BugWise

Garden Orb Spider on Ash Island. Photo: E Burton © E Burton.

About Kooragang Wetland Rehabilitation Project

The Kooragang Wetland Rehabilitation Project (KWRP) is a project of the Hunter-Central Rivers Catchment Management Authority. KWRP covers 1590 hectares on three sites in the Hunter River estuary adjacent to a major port and industrial complex as well as a large urban area (Newcastle) in New South Wales. It is one of the largest active coastal rehabilitation projects in Australia. KWRP was initiated in 1993 to compensate for the loss of fish, shorebird and other wildlife habitat in the Hunter estuary caused by 200 years of draining, filling and clearing.

The wetlands features mangrove and saltmarsh, and in non-tidal areas, riparian woodlands, remnants of lowland floodplain rainforest and ephemeral, freshwater wetlands.

KWRP has focused on adaptive ecosystem management. With increased knowledge gained through research, management of threatened species (e.g. green and golden bell frog, white cynanchum) and ecological communities (e.g. saltmarsh) has become a central feature of rehabilitation activities.

Find out more about KWRP http://www.hcr.cma.nsw.gov.au/kooragang/

How is Web2Spider being used at the wetlands?

KWRP communications officer, Sue Rostas, attended a BugWise workshop at Tocal in November 2007. Sue saw great potential in the use of Web2Spider at the wetlands and led a team of volunteers in collecting data in plots of differing ages. Sue and her volunteers were interested in determining if diversity and abundance increased with rehabilitation age. The rationale for doing this was to assess the recovery of web-building spider communities, with a view that the recovery trajectory could be used as baseline for future monitoring and assessment.

Results and Discussion

Surveys were conducted over five days (January 16, February 6, March 6, April 2 and 7 May 2008). A total of 1031 webs were counted, the majority (33% of total) of which, were found in the rainforest remnant. Fewest webs were found in the unplanted grassland (21% of total). In revegetated locations, web abundance was intermediate of the unplanted grassland and rainforest remnant (See figures below). Of the two revegetated sites, the semi-mature planting had the higher web abundance (25% of total). Similar patterns to those of web abundance were also found for web diversity. In revegetated locations, web diversity was intermediate of the unplanted grassland and rainforest remnant (See figures below). A total of 27 web types were found with the highest diversity found in the rainforest remnant (21 types) and lowest in unplanted grassland (16 types). Four web-types (W10, W14, W20, W22) were unique to rainforest remnants. There were no web types unique to unplanted grassland as all were found in either revegetation plots or the rainforest remnant. Web type 3 and 23 were unique to semi-mature sites, W7 was unique to the youngest planting, and W15 was only found in revegetation sites.

Results indicated that web diversity and abundance was positively correlated with maturation of the vegetation. The provision of native plants appears to increase both richness and abundance of web-building spiders at the Kooragang Wetlands. These data provide a useful reference curve for which monitoring of future rehabilitation attempts can be compared against. Notably, there were four web types that were found only in the rainforest remnant, and thus are potential indicators of success when taken in isolation.