata. The Triphyllozoon species ( T. moniliferum , T. munitum ) are fenestrate forming rounded colonies with intricate laminal folding, with T . moniliferum exhibiting a higher degree of folding, while C. foliata , a non‐fenestrate species, forms plate‐like colonies. Based on their differing morphology, we sought to determine if Celleporaria foliata and the two Triphyllozoon species harboured different matrix fauna and/or differing abundances. In total, bryozoan reef samples contained 7266 individuals, representing 120 different morphospecies from 57 different families across nine phyla. The assemblage was dominated by crustaceans (78% of the total abundance of taxa from 66 morphospecies). There was no significant difference in overall species richness or abundance of matrix fauna between the bryozoan species, although C. foliata harboured a significantly higher number of annelid species. Matrix epifauna richness was significantly higher in spring for all three bryozoan species. The relatively high invertebrate abundance and diversity associated with the Western Port bryozoan reefs potentially represents a spatially constrained area of enhanced foraging by demersal fishes and other taxa with links to other ecosystem functions. Further research is required to establish the conservation value of these reefs and determine what protective measures, if any, are required.