caa a22 4500 378902296 CHVBK 20180305123521.0 cr unu---uuuuu 161128e20041201xx s 000 0 eng 10.1515/BOT.2004.068 doi (NATIONALLICENCE)gruyter-10.1515/BOT.2004.068 The effect of thallus size, life stage, aggregation, wave exposure and substratum conditions on the forces required to break or dislodge the small kelp Ecklonia radiata [Elektronische Daten] [Mads S. Thomsen, Thomas Wernberg, Gary A. Kendrick] Canopy removal by storms is a primary cause of mortality for the small kelp Ecklonia radiata in temperate Australasia. We simulated hydrodynamic drag from storms with in situ pull-tests to determine whether thallus size, life stage, aggregation, wave exposure and substratum affect the canopy removal process. A total of 466 individuals were pulled off 20 rocky reefs at 8-10m depth in southwestern Australia. The majority (71%) of thalli dislodged at the rock implying that the canopy removal process in southwestern Australia is a substratum-controlled process. Dislodgment bared clean substratum where re-invasion by propagules or encroachment would be necessary to fill up the gaps. Maximum break forces (150-250N) were found for large late stage kelps and kelp aggregates from wave exposed sandstone and granite reefs, and minimum values (25-100N) for small juveniles and solitary kelps from protected limestone reefs. By applying size and break force data to the drag equation, water velocities required to break or dislodge E. radiata were calculated to 2-5ms-1 for large kelps. These velocities are frequently encountered in wave-exposed shallow subtidal habitats, suggesting that thallus size is limited by the hydrodynamic environment. ©2004 by Walter de Gruyter Berlin New York Hydrobiology nationallicence Mycology, fungi nationallicence Botany & plant sciences nationallicence break force nationallicence break place nationallicence canopy removal nationallicence dislodgment nationallicence disturbance nationallicence Ecklonia nationallicence pruning nationallicence Thomsen Mads S. Department of Environmental Science, University of Virginia, 22903 Charlottesville, VA, USA aut Wernberg Thomas School of Plant Biology, Building MO90, University of Western Australia, Crawley WA 6009, Australia aut Kendrick Gary A. School of Plant Biology, Building MO90, University of Western Australia, Crawley WA 6009, Australia aut Botanica Marina Walter de Gruyter 47/6(2004-12-01), 454-460 0006-8055 47:6<454 2004 47 botm https://doi.org/10.1515/BOT.2004.068 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/BOT.2004.068 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Thomsen Mads S. Department of Environmental Science, University of Virginia, 22903 Charlottesville, VA, USA aut NATIONALLICENCE 700 1- Wernberg Thomas School of Plant Biology, Building MO90, University of Western Australia, Crawley WA 6009, Australia aut NATIONALLICENCE 700 1- Kendrick Gary A. School of Plant Biology, Building MO90, University of Western Australia, Crawley WA 6009, Australia aut NATIONALLICENCE 773 0- Botanica Marina Walter de Gruyter 47/6(2004-12-01), 454-460 0006-8055 47:6<454 2004 47 botm CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter