To see photos of the large numbers of marine organisms and plants we have already recorded why not go and have a look at our Jawbone Species Inventory ..accessible from this web site.
The Parks Victoria publication ‘The Marine Natural Values Study Summary’ for Jawbone Marine Sanctuary notes that ‘Patches of all marine habitats from northern Port Phillip Bay are packed into this small area. On the west of the promontory, there is saltmarsh and the largest occurrence of mangroves within Port Phillip Bay. Offshore there are areas of fine clayey sand and patches of seagrass. The eastern side has a complete set of rocky environments. There are areas high up on the shore that only occasionally get wet from storm waves and submerged boulders and ledges that lie below the lowest tides’.
It also notes that ‘Jawbone Marine Sanctuary shoreline geology is basalt, the seaward end of lava flows that characterize Melbourne’s western plains. The sanctuary is shallow and mostly < 4 metres deep. It is not subject to large waves, strong currents or swell but in strong westerly conditions waves can reach heights of 2 metres.
The subtidal reef is not diverse, with low to moderate abundances of the common kelp Ecklonia radiata, large browns Sargassum spp, filamentous brown algae Ectocarpales and often abundant encrusting coralline algae. The algal communities are indicative of high nutrients and low salinities which suggests a large estuarine influence from Kororoit Creek.
The invasive marine pest Japanese kelp Undaria pinnatifida and broccoli weed Codium fragile subspecies fragile have been observed in the sanctuary since 2009.
Sessile invertebrates include the coral Plesiastrea versipora and sponges.
The mobile invertebrate assemblage of the subtidal reef is dominated by the sea urchin Heliocidaris erythrogramma, seastars Meridiastra gunnii, M. calcar and Coscinasterias muricata and blacklip abalone Haliotis rubra and to a lesser extent the biscuit star Tosia australis.
The introduced northern Pacific seastar Asterias amurensis and European fanworm Sabella spallanzanii have been observed sporadically in low numbers in the sanctuary.
More than seventeen species of fish have been observed on the subtidal reefs with the southern hulafish Trachinops caudimaculatus the most abundant. Present in very low abundance are zebrafish Girella zebra, dusky morwong Dactylophora nigricans and little rock whiting Neoodax balteatus.
The water column is home to a variety of planktonic and pelagic organisms. Those that make their permanent home in the water column include sea jellies, salps, fish, and phytoplankton and zooplankton. Some seabirds also use the waters of the sanctuary.’