the reef biota at Wilsons promontory marine national - Parks Victoria

Parks Victoria Technical Series #74SRMP Wilsons Promontory MNP3. RESULTS3.1. Macroalgae3.1.1. Macroalgal Community StructureThe majority of algal assemblages at Wilsons Promontory are dominated by Phyllosporacomosa (> 30 % cover), with assemblages at a few sites dominated by a combination ofEcklonia radiata and Seirococcus axillaris. The understorey associated with this canopy wassparse cover of thallose red algae, with much of the underlying rock covered by encrustingcorallines. Common understorey species included Phacelocarpus peperocarpus, Plocamiumangustum, Plocamium dilatatum, Pterocladia lucida, Ballia callitricha, Haliptilon roseum andMelanthalia obtusata.Phyllospora assemblages were present at the most exposed sites, particularly on thewestern and southern coasts of the Promontory. Ecklonia radiata was the dominant canopyspecies in less exposed sites.Pillar Point (3106) had a canopy almost exclusively composed of Phyllospora, but wasnotably different from other Phyllospora assemblages in having very low percentage coveralgal understorey and high numbers of sessile invertebrates. This reef community is possiblyinfluenced by freshwater flows from Tidal River, on the south side of Pillar Point.Ecklonia radiata and Seirococcus axillaris were the dominant canopy cover species atmoderately exposed to sheltered sites. Phyllospora comosa was sometimes present at thesesites, but contributed less than 20 % to canopy cover. Thallose understorey algae were agreater component of the Ecklonia-Seirococcus assemblages, with 50-70 % cover comparedwith less than 30 % cover in the Phyllospora assemblages. As with the Phyllosporaassemblages, Phacelocarpus peperocarpus, Melanthalia obtusata, Plocamium angustumand Pterocladia lucida were common understorey species. However, Ballia callitricha and theerect coralline Haliptilon roseum were generally reduced in abundance in the Ecklonia-Seirococcus assemblages, with smaller brown species more prevalent. These brown speciesincluded Sargassum verruculosum, Sargassum sonderi, Perithalia cordata and Acrocarpiapaniculata.Algal community structure appeared largely stable over time, with differences in betweensites generally being preserved through time (Figure 3.1a-d). The greatest variation overtime was in the northwestern reference zone, particularly at Pillar Point and East GlennieIsland (Figure 3.1c). The crayweed Phyllospora dominated assemblages in the southwestand southeast tended to have smaller temporal variation than the other assemblages.The multivariate control charts indicated there were some sites that trended in communitystructure away from the baseline period conditions. These sites were predominantly32