Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 506:61-70 (2014) - DOI: https://doi.org/10.3354/meps10778 Length, strength and water flow: relative importance of wave and current exposure on morphology in kelp Laminaria hyperborea Trine Bekkby1,2,*, Eli Rinde1, Hege Gundersen1,3, Kjell Magnus Norderhaug1,4, Janne K. Gitmark1, Hartvig Christie1 1Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway 2Geo-Ecology Research Group, Natural History Museum, and 3Centre for Ecological and Evolutionary Synthesis (CEES), and 4Department of Biosciences, University of Oslo, 0316 Oslo, Norway *Corresponding author: trine.bekkby@niva.no ABSTRACT: Water flow is a strong determinant of kelp growth, but it is also a stress factor causing breakage and dislodgement. As wave exposure and currents differ with respect to flow pattern, the 2 forces are expected to affect kelp morphology differently. We investigated how wave exposure and current speed interact and influence kelp Laminaria hyperborea morphology. We sampled thalli from 27 stations on the Midwest coast of Norway and recorded age, and length- and strength-related characters. We found that high wave exposure and current speed influenced holdfast biomass and stipe thickness. Wave exposure had, overall, a stronger effect than current speed. An increase in current speed seemed to have a considerable effect at low wave exposure levels, but the relationship weakened at high wave exposure levels. The length-related (‘go with the flow’) characters thallus and stipe length were influenced by wave induced water flow but not by current speed. Differences in wave exposure and current speed had very weak influences on lamina biomass and length. Thus, the proportion of the thallus being lamina was high in the most sheltered areas and decreased as the wave exposure increased. Our study suggests that the strong, orbital and stochastic mode of wave exposure has a different and stronger effect as a stressor than the more regular and bidirectional stress caused by currents. KEY WORDS: Physical disturbance · Stress · Water flow · Kelp morphology · Biomass · Size Full text in pdf format Supplementary material PreviousNextCite this article as: Bekkby T, Rinde E, Gundersen H, Norderhaug KM, Gitmark JK, Christie H (2014) Length, strength and water flow: relative importance of wave and current exposure on morphology in kelp Laminaria hyperborea. Mar Ecol Prog Ser 506:61-70. https://doi.org/10.3354/meps10778 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 506. Online publication date: June 23, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.
Highlights
Water flow is a key environmental factor for macroalgae, both directly through environmental stress causing breakage and dislodgement and indirectly by affecting factors such as light levels and carbon metabolism (e.g. Wing & Patterson 1993), photosynthesis and nutrient uptake (Wheeler 1988), transport across boundary layers (Raven 1981), settlement and recruitment (Vadas et al 1990), resource allocation (Raven 1988) and growth (Hepburn et al 2007)
We investigated how wave exposure and current speed interact and influence kelp Laminaria hyperborea morphology
An increase in current speed seemed to have a considerable effect at low wave exposure levels, but the relationship weakened at high wave exposure levels
Summary
Water flow is a key environmental factor for macroalgae, both directly through environmental stress causing breakage and dislodgement and indirectly by affecting factors such as light levels and carbon metabolism (e.g. Wing & Patterson 1993), photosynthesis and nutrient uptake (Wheeler 1988), transport across boundary layers (Raven 1981), settlement and recruitment (Vadas et al 1990), resource allocation (Raven 1988) and growth (Hepburn et al 2007). Many kelp species show an increase in length-related characters, such as thallus, stipe and lamina length, with greater wave exposure (e.g. Wernberg & Thomsen 2005, Wernberg & Vanderklift 2010, Pedersen et al 2012). This is considered an adaptation to orbital water flow, as a long and flexible thallus ‘going with the flow’ reduces hydrodynamic forces (Friedland & Denny 1995, Denny et al 1998, Koehl 1999). Studies have shown greater strength-related characters, such as stipe thickness and holdfast size, with increasing water flow, reducing the risk of being dislodged (e.g. Koehl et al 2008, Wernberg & Vanderklift 2010). The importance of L. hyperborea as a habitat is related to its size and structural complexity (Christie et al 2003, Norderhaug et al 2007)
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