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  • 1
    Online Resource
    Online Resource
    Phenology and seasonal physiological performance of polar seaweeds
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 585-592
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 585-592
    Abstract: The phenology of polar seaweeds is strongly tuned to the strong seasonal changes in underwater radiation. Daylength triggers the onset of reproduction and growth during winter in season anticipators, particularly in endemic species. More widely distributed species are often season responders growing predominantly in summer in direct response to light, temperature and nutrient conditions. The physiology of polar seaweeds is strongly linked to the life strategy of the individual species. For season anticipators, photosynthetic rates are often highest in late winter-spring when sunlight penetrates deep into the clear waters. Since Antarctic species are seldom nutrient-limited, even during summer, they mostly incorporate photosynthetically fixed carbon directly into biomass. In contrast, Arctic kelps, such as Laminaria solidungula utilise the carbon fixed during summer for synthesis of storage compounds, which are used to fuel growth during the dark winter period when nutrients are sufficient for new tissue formation. This growth pattern reflects a strategy for species optimally adapted to the seasonal changes of nutrient concentrations, which in the Arctic are low (or nearly undetectable) in summer, and high in winter. This review concludes with a discussion of possible implications of global climate changes on the phenology and productivity of polar seaweed communities.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.078
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 2
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    Online Resource
    The abiotic environment of polar marine benthic algae
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 483-490
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 483-490
    Abstract: Due to different oceanographic and geological characteristics, benthic algal communities of Antarctica and the Arctic differ strongly. Antarctica is characterized by high endemism, whereas in the Arctic only a few endemic species occur. In contrast to the Antarctic region, where nutrient levels never limit algal growth, nutrient levels in the Arctic region are depleted during the summer season. Both regions have a strongly seasonally changing light regime, fortified by an ice covering throughout the winter months. After months of darkness, algae are suddenly exposed to high light caused by the breaking up of sea ice. Simultaneously, harmful ultraviolet radiation (UVR) enters the water column and can significantly affect algal growth and community structure. In the intertidal zone, fluctuations of temperature and salinity can be very large. Ice scours can further influence growth and settlement of intertidal algae. The subtidal zone offers a more stable habitat than the intertidal, permitting the growth of larger perennial algae and microbial mats. Polar regions are the areas most affected by global climate change, i.e., glacier retreat, increasing temperature and sedimentation, with as yet unknown consequences for the polar ecosystem.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.082
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 3
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    Online Resource
    Species composition, zonation, and biomass of marine benthic macroalgae in Kongsfjorden, Svalbard
    Walter de Gruyter GmbH ; 2012
    In:  botm Vol. 55, No. 4 ( 2012-08-01), p. 399-414
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 55, No. 4 ( 2012-08-01), p. 399-414
    Abstract: We surveyed macroalgae at Hansneset, Blomstrand (78°39′N, 11°57′E) in Kongsfjorden, Svalbard, down to 30 m depth between 1996 and 1998. In total, 62 species were identified: 16 Chlorophyta, 25 Phaeophyceae, and 21 Rhodophyta. The majority of species (53.5%) belonged to the Arctic cold-temperate group, followed in frequency by species distributed from the Arctic to the warm-temperate region (25.9%). Four endemic Arctic species ( Laminaria solidungula , Acrosiphonia flagellata , A. incurva , and Urospora elongata ) were found. Two species ( Pogotrichum filiforme and Mikrosyphar polysiphoniae ) were new to Svalbard. Chlorophyta, Phaeophyceae, and Rhodophyta extended from the eulittoral zone down to 11, 21, and 〉 30 m depths with maximum biomasses at 1–5 m, 5–10 m, and 5–30 m depths, respectively. Annual and pseudoperennial species had highest biomasses in the upper 5 m, while perennials were distributed deeper. The highest biomass (8600 g m -2 wet weight) at 5 m depth comprised mainly L. digitata , Saccorhiza dermatodea , Alaria esculenta , and Saccharina latissima . The biogeographic composition of macroalgae at Hansneset was rather similar to that of northeastern Greenland, but different from that of northern Norway, which has a higher proportion of temperate species. Climate warming and ship traffic may extend some of the distribution ranges of macroalgae from mainland Norway to Svalbard.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/bot-2012-0097
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 4
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    Online Resource
    Effects of ocean acidification on different life-cycle stages of the kelp Laminaria hyperborea (Phaeophyceae)
    Walter de Gruyter GmbH ; 2012
    In:  botm Vol. 55, No. 5 ( 2012-10-01), p. 511-525
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 55, No. 5 ( 2012-10-01), p. 511-525
    Abstract: Our objective for this study was to evaluate the influence of preindustrial and expected future atmospheric CO 2 concentrations (280 μatm and 700 μatm pCO 2 , respectively) on different life-cycle stages of the kelp Laminaria hyperborea from Helgoland (Germany, North Sea). Zoospore germination, gametogenesis, vegetative growth, sorus formation and photosynthetic performance of vegetative and fertile tissue were examined. The contribution of external carbonic anhydrase (exCA) to C-supply for net-photosynthesis (net-PS) and the Chl a - and phlorotannin content were investigated. Female gametogenesis and vegetative growth of sporophytes were significantly enhanced under the expected future pCO 2 . rETR(max) and net-PS of young vegetative sporophytes tended to increase performance at higher pCO 2 . The trend towards elevated net-PS vanished after inhibition of exCA. In vegetative sporophytes, phlorotannin content and Chl a content were not significantly affected by pCO 2 .
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/bot-2012-0163
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
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  • 5
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    Online Resource
    Microphytobenthic biomass along gradients of physical conditions in Arctic Kongsfjorden, Svalbard
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 573-583
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 573-583
    Abstract: In contrast to numerous studies on the biomass of marine microphytobenthos from temperate coastal ecosystems, little is known from polar regions. Therefore, microphytobenthos biomass was measured at several coastal sites in Arctic Kongsfjorden (Spitsbergen) during the polar summer (June–August 2006). On sandy sediments, chl a varied between 8 and 200 mg m -2 and was related to water depth, current/wave exposure and geographical location. Biomass was rather independent of abiotic parameters such as sediment properties, salinity, temperature or light availability. At three stations, sediments at water depths of 3–4, 10, 15, 20 and 30 m were investigated to evaluate the effect of light availability on microalgae. Significant differences in distribution patterns of biomass in relation to deeper waters 〉 10 m were found. The productive periods were not as distinct as phytoplankton blooms. Only at 3–4 m water depth at all three stations were two- to threefold increases of biomass measured during the investigation period. Hydrodynamic conditions seemed to be the driving force for differences in sediment colonisation by benthic microalgae. In spite of the extreme Arctic environmental conditions for algal growth, microphytobenthos biomass was comparable to marine temperate waters.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.075
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 6
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    Biology of polar benthic algae
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 479-481
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 479-481
    Abstract: No abstract available
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.083
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 7
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    Light and temperature demands of marine benthic microalgae and seaweeds in polar regions
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 593-608
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 593-608
    Abstract: Polar algae have a striking ability to photosynthesize and grow under very low light and temperatures. In seaweeds, minimum light demands for photosynthetic saturation and compensation can be as low as 10 and 2 μmol photons m -2  s -1 , respectively. For benthic microalgae, these values can be even lower because of the limited irradiance reaching deep sea floors. The extreme shade adaptation of these organisms sets their distributional limits at depths close to 40 m and enables them to tolerate long periods of extended darkness. In addition to their capability for efficient photosynthesis at extremely low light levels, polar algae possess metabolic adaptations to persist at low temperatures, which permit them to complete their life cycles at year-round temperatures close to 0°C. Seaweeds with the lowest temperature demands are the species endemic to the Antarctic while Arctic algae are comparatively less cold-adapted. These adaptive characteristics allow benthic marine algae to make high contributions to high latitude coastal primary productivity and energy fluxes, exceeding or equaling the production of primary producers in more temperate systems. The studies summarized here give important insights into the major physiological adaptations allowing marine benthic microalgae and seaweeds to colonize these extreme habitats.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.073
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 8
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    Online Resource
    Biodiversity, biogeography and zonation of marine benthic micro- and macroalgae in the Arctic and Antarctic
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 491-507
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 491-507
    Abstract: This paper reviews the composition, biogeography and zonation of benthic algae in Arctic and Antarctic polar regions. There is a marked contrast in the literature between the amount of information on microalgae vs. macroalgae. Perhaps not surprising in view of their size and conspicuous nature, the macroalgae are better known than the microalgae and they have been studied more intensively. Macroalgal biodiversity is greater in Antarctica than in the Arctic, as is the number of endemic species. Both these characteristics of the Antarctic marine macroalgal flora can be explained by the biogeographical histories of the regions. In contrast, endemism amongst Arctic and Antarctic benthic microalgae is generally considered to be low; however, there is very little evidence to support this and further molecular research is needed to document and clarify the biodiversity of marine benthic microalgae of both polar regions. The zonation or local distribution of polar macroalgae and microalgae is influenced by physiological, morphological, chemical and ecological characteristics that determine responses to a range of environmental factors, including the ability to resist and survive algal grazing. Typically, the lower depth distribution limit elevates with increasing latitude.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.072
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 9
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    Online Resource
    Drivers of colonization and succession in polar benthic macro- and microalgal communities
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 655-667
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 655-667
    Abstract: Information on succession in marine benthic primary producers in polar regions is very scarce, particularly with regard to effects of abiotic and biotic drivers of community structure. Primary succession begins with rapid colonizers, such as diatoms and ephemeral macroalgae, whereas slow, highly seasonal recruitment and growth are characteristic of annual or perennial seaweed species. Colonization of intertidal and subtidal assemblages on polar rocky shores is severely affected by physical disturbance and by seasonal changes in abiotic conditions. Biotic factors, such as grazing, can strongly affect colonization patterns and also alter competitive interactions among benthic algae. Ambient UV radiation affects the diversity of macroalgal communities during early and later stages of succession. In contrast, microalgal assemblages have high tolerance to UV stress. Climate warming could alter algal latitudinal distribution and favor invasion of polar regions by cold-temperate species. Reduced sea ice cover and retreating glaciers could expand colonization areas but alter light, salinity, sedimentation and disturbance processes. Although the key role of macroalgae in coastal systems and, to a much reduced extent, the importance of microphytobenthos have been documented for polar regions, information on the successional process is incomplete and will benefit from further ecological studies.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.076
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
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  • 10
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    Online Resource
    Impact of oceanic warming on the distribution of seaweeds in polar and cold-temperate waters
    Walter de Gruyter GmbH ; 2009
    In:  botm Vol. 52, No. 6 ( 2009-12-01), p. 617-638
    Details
    In: botm, Walter de Gruyter GmbH, Vol. 52, No. 6 ( 2009-12-01), p. 617-638
    Abstract: Temperature is one of the most important factors controlling the biogeographic distribution of seaweeds and is expected to increase due to the rise in anthropogenic greenhouse gas concentrations, especially in polar and cold-temperate regions. To estimate prospective distributional shifts in cold-water key structural seaweeds from both hemispheres, we related temperature requirements and recent distributions of seaweeds to observed mean sea surface temperature (SST) isotherms for the periods 1980–1999 (Meteorological Office Hadley Centre's SST data set; HadISST) and to modelled temperatures for 2080–2099 [Coupled Model Intercomparison Project 3 (CMIP3) database prepared for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) report] based on moderate greenhouse gas emissions Special Report on Emission Scenarios – Scenario B1 (SRESA1B). Under this scenario, North Atlantic polar to cold-temperate seaweeds investigated will extend their distribution into the High Arctic until the end of the 21st century, but retreat along the northeastern Atlantic coastline. In contrast, selected Antarctic seaweeds will probably not significantly alter their latitudinal distributions, as deduced from our presently incomplete knowledge of their temperature requirements. We identified several cold-temperate regions where seaweed composition and abundance will certainly change with elevated temperatures. The results are discussed in the context of local temperature conditions, effects of multifactorial abiotic and biotic interactions and expected ecological consequences for seaweed-dominated ecosystems.
    Type of Medium: Online Resource
    ISSN: 1437-4323 , 0006-8055
    URL: Article
    DOI: 10.1515/BOT.2009.080
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1475447-2
    detail.hit.zdb_id: 1197-6
    SSG: 12
    Location Call Number Limitation Availability
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