Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic

Franke, Kiara; Liesner, Daniel; Heesch, Svenja; Bartsch, Inka

doi:10.1515/bot-2021-0014

Cited by 14 publications

(29 citation statements)

References 43 publications

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“…survival of excised meristematic discs, although kelp thalli under heat stress usually start degenerating from the tip (Franke et al, 2021). Furthermore, it has to be considered that adult meristematic tissue collected from the field might be more resilient than laboratory cultures or young sporophytes (Hanelt et al, 1997;Heinrich et al, 2016).…”

Section: Test Statistic P-value Direct Comparisonmentioning

confidence: 99%

“…However, local adaptation and phenotypic plasticity can result in intraspecific differences in thermal tolerance, and population loss might occur not only among thermal rear edges but also in other regions (King et al, 2018). Recently, studies on the kelp Laminaria digitata, revealed that despite considerable plasticity at intermediate temperatures, plasticity at the upper survival limit was low (Liesner et al, 2020a,b;Franke et al, 2021). Thus, models assuming a uniform climatic envelope for wide-ranging species, particularly the local temperature threshold for survival, may underestimate local adaptation and extinction (Kelly et al, 2012;Filbee-Dexter et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Summer Heatwave Impacts on the European Kelp Saccharina latissima Across Its Latitudinal Distribution Gradient

et al. 2021

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Kelps are important foundation species in coastal ecosystems currently experiencing pronounced shifts in their distribution patterns caused by ocean warming. While some populations found at species’ warm distribution edges have been recently observed to decline, expansions of some species have been recorded at their cold distribution edges. Reduced population resilience can contribute to kelp habitat loss, hence, understanding intraspecific variations in physiological responses across a species’ latitudinal distribution is crucial for its conservation. To investigate potential local responses of the broadly distributed kelp Saccharina latissima to marine heatwaves in summer, we collected sporophytes from five locations in Europe (Spitsbergen, Bodø, Bergen, Helgoland, Locmariaquer), including populations exposed to the coldest and warmest local temperature regimes. Meristematic tissue from sporophytes was subjected to increasing temperatures of Δ+2, Δ+4 and Δ+6°C above the respective mean summer temperatures (control, Δ±0°C) characteristic for each site. Survival and corresponding physiological and biochemical traits were analyzed. Vitality (optimum quantum yield, Fv/Fm) and growth were monitored over time and biochemical responses were measured at the end of the experiment. Growth was highest in northern and lowest in southern populations. Overall, northern populations from Spitsbergen, Bodø and Bergen were largely unaffected by increasing summer temperatures up to Δ+6°C. Conversely, sporophytes from Helgoland and Locmariaquer were markedly stressed at Δ+6°C: occurrence of tissue necrosis, reduced Fv/Fm, and a significantly elevated de-epoxidation state of the xanthophyll cycle (DPS). The variations in phlorotannins, mannitol and tissue C and N contents were independent of temperature treatments and latitudinal distribution pattern. Pronounced site-specific variability in response to increasing temperatures implies that exceeding a threshold above the mean summer temperature exclusively affect rear-edge (southernmost) populations.

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Section: Test Statistic P-value Direct Comparisonmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Summer Heatwave Impacts on the European Kelp Saccharina latissima Across Its Latitudinal Distribution Gradient

et al. 2021

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“…We used sibling clonal gametophyte cultures each derived from a single gametophyte isolate in 2015 of one Laminaria digitata sporophyte from Kongsfjorden, Spitsbergen, Norway (AWI seaweed culture collection number: ♀ 3472, ♂ 3471) and one sporophyte from Helgoland, Germany (AWI seaweed culture collection number: ♀ 3436, ♂ 3435). Spitsbergen material had been verified as L. digitata morphologically and by DNA barcoding of the sporophyte (ID 78 in Dankworth et al, 2020) to avoid confusion with the morphologically similar Arctic kelp Hedophyllum nigripes (Franke et al, 2021). Prior to the start of the experiment, cultures were maintained vegetatively under red light (approx.…”

Section: Culture Material Preparation and Fertilizationmentioning

confidence: 99%

“…Macroscopic sporophytes were subsequently cultivated in 1 L glass beakers and 5 L bottles with gentle aeration at 10 • C under increased irradiance of 30-35 µmol photons m −2 s −1 with weekly changes of 1 /2 PES and were then used in the heat stress experiment on cm-long juvenile sporophytes (experiment 2). Throughout the experiments, 10 • C served as the control temperature because it has been described as an optimal growth temperature for temperate and Arctic sporophytes of L. digitata (Bolton and Lüning, 1982;tom Dieck, 1992;Franke et al, 2021).…”

Section: Culture Material Preparation and Fertilizationmentioning

confidence: 99%

“…Sex determination occurs during meiosis, creating the haploid gametophyte stage (UV sexual system; Coelho et al, 2018), whereas the diploid sporophyte is asexual. Life cycle stages differ in their thermal limits, as gametophytes can tolerate higher temperature (23 • C over two weeks; Bolton and Lüning, 1982) than sporophytes (21 • C over two weeks; Lüning, 1984;tom Dieck, 1992;Franke et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Increased Heat Resilience of Intraspecific Outbred Compared to Inbred Lineages in the Kelp Laminaria digitata: Physiology and Transcriptomics

et al. 2022

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Marine forests and kelps as their foundation species are threatened by ocean warming especially at the warm distributional edges. Previously identified genetic divergence and ecotypic differentiation within kelp species may allow to produce more resilient lineages by intraspecific outbreeding among populations. In a mechanistic investigation of heat stress, heterosis (hybrid vigour), and underlying gene expression patterns, we assessed the thermal performance of inbred (selfings) and outbred (reciprocal crosses) sporophytes of the N-Atlantic kelp Laminaria digitata among clonal isolates from two divergent populations; one from the temperate North Sea (Helgoland) and one from the Arctic (Spitsbergen). First, we investigated the upper thermal tolerance of microscopic sporophytes in a 14-day experiment applying sublethal to lethal 20–23°C. The upper survival temperature of microscopic sporophytes was lower for the inbred Arctic selfing (21°C) than for the temperate selfing and the reciprocal crosses (22°C). Only in the temperate selfing, 4.5% of sporophytes survived 23°C. We then subjected 4–7 cm long sporophytes to a control temperature (10°C), moderate (19°C) and sublethal to lethal heat stress (20.5°C) for 18 days to assess gene expression in addition to physiological parameters. Growth and optimum quantum yield decreased similarly in the reciprocal crosses and the temperate selfing at 19 and 20.5°C, while inbred Arctic sporophytes died within seven days at both 19 and 20.5°C. In response to 20.5°C, 252 genes were constitutively regulated across all surviving lineages, which we use to describe metabolic regulation patterns in response to heat stress in kelp. At sublethal 20.5°C, ca. 150 genes were differentially expressed by either crossed lineage in comparison to the temperate selfing, indicating that they maintained a growth response similar to the temperate selfing with differential metabolic regulation during sublethal heat stress. Subtle differences in physiology and the differential expression of nine genes between the reciprocal crosses at 20.5°C indicate that female and male gametophytes may contribute differently to offspring traits. We consider potential inbreeding depression in the Spitsbergen selfing and quantify the better performance of both crosses using heterosis-related parameters. We discuss the potential and risks of outbreeding to produce more resilient crops for mariculture and marine forest restoration.

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Kelp forest community structure and demography in Kongsfjorden (Svalbard) across 25 years of Arctic warming

Düsedau,

Fredriksen,

Brand

et al. 2024

Ecology and Evolution

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The Arctic archipelago of Svalbard is a hotspot of global warming and many fjords experience a continuous increase in seawater temperature and glacial melt while sea‐ice cover declines. In 1996/1998, 2012–2014, and 2021 macroalgal biomass and species diversity were quantified at the study site Hansneset, Kongsfjorden (W‐Spitsbergen) in order to identify potential changes over time. In 2021, we repeated the earlier studies by stratified random sampling (1 × 1 m2, n = 3) along a sublittoral depth transect (0, 2.5, 5, 10, and 15 m) and investigated the lower depth limits of dominant brown algae between 3 and 19 m. The maximum fresh weight (FW) of all seaweeds was 11.5 kg m−2 at 2.5 m and to 99.9% constituted of kelp. Although biomass distribution along the depth transect in 2021 was not significantly different compared to 2012/2013, the digitate kelp community (Laminaria digitata/Hedophyllum nigripes) had transformed into an Alaria esculenta‐dominated kelp forest. Consequently, a pronounced shift in kelp forest structure occurred over time as we demonstrate that biomass allocation to thallus parts is kelp species‐specific. Over the past decade, kelp demography changed and in 2021 a balanced age structure of kelps (juveniles plus many older kelp individuals) was only apparent at 2.5 m. In addition, the abundances and lower depth limits of all dominant brown algae declined noticeably over the last 25 years while the red algal flora abundance remained unchanged at depth. We propose that the major factor driving the observed changes in the macroalgal community are alterations in underwater light climate, as in situ data showed increasing turbidity and decreasing irradiance since 2012 and 2017, respectively. As a consequence, the interplay between kelp forest retreat to lower depth levels caused by coastal darkening and potential macroalgal biomass gain with increasing temperatures will possibly intensify in the future with unforeseen consequences for melting Arctic coasts and fjord ecosystem services.

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Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic

Cited by 14 publications

References 43 publications

Summer Heatwave Impacts on the European Kelp Saccharina latissima Across Its Latitudinal Distribution Gradient

Summer Heatwave Impacts on the European Kelp Saccharina latissima Across Its Latitudinal Distribution Gradient

Increased Heat Resilience of Intraspecific Outbred Compared to Inbred Lineages in the Kelp Laminaria digitata: Physiology and Transcriptomics

Kelp forest community structure and demography in Kongsfjorden (Svalbard) across 25 years of Arctic warming

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