the reef biota at bunurong marine national park - Parks Victoria

Parks Victoria Technical Series No. 84
Bunurong Subtidal Reef Monitoring
3.2 Ecosystem Components
Habitat and Production
Canopy browns are the dominant functional algae group in the Bunurong area, with average
percent cover of between 40 and 80 percent (Figure 3.13a). Since the previous survey in
2010 a slight increase in the cover of crustose coralline algae cover in both MNP and
reference areas (Figure 3.13b), a decrease in erect coralline algae in MNP sites, and a
decrease in smaller browns in reference sites were recorded (Figure 3.13c and d). Over a
larger time scale, percent cover of canopy browns, smaller browns and green algae have
remained relatively similar throughout the monitoring period (Figure 3.13a, d and e).
Crustose coralline algae has varied considerably between surveys with a significant
decrease in both MPA and reference sites in 2006 and subsequent increases in 2010 and
2011 (Figure 3.13b). Since declaration of the park in 2002 there has been a steady increase
in the cover of thallose red algae and a corresponding decrease in erect coralline algae
cover in MNP sites (Figure 3.13f and c).
Invertebrate Groups
Grazers were the most abundant of the invertebrate functional groups in all surveys (Figure
3.14a). Peaks in the densities of invertebrate grazers and predators occurred prior to the
MNP introduction. Densities have since declined and remained relatively constant through
several surveys in both reference and MNP sites (Figure 3.14a and b). No trends were
detected in the density of invertebrate filter feeders, with low abundances in most surveys
(Figure 3.14c). Abundances did increase in the first survey after the MNP declaration,
however this was a single occurrence and does not represent an overall trend (Figure 3.14c).
Seastar densities in the MNP have been in decline since the 2002 surveys. Seastar densities
at reference sites have shown considerably more variability, but an overall decline is evident
(Figure 3.14d).
Fish Groups
Fish hunter and fish forager functional groups showed similar interannual variability, being
consistent inside and outside the MNP, (Figure 3.15a and b). Fish grazer abundance inside
the MNP was consistently lower densities than references sites in surveys after 2005 (Figure
3.15a). Fish planktivores occurred in low abundances in both the MNP and reference sites,
spikes in abundance were attributed to large numbers of bullseyes, Pempheris multiradiata,
at a small number of sites (Figure 3.15d).
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