Growth allocation in Laminaria hyperborea (Laminariales, Phaeophyceae) in relation to age and wave exposure

Sjøtun, Kjersti; Fredriksen, Stein

doi:10.3354/meps126213

Cited by 59 publications

(34 citation statements)

References 9 publications

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“…Strong holdfasts and robust stipes are important adaptations to water flow, and allow the kelp to utilise areas with high nutrient transport and little epiphytic growth on the lamina without being broken or completely removed from the substrate (as also observed by e.g. Sjøtun & Fredriksen 1995, Wernberg & Vanderklift 2010.…”

Section: Discussionmentioning

confidence: 99%

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Length, strength and water flow: relative importance of wave and current exposure on morphology in kelp Laminaria hyperborea

Bekkby¹,

Rinde²,

Gundersen³

et al. 2014

Mar. Ecol. Prog. Ser.

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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.

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Section: Discussionmentioning

confidence: 99%

“…Svendsen & Kain 1971, Sjøtun & Fredriksen 1995, Sjøtun et al 1998, Bekkby et al 2009, Pedersen et al 2012. Few have studied the effect of current speed on this species (but see Bekkby et al 2009 and the discussion in Kain 1971b), but such studies exist for other macroalgae species (e.g.…”

Section: Introductionmentioning

confidence: 99%

Length, strength and water flow: relative importance of wave and current exposure on morphology in kelp Laminaria hyperborea

Bekkby¹,

Rinde²,

Gundersen³

et al. 2014

Mar. Ecol. Prog. Ser.

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“…Average lamina biomass (across sites) increased from April (~1900 FW m ). The leaf area index (LAI) was estimated from the frond biomass and weight: area ratios published by Sjøtun & Fredriksen (1995). LAI increased from April to September and was higher at sites with high wave exposure.…”

Section: Kelp Forest Characteristicsmentioning

confidence: 99%

Sub-canopy light conditions only allow low annual net productivity of epiphytic algae on kelp Laminaria hyperborea

Pedersen

Nejrup²,

Pedersen³

et al. 2014

Mar. Ecol. Prog. Ser.

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The stipes of older Laminaria hyperborea individuals are heavily covered by epiphytic assemblages that are dominated by macroalgae, and we hypothesized that the production of these algae may contribute significantly to total primary production of the kelp forest ecosystem. The epiphytic assemblages on the stipes of Laminaria were dominated by potentially fastgrowing red algae with total biomass ranging from 25 to 120 g dry weight (DW) m −2 seafloor depending on season and site. Sub-canopy light conditions were poor and averaged only ~10% of the surface irradiance in summer. Photosynthetic profiles of the epiphytic assemblages indicated that they were acclimated to shade, and the poor sub-canopy light conditions were nevertheless sufficient to ensure positive net photosynthesis for at least 2 to 3 h daily throughout the year. Photo synthetic efficiency at low light and dark respiration varied seasonally, which led to a threefold increase in minimum light requirements in early fall, simultaneously with high water temperatures and declining surface irradiance. This resulted in low productivity and net carbon loss from September throughout winter. Net productivity became positive in February− March and rose through spring as surface irradiance increased. Annual net productivity was relatively low, ranging from 42 to 96 g DW m −2 seafloor depending on site. We conclude that the net productivity of these macroalgal epiphytes is insignificant relative to that of kelp itself, and that the large observed biomass needs several years to accumulate.

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“…Within the park, the net kelp trawling ranged officially between 2,000 and 12,300 tons per year during the last decade. With regards to previous studies dealing with kelp dynamics and rate of stipe production with age (Sjøtun et al, 1993;Sjøtun and Fredriksen, 1995), harvesting has been zoned on the basis of a five year-rotation system. Up to now, the lack of knowledge about the recovery of communities and food web associated with kelp forests points out the needs for further long-term researches, taking into account their overall components (Sivertsen, 1997;Christie et al, 1998;Waage-Nielsen et al, 2003;Lorentsen et al, 2010;Smale et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Community, trophic structure and functioning in two contrasting Laminaria hyperborea forests

Leclerc

Riera

Laurans

et al. 2015

Estuarine, Coastal and Shelf Science

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Abstract:Worldwide kelp forests have been the fields of several studies concerning ecosystems dysfunction in the past decades. Multifactorial kelp threats have been described and include deforestation due to human impact, cascading effect and climate change. Here, we compared community and trophic structure in two contrasting kelp forests off the coasts of Brittany. One has been harvested five years before sampling and shelters abundant omnivorous predators, nearly absent from the other, which has been treated as preserved from kelp harvest. δ 15 N analyses conducted on the overall communities were linked to the tropho-functional structure of different strata featuring these forests (stipe and holdfast of canopy kelp and rock). Our results yielded site-to-site differences of community and tropho-functional structures across kelp strata, particularly contrasting in terms of biomass on the understorey. Likewise, isotope analyses inferred the top trophic position of Marthasterias glacialis and Echinus esculentus which may be considered as strong interactors in the sub-canopy. Our intention is to discuss these patterns and propose a series of probable and testable alternative hypotheses to explain them. For instance, we propose that differences of trophic structure and functioning result from confounded effects of contrasting wave dissipation depending on kelp size-density structure and community cascading involving these omnivorous predators. Given the species diversity and complexity of food web highlighted in these habitats, we call for further comprehensive research about the overall strata and tropho-functional groups for conservation management in kelp forests.

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Growth allocation in Laminaria hyperborea (Laminariales, Phaeophyceae) in relation to age and wave exposure

Cited by 59 publications

References 9 publications

Length, strength and water flow: relative importance of wave and current exposure on morphology in kelp Laminaria hyperborea

Length, strength and water flow: relative importance of wave and current exposure on morphology in kelp Laminaria hyperborea

Sub-canopy light conditions only allow low annual net productivity of epiphytic algae on kelp Laminaria hyperborea

Community, trophic structure and functioning in two contrasting Laminaria hyperborea forests

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