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Engkvist, Roland; Malm, Torleif; Tobiasson, Stefan

doi:10.1023/a:1009919526259

Cited by 65 publications

(9 citation statements)

References 32 publications

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“…Variation may be maintained, for example, by balancing selection in situations where trade-offs between resistance and growth exist (Simms 1992) or by varying selection due to heterogeneity in resource availability or grazing pressure. Trade-offs between defense metabolites and growth (Jormalainen and Ramsay 2009) or spatially varying grazing pressure, either within a belt along the depth gradient or among belts (Engkvist et al 2000), together with gene flow, may serve to explain the maintenance of genetic variation in the defensive traits of F. vesiculosus.…”

Section: Discussionmentioning

confidence: 99%

Induced resistance in a brown alga: phlorotannins, genotypic variation and fitness costs for the crustacean herbivore

2009

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In the marine littoral, strong grazing pressure selects for macroalgal defenses such as the constitutive and inductive production of defense metabolites. Induced defenses are expected under spatiotemporally varying grazing pressure and should be triggered by a reliable cue from herbivory, thereby reducing grazing pressure via decreased herbivore preference and/or performance. Although induced resistance has frequently been demonstrated in brown macroalgae, it is yet to be investigated whether induced macroalgal resistance shows genetic variation, a prerequisite for evolutionary responses to selection. In addition, consequences of induced resistance on herbivore performance have rarely been tested while the role of brown algal phlorotannins as inducible defense metabolites remains ambiguous. Using preference bioassays, we tested various cues, e.g., natural grazing, waterborne cues or simulated grazing to induce resistance in the brown alga Fucus vesiculosus. Further, we investigated whether there are induced responses in phlorotannin content, genetic variation in induced resistance or incurred performance costs to the mesoherbivore isopod, Idotea baltica. We found that both direct grazing and waterborne grazing cues decreased the palatability of F. vesiculosus, while increasing the total phlorotannin content. Since the sole presence of the herbivore also increased the total soluble phlorotannins, yet failed to stimulate deterrence, we concluded that phlorotannins alone do not explain increased resistance. Induced resistance varied between algal genotypes and thus showed potential for evolutionary responses to variation in grazing pressure. Induced resistance also incurred performance costs for female I. baltica via reduced egg production. Our results show that the induced resistance of F. vesiculosus decreases grazing pressure by deterring herbivores as well as impairing their performance. Resistance may be induced in advance by waterborne cues and spread effectively throughout the F. vesiculosus belt. Through lowering herbivore performance, induced resistance may also reduce future grazing pressure by decreasing the population growth rate of I. baltica.

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Section: Discussionmentioning

confidence: 99%

Induced resistance in a brown alga: phlorotannins, genotypic variation and fitness costs for the crustacean herbivore

2009

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“…Grazing rates on Fucus are highly variable but can be a significant loss term (e.g., Engkvist et al 2000;Jormalainen et al 2001;Wahl et al 2011). The most abundant grazers in the Fucus-associated mesofauna are gammarid amphipods, isopods of the genus Idotea, and the gastropod Littorina littorea (L.) (Anders and Möller 1983).…”

Section: Herbivorymentioning

confidence: 99%

Model simulation of seasonal growth of Fucus vesiculosus in its benthic community

Graiff

Karsten

Radtke

et al. 2020

Limnology & Ocean Methods

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Numerical models are a suitable tool to quantify impacts of predicted climate change on complex ecosystems but are rarely used to study effects on benthic macroalgal communities. Fucus vesiculosus L. is a habitat‐forming macroalga in the Baltic Sea and alarming shifts from the perennial Fucus community to annual filamentous algae are reported. We developed a box model able to simulate the seasonal growth of the Baltic Fucus–grazer–epiphyte system. This required the implementation of two state variables for Fucus biomass in units of carbon (C) and nitrogen (N). Model equations describe relevant physiological and ecological processes, such as storage of C and N assimilates by Fucus, shading effects of epiphytes or grazing by herbivores on both Fucus and epiphytes, but with species‐specific rates and preferences. Parametrizations of the model equations and required initial conditions were based on measured parameters and process rates in the near‐natural Kiel Outdoor Benthocosm (KOB) experiments during the Biological Impacts of Ocean Acidification project. To validate the model, we compared simulation results with observations in the KOB experiment that lasted from April 2013 until March 2014 under ambient and climate‐change scenarios, that is, increased atmospheric temperature and partial pressure of carbon dioxide. The model reproduced the magnitude and seasonal cycles of Fucus growth and other processes in the KOBs over 1 yr under different scenarios. Now having established the Fucus model, it will be possible to better highlight the actual threat of climate change to the Fucus community in the shallow nearshore waters of the Baltic Sea.

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“…"protective coating" (Wahl and Hay 1995;Karez et al 2000;Råberg and Kautsky 2008). In the Baltic Sea, the isopod Idotea balthica exerts strong control on primary producers and is the main consumer of F. vesiculosus (Engkvist et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Effects of temperature on carbon circulation in macroalgal food webs are mediated by herbivores

et al. 2019

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Warming is one of the most dramatic aspects of climate change and threatens future ecosystem functioning. It may alter primary productivity and thus jeopardize carbon sequestration, a crucial ecosystem service provided by coastal environments. Fucus vesiculosus is an important canopy-forming macroalga in the Baltic Sea, and its main consumer is Idotea balthica. The objective of this study is to understand how temperature impacts a simplified food web composed of macroalgae and herbivores to quantify the effect on organic carbon storage. The organisms were exposed to a temperature gradient from 5 to 25 °C. We measured and modeled primary production, respiration, growth and epiphytic load on the surface of Fucus and respiration, growth and egestion of Idotea. The results show that temperature affects physiological responses of Fucus and Idotea separately. However, Idotea proved more sensitive to increasing temperatures than the primary producers. The lag between the collapse of the grazer and the decline of Fucus and epiphytes above 20 °C allows an increase of carbon storage of the primary productivity at higher temperatures. Therefore, along the temperature gradient, the simplified food web stores carbon in a non-monotonic way (reaching minimum at 20 °C). Our work stresses the need of considering the combined metabolic performance of all organisms for sound predictions on carbon circulation in food webs.

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Cited by 65 publications

References 32 publications

Induced resistance in a brown alga: phlorotannins, genotypic variation and fitness costs for the crustacean herbivore

Induced resistance in a brown alga: phlorotannins, genotypic variation and fitness costs for the crustacean herbivore

Model simulation of seasonal growth of Fucus vesiculosus in its benthic community

Effects of temperature on carbon circulation in macroalgal food webs are mediated by herbivores

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