Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Critically Endangered
Listing and Conservation Advices Commonwealth Listing Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009as) [Listing Advice].
 
Commonwealth Conservation Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009at) [Conservation Advice].
 
Recovery Plan Decision Recovery Plan not required, a recovery plan will have limited benefit for the species. The actions covered by the conservation advice are considered to be sufficient at this time (17/06/2009).
 
Adopted/Made Recovery Plans
Federal Register of
    Legislative Instruments
Inclusion of species in the list of threatened species under Section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (80) (17/06/2009) (Commonwealth of Australia, 2009j) [Legislative Instrument].
 
State Government
    Documents and Websites
TAS:Marginaster littoralis (Derwent River Seastar): Species Management Profile for Tasmania's Threatened Species Link (Threatened Species Section (TSS), 2014tt) [State Action Plan].
State Listing Status
TAS: Listed as Endangered (Threatened Species Protection Act 1995 (Tasmania): September 2012 list)
Scientific name Marginaster littoralis [66762]
Family Poraniidae:Valvatida:Asteroidea:Echinodermata:Animalia
Species author Dartnall, 1970
Infraspecies author  
Reference ANZECC Threatened Fauna List May 2000
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images
http://www.parks.tas.gov.au/file.aspx?id=6917

Scientific name: Marginaster littoralis

Common name: Derwent River Seastar

The species is conventionally accepted (Dartnall 1970).

Materia (1994) collected several specimens exhibiting morphological characteristics between the Derwent River Seastar and the New Zealand Seastar (Patiriella regularis) (an introduced species from New Zealand) but states that no material confidently assigned to the Derwent River Seastar was collected. Materia (1994) subsequently undertook microscopic examination of the collected specimens and comparative material of the New Zealand Seastar and the Derwent River Seastar from the Tasmanian Museum collection and concludes there was very little morphological difference between the two species. Materia (1994a) suggests a possibility of hybridisation between the two species and that the current lack of any of specimens identified as the Derwent River Seastar, may be a result of genetic swamping by the New Zealand Seastar. Alternatively, the New Zealand Seastar may have a great variety of morphologies. Materia (1994) also indicates that the familial placement of the genus Marginaster, is perhaps better included in the Asteriniidae rather than the Poraniidae.

The Derwent River Seastar is a small seastar up to 17 mm across. The species usually has five arms and is a rounded pentagonal shape. It is bluish-greenish-brown on the upper (dorsal) surface, bordered by off-white around the outer edge. The under parts are off-white while the epidermis of the upper surface exhibits brown pigmentation around the base of the spinelets (Bryant & Jackson 1999b; Dartnall 1970; Materia 1994).

The Derwent River Seastar is endemic to Tasmania. The species is only known from five locations in the Derwent River, adjacent to Hobart, in the state's south-east (Bryant & Jackson 1999b; Dartnall 1970; Materia 1994).

A minimum convex polygon around the five known subpopulations provides an estimate of the extent of occurrence of approximately 1.51 km2, although it should be noted that the vast majority of this area is completely unsuitable for the species because of the depth of water (M. Wapstra 2007, pers. comm.).

Insufficient data exists on the current area of occupancy of the Derwent River Seastar, but it is unlikely to exceed 0.01 km2 (based on an estimate of less than 10 m horizontal extent and 200 m linear extent along the shore at any of the five locations) (M. Wapstra 2007, pers. comm.).

The five known subpopulations are all geographically isolated from one another, albeit within the tight confines of the Derwent River (Bryant & Jackson 1999; Dartnall 1970; Materia 1994).

Although all five populations are separated by distances unlikely to be crossed by an adult seastar, the species' distribution is not considered to be severely fragmented. Migration between populations would require travel across open and deep water, away from the preferred mid-littoral zone. (M. Wapstra 2007, pers. comm.).

The Derwent River Seastar was described by Dartnall (1970) from: a dried specimen collected in 1970 from the Powder Jetty; 12 spirit specimens collected in 1969 from Cornelian Bay; and from five spirit specimens from the type locality (Powder Jetty) collected in 1969. The intensity and extent of the survey associated with these collections is not reported but is suspected to be little more than brief surveys for the purpose of specimen collection (M. Wapstra 2007, pers. comm.).

Materia (1994) conducted surveys to locate populations of the species. These surveys failed to locate any clearly identifiable populations. However, specimens exhibiting a morphological appearance similar to the Derwent River Seastar were observed.

The likelihood of the species' current known distribution and/or population size being its actual distribution and/or population size is quite high (Materia 1994).

There is insufficient data to indicate the species' total population size. None of the published accounts of the species provide estimates of abundance. Dartnall (1970) indicates the number of specimens examined and Materia (1994) indicates that the species is likely to be extinct.

A total of 28 specimens are held at the The Tasmanian Museum and Art Gallery (TMAG) in 13 formal collections, collected from between 1969-1991 (TSSC 2009as ).

The Derwent River Seastar is known from five subpopulations (Materia 1994):

  • Cornelian Bay Point (first and last seen in 1969)
  • Powder Jetty (Type locality) (first and last seen in 1969)
  • Botanical Gardens near Pavillion Point (first and last seen in 1969)
  • Granville Avenue, Risdon (first seen in 1880-1900?, last seen in 2004)
  • Paloona Street, Lindisfarne (first seen in 1990, last seen in 2002).

There is insufficient data to determine historic or current population trends in the Derwent River Seastar (TSSC 2009as). Periodic visits to the known localities from 1975 through to the 1980s, found populations of the species (Materia 1994). It is thought that the species is most likely extinct from the Derwent River, at least at the five previously recorded locations (Materia 1994).

The generation length of the Derwent River Seastar is not known. However, the similar Live-bearing Seastar (Patiriella vivipara) is likely to have a comparable generation length (TSSC 2009as). The Live-bearing Seastar reaches maturity at one year and may live up to ten years (Prestedge 1998). Therefore, the generation length for the Live-bearing Seastar has been estimated to be four years, using standard formula for generation length based on longevity and age at sexual maturity (TSSC 2009as).

However, if the generation length of the Derwent River Seastar is in the order of four years, the decline in the species' numbers is likely to have taken place more than three generations ago, as the species has not been conclusively located since the 1980s (Materia 1994).

All populations are considered necessary for the species' long-term survival and recovery.

After a survey for the species, Materia (1994a) reported that Derwent River Seastar was not recorded at any of the study sites included in that survey and suggests the species had been genetically swamped (hybridised) by the introduced New Zealand Seastar.

None of the subpopulations of Derwent River Seastars occur in reserves.

The Derwent River Seastar lives in rocky, shallow waters in the Derwent River (Bryant & Jackson 1999b; Dartnall 1970) in the mid-littoral zone in waters between 0–1.5 m depth (Materia 1994).

The distribution of this species is not known to overlap with any listed threatened ecological communities or species (M. Wapstra 2007, pers. comm.; TSSC 2009at).

Insufficient information is available on age of sexual maturity, life expectancy and natural mortality of the Derwent River Seastar.

Little information is available on the reproduction of the Derwent River Seastar, however, the species is known to belong to a group of Seastars that exhibit a free-swimming larval stage. This enables the larvae to be distributed on the currents present in the tidal section of the Derwent River (M. Wapstra 2007, pers. comm.).

The species is thought to be a particulate feeder/algae grazer because of the morphology and anatomy of the digestive system (the stomach is extensible and surface mucus is abundant) and the fact that only detritus and algal fragments have been identified in the stomachs of observed specimens (Dartnall 1970).

Insufficient information exists on the species' daily or seasonal patterns of movement.

Identification of Derwent River Seastar requires specialist confirmation, as it is easily confused with the New Zealand Seastar which occurs in close proximity throughout its range (Bryant & Jackson 1999; Dartnall 1970). Dartnall (1970) indicates that the pale fringing border to the body and the large papulae (respiratory organ projecting through the pores in the Seastar body wall, mainly on the upper surface) which extend far on to the distal areas of the arms, are good field characters.

Materia (1994) has conducted surveys between August and October (although the timing of survey is not particularly relevant to this species). Quantitative counts were made by running a series of 25 m transects parallel with the shore along the 0.5 m, 1 m and 1.5 m depth contours and counting the number of specimens in a 1 m2 quadrat every 5 m. Collected specimens were narcotised in a solution of 95% seawater and 5% menthol crystals and fixed in 70% ethyl alcohol.

Interspecific competition from introduced seastars
The main threat to the Derwent River Seastar is interspecific competition and displacement from introduced seastars such as the New Zealand Seastar (Patiriella regularis) and the Northern Pacific Seastar (Asterias amurensis) (M. Wapstra 2007, pers. comm.).

A potential threat from these introduced seastars is genetic swamping (hybridisation). Materia (1994a) suggested that the Derwent River Seastar may have been genetically swamped by the introduced New Zealand seastar. Dartnall (1969a) suggested that the New Zealand Seastar was introduced to Tasmanian waters as a result of the oyster trade between Bluff (South Island, NZ) and Hobart (Tasmania) in the early 1900s.

As recently as the 1930s, live oysters were shucked as ships approached the port of Hobart, and waste was thrown into the Derwent River estuary. A number of invertebrate species previously restricted to New Zealand were first recorded in south-east Tasmania around this time, including two seastars, two crabs, five molluscs and a brachiopod species (Dartnall 1969a). Many of these introduced species are now abundant in southern Tasmania, and some have spread to further afield: the New Zealand Seastar for instance, was not recorded in south-east Tasmania in a 1929 survey, but is now the most abundant asteroid in the south-east of the state. The rapid invasion of the species is consistent with its extended planktotrophic phase. A 2003 record from eastern Tasmania indicates that the species has continued to spread (Waters & Roy, 2004).

A microscopic examination that compared hybridised specimens with the TMAG specimens of the Derwent River Seastar and the New Zealand Seastar, concluded that there was very little morphological difference between the original two species. No specimens that could be conclusively identified as the Derwent River Seastar were found in a 1993 study, which may indicate the species had been subsumed by hybrids at that time, or that it had been excluded from its former range by morphological varieties of the New Zealand Seastar (Materia 1994a).

Habitat modification and destruction
An additional threat is habitat modification and destruction. The recorded range of the Derwent River Seastar is in close proximity to Hobart and consequently the species is impacted by habitat degradation and modification through anthropogenic causes such as urban encroachment and run-off of pollutants. Fluctuations in the amounts of organic run-off leading to eutrophication of the aquatic environment, oil pollution, and domestic and industrial pollution such as plastics, glass and tin have been observed within the species' range (Materia, 1994) and are suspected to impact the species adversely (TSSC 2009as).

Minister's Reasons for Recovery Plan decision

A recovery plan is not considered to be necessary for this species as a recovery plan will have limited benefit for the species. The actions covered by the conservation advice are considered to be sufficient at this time.

The Conservation Advice for the Derwent River Seastar (TSSC 2009at) recommends the following priority research, recovery and threat abatement actions to support the recovery of the species:

  • Design and implement a monitoring program.
  • Undertake survey work in suitable habitat and potential habitat to locate any additional populations.
  • Control and monitor ballast water.
  • Undertake further genetic analysis.
  • Undertake regular surveys to determine the species range and monitor changes in the species population size.
  • Manage any changes to hydrology that may result in increased run-off, sedimentation or pollution.
  • Develop and implement a management plan for the control of New Zealand Seastar (Patiriella regularis) and the Northern Pacific Seastar (Asterias amurensis) in the local region.
  • Raise awareness of the Derwent River Seastar within the local community.

  • Dartnall (1970) provided the formal description of the species and included some basic information on distribution, habitat and feeding biology.
  • Materia (1994) reported on periodic visits to the type localities.
  • Materia (1994a) reported on efforts to locate populations of the species and to determine how they are affected by competition with the New Zealand Seastar.

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat loss, modification and/or degradation Commonwealth Listing Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009as) [Listing Advice].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat modification, destruction and alteration due to changes in land use patterns Commonwealth Listing Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009as) [Listing Advice].
Ecosystem/Community Stresses:Ecosystem Degradation:Decline in habitat quality Commonwealth Conservation Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009at) [Conservation Advice].
Invasive and Other Problematic Species and Genes:Invasive and Other Problematic Species and Genes:Predation, competition, habitat degradation and/or spread of pathogens by introduced species Commonwealth Listing Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009as) [Listing Advice].
Commonwealth Conservation Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009at) [Conservation Advice].
Pollution:Pollution:Deterioration of water and soil quality (contamination and pollution) Commonwealth Listing Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009as) [Listing Advice].
Commonwealth Conservation Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009at) [Conservation Advice].
Residential and Commercial Development:Housing and Urban Areas:Habitat loss, modification and fragmentation due to urban development Commonwealth Conservation Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009at) [Conservation Advice].
Residential and Commercial Development:Residential and Commercial Development:Habitat modification (clearance and degradation) due to urban development Commonwealth Listing Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009as) [Listing Advice].
Species Stresses (suggest Reproductive Resilience?):Indirect Species Effects:Reduction of genetic intergrity of a species due to hybridisation Commonwealth Listing Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009as) [Listing Advice].
Commonwealth Conservation Advice on Marginaster littoralis (Threatened Species Scientific Committee (TSSC), 2009at) [Conservation Advice].

Bryant, S. & J. Jackson (1999b). Tasmania's Threatened Fauna Handbook: What, Where and How to Protect Tasmania's Threatened Animals. Hobart, Tasmania: Threatened Species Unit, Parks and Wildlife Service.

Dartnall, A.J. (1969a). New Zealand sea stars in Tasmania. Papers and Proceedings o f the Royal Society of Tasmania. 103:53-55.

Dartnall, A.J. (1970). A new species of Marginaster (Asteroidea: Poraniidae) from Tasmania. Proceedings of the Linnaean Society of N.S.W. 94(3):207-211.

Materia, C.J. (1994). A Study of Native Asteroids in South Eastern Tasmania. Wildlife Report 94/9. Hobart, Tasmania: Tasmania Parks and Wildlife Service, and the Tasmanian Museum and Art Gallery.

Materia, C.J. (1994a). The Status of the Tasmanian Seastar Marginaster littoralis Dartnall, 1970. Prepared for the Australian Nature Conservation Agency Feral Pests Program, Number 19. Wildlife Report 94/8. Hobart, Tasmania: Tasmania Parks and Wildlife Service.

Prestedge, G.K. (1998). The distribution and biology of Patiriella vivipara (Echinodermata: Asteroidea: Asterinidae) a Seastar endemic to southeast Tasmania. Records of the Australian Museum. 50:161-170.

Threatened Species Scientific Committee (TSSC) (2009as). Commonwealth Listing Advice on Marginaster littoralis. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/66762-listing-advice.pdf.

Threatened Species Scientific Committee (TSSC) (2009at). Commonwealth Conservation Advice on Marginaster littoralis. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/66762-conservation-advice.pdf.

Turner, E. (2008). Personal communications to compiler, April/May 2008.

Wapstra, M. (2007). Personal communications. Hobart, Tasmania: Environmental Consulting Options Tasmania.

Waters, J.M. & M.S. Roy (2004). Phylogeography of a high-dispersal New Zealand sea-star: does upwelling block gene-flow?. Molecular Ecology. 13:2797-2806.

EPBC Act email updates can be received via the Communities for Communities newsletter and the EPBC Act newsletter.

This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Marginaster littoralis in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Thu, 24 Jul 2014 11:20:50 +1000.