parks victoria technical series marine natural values study vol 2 ...

Parks Victoria Technical Series No. 79
Flinders and Twofold Shelf Bioregions Marine Natural Values Study
ascidians (Power and Boxshall 2007). Deep reef assemblages contain a unique combination
of organisms and the biological and physical differences mean that deeper areas may also
respond differently to threats.
Flora
Seaweeds provide important habitat structure for other organisms on the reef. This habitat
structure varies considerably, depending on the type of seaweed species present (Williams
et al. 2007). The major canopy species of the shallow reef at Beware Reef MS are bull kelp
Durvillaea potatorum and crayweed Phyllospora comosa, with a lesser contribution by the
common kelp Ecklonia radiata (Edmunds et al. 2010b). These species have large, stalk-like
stipes and form a canopy 0.5 - 2 m above the rocky substratum (Williams et al. 2007). Lower
layers of structure are formed by red algae typically 10 - 30 cm high and includes
Rhodymenia wilsonii, Plocamium dilatatum and R. linearis (Edmunds et al. 2010b). There is
a general absence of green algal and filamentous brown and red turf species (Edmunds et
al. 2010b). Beware Reef has a similar shallow reef flora to the monitored sites at Point Hicks,
including a similar mixed algal canopy and a higher cover of fucalean species, such as
Cystophora spp. and Sargassum spp., and fleshy thallose red algae (Edmunds et al. 2010b).
The cover of crustose coralline algae at Beware Reef MS varies a lot between monitoring
times, but is characterised by a lower cover of encrusting coralline algae than Cape Howe
(Edmunds et al. 2010b).
Bull kelp D. potatorum has not been observed at the other MPA or reference monitoring sites
in the bioregion. It is a large robust species adapted to living in highly exposed conditions. Its
abundance has been observed to increase with decreasing abundance of E. radiata
(Edmunds et al. 2010b). There have been limited studies on seaweeds in the Twofold Shelf
bioregion, but a considerable number of rare and new species have been documented
(Edmunds et al. 2010b).
Figure 44. Banjo ray Trygonorrhina fasciata on subtidal reef in Beware Reef Marine Sanctuary. Photo
taken by Friends of Beware Reef Marine Sanctuary.
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