Notes on the Biology of Australian Seagrasses* J.KUO (Communicated by A. W. D. LARKUM) Kuo, J. Notes on the biology of Australian seagrasses. Proc. Linn. Soc. N.S. W. 106 (3), (1982)1983:225-245. This contribution focuses on the anatomy, histochemistry and ultrastructure of vegetative organs of Australian seagrasses in relation to their possible functions. Detailed anatomical and ultrastructural structures vary with species. Some structures are similar to those in terrestrial plants and others are unique in seagrasses for adaptation to a marine environment. Some details of the taxonomy, distribution, habitat and life history of Australian seagrasses are also included. The structure of the phyllosphere and rhizosphere in seagrasses is discussed as well as the possible significance of the role of epiphytes and epifauna. J. Kuo, Electron Microscopy Centre, University oj Western Australia, Nedlands, Australia 6009; manuscript received 19 May 1981 , accepted/or publication in revisedjorm 1 7 November 1982. Introduction Seagrasses are aquatic angiosperms which are completely adapted to life in the marine environment. According to Arber (1920) and den Hartog (1970) they require at least the following adaptations to be able to colonize the marine environment suc-cessfully: (1) they live fully submerged in seawater, (2) they have an anchoring system, (3) they have a hydrophilous pollination, (4) they are able to cope with a high salinity. Seagrasses are abundant in Australian waters and play a significant role in marine food chains (Larkum, 1977; King, 1981; McComb et al. , 1981). The ecology of seagrasses including Australian species has been intensively reviewed (McRoy and Helfferich, 1977; Larkum, 1977; Phillips and McRoy,. 1980; McComb rf al., 1981) and will not be dealt with here. Knowledge on other biological aspects of these marine vascular plants is still fragmented. This contribution, which emphasizes anatomy, cellular structure and function, is concerned with these adaptations and other biological aspects of marine angiosperms in Australian waters. A comparative leaf morphology and gross anatomy of seagrasses has been described by Tomlinson (1980). Taxonomy, Distribution and Habitats Taxonomy Den Hartog (1970) contributed an excellent taxonomic study on seagrasses of the world, listing 49 species belonging to twelve genera and four families of angiosperms regarded as seagrasses. A brief taxonomic study of eastern Australian Zostera has been made by Jacobs and Williams (1980). A comprehensive taxonomy of temperate Australian seagrasses will be available soon (Womersley and Robinson, in preparation). Australia is well endowed with seagrasses; there are 25 described species belonging to all genera except the genus Phyllospadix represented in Australian waters (Table 1). Three of these species have only recently been described (Greenway, 1979; Cambridge and Kuo, 1979), and four new Posidonia species are to be described (Kuo and Cambridge, in preparation). Dehydrated specimens, which were collected as drift on the beach and deposited in herbaria, were used by den Hartog (1970). However, herbaria have recently received an increasing number of seagrass specimens taken from their natural habitats. Unfortunately, most herbaria have stored seagrasses in a dehydrated state and the author found it difficult to study the morphology of these dried seagrasses. * A paper presented at the Australian Seagrass Workshop, University of Sydney, 1981 . Proc. Linn Soc N.S.W. 106 (3), (1982) 1983
BioStor
