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
2.2.3 MARINE ECOLOGICAL COMMUNITIES
General
Since the first natural values report by Plummer et al. (2003) there has been limited further
research or mapping surveys in Ninety Mile Beach MNP. There has been broadscale
bathymetric mapping, with the intertidal and shallow subtidal areas mapped by aerial LiDAR
surveys. There have been no surveys of the pelagic habitats.
No new surveys of biota have been done in the MNP since declaration. Our knowledge of
biota found in Ninety Mile Beach MNP is limited to large fauna such as birds and mammals
(Appendix 1). Forty-nine species of birds and over six species of marine mammals have
been recorded in or in the immediate surrounds of the MNP.
Intertidal
Soft sediment
The intertidal soft sediment is in the north of Ninety Mile Beach MNP as a high-energy steepfaced,
coarse-grained sandy beach fronting an extensive dune barrier system. The intertidal
sand communities at McGaurans and Woodside Beaches to the west of the MNP are
species-poor (LCC 1993). Between 1983 and 1990 eight surveys were conducted at these
beaches and found low biodiversity (nine species per sample) and dominated by isopods,
with bivalves, polychaetes, amphipods and insect larvae (LCC 1993). Bivalves (such as
pipis) and worms are known to occur in the sand in the lower intertidal area (LCC 1993).The
abundance of beach infauna was also low (5 to 102 m 2 ), with invertebrate populations on
both beaches being extremely variable, fluctuating considerably between years. This is
typical of these types of beaches.
Flora is restricted to macroalgae drift and macroalgal epiphytes. Beach-washed materials in
sandy beach habitats are a significant source of food for scavenging birds, and contribute to
the detrital cycle that nourishes many of the invertebrates, such as bivalves, living in the
sand.
Reef
There is no intertidal rocky reef in the Ninety Mile Beach MNP.
Subtidal
Soft sediment
Invertebrate species diversity of subtidal soft sediment in the Orbost region at the eastern
end of Ninety Mile Beach is regarded as one of the most biologically diverse marine
environments in the world (Coleman et al. 1997). Invertebrate diversity in East Gippsland
was therefore higher compared to the rest of the Victorian coastline and was generally
greater with depth (Coleman et al. 2007; Heislers and Parry 2007). A transect east of the
MNP was sampled with 0.1 m 2 grab samples in 10 and 40 m of water depth. The shallow
sediment was fine sand and deep was medium sand (Coleman et al. 2007). The grab
samples contained between 260 to 430 individuals and 36 to 72 species (Coleman et al.
2007). Crustaceans were the dominant taxa in both depth classes, representing more than
13 of the 21 most abundant families (Heislers and Parry 2007). Ten families were common
in both depth classes (Heislers and Parry 2007). These organisms live in or on the sand and
their ecological relationships are poorly known, except that they are a key component of the
local food web and that their population dynamics are extremely variable (Parks Victoria
2006e).
No information on nearshore fish is available from within the MNP, but recreational fishing
guides indicate that Seaspray Beach, (just east of the MNP), is known for populations of
Australian salmon Arripis sp., snapper Pagrus auratus, tailor Pomatomus saltatrix and
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