Macroalgae charophytes and bryophytes

Sphagnum bogs in alpine headwaters, moss gardens near waterfalls, leafy mats of liverworts, great skeins of filamentous green algae, beds and clumps of Chara and Nitella with bright orange reproductive organs, delicate, feathery red algae, the amazing emergence of life in once-desolate saltpans after a flood and the slime on rocks that makes keeping your footing in a stream so difficult – macroalgae, charophytes and bryophytes are found in all parts of Australia’s riverine landscapes. Bryophytes are essentially terrestrial; however, many species require the presence of free water only for transport of motile sperm cells and fertilisation of the gametangia borne on the haploid gametophyte. Algae (macroalgae and charophytes), in contrast, usually require free water, or at least a humid environment, for all stages of their life cycle. Bryophytes and algae are highly water dependent, and as such have the potential to be good indicators of water regime, water chemistry and the physical consequences of flow and water presence in riverine systems. Despite this reliance on water, these groups are also great survivors. Some groups of algae are characterised by desiccation-resistant spores or resting cells and some mosses and liverworts can be revived from the smallest shrivelled scrap of tissue through the addition of water. In Australia’s riverine ecosystems there are over 400 species of macroalgae. These species are confined to flowing or still water or, in the case of charophytes, as oospores when systems are dry ( Day et al . 1995 ; Casanova 2007 , 2009a ). Twenty species of Australian bryophytes occur either wholly or partly under water, a further 24 species in boggy headwaters or marshes and an additional 40–50 species near streams in forests ( Meagher and Fuhrer 2003 ). The study of these taxa in riverine systems has been hindered by their inconspicuous nature as most are small and noticeable only in large populations. Until quite recently there has been a lack of accessible taxonomic treatments of these taxa and a paucity of interest and expertise in their recognition and identification. Despite this, bryophytes and macroalgae play a significant role in many riparian systems and have great potential as indicators of riverine health, connectivity and resilience. Copyright © 2016. CSIRO Publishing. All rights reserve