sgarea.htm

Seagrass Beds and Fauna of St Kilda Harbour Continued

2. The Study Area
	The Sea-grass beds are found in the sheltered waters on the northern side of the breakwater protected from the prevailing southwesterly winds. This preferred habitat for the sea-grass dictated the study area. Aerial photographs indicated the areas that this study should be focus on. However, in the course of data collection it was often easier to swim from one site to another giving the members of the group a comprehensive picture of the harbour habitat. The dive sites indicated in Appendix 1 include all connected seagrass in the immediate area not a discrete point.
	Specifically the site can be sub-divided into sea-grass beds that are found Site 1 north-east of the boat pens Site 2 the first section of the breakwater where the boat-pen jetty branches at the teahouse Site 3 between the shore and the first section of the pier
	These 3 areas became the focus of the study survey as they incorporate both the beds and immediately adjacent pylons. An aerial photograph identifies the sites and gives a setting for the study (Appendix 1 Study Area and Seagrass Distribution)

3. Project Scope	A subgroup of St Kilda's Earthcare community group undertook the project. The skills of this group varied considerably and to achieve the best result we divided tasks between professional and non-technical to give maximum opportunity to the groups while maintaining quality information in the final report.
	The project included investigation of seagrass distribution using aerial photographs to determine the areas where obvious marine vegetation existed, then a verification process was used with dives to determine species type. An attempt to quantify seagrass area was made using digitised information that allowed aggregation of defined areas. The accuracy and extent of area was limited by the surface conditions which effected information quality derived from photographs.
	The fauna of the harbour was investigated looking primarily at species diversity with some interpretation of species distribution as it relates to habitat included in the discussion provided by the marine scientists report (Appendix 2). A photographic collection of fauna species is included in Appendix 5.
	Threats to the health of this marine habitat were investigated with heavy metal contamination considered a potential threat due to the proximity of a boat yard and drains. Investigation within the foodchain is beyond the scope of this project but an investigation of sediments was considered a measurable baseline for contamination.

4. Method
4.1 Seagrass Beds Distribution and Coverage	Aerial photographs from 1997 and 2000 were electronically scanned allowing digital analysis of the areas. A number of aerial photographs were available but not all of them provided enough detailed information of the seagrass beds due to water surface conditions. View seagrass map NOTE The year 2000 aerial photograph has poorer quality making area measurement more qualitative. Seagrass was also divided into density of coverage which gives two sets of figures per year for coverage.. See Appendix 1 Study area and seagrass distribution
4.2 Flora and Fauna of St Kilda Harbour	Scientists from the Marine Science Department based at Queenscliff undertook detailed flora and fauna sampling at 3 sites using SCUBA and snorkelling to closely examine the environment. Night dives were also undertaken as many fauna species utilize the cover of darkness for food gathering and travel. Members of Earthcare St Kilda contributed to these activities and augmented the data capture exercise using sample collection and underwater photography to verify species identification.

Back to Projects	Continue: The Results