Spatial distribution and seasonal variation in Undaria pinnatifida ...

Figure 4: Western Coromandel Peninsula coastal survey sites: Green paths indicate no Undaria was sightedand orange represents sites where Undaria plants were present.Undaria was found in shallow reef habitats with easily colonisable open spaces, it was not found to be present atcomparable sites with dense algal canopies. Plants were seen to be colonising areas of small to medium boulders orpatches of clear rocky reef inside the subtidal algal belt or adjacent to it (low-intertidal or reef-sand border). Infestationlevels were low (Category 1) at five of the coastal sites. Between two and six plants were recorded at these five sites, ateach site the Undaria seen was clustered within one 50m transect only. A medium level of infestation (Category 2) wasseen at Kirita Bay where forty-nine plants were counted. This site comprised a relatively large area (~30 x 30m) ofrelatively flat reef at ~mean low water that was dominated by coralline turf (Corallina officinalis). A sparse mixed algalassemblage, comprising Ecklonia radiata, Carpophyllum maschalocarpum (dominant) and Carpophyllum plumosum,occurred in a marginal subtidal fringe and sand occurred at about one meter depth.11