red algae Phyllophora antarctica

Phyllophora antarctica is endemic to Antarctica being found throughout Antarctica and the Antarctic Peninsula, and South Orkney Islands [1,3,8]. P. antarctica is abundant at depths from 10 to 25 meters, and found down to 35 meters depth [1,7,8]. Determinants for depth ranges of algae are ice scouring, anchor ice formation, salinity changes from land runoff and melting of platelet ice under the sea ice, and photosynthetic efficiency with reduced levels of light [1]. P. antarctica has a short stipe and a blade up to seventeen centimeters long and 1.5 centimeters wide [1,8].

McMurdo Sound has the world's southernmost populations of benthic marine algae and three red algae are the dominant macroalgae south of 77 degrees latitude: Iridaea cordata, Leptophytum coulmanicum, and Phyllophora antarctica [1]. P. antarctica forms dense beds from 10-25 meters depth in Terra Nova Bay by the end of January, reaching 10,000 plants per square meter and 1.5 kilograms wet weight per square meter [6].

Antarctic seaweeds can tolerate dark periods up to one year without damage and they can grow and complete their life cycle with very low levels of light; both of these are important for surviving long periods of winter darkness and also living under a cover of sea ice [8].


Here is Phyllophora antarctica attached to a Sterechinus neumayeri sea urchin. S. neumayeri attaches pieces of algae like P. antarctica and Iridaea cordata to itself as protection against the anemone Isotealia antarctica [54]. Both algae manufacture unpalatable defensive chemicals to avoid getting eaten by S. neumayeri, yet the urchin attaches algal pieces to itself as a detachable shield to shed when the anemone's tentacles grab onto the attached algae [4,5].

Serpulid polychaetes and hydroids can be found colonizing the surface of P. antarctica, along with the bryozoans Beania livingstonei, Celleporella antarctica, and Harpecia spinosissima [2,7].

At some sites where these algae occur with S. neumayeri, 96.5% of the urchins were using Phyllophora antarctica for 90% or more of their cover [5]. This is a mutually beneficial relationship between Sterechinus neumayeri and the algae [5]. The urchins move fertile drift algae throughout sunlit waters, thereby keeping drift algae in the reproductive area with other attached and drift algae; the urchins also extend the vertical and horizontal range of the algae and facilitate recolonization after ice scouring of the bottom or when conditions allow growth of attached plants at greater depths [5].

1: American Zoologist 31(1):35-48, 1991; 2: Boletin de la Sociedad de Biologia de Concepcion 62:179-186, 1991; 3: Oceanografia in Antartide, Oceanografia en Antartica. VA Gallardo, O Ferretti, HI Moyano, eds. ATTI Seminario Internazionale, ACTAS Seminario Internacional. Concepcion, Chile, 7-9 March 1991. ENEA, Progetto Antartide, Italy & Centro EULA, Universidad de Concepsion, Concepcion, Chile, 1992. pp. 395- 408; 4: Journal of Phycology 34(1):53-59, 1998; 5: Marine Ecology Progress Series 183:105-114, 1999; 6: Scientia Marina 63(Supplement 1):113- 121, 1999; 7: Ross Sea ecology : Italiantartide Expeditions (1987- 1995). FM Faranda, L Guglielmo, A Ianora, eds. Berlin : Springer, 2000; 8: Antarctic seaweeds. C Wiencke & MN Clayton. Ruggell, Lichtenstein : A.R.G. Gantner Verlag, 2002

Text ©Peter Brueggeman. Photographs ©Canadian Museum of Nature (Kathleen Conlan) & Norbert Wu. Photographs may not be used in any form without the express written permission of Canadian Museum of Nature (Kathleen Conlan) and Norbert Wu. Norbert Wu no longer grants permission for uncompensated use of his photos under any circumstances whatsoever; want more info?