Living on Cold Substrata: New Insights and Approaches in the Study of Microphytobenthos Ecophysiology and Ecology in Kongsfjorden

Karsten, Ulf; Schaub, Iris; Woelfel, Jana; Sevilgen, Duygu S.; Schlie, Carolin; Becker, Burkhard; Wulff, Angela; Graeve, Martín; Wagner, Heiko

doi:10.1007/978-3-319-46425-1_8

Cited by 6 publications

(14 citation statements)

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“…The few data available on benthic diatoms from polar regions confirm a high photophysiological plasticity to acclimate to the prevailing, often very low light conditions [ 10 , 11 , 21 , 22 , 23 , 67 ]. In addition, this wide photophysiological plasticity seems to be a rather general trait of many diatom species [ 24 ], as documented in species from Arctic Kongsfjorden [ 27 ], but also in numerous species from the shallow waters of the temperate Baltic Sea [ 48 , 54 ].…”

Section: Discussionmentioning

confidence: 99%

“…While Arctic benthic diatoms can be characterized as eurythermal and psychrotolerant microalgae with growth optima at around 15 °C [ 26 , 27 ], this seems to be in sharp contrast to their Antarctic counterparts, which show stenothermal and psychrophilic traits [ 28 ]. Psychrophilic and psychrotolerant species can be physiologically distinguished, as the former can survive at freezing temperatures but will die at more moderate temperatures [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

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Photosynthetic, Respirational, and Growth Responses of Six Benthic Diatoms from the Antarctic Peninsula as Functions of Salinity and Temperature Variations

Prelle

Schmidt

Schimani

et al. 2022

Genes

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Temperature and salinity are some of the most influential abiotic parameters shaping biota in aquatic ecosystems. In recent decades, climate change has had a crucial impact on both factors—especially around the Antarctic Peninsula—with increasing air and water temperature leading to glacial melting and the accompanying freshwater increase in coastal areas. Antarctic soft and hard bottoms are typically inhabited by microphytobenthic communities, which are often dominated by benthic diatoms. Their physiology and primary production are assumed to be negatively affected by increased temperatures and lower salinity. In this study, six representative benthic diatom strains were isolated from different aquatic habitats at King George Island, Antarctic Peninsula, and comprehensively identified based on molecular markers and morphological traits. Photosynthesis, respiration, and growth response patterns were investigated as functions of varying light availability, temperature, and salinity. Photosynthesis–irradiance curve measurements pointed to low light requirements, as light-saturated photosynthesis was reached at <70 µmol photons m−2 s−1. The marine isolates exhibited the highest effective quantum yield between 25 and 45 SA (absolute salinity), but also tolerance to lower and higher salinities at 1 SA and 55 SA, respectively, and in a few cases even <100 SA. In contrast, the limnic isolates showed the highest effective quantum yield at salinities ranging from 1 SA to 20 SA. Almost all isolates exhibited high effective quantum yields between 1.5 °C and 25 °C, pointing to a broad temperature tolerance, which was supported by measurements of the short-term temperature-dependent photosynthesis. All studied Antarctic benthic diatoms showed activity patterns over a broader environmental range than they usually experience in situ. Therefore, it is likely that their high ecophysiological plasticity represents an important trait to cope with climate change in the Antarctic Peninsula.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photosynthetic, Respirational, and Growth Responses of Six Benthic Diatoms from the Antarctic Peninsula as Functions of Salinity and Temperature Variations

Prelle

Schmidt

Schimani

et al. 2022

Genes

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“…In contrast, Wulff et al (2008) found degradation of pigments from a natural benthic diatom community from Antarctica after "only" 64 days in darkness. Similarly, Karsten et al (2019) reported that pigments in the benthic diatom Surirella cf. minuta from Kongsfjorden began to degrade after a few days in darkness.…”

Section: Discussionmentioning

confidence: 84%

“…Polar macrophytes must show a high potential for dark survival, as they must live up to 4 months (or even more) in complete darkness (Schlie et al, 2011), but the physiological, biochemical, and molecular mechanisms behind this adaptation for dark survival are still poorly understood (Karsten et al, 2019). Some mechanisms for long-term dark survival have been described in polar diatoms (McMinn and Martin, 2013), including the utilization of stored products (Palmisano and Sullivan, 1983;Schaub et al, 2017), the reduction of respiration and metabolic rates (Peters and Thomas, 1996), the formation of resting stages (reviewed by McQuoid and Hobson, 1996), or facultative heterotrophy (Hellebust and Lewin, 1977;Armbrust et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

A Warmer Arctic Compromises Winter Survival of Habitat-Forming Seaweeds

2022

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Continuous winter darkness at a latitude of 79°N was simulated in cultures of four species of Arctic seaweeds at 3 and 8°C. The laminarians Saccharina latissima and Alaria esculenta, and the rhodophytes Phycodrys rubens and Ptilota gunneri were monitored for 4 months in total darkness and after 1 week following light return in early spring, under controlled laboratory conditions. Biomass loss during darkness was enhanced by the high temperature in all species. At 8°C, the two laminarians were unable to resume growth upon re-illumination. Alaria esculenta showed new blade production by the end of the dark period, but only at 3°C. In all species, the photosynthetic ability was sustained, not suspended, during the whole dark period. P. rubens exhibited lower photosynthetic potential at 8°C than at 3°C during the darkness period, but it was able to recover its O2 evolving potential upon re-illumination, as P. gunneri and S. latissima did, but the latter only at 3°C. The reactivation of photosynthesis seemed to involve photosystem II over photosystem I, as 7 d of photoperiod after the prolonged darkness was not enough to fully recover the PAM-related photosynthetic parameters. Only small changes were recorded in the internal chemical composition (total C, total N, carbohydrates, proteins, and lipids), but species-specific differences were observed. Unlike subarctic areas with an operating photoperiod along the year, a warmer polar night might pose a limit to the ability of multi-year seaweeds to occupy the new ice-free illuminated areas of the Arctic coasts, so that newcomers will potentially be restricted to the spring-summer season.

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“…Historically, studies on algae exposed to prolonged dark periods were mainly focused on the growth patterns (Lüning, 1969;Smayda and Mitchell-Innes, 1974;Chapman and Lindley, 1980;Dunton, 1985), physiological performances and biochemical mechanisms (Weykam et al, 1997;Lüder et al, 2002;Karsten et al, 2019). Mcminn and Martin (2013) concluded several strategies for algae to survive long periods of darkness.…”

Section: Introductionmentioning

confidence: 99%

Transcriptomic Responses to Darkness and the Survival Strategy of the Kelp Saccharina latissima in the Early Polar Night

Scheschonk

Heinrich³

et al. 2020

Front. Mar. Sci.

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Kelps in the Arctic region are facing challenging natural conditions. They experience over 120 days of darkness during the polar night surviving on storage compounds without conducting photosynthesis. Furthermore, the Arctic is experiencing continuous warming as a consequence of climate change. Such temperature increase may enhance the metabolic activity of kelps, using up storage compounds faster. As the survival strategy of kelps during darkness in the warming Arctic is poorly understood, we studied the physiological and transcriptomic responses of Saccharina latissima, one of the most common kelp species in the Arctic, after a 2-week dark exposure at two temperatures (0 and 4°C) versus the same temperatures under low light conditions. Growth rates were decreased in darkness but remained stable at two temperatures. Pigments had higher values in darkness and at 4°C. Darkness had a greater impact on the transcriptomic performance of S. latissima than increased temperature according to the high numbers of differentially expressed genes between dark and light treatments. Darkness generally repressed the expression of genes coding for glycolysis and metabolite biosynthesis, as well as some energy-demanding processes, such as synthesis of photosynthetic components and transporters. Moreover, increased temperature enhanced these repressions, while the expression of some genes encoding components of the lipid and laminaran catabolism, glyoxylate cycle and signaling were enhanced in darkness. Our study helps to understand the survival strategy of kelp in the early polar night and its potential resilience to the warming Arctic.

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Living on Cold Substrata: New Insights and Approaches in the Study of Microphytobenthos Ecophysiology and Ecology in Kongsfjorden

Cited by 6 publications

References 105 publications

Photosynthetic, Respirational, and Growth Responses of Six Benthic Diatoms from the Antarctic Peninsula as Functions of Salinity and Temperature Variations

Photosynthetic, Respirational, and Growth Responses of Six Benthic Diatoms from the Antarctic Peninsula as Functions of Salinity and Temperature Variations

A Warmer Arctic Compromises Winter Survival of Habitat-Forming Seaweeds

Transcriptomic Responses to Darkness and the Survival Strategy of the Kelp Saccharina latissima in the Early Polar Night

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