Nitella partita (a form of algae) - endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the alga Nitella partita Nordst. as an ENDANGERED SPECIES in Part 1 of Schedule 1 of the Act. Listing of endangered species is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Nitella partita Nordst.  (alga, Characeae) is a macroscopic green alga (charophyte) superficially similar to submerged flowering plants, with flexible stems and whorls of branch-like structures that carry the reproductive organs. It is described by Casanova  et al., 2003: Rooted annual aquatic plant to 10cm high, dioecious. Internodes 8-23 mm long, 0.3-0.5 mm wide. Branchlets 6 in a whorl, 2-3 furcate. 1° branchlet segments: 1.8-2.5 mm long, 0.1-0.25 mm wide. 2° branchlet segments: 4-6 in number, 0.5-1 mm long, 0.08-0.15 mm wide. 3° branchlet segments: 4-6 in number, same as 2° or dactyls. Dactyls: bicellulate, 4-6 in number, 0.7-1.2 mm long, 0.1 mm wide, end cells partite with 2-4 spreading points, 0.1-0.15 mm diameter and 0.05-0.1 mm high. End cells are occasionally deciduous. Gametangia at first, second (and third) furcations, apparently whole plants are synchronously fertile. Oogonia 0.6 mm long, 0.4 mm wide, beaked, 4-6 convolutions. Antheridia 0.3 mm diameter, 8-scutate. Oospores up to 290 µm long (including wings) 200 µm wide (220 µm including wings), 5 striae with very large and delicate wings, up to 60 µm wide. Fossa 40-45 µm wide occasionally ornamented with low, conical papillae, 0.6 µm high, 0.5-0.7 µm wide at the base, sometimes forming low uneven ridges on the fossa, not extending onto the wings. Chromosomes: n=9.  N. partita appears to be a summer annual, germinating in response to inundation and higher temperatures, growing rapidly during the warmer months before fruiting and dying off in winter (Casanova et al. 2003). Charophyte sexual propagules (oospores) although tiny (usually

2. Nitella partita was recorded, for the first time in NSW in 1999, in the seed banks of four wetlands in north western New South Wales: the saline permanent Lake Altibouka in the Bulloo catchment; the freshwater permanent Waitchie Lake; freshwater temporary Pied Stilt Swamp and Momba Swamp in the Paroo catchment by John Porter (JLP 242, 251). Local government areas covered are Central Darling Area and Unincorporated Area. All collections were germinated from sediment samples during a comparative study on seed banks in arid zone wetlands (Porter 2002). To date, no collections have been made from extant wild populations in NSW. Until these recent collections, the only record of  Nitella partita was from a collection by Alfred Henry in c.1889 near the Georgina River of central western Queensland (Wood & Imahori 1965).

3. Charophytes occur in a wide range of temporary and permanent wetland habitats including those with fresh, brackish and saline water. Nitella partita may be patchily distributed and its abundance is difficult to quantify because of the ephemeral nature of its habitat. Minor floods in the Paroo occur several times a year, with moderate floods every 2-3 years and major floods about every 5 years (Kingsford  et al. 1994). The Bulloo River floods less frequently.

4. The threats to Nitella partita include reduced flooding due to alteration of river flows, climate change and invasive species. Reduced flooding will render the habitat unsuitable, reduce riverine connectivity, increase fragmentation and affect recruitment.

5. In view of the above the Scientific Committee is of the opinion that Nitella partita Nordst.  (Characeae) is likely to become extinct in nature in New South Wales because its numbers have been reduced to such a critical level, or its habitats have been so drastically reduced that it is in immediate danger of extinction.

Associate Professor Paul Adam
Chairperson
Scientific Committee

Proposed Gazettal date: 03/12/04
Exhibition period: 03/12/04 - 28/01/05

References:

Casanova MT, Brock MA (1996) Can oospore germination patterns explain distribution in permanent and temporary wetlands? Aquatic Botany 54, 297-312.

Casanova MT, Garcia A, Porter JL (2003) Charophyte rediscoveries in Australia: What and why? Acta Micropalaeontologica Sinica 20, 129-138.

Kingsford RT, Bedward M, Porter JL (1994) Wetlands and waterbirds in northwestern New South Wales. National Parks and Wildlife Service Occ. Pap. 19, 105pp.

Porter J (2002) Effects of salinity, turbidity and water regime on arid zone wetland seed banks. Verhandlungen Internationale Vereinigung fur theoretische und Anggewandte Limnologie 28, 1468-1471.

Wood RD, Imahori K (1965) A Revision of the Characeae Volume I: Monograph of the Characeae, Verlag Von J. Cramer, New York.