|Sedimentation disrupts natural regeneration of Zannichellia palustris in Fall River, California|
Spencer, D.F.; Ksander, G.G. (2002). Sedimentation disrupts natural regeneration of Zannichellia palustris in Fall River, California. Aquat. Bot. 73(2): 137-147
In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770, more
Accumulation; Germination; River banks; Sediments; Seeds; Zannichellia palustris L. [WoRMS]; INE, USA, California [Marine Regions]
|Authors|| || Top |
- Spencer, D.F.
- Ksander, G.G.
Aquatic plants growing in flowing waters frequently inhabit dynamic substrates, subject to erosion or sediment deposition. Rooted macrophytes have disappeared from the upper portions of Fall River, CA where from 0.6 to 1.2 m of sandy sediments have accumulated. We assessed the abundance of Zannichellia palustris L. seeds in the seed bank, and performed experiments to determine the effect of sediment accumulation on germination and emergence of Z. palustris seedlings. In 1996 and 1997, sediment cores were collected from the upper 15 km of Fall River. Cores were placed in a greenhouse and germination monitored for the next 30-40 days. Viable germinating Z. palustris seeds were present in 67% of the cores collected in 1996. Z. palustris seed density was 1219 seeds m-2 on average and ranged from 0 to 5920 seeds m-2. Seed abundance did not differ between the upper (<11 cm) and lower portions (>11 cm) of cores collected in 1996 or 1997. We conducted four experiments in which Z. palustris seeds and natural sediments containing Z. palustris seeds were buried at various depths under sand. Burial by more than 2 cm of sand inhibited germination and emergence. The implication is that significant sediment accumulation may disrupt natural annual regeneration of Z. palustris from seeds, although a viable seed bank is maintained for several years.