Thermal stress resistance of the brown alga Fucus serratus along the North-Atlantic coast: Acclimatization potential to climate change

Abstract

Seaweed-dominated communities are predicted to disappear south of 45°latitude on NorthAtlantic rocky shores by 2200 because of climate change. The extent of predicted habitat loss, however, could be mitigated if the seaweeds' physiology is sufficiently plastic to rapidly acclimatize to the warmer temperatures. The main objectives of this study were to identify whether the thermal tolerance of the canopy-forming seaweed Fucus serratus is populationspecific and where temperatures are likely to exceed its tolerance limits in the next 200 years. We measured the stress response of seaweed samples from four populations (Norway, Denmark, Brittany and Spain) to common-garden heat stress (20°C -36°C) in both photosynthetic performance and transcriptomic upregulation of heat shock protein genes. The two stress indicators did not correlate and likely measured different cellular components of the stress response, but both indicators revealed population-specific differences, suggesting ecotypic differentiation. Our results confirmed that thermal extremes will regularly reach physiologically stressful levels in Brittany (France) and further south by the end of the 22 nd century. Although heat stress resilience in photosynthetic performance was higher at the species' southern distributional edge in Spain, the hsp expression pattern suggested that this edge-population experienced reduced fitness and limited responsiveness to further stressors.Thus, F. serratus may be unable to mitigate its predicted northward shift and may be at high risk to lose its center of genetic diversity and adaptability in Brittany (France). As it 1

Reduced up-regulation of gene expression in response to elevated temperatures in the mid-Atlantic population of Calanus finmarchicus

“…Population specificity, similar to that shown by the hsp genes in Calanus has been observed in the expression of stress-associated genes in response to elevated temperatures in southern and northern populations of the copepod Tigriopus californicus (Schoville et al, 2012), the killifish Fundulus heteroclitus (Whitehead and Crawford, 2006), the seagrass Zostera marina (Bergmann et al, 2010;Franssen et al, 2011), and the seaweed Fucus (Jueterbock et al, 2014;Pearson et al, 2009;Smolina et al, 2016). Such variation in a species ability to cope with diverse environmental pressure has been shown to be a result of phenotypic plasticity (Lardies and Bozinovic, 2008) and/or local adaptation (Yampolsky et al, 2014).…”

A novel cyclophilin gene from the dinoflagellate Prorocentrum minimum and its possible role in the environmental stress response

“…A similar reduction in Fv/Fm was previously reported in the macroalgae Ulva pertusa (Kumar et al, 2009) and in Ulva rigida exposed to copper (Barraza and Carballeira, 1999). In addition, a decrease in PI ABS was observed under thermal stress in the cyanobacterium Arthrospira platensis and in the macroalgae Fucus serratus (Jueterbock et al, 2014). Altogether, these results indicated that environmental contaminants (copper and PCB) could exhibit negative effects on the photosystem of dinoflagellates.…”

Temperature tolerance of western Baltic Sea Fucus vesiculosus – growth, photosynthesis and survival

“…Consequently, the Baltic F. vesiculosus is characterized by two traits: (1) it is able to adjust growth to a wider temperature range if there is sufficient acclimation time and (2) it seems to be a biogeographical strain adapted to slightly higher optimum temperatures than North Sea plants while survival limits are the same. Tolerance limits and optimum temperature may vary within the geographic range of a species as a function of genotypic adaptation, resulting in the presence of distinct ecotypes with different tolerance limits and optima (Davison, 1991;Jueterbock et al, 2014). Phenotypic differences in emersion stress tolerances (F. vesiculosus is submerged in the atidal Baltic Sea) (Pearson et al, 2000) and fertilization success (Serrão et al, 1996a,b) are known from Baltic Sea F. vesiculosus compared to the North Sea pendant.…”