Applicant: Ecomarine Consulting

Species/Taxon: Tasmanian live-bearing seastar (Parvulastra vivipara)

Location: Rocky intertidal zone, Crown intertidal land, at the following locations: 

 Sorell Causeway, lower Pitt Water (source site)

 Pipe Clay Lagoon (release site)

 Ralphs Bay (release site)

Title of research: Trial translocations of the threatened seastar Parvulastra vivipara from a proposed development site on the Sorell Causeway to potential new receiver and habitat offset sites in Pipe Clay Lagoon and Ralphs Bay.

Aim of project: To determine if sites outside Pitt Water, selected through careful research and risk assessment, may provide suitable receiver and habitat offset sites for the threatened seastar Parvulastra vivipara.

Justification: The threatened live-bearing seastar Parvulastra vivipara occurs in rocky intertidal habitat along the causeways at Pitt Water that are proposed to be widened for duplication of east and west bound lanes as part of the South East Traffic Solution (SETS) program. While avoidance and mitigation measures are proposed, there is a risk that disturbance could temporarily compromise large areas of habitat. It has therefore been suggested that P. vivipara individuals will require relocation away from causeways prior to commencement of construction works, to avoid mortalities. It is proposed that upon completion of works, causeway habitat will be re-populated with this species. As a result of widespread environmental degradation of natural shorelines in Pitt Water, there are few potentially suitable receiver sites for relocated animals in that system, and these are characterised by limited rocky habitat which is likely to be at population capacity for P. vivipara. Habitat augmentation trials are underway at remaining healthy sites and are providing promising results, but these areas are not likely to provide the capacity needed to receive all causeway animals. 

A comprehensive site selection process has therefore been conducted to identify potential supplementary receiver sites outside Pitt Water, with two sites in each of Pipe Clay Lagoon and Ralphs Bay identified. Trial translocations are proposed for these sites. Translocations to these sites could have the following benefits:

 Contribute to receiver site capacity needed for relocated animals, to avoid net loss of animals

 Provide a potential source of ‘seed animals’ for subsequent causeway re-population

 Potential longer-term and broader conservation benefits through leaving a portion of animals at translocation sites, providing an expansion of habitat area.

Maximum likely numbers of individuals involved: 68, with 48 animals to be translocated to Pipe Clay Lagoon (2 sites, 24 animals each), and 20 to Ralphs Bay sites (2 sites, 10 animals each).

Activities undertaken and methods: Animals will be collected by hand in low tide, calm conditions from the Sorell Causeway and placed in containers with water supersaturated to 200% dissolved oxygen and maintained at ambient water temperature in eskis, and transported to two sites at Pipe Clay Lagoon and two sites in Ralphs Bay. At Pipe Clay Lagoon, they will be placed in 1m² augmented mudstone rubble habitat quadrats at several shore heights and alongshore positions, with 4 animals placed per quadrat in a total of six quadrats per site, involving a total of 48 animals across both sites. At Ralphs Bay, animals will be placed in natural rubble habitat, with 5 animals placed in each of two habitat patches per site, involving a total of 20 animals across both sites.

Fate of animals: Animals will be monitored 2 weeks, 1 month, 6 months and 12 months following translocation and success determined using performance indicators based on survival rates and evidence of recruitment. If successful, animals will remain at sites and contribute to a larger subsequent translocation proposal. If unsuccessful, NRE will be consulted and remaining animals will be returned to the causeway source site.

Likely impact on species involved (including any by-catch): Risk of mortality of a small number of individuals, although if translocations are successful, recruitment will rapidly counter this loss. Animals being translocated represent 0.5% of the Pitt Water population.