Resistance, Extinction, and Everything in Between – The Diverse Responses of Seaweeds to Marine Heatwaves

Straub, Sandra C.; Wernberg, Thomas; Thomsen, Mads S.; Moore, Pippa J.; Burrows, Michael T.; Harvey, Ben P.; Smale, Dan

doi:10.3389/fmars.2019.00763

Cited by 108 publications

(75 citation statements)

References 103 publications

(153 reference statements)

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“…That is, kelp survival and growth were more closely related to the maximum temperatures they had experienced prior to being transplanted, than to the cumulative or average temperatures experienced over the experiment. This is consistent with laboratory studies showing reduced photosynthetic performance, growth, and depletion of energy stores for weeks following extreme temperature events 27 , 29 . In general, however, our understanding of the time scales (including potential time lags) that kelps and other plants respond to extreme environmental change is incomplete 10 , 58 .…”

Section: Discussionsupporting

confidence: 91%

“…When temperatures are already above the thermal optimum, warming will have direct negative effects on kelps, such as tissue damage, increased dislodgement, reduced photosynthetic performance, reduced reproduction and reduced growth 14 , 26 – 28 . Negative effects of high temperatures are not always immediately visible, and can include stress-induced depletion of nutrient reserves and reduced metabolic capacity at the individual level, or reduced genetic diversity at the population scale, all of which can reduce performance of species in the long-term, creating lagged responses to temperature extremes 27 , 29 , 30 . Alternatively, natural selection following disturbance events can result in reduced impacts of future events on marine populations (i.e., ‘ecological memory’) 31 .…”

Section: Introductionmentioning

confidence: 99%

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Marine heatwaves and the collapse of marginal North Atlantic kelp forests

Filbee‐Dexter

Wernberg

Grace

et al. 2020

Sci Rep

100

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Extreme climatic events including marine heatwaves (MHWs) are becoming more frequent and severe in the Anthropocene. However, our understanding of how these events affect population dynamics of ecologically important species is limited, in part because extreme events are rare and difficult to predict. Here, we quantified the occurrence and severity of MHWs over 60 years in warm range edge kelp forests on both sides of the North Atlantic. The cumulative annual intensity of MHWs increased two-to four-fold during this period, coinciding with the disappearance of kelps. We experimentally demonstrated a relationship between strong and severe 2018 heatwaves and high kelp mortality in both regions. Patterns of kelp mortality were strongly linked to maximum temperature anomalies, which crossed lethal thresholds in both regions. translocation and tagging experiments revealed similar kelp mortality rates on reefs dominated by healthy kelp forests and degraded sediment-laden algal 'turfs', indicating equal vulnerability to extreme events. These results suggest a mechanistic link between MHWs and broad-scale kelp loss, and highlight how warming can make ecosystem boundaries unstable, forcing shifts to undesirable ecosystem states under episodically extreme climatic conditions. Extreme events may pose a stronger, more immediate threat to ecosystem function than shifts in average conditions, and are increasingly manifesting as key drivers of ecosystem reconfiguration as environmental conditions become more variable and extremes more frequent with climate change 1-3. Discrete periods of anomalously high ocean temperatures, known as "marine heatwaves" (MHWs) 4 , can have serious consequences for ecosystems, and are often associated with loss of ecological function and services 5,6. The increased severity and frequency of MHWs threaten biodiversity and ecosystem function on global scales 5 and the total number of MHW days per year has increased by > 50% in recent decades 1,7,8. Yet, the ecological consequences of extreme events such as MHWs have been identified as a key knowledge gap in ecology 9,10 , and our understanding of population dynamics during MHWs is limited 5. This is partly because these processes are not often studied in the field because MHWs are difficult to predict, and their impacts challenging to manipulate in situ 11,12. Compounding these problems, until recently, most ecological research on MHWs has been conducted on local scales using varying definitions of extremity, making broadscale measures and comparisons of the ecological effects of MHWs challenging 4,13. Temperature extremes appear to be particularly damaging for species located at their range edge, because they can abruptly push conditions beyond thermal tolerances, causing direct mortality 5,14. Kelps are cool-water species that are broadly distributed and respond strongly to changing abiotic conditions 15. Temperature is the most important factor controlling the range distribution of kelps 16-18 , and kelp forests in many regions have been shown to ...

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Marine heatwaves and the collapse of marginal North Atlantic kelp forests

Filbee‐Dexter

Wernberg

Grace

et al. 2020

Sci Rep

100

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“…Typically, in European Atlantic mudflats, organisms can experience daily rise in sediment temperature up to 20 °C in 2 h at emersion 19 . Consequently, intertidal species are more eurytherm than their subtidal counterparts 21 – 23 . However, these organisms often live close to the upper limit of their thermal tolerance window, which make them also sensitive to thermal stress 21 , 24 .…”

Section: Introductionmentioning

confidence: 99%

Effects of temperature on the behaviour and metabolism of an intertidal foraminifera and consequences for benthic ecosystem functioning

Deldicq

Langlet

Delaeter

et al. 2021

Sci Rep

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Heatwaves have increased in intensity, duration and frequency over the last decades due to climate change. Intertidal species, living in a highly variable environment, are likely to be exposed to such heatwaves since they can be emerged for more than 6 h during a tidal cycle. Little is known, however, on how temperature affects species traits (e.g. locomotion and behaviour) of slow-moving organisms such as benthic foraminifera (single-celled protists), which abound in marine sediments. Here, we examine how temperature influences motion-behaviour and metabolic traits of the dominant temperate foraminifera Haynesina germanica by exposing individuals to usual (6, 12, 18, 24, 30 °C) and extreme (high; i.e. 32, 34, 36 °C) temperature regimes. Our results show that individuals reduced their activity by up to 80% under high temperature regimes whereas they remained active under the temperatures they usually experience in the field. When exposed to a hyper-thermic stress (i.e. 36 °C), all individuals remained burrowed and the photosynthetic activity of their sequestered chloroplasts significantly decreased. Recovery experiments subsequently revealed that individuals initially exposed to a high thermal regime partially recovered when the hyper-thermic stress ceased. H. germanica contribution to surface sediment reworking substantially diminished from 10 mm3 indiv−1 day−1 (usual temperature) to 0 mm3 indiv−1 day−1 when individuals were exposed to high temperature regimes (i.e. above 32 °C). Given their role in sediment reworking and organic matter remineralisation, our results suggest that heatwaves may have profound long-lasting effects on the functioning of intertidal muddy ecosystems and some key biogeochemical cycles.

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“…However, as the distribution of species can be strongly controlled by temperature, such latitudinal gradients of genetic diversity may have also arisen due to selective effects [ 10 ]. For example, due to global warming, loss of the most diverse populations has been reported for numerous species [ 11 ], in particular for marine kelp forests [ 12 ]. In the context of the management of genetic resources, it is crucial to know which populations are more diverse and could therefore serve as a “reservoir” of genetic diversity [ 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Seascape Genomics of the Sugar Kelp Saccharina latissima along the North Eastern Atlantic Latitudinal Gradient

Guzinski

Ruggeri

Ballenghien

et al. 2020

Genes

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Temperature is one of the most important range-limiting factors for many seaweeds. Driven by the recent climatic changes, rapid northward shifts of species’ distribution ranges can potentially modify the phylogeographic signature of Last Glacial Maximum. We explored this question in detail in the cold-tolerant kelp species Saccharina latissima, using microsatellites and double digest restriction site-associated DNA sequencing ( ddRAD-seq) derived single nucleotide polymorphisms (SNPs) to analyze the genetic diversity and structure in 11 sites spanning the entire European Atlantic latitudinal range of this species. In addition, we checked for statistical correlation between genetic marker allele frequencies and three environmental proxies (sea surface temperature, salinity, and water turbidity). Our findings revealed that genetic diversity was significantly higher for the northernmost locality (Spitsbergen) compared to the southern ones (Northern Iberia), which we discuss in light of the current state of knowledge on phylogeography of S. latissima and the potential influence of the recent climatic changes on the population structure of this species. Seven SNPs and 12 microsatellite alleles were found to be significantly associated with at least one of the three environmental variables. We speculate on the putative adaptive functions of the genes associated with the outlier markers and the importance of these markers for successful conservation and aquaculture strategies for S. latissima in this age of rapid global change.

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Resistance, Extinction, and Everything in Between – The Diverse Responses of Seaweeds to Marine Heatwaves

Cited by 108 publications

References 103 publications

Marine heatwaves and the collapse of marginal North Atlantic kelp forests

Marine heatwaves and the collapse of marginal North Atlantic kelp forests

Effects of temperature on the behaviour and metabolism of an intertidal foraminifera and consequences for benthic ecosystem functioning

Seascape Genomics of the Sugar Kelp Saccharina latissima along the North Eastern Atlantic Latitudinal Gradient

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