Year: 2012
Type: dissertation
Abstract: Sea urchins can have a significant influence upon the ecological structure of coral reefs through both bioerosion of substrata and by affecting competition for space.Loss of reef structure can limit space for algal and coral recruitment which further alters the balance between reef growth and reef destruction.Urchins are important grazers in many marine systems and can cause major ecosystem changes when their numbers reach high levels (generally after a decline in the numbers of their fish predators).However, the relative importance of the role of urchins in influencing the composition and structure of coral reef habitats has rarely been explored.This thesis investigated the habitat preferences, distribution, grazing, bioerosion, and behaviour of the grazing urchin Echinometra mathaei at Ningaloo Marine Park (NMP), Western Australia.Coral reef habitats of the NMP were characterised using field surveys and validations of broad-scale hyper-spectral benthic habitat maps; the effects of habitat type and different closure regimes (e.g.Sanctuary zones) on urchin distribution and abundance were then examined and compared.This thesis represents the first study to quantify the grazing and consequent bioerosion rates of E. mathaei at Ningaloo Reef and the first to study their animistic behaviour and diurnal movement patterns.Data were collected from over 100 sites within the Marine Park, focussing on near shore, lagoonal and back reef areas within Sanctuary zones and adjacent Recreation zones.Data analyses indicated that the distribution of urchins was variable and appears not to be affected by the management zones of the park (i.e.no significant evidence has been found of indirect effects from fishing of known urchin predators).Control -1.310 -4.265Control -0.013 -0.044Control 1.000 3.378 Control 4.772 17.279Control 2.343 7.932 Open -0.863 -2.868 1.964 6.974 Open 0.482 1.674 0.936 3.179 Open 2.600 8.899 -0.531 -1.781 Open 2.877 9.739 -0.055 -0.188 Open 2.051 6.977 2.404 8.274 Open 2.789 9.745 -1.327 -4.362 Open 0.536 1.872 Closed -0.672 -2.134 0.903 2.996 Closed 0.898 2.979 1.002 3.472 Closed 0.733 2.
Author: M. Langdon
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1936325687