Charophyte Occurrence, Seed Banks and Establishment in Farm Dams in New South Wales

Abstract

Farm dams are an important and common water resource in rural Australia. They provide relatively permanent surface water for stock and wildlife. They typically have high turbidity and high levels of disturbance by stock. The occurrence of charophytes in these water bodies was examined, as well as the conditions under which they germinated and established. Charophytes were found in 15% of 65 farm dams surveyed in two regions in New South Wales, Australia. However, charophytes germinated from 64.5% of farm dam seed banks sampled (n = 17). Species found were Chara australis R.Br., C. fibrosa Agardh ex Bruzelius, C. globularis Thuillier, C. muelleri A.Br., Nitella cristata A.Br. and N. tasmanica A.Br. Farm dams in which charophytes were found both in the survey and in the seed bank had lower turbidity, lower dissolved phosphorus levels and more extensive submerged plant communities than average. Charophytes established from the seed banks under experimentally induced water regimes when high water clarity was maintained and the disturbance of stock grazing was removed. Farm dams can support populations of perennial and annual charophyte species, and provide a habitat that is less available in naturally occurring shallow water bodies of the regions.