In the marine environment, relatively little is known about how the effects of climatic change will manifest into future patterns of biodiversity and community stability, with the exception of recent work on corals in tropical reef ecosystems. In this thesis, I examine quantitatively how patterns of coral reef biodiversity will respond to the impacts of climatic change and provide essential information (i) to address a critical knowledge gap in the understanding of coral reef biodiversity and (ii) predict how a wide range of sessile invertebrates from coral reef ecosystems will respond to a range of potential impacts of climatic change such as increased physical disturbance and rising sea level. An initial descriptive component of my thesis was required to determine the distribution and abundance of a diverse assemblages of sessile non-scleractinian invertebrates, found along gradients of increasing physical disturbance from wave action and increasing intertidal shore height. I also examined the source, intensity and frequency of disturbance along these environmental gradients. This information was used to derive testable hypotheses about the potential impacts of increasing physical disturbance and rising sea level associated with climatic change. I found that physical disturbance had a substantial influence on the types of species that are able to survive in these intertidal rubble habitats, with diversity decreasing at more exposed shores and further down the shore. Physical disturbance was more important for determining the composition of sessile assemblages than other biotic factors such as predation, which only had weak effects on these sessile assemblages. Increased frequency and intensity of waves and storms will increase rates of physical disturbances such as scraping and overturning of rubble plates, which will have a substantial negative impact on biodiversity in these tropical intertidal habitats. These effects may be more complicated that first thought when combined with the effects of rising sea level which will not only alter the extent of inundation, but may also allow wave energy to propagate further up the shore, which has the potential to modify interactions among species through changes to the supply and recruitment of larvae, predator-prey interactions, competition and survival in harsher environments. However, the magnitude of these impacts may depend on how increased physical disturbance and rising sea level affect established species, and whether they will have a substantial effect on larval mortality rates, which currently appears to be limited by physical disturbance. Declines in biodiversity as a result of climatic change over the next 100 years could have important implications for the future health and productivity of coral reef ecosystems, especially given the ecosystem services these organisms provide. A greater understanding of the processes that drive the distribution and abundance of many different types of organisms on coral reefs, and indeed in other ecosystems, will provide essential information that managers can use to better understand and maintain these important ecosystems for future generations.
| Identifer | oai:union.ndltd.org:ADTP/279152 |
| Creators | Simon Walker |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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