Diversity of Antarctic Seaweeds

Abstract

Antarctica is characterized by extremes of climate and biogeographic isolation from other continents by distance, high depths, and the Antarctic Circumpolar Current. Even under these harsh conditions, macroalgae thrive in different coastal ecosystems contributing to primary production and serving as habitat and food for a variety of species of marine fauna. However, it is known that the Antarctic marine flora presents low species richness compared to other biogeographical regions: until the past decade a number of 120 Antarctic seaweeds had been reported. On the other hand, long geographical isolation and extreme climatic and oceanographic conditions justify their high degree of endemism (ca. of 33–40%). A new compilation of the Antarctic seaweed diversity is presented in this chapter, reporting a list of 151 species cited to the entire Antarctica, comprising 85 Rhodophyta, 34 Ochrophyta (Phaeophyceae and Chrysophyceae), and 32 Chlorophyta with an endemism degree of 27%, lower than in previous reports. Molecular approaches based on different markers (ITS, UPA, COI-5P) are being used to assist species identification. The collection of marine specimens in Antarctica is expensive and still very difficult, and therefore, the occurrence for many species can become inaccurate. The difficult access to samples is another limitation, which could explain that most of the best known species are concentrated around scientific stations. Consequently, the macroalgal diversity in Antarctica and its distribution is probably underestimated. A better knowledge on this diversity and its distribution is urgent, as the region is facing significant climate changes that may drive shifts on the assemblages of macroalgae.