Seaweed morphology is often shaped by the hydrodynamic environment. However, exposure to air at low tide represents an additional factor potentially affecting the morphology of intertidal species. Here, we examined the relationships between the morphology of Hormosira banksii, an important intertidal habitat-forming seaweed in southern Australia, and environmental factors across multiple spatial scales around the island of Tasmania, Australia. Tasmania is surrounded by a diverse coastline with differences in wave exposure, tidal parameters, and temperature. We sampled Hormosira from four regions (100s km apart), three sites (10s km apart) within each region, and two zones (meters apart; eulittoral and sublittoral) at each site, and measured multiple morphological variables to test for differences in morphology at those different spatial scales. Thirteen environmental variables reflecting wave exposure, tidal conditions, and temperature for each site were generated to assess the relationship between Hormosira morphology and environmental variation. Morphology varied at all spatial scales examined. Most notably, north coast individuals had a distinct morphology, generally having smaller vesicles and shorter fronds, compared to other regions. Tidal conditions were the main environmental factors separating north coast sites from other sites and tidal regime was identified as the best predictor of morphological differences between regions. In contrast to other studies, we found little evidence that wave exposure was associated with morphological variation. Overall, our study emphasizes the role of tidal conditions, associated with emersion stress during low tide, in affecting the morphology of intertidal seaweeds.

Item Type:	Refereed Article
Keywords:	biogeographical scales, environmental variability, intertidal macroalgae, morphology, tidal rhythms
Research Division:	Biological Sciences
Research Group:	Ecology
Research Field:	Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:	Environment
Objective Group:	Flora, Fauna and Biodiversity
Objective Field:	Coastal and Estuarine Flora, Fauna and Biodiversity
UTAS Author:	Mueller, R (Ms Rebecca Mueller)
UTAS Author:	Fischer, AM (Dr Andy Fischer)
UTAS Author:	Bolch, CJS (Associate Professor Christopher Bolch)
UTAS Author:	Wright, JT (Associate Professor Jeffrey Wright)
ID Code:	106116
Year Published:	2015
Web of Science® Times Cited:	9
Deposited By:	IMAS Research and Education Centre
Deposited On:	2016-01-29
Last Modified:	2017-11-06
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