Advice to the Minister for Sustainability, Environment, Water, Population & Communities
from the Threatened Species Scientific Committee (the Committee)
on amendment to the list of Threatened Species under the
Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)
1. Reason for Conservation Assessment by the Committee
This advice follows assessment of information gathered through the Commonwealth’s
partnership with Queensland on:
Sargassum amaliae (an alga)
2. Summary of Species Details
Taxonomy
Conventionally accepted as Sargassum amaliae Grunow 1874.
There is some uncertainty about the taxonomy of the genus
Sargassum in tropical Australia (Phillips and Price, 1997; Millar,
pers. comm., 2012; McCook, pers. comm., 2012). Sargassum
amaliae can be confused with other Sargassum species which
are widespread, therefore it can be difficult to identify in field
surveys.
For the purpose of this assessment the Committee recognises
Sargassum amaliae as a distinct species.
State/ Territory Listing
Status
This species is not listed as threatened under Queensland
legislation.
Description
Sargassum amaliae is a brown alga with several primary
branches up to 45 cm in length arising from the base. Primary
branches produce densely crowded stems composed of many
simple leaf-like structures 20–40 mm long and 3–5 mm broad.
These structures have rounded or tapering tips and numerous
spherical sacs 2–3 mm in diameter (Phillips, pers. comm.,
2010). Morphology of Sargassum species can be influenced by
environmental conditions, and hence identification depends on
DNA sequence data (Millar, pers. comm., 2012).
Distribution
In Australia, Sargassum amaliae is known from Queensland
(Bostock and Holland, 2010) and Norfolk Island (Lewis, 1985;
Millar, 1999; Guiry and Guiry, 2012). It occurs in the lower
intertidal zone on wave-exposed rocky substrata (Phillips, pers.
comm., 2010) and possibly also in subtidal habitat (Diaz-Pulido,
pers. comm., 2011). In Queensland the species has been
recorded from:
-
Bribie Island (isotype) – specimen collected in the 1860s
and held by the National Herbarium of Victoria (Phillips and
Blackshaw, 2011);
-
Rockingham Bay near Cardwell – specimen collected in
1870 and held by the National Herbarium of Victoria (Phillips
and Blackshaw, 2011);
-
Cooktown – doubtful record (Phillips and Blackshaw, 2011);
-
Caloundra – specimens collected in 1961 and held by the
Queensland Herbarium (Phillips and Blackshaw, 2011); and
-
Point Cartwright at Mooloolaba – description only (Cribb,
1958).
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Quantitative surveys in 2004–06 showed that S. amaliae no
longer occurred at Caloundra and Point Cartwright (Phillips and
Blackshaw, 2011; Phillips, pers. comm., 2010) where
photographs, descriptions and herbarium specimens
documented well-developed populations in the mid 1950s and
1961 (Cribb, 1958; Phillips, pers. comm., 2010). The Bribie
Island specimen was likely to have drifted from Caloundra, and
the Cooktown record is regarded as spurious (Phillips and
Blackshaw, 2011). The species has not been recorded in the
well-studied Townsville region, where eight common Sargassum
species occur (Martin-Smith, 1993).
The most recent record of this species in Queensland is from
Caloundra in 1961. Recent surveys suggest that it no longer
occurs at this or at any of the other previously known
Queensland sites (Phillips and Blackshaw, 2011).
A large source of uncertainty in this assessment is the current
distribution of S. amaliae because other Sargassum species
with which it might be confused on morphological grounds are
widely distributed.
Relevant
Biology/Ecology
Sargassum species generally reach sexual maturity at six
months, are estimated to have a life expectancy of 5–15 years
(Womersley, 1987) and persist for several decades as stable
populations (Phillips, pers. comm., 2010).
Sargassum amaliae is a ‘foundation’ species (Cribb, 1958) that
provides three-dimensional habitat, food and protection for
many invertebrates (including crustaceans, mites, echinoderms
and polychaetes) and algae. Sargassum species are also an
important food source for Chelonia mydas (green turtle)
(Garnett et al., 1985), which is listed as vulnerable under the
EPBC Act.
Threats
Known
The only known threats to S. amaliae are the impacts
associated with urbanisation, such as eutrophication (nutrient
enrichment by sewage) which affects recruitment due to the
sensitivity of juveniles to high nutrient levels (Phillips, pers.
comm., 2010). Range contractions of Sargassum species and
other large brown algae have occurred world-wide, including
Mediterranean-wide extinctions (e.g. Thibaut et al., 2005;
Pinedo et al., 2007). Large brown algal communities typically
disappear from urbanised coastlines and areas in the vicinity of
sewage outfalls (Brown et al., 1990; Pinedo et al., 2007).
Potential
There are no known potential threats to this species.
3. Public Consultation
Notice of the proposed amendment was made available for public comment for 30 business
days. No comments were received from members of the public. Comments received from six
algal experts as a result of targeted consultation have been considered as part of this
assessment.
4. How judged by the Committee in relation to the EPBC Act criteria and Regulations
Criterion 1:
It has undergone, is suspected to have undergone or is likely to undergo in the
immediate future a very severe, severe or substantial reduction in numbers.
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For this criterion to be met, the population size of this species must have been observed,
estimated, inferred or suspected to have declined by at least 30% over the last ten years or
three generations of the species (whichever is the longer), with this threshold value (30%) linked
specifically in the Act to threats that may not have ceased or may not be reversible.
Not eligible
Criterion element
Evidence
Reduction in numbers
Insufficient data – Based on the disappearance of S. amaliae
from Caloundra and Point Cartwright, this species is inferred to
have declined. However, as the species is difficult to recognise
in the field, there are insufficient data to determine the severity
of this decline and whether it occurred over a timeframe
appropriate to this criterion, therefore the species is not eligible
for listing under this criterion.
Criterion 2:
Its geographic distribution is precarious for the survival of the species and is
very restricted, restricted or limited.
For this criterion to be met, this species’ extent of occurrence must be less than 20 000 km2
and/or its area of occupancy must be less than 2000 km2, its geographic distribution must be
precarious for its survival based on severe fragmentation or known to exist at a limited location,
and a continuing decline must be observed, inferred or projected based on the degree of threat
operating on the species.
Not eligible
Criterion element
Evidence
Geographic distribution
AND
Insufficient data – The Committee considers that the species’
range cannot be accurately determined due to the lack of
surveys undertaken in potential sub-tidal habitat and the
difficulty in identifying the species in the field.
Geographic distribution
precarious
Insufficient data – The species is difficult to recognise in the
field and as such its distribution is uncertain. Therefore, the
species is not eligible for listing under this criterion.
Criterion 3:
The estimated total number of mature individuals is very low, low or limited;
and either
(a) evidence suggests that the number will continue to decline at a very high, high
or substantial rate; or
(b) the number is likely to continue to decline and its geographic distribution is
precarious for its survival
For this criterion to be met, the estimated number of mature individuals of this species must be
less than 10 000, and the rate of continuing decline is at least 10% in 10 years or three
generations, or there is a continued decline and the geographic distribution is precarious, having
regard to the degree of threat operating on the species.
Not eligible
Criterion element
Evidence
Total no. of mature
individuals
Insufficent data – refer to Section 5 below.
AND
Rate of continued decline
Insufficient data – refer to Section 5 below.
OR
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Total no. of mature
individuals
Insufficient data – refer to Section 5 below.
AND
Continued decline likely
AND
Geographic distribution
precarious
Criterion 4:
Insufficient data – Eutrophication (nutrient enrichment) from the
continuing development of the Queensland coast would be
expected to reduce the geographic distribution and number of
populations of S. amaliae (Phillips, pers. comm., 2010),
particularly given the species’ already fragmented distribution
and limited dispersal capabilities. However, the species’
distribution is uncertain and there is no evidence to suggest
this threat is affecting the Norfolk Island population.
Insufficient data – See Criterion 2
The estimated total number of mature individuals is extremely low, very low or
low
For this criterion to be met, the estimated total number of mature individuals must be less than
1000.
Not eligible
Criterion element
Evidence
Total no. of mature
individuals
Insufficient data – refer to Recommendation 5 below.
Criterion 5:
Probability of extinction in the wild that is at least
(a) 50% in the immediate future; or
(b) 20% in the near future; or
(c) 10% in the medium-term future
For this criterion to be met, the probability of extinction in the wild must be at least 10% in the
medium-term future (within 100 years).
Not eligible
Criterion element
Evidence
Probability of extinction in
the wild
There has been no formal modelling of the probability of
extinction of this species.
5. Recommendations
The Committee recommends that Sargassum amaliae is not eligible for inclusion in the list
referred to in section 178 of the EPBC Act. There are insufficient data to assess the species’
status effectively and thus the Threatened Species Scientific Committee finds this species to be
‘data deficient’.
The species is difficult to recognise in the field and as such its distribution is uncertain. Given
that the species could occur in other areas, it is unlikely that the whole of the species’ population
would be impacted by stochastic events or a single threatening process. Until further surveys
and associated molecular work are undertaken the Committee cannot conclude that the species’
geographic distribution is precarious for the survival of the species or limited. The Committee
therefore considers that the species is not eligible for listing against any of the criteria.
The Committee recommends the following research could be undertaken to overcome the lack
of data:
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

Survey appropriate habitats within the known previous extent of occurrence of the species,
particularly in the northern end of the Queensland part of the species’ range (especially
Rockingham Bay) and Norfolk Island. Surveys should include rocky substrates in both
intertidal and subtidal zones.
Ensure that identification of the species from the above surveys is verified using appropriate
molecular techniques.
Until such research is done, the Committee is unable to undertake any form of risk analysis for
this species.
The Threatened Species Scientific Committee encourages a subsequent nomination of this
species for status assessment should the data deficiency be adequately addressed.
Threatened Species Scientific Committee
4 May 2013
6.
References cited in the advice
Bostock PD and Holland AE (2010). Census of the Queensland Flora. Queensland Herbarium
Biodiversity and Ecosystem Sciences, Department of Environment and Resource
Management, Brisbane.
Brown VB, Davies SA and Synnot RN (1990). Long-term monitoring of the effects of treated
sewage effluent on the intertidal macroalgal community near Cape Schanck, Victoria,
Australia. Botanica Marina 33: 85–98.
Cribb AB (1958). An ecological and taxonomic account of the marine algae of south-eastern
Queensland. PhD thesis, University of Queensland, Brisbane, Australia.
Diaz-Pulido, G (2011). Personal communication by email. 7 December 2011. Lecturer, Griffith
University, Queensland.
Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC)
(2012). Environmental Resources Information Network (ERIN) database. Accessed 5
March 2012.
Garnett ST, Price IR and Scott FJ (1985). The diet of the green turtle Chelonia mydas (L.) in
Torres Strait. Australian Wildlife Research 13: 103–112.
Guiry MD and Guiry GM 2012. AlgaeBase. World-wide electronic publication, National
University of Ireland, Galway.
Viewed: 10 May 2012
Available on the Internet at: http://www.algaebase
Lewis JA (1985). Checklist and bibliography of benthic marine macroalgae recorded from
northern Australia II. Phaeophyta. Defense Science and Technology Organisation.
Department of Defense, Melbourne. Report MRL-R-962, pp. 1–40.
Martin-Smith KM (1993). The phenology of four species of Sargassum at Magnetic Island,
Australia. Botanica Marina 36: 327–334.
McCook L (2012). Personal communication by phone, 22 March 2012. Great Barrier Reef
Marine Park Authority.
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Millar AJK (2012). Personal communication by email, 20 March 2012. Principal Research
Scientist, Royal Botanic Gardens, Sydney.
Millar AJK (1999). Marine benthic algae of Norfolk Island, South Pacific. Australian Systematic
Botany 12:479–547.
Phillips JA (2010). Personal communication by nomination form, 23 March 2010, EcoAlgae
Research Pty Ltd.
Phillips JA and Blackshaw JK (2011). Extirpation of macroalgae (Sargassum spp.) on the
subtropical east Australian coast. Conservation Biology 25(5): 913–921.
Phillips JA and Price IR (1997). A catalogue of Phaeophyta (brown algae) from Queensland,
Australia. Australian Systematic Botany 10: 683–721.
Pinedo S, García M, Satta MP, deTorres M and Ballesteros E (2007). Rocky-shore communities
as indicators of water quality: A case study in the northwestern Mediterranean. Marine
Pollution Bulletin 55: 126–135.
Thibaut T, Pinedo S, Torras X and Ballesteros E (2005). Long-term decline in the populations of
Fucales (Cystoseira spp. and Sargassum spp.) in the Albères coast (France, Northwestern Mediterranean). Marine Pollution Bulletin 50:1472–1489.
Womersley HBS (1987). The marine benthic flora of Southern Australia Part II. Adelaide, South
Australian Government Printing Division.
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