Botanic Gardens Trust, Sydney, Australia

Marine Algae 2008-2009

Dr Alan J.K. Millar, Principal Research Scientist and Yola Metti

It is now a well accepted fact that anthropogenic instigated global warming is real and having an affect on our climate. Research by Dr Alan Millar is finding disturbing changes to the marine environment as a result of increasing sea surface temperatures. At the International Phycological Congress in Tokyo, Dr Millar gave a paper on the changing distributions of four iconic large brown algae along the New South Wales coast. Based on herbarium records, published accounts and anecdotal evidence, it has been shown that the large Bull kelp, Durvillaea potatorum, has retracted south from Bermagui (where it grew in the 1920s) to Tathra (where its northern-most limit is today). The common shallow water kelp, Ecklonia radiata, has undergone a much larger retraction south from Caloundra to Byron Bay in northern New South Wales, although reports suggest it can survive at 30 m depths off Moreton Island. The intertidal brown alga Hormosira banksii (Neptune’s necklace) has also retracted south from Caloundra to Ballina and what is most disturbing, has become locally extinct on Lord Howe Island. Even our local Sydney kelp, Phyllospora comosa, has disappeared from the Sydney metropolitan area where it used to grow in the 1920s-1940s. CSIRO have detailed and accurate records of sea surface temperatures along the eastern seaboard of Australia and have recorded temperature increases within the East Australian Current of 3-5oC. Dr Millar is staring a project in collaboration with the Sydney Institute of Marine Science (SIMS) and Macquarie University to grow gametophytes of some of these kelps to ascertain the upper temperature tolerance of their gametes. It is these microscopic algal gametes that most likely are not surviving the increased water temperatures and thus not germinating to recruit the larger kelp sporophytes.

Research by Yola Metti, Dr Millar’s PhD student, is clearing up major taxonomic confusion with the red algal group know as the Laurencia complex. Using molecular gene sequences, Yola has shown there are four clear genera involved with a fifth new and undescribed genus from Norfolk Island.

The giant Bull kelp, Durvillaea potatorum. Photo by Dr Alan Millar

Lord Howe Island seaweeds - Caulerpa racemosa (green), Dilophus intermedius (brown) and Asparagopsis taxiformis (red) on the reef toward the southern end near the base of Mt Lidgbird, Lord Howe Island. Photo: Elizabeth Brown