Abstract
Non-native species and invasive species are widely accepted as a growing threat to global biodiversity. Yet monitoring, although vital, is patchy and inconsistent. With human influence regarded as a key contributor in the spread of non-natives, it is important for us to actively participate in long-term monitoring. In this study, the percentage cover of the non-native Caulacanthus okamurae (Okamura’s pom-pom weed) was monitored in 30 quadrats over 8 months, in order to look for trends in growth with seasonality, sea temperature and substrate. In addition to this, frequencies of other non-natives were also recorded, demonstrating the level of monitoring able to be put into practice by staff at an environmental education centre. No overall increase in the percentage cover of the species was shown, nor a correlation between percentage cover and sea temperature. However, a statistically significant difference was shown in the percentage cover of the seaweed on two different substrates (artificial and natural), which is thought to be attributable to the seaweed’s ability to colonise rapidly as an ‘aggressive coloniser’ on flat surfaces, thriving better on the Victorian jetty at this site, in comparison to a rocky beach. Although short for a study of this kind and failing to quantify the effect of the non-natives in this ecosystem, this study is important in highlighting the continued need for close and consistent monitoring of non-native and invasive species, and in suggesting further questions to be asked about the non-native Caulacanthus okamurae.