State of the Bay Report 2010-Final - Anchor Environmental

Table 9.5. Results from the SIMPER analysis listing the species that contribute >5% to the dissimilarity
among the years at each site. The % cover data are averages across the six replicates per site,
and are on the fourth-root transformed scale.
Site Species
State of the Bay 2010: Saldanha Bay and Langebaan Lagoon 211
2008
% cover
2009
% cover
Contribution
Dive School Nothogenia erinacea 0.32 0.66 5.11
Jetty
Gigartina polycarpa 0.24 1.02 8.62
Porphyra capensis 0.82 0.11 8.21
Ulva spp. 0.41 1.03 7.41
Cymbula granatina 0.49 1.01 5.75
Schaapen East Blue-green algae 0 1.76 9.47
Schaapen West Blue-green algae 0 1.85 11.54
Iron Ore Jetty
Amphibalanus amphitrite 0 1.24 7.59
Hildenbrandia lecanellierii 0 1.22 7.41
Centroceras clavulatum 1.10 0 6.77
Austromegabalanus
cylindricus
0.96 0.11 5.25
Lynch Point Porphyra capensis 1.43 0.5 4.90*
North Bay Mytilus galloprovincialis 1.15 1.78 4.06*
Marcus Island
Cladophora spp. 1.93 0.27 9.15
Blue-green algae 0 1.05 5.78
*Note that at these sites none of the species contributed >5% to the dissimilarity. The species with the highest
contribution is thus listed.
Figure 9.14 depicts the contributions of the various functional groups to the biotic
community at the study sites over the four survey years. At the two sheltered boulder shores, filterfeeders
had decreased over the years, whereas corticated algae and grazers had increased. At
Schaapen East, filter-feeders have slightly increased with time. Ephemeral algae were highest in
2008, replacing encrusting algae, but this had reversed in 2010. At Schaapen West, there was a
continuous increase in biotic cover, especially in the amount of encrusting algae but also in filterfeeders.
Functional groups showed minor variations at Iron Ore Jetty and Lynch Point, whereas
North Bay experienced an increase in filter-feeders with a concomitant decline in encrusting algae.
At Marcus Island, ephemeral algae had greatly increased from 2005 to 2009 while at the same time
corticated algae and filter-feeders declined. The substantial ephemeral cover resulted in an overall
greater biotic cover in 2009. In 2010, however, ephemerals have reduced and corticated algae as
well as filter-feeders are starting to return.
%