Arctic Macroalgae Research Articles

Color class and structure-related observable fluorescence response in arctic macroalgae as coastal underwater lidar substrates

In the context of underwater marine biological remote sensing surveys, we consider the fluorescence response of macroalgal and kelp targets to underwater fluorescence laser serial and lidar imaging applications. An investigation of absorption and fluorescence emission via excitation–emission (EEM) spectra of Arctic macroalgal substrates is presented via naturally and artificially generated structural scenarios. Fluorescence was found to increase with algal structure thickness for the kelp Alaria esculenta, both when its output is tested with or without structural modification (increase thickness) of the kelp thallus. Several trials involving other species of all three color classes showed fluorescence output decreased after a thickness increase via layering or structure reconfiguration: a process we suggest is due to fluorescence re-absorption sometimes occurring within and between the rearranged algal structures.

Photophysiologically active green, red, and brown macroalgae living in the Arctic Polar Night

Arctic macroalgae species have developed different growth strategies to survive extreme seasonal changes in irradiance in polar regions. We compared photophysiological parameters such as the light saturation parameter (Ek) and pigment composition of green, red, and brown macroalgae collected in January (Polar Night) and October 2020 (end of the light season). Macroalgae in January appeared healthier (morphologically) and had longer lamina (new growth) than those in October. EK values for red, and brown algae were higher with lower maximum quantum yield of PS II fluorescence (Fv/Fm) in January versus October. Furthermore, in January, new tissues in kelp species had higher EK than the older tissue. Higher EK and lower Fv/Fm during the Polar Night indicates that the photosynthetic apparatus is active but slow. Furthermore, we discuss Chlorophyll (Chl) a emission spectra under blue and green excitation light to determine the ratio of Chl a in photosystem II (PS II) vs photosystem I (PS I). Absorbance spectra of P. palmata was used to interpret the emission spectra. The observed spectral shifts in the absorbance and reflectance spectra of different macroalgae is discussed. Photophysiological methods provide health information complementary to future mapping and monitoring of macroalgae. These results reveal that macroalgae grow new tissue in darkness.

Impact of climate change on Arctic macroalgal communities

The Arctic region faces a warming rate that is more than twice the global average. Sea-ice loss, increase in precipitation and freshwater discharge, changes in underwater light, and amplification of ocean acidification modify benthic habitats and the communities they host. Here, we synthesize existing information on the impacts of climate change on the macroalgal communities of Arctic coasts. We review the short- and long-term changes in environmental characteristics of shallow hard-bottomed Arctic coasts, the floristics of Arctic macroalgae (description, distribution, life-cycle, adaptations), the responses of their biological and ecological processes to climate change, the resulting winning and losing species, and the effects on ecosystem functioning. The focus of this review is on fucoid species, kelps, and coralline algae which are key ecosystem engineers in hard-bottom shallow areas of the Arctic, providing food, substrate, shelter, and nursery ground for many species. Changes in seasonality, benthic functional diversity, food-web structure, and carbon cycle are already occurring and are reshaping Arctic benthic ecosystems. Shallow communities are projected to shift from invertebrate- to algal-dominated communities. Fucoid and several kelp species are expected to largely spread and dominate the area with possible extinctions of native species. A considerable amount of functional diversity could be lost impacting the processing of land-derived nutrients and organic matter and significantly altering trophic structure and energy flow up to the apex consumers. However, many factors are not well understood yet, making it difficult to appreciate the current situation and predict the future coastal Arctic ecosystem. Efforts must be made to improve knowledge in key regions with proper seasonal coverage, taking into account interactions between stressors and across species.

Observation of a living macroalga at 166 m in a high Arctic fjord

Still photos of the seafloor in Raudfjorden, Spitsbergen, recorded in 2011, showed an abundant macroalga at a depth of 166 m. The macroalga was observed attached to stones of varying size and streaming in the bottom current, which would imply that the alga was alive and growingin situ. The alga likely experiences very low-light conditions, as it is present in a turbid fjord influenced by glacial sedimentation. Arctic macroalgae are often adapted to low-light conditions, but to the authors’ knowledge, the present report is the deepest record of living macroalgae in the high Arctic.

Defenses of polar macroalgae against herbivores and biofoulers

Abstract Chemical defenses against herbivores are common in macroalgae from Antarctica, particularly in those species that typically dominate benthic communities. Conversely, although little studied, chemical defenses do not appear to be as important in the ecological relationships of Arctic macroalgae. Mesoherbivory may be particularly heavy in Antarctic macroalgal communities, but Antarctic macroalgae produce chemical defenses against both mesoherbivores and macroherbivores. Antarctic macroalgae have been useful in testing and extending chemical defense theories. While physical defenses may also be important in some Antarctic macroalgal-herbivore relationships, particularly with respect to mesoherbivores, physical defenses do not appear to have wide-spread importance against macroherbivores. In Arctic macroalgae, physical defenses may be of more overall importance in reducing mesoherbivory. Antarctic macroalgae also produce compounds with the potential to control biofouling by sympatric microalgae.

Macrofauna associated with macroalgae in the Kongsfjord (Spitsbergen)

Macrofauna associated with six abundant macroalgal species was investigated in Kongsfjord, Spitsbergen, in order to qualitatively and quantitatively describe macroalgal epifauna composition. A total of 104 invertebrate species were identified, with bryozoans and amphipods representing the most abundant taxa. Analysis of similarity of epifaunal composition showed differences between algal species, and four groups could be distinguished: a Laminaria-Alaria group, a Ptilota-Phycodrys group, Desmarestia aculeata and Acrosiphonia aff. flagellata. Abiotic factors such as temperature and salinity were found to play a minor role in structuring epifaunal communities, while wave action and ice abrasion at least partially determine the epifauna on plants growing in the upper sublittoral. Major factors influencing composition of associated epifauna are the overall growth form and the three-dimensional thallus structure of macroalgae. None of the epifaunal species showed high host specificity. Patterns of dominating animal taxa and distribution among algal groups in Kongsfjord are similar compared to other biogeographic regions, although epifauna associated with Arctic macroalgae seems to be less rich in species.

Photosynthetic performance of Arctic macroalgae after transplantation from deep to shallow waters.

Transplantation experiments conducted in the Arctic Kongsfjord (Spitsbergen) in summer 1997 investigated the effects of various types of filtered natural radiation (solar, solar without UV-B, solar without UV-A/B) on photosynthesis of various macroalgae. Two brown algal species (Laminaria solidungula, Saccorhiza dermatodea) and four red algal species (Palmaria palmata, Phycodrys rubens, Phyllophora truncata, Ptilota plumosa) were collected from deeper waters, kept in UV-transparent plexiglass tubes wrapped with different spectral cut-off filter foils and positioned at fixed depths in shallow waters for 7-9days. At regular intervals, chlorophyll fluorescence of photosystem II (optimum quantum yield, F v/F m) was determined, as an indicator of photosynthetic performance. The data demonstrate that shallow-water species such as P. palmata are much less affected by natural photosynthetically active radiation (PAR) and UV radiation near the surface than extremely sensitive deep-water species such as Phyc. rubens which exhibited strong decreases in photosynthetic performance, as well as photobleaching of part of the thallus. The other species showed intermediate response patterns. In most species investigated inhibition of photosynthesis was mainly caused by the UV-B wavelengths. Interpretation of the data clearly indicates species-specific tolerances of photosynthesis to ambient solar radiation which can be explained by broad physiological acclimation potentials and/or genetic adaptation to certain (low or high) irradiances. The species-specific photosynthetic performance under radiation stress is in good accordance with the vertical distribution of the macroalgae on the shore.

Photosynthesis of two Arctic macroalgae under different ambient radiation levels and their sensitivity to enhanced UV radiation

The change in optimal quantum efficiency (F-v/F-m) of the Arctic species Laminaria saccharina and Palmaria palmata was investigated in a long-term experiment in situ under different radiation levels during the summer of 1997 in the Kongsfjord (Ny-Alesund, Spitsbergen, Norway, 78 degrees 55.5'N, 11 degrees 56.0'E). Whole plants were incubated in an open box system made of UV-transparent Perspex and exposed to solar radiation (lambda > 295 nm), solar radiation excluding UVB (lambda > 320 nm) and solar radiation excluding UVA + UVB (lambda > 400 nm). Increasing radiation levels were simulated by transplantation of the pre-adapted algae from their growth depth at 2 m to a water depth of 1 m. Sensitivity to artificially increased UV radiation was determined by exposure of algae from the three treatments to 6 h of strong UV radiation. P. palmata was relatively insensitive to increasing UV radiation and recovered very fast and almost completely in 2 h. Even plants pre- cultured in ambient radiation levels excluding UVA + UVB or UVB only showed no photoinhibition after exposure to extra UV radiation in the laboratory. L. saccharina was, in comparison to P. palmata, more sensitive and showed photoinhibition under solar radiation and solar minus UVB radiation after transplantation from 2 to Im water depth. However, after 3 weeks at 1 m depth, F-v/F-m of L. saccharina was equal in all treatments and restored to the original values at the start of the experiment. Sensitivity to extra UV radiation in the laboratory increased in time, although recovery was also fast and occurred within 20 h. [KEYWORDS: Life-history stages; chlorophyll fluorescence ultraviolet-radiation; solar-radiation; marine macroalgae; oxygen production; b radiation; photoinhibition; algae; ozone]

Activity of phase I and phase II detoxication enzymes in Antarctic and Arctic macroalgae

Presented data demonstrate the existence of various phase I and phase II detoxication enzymes in nine species of Antarctic and Arctic macroalgae cultivated under laboratory conditions. The different enzyme activities were widely distributed in the tested Chlorophyta, Phaeophyta and Rhodophyta. Concerning the cytochrome P-450 monooxygenase system, it was possible to determine several activities for fatty acid substrates such as lauric acid, palmitic acid and stearic acid and furthermore for 3-chlorobiphenyl, a xenobiotic substrate. The conversion of the 3-chlorobiphenyl to a monohydroxymonochlorobiphenyl was established using gas chromatography–mass spectrometry (GC–MS). Also phase II enzyme activity such as microsomal and soluble glutathione S-transferases and O- and N-glucosyltransferases were detected in these marine algae. These results point to similarities with detoxication in mammalian liver and confirm the concept of the `green liver' described previously and extend this concept also to marine plants, which may be important as a sink because of their large biomass. ©

Effects of solar radiation on growth, photosynthesis and respiration of marine macroalgae from the Arctic

The effect of artificial ultraviolet (UV) and natural solar radiation on photosynthesis, respiration and growth was investigated in 14 red, green and brown macroalgal species on Spitsbergen (Norway) during summer 1998. In June, maximum mean solar radiation at sea level was 120 W m -2 of visible (370 to 695 nm) and 15 W m -2 of UV radiation (300 to 370 nm), and decreased gradually until the end of the summer. In spite of incident irradiance, levels were low in comparison with other latitudes, and UV radiation stress on growth of Arctic macroalgae was evident. Transplantation experiments of plants from deeper to shallow waters showed, for most algae, an inhibitory effect of both UVA and UVB on growth, except in the intertidal species Fucus distichus. The growth rate of selected macroalgae was directly correlated to the variations in natural solar radiation during the summer. Underwater experiments both in situ and using UV-transparent incubators revealed a linear relationship between the depth distribution and the growth rate of the algae. In almost all species the photosynthetic oxygen production decreased after 2 h incubation in the laboratory under 38 μmol m -2 s -1 photosynthetic active radiation (PAR 400 to 700 nm) supplemented with 8 W m -2 UVA (320 to 400 nm) and 0.36 W m -2 UVB (280 to 320 nm) compared to only PAR without UV. Like in the growth experiments, the only exception was the brown alga F. distichus, in which photosynthesis was not affected by UV. The degree of inhibition of photosynthesis showed a relation to the depth distribution, i.e. algae from deeper waters were more inhibited than species from shallow waters. In general, no inhibitory UV effect on respiratory oxygen consumption in all macroalgae studied was detected under the artificial radiation regimes described above, with the exception of the brown alga Desmarestia aculeata and the green alga Mono-stroma arcticum, both showing a significant stimulation of respiration after 2 h of UV exposure. The ecological relevance of the seasonal variations in the solar radiation and the optical characteristics of the water column with respect to the vertical zonation of the macroalgae is discussed.

Capability of dynamic photoinhibition in Arctic macroalgae is related to their depth distribution

The capability of several macroalgal species to protect photosynthesis from excessive irradiance by dynamic photoinhibition was investigated relative to their depth distribution in summer 1995 in the Kongsfjord (79°N; 12°E, Ny Alesund, Spitsbergen, Norway). Photoinhibition of photosynthesis was induced by exposure of algae from different water depths to a high photon fluence rate of 500 μmol m−2 s−1 for 2 h. Changes in optimal quantum yield (F v/F m) were measured during the inhibition phase. Recovery of photosynthesis was subsequently induced by dim white light (10 μmol m−2 s−1) and observed as changes in the variable fluorescence. With a newly developed mathematical model different parameters of the response kinetics of inhibition and recovery were calculated and related to the depth distribution of each algal species. It is shown that two components with slow and fast reaction kinetics, respectively, are involved in photoinhibition and recovery of photosynthesis. Their possible molecular bases are discussed. The half-life time (τ) of the inhibition and recovery phases, i.e. the time necessary to reach half maximal response, is clearly related to the depth distribution of the investigated species. Algae collected close to the water surface show a fast reaction of both photoinhibition and recovery and, hence, have a low τ. With increasing depth the reactions become slower and τ increases. τ was highest in deep water algae. Further analysis of the reaction kinetics in Laminaria saccharina shows that the relative proportion of the two kinetics involved change with the collection depth. In contrast, a significant difference in the reaction rates of both kinetics was not observed.

Influence of UV radiation on the photosynthesis of arctic macroalgae in the field

The photoinhibition in brown and red macroalgae from Spitsbergen (79°N, 12°E) was investigated to study the effects of UV under balanced UV /photosynthetically active radiation (PAR) conditions. Algae were collected from different depths and exposed to natural solar radiation. Various parts of the UV radiation spectrum were successively cut off by filters absorbing wavelengths of less than 295 nm, less than 320 nm and less than 400 nm. The samples were covered with these filters and exposed to daylight 10 cm below the water surface in outdoor tanks near the shore supplied with running seawater. PAR and UV radiation were continuously measured during the experiments. The degree of photoinhibition was observed during the course of the day by measuring the in vivo fluorescence of photosystem II ( F v F m ). In addition, the transmittance of the water body of the Kongsfjord (Spitsbergen, Norway) related to the UV and PAR wavelength ranges was determined. Even on a sunny day in August, only relatively low fluence rates of UVA (approximately 13 W m −2), UVB (approximately 0.14 W m −2) and PAR (approximately 1100 μmol m −2 s −1 ) were measured in the air at noon due to the low position of the sun at this high latitude. The UV transmittance of the water body in the fjord was also low. As a result, UV stress occurred only in seaweeds growing in the intertidal zone or in shallow water. The photoinhibition of photosynthesis was mainly induced by white light in shallow water. The inhibitory effects of UV radiation caused a delay in the recovery processes in the afternoon and evening, rather than an inhibitory effect on photosynthesis in the morning. Fucus distichus, growing in the upper intertidal zone, was most insensitive to UV radiation. Algae from the sublittoral zone had problems coping with the natural UV radiation in shallow water, whereas those from the intertidal zone were acclimatized to the unfavourable UV /PAR conditions. By cutting off sequentially the shorter wavelengths of the UV range, the investigated brown algae showed no significantly different effects. In contrast, the red alga Palmaria palmata showed a clear response to the different UV ranges, i.e. the UVB wavelength range was very effective in causing photoinhibition. In addition, the recovery phase was delayed in spite of the low fluence rates impinging on the alga during the course of the day.

Volatile halocarbons released from Arctic macroalgae

Twenty-two different species of Arctic brown, red and green macroalgae, collected in the Kongsfjord at Ny-Ålesund (Spitsbergen), were incubated under polar conditions and investigated for their release of volatile halogenated organic compounds (VHOC). Bromoform, dibromomethane, dibromochloromethane, bromodichloromethane, 1,2 -dibromoethane, diiodomethane and chloroiodomethane have been identified and their net releases during incubations were determined. Generally, brown and green macroalgae showed higher VHOC release, while red macroalage had only low release. Bromoform was released in relatively large quantities from all species studied, with the highest release observed from the brown algae Dictyosyphon foeniculaceus (0.3 μg g −1 wet algal weight day −1 ) and Laminaria saccharina (0.15 μg g −1 wet algal weight day −1 ), and from the green algae Monostroma arcticum (0.3 μg g −1 wet algal weight day −1 ) and Blidingia minima (0.27 μg g −1 wet algal weight day −1 ). Dibromomethane, diiodomethane, dibromochloromethane and 1,2 -dibromoethane showed lower net release during the incubations. The net release of chloroiodomethane and bromodichloromethane was very low for the most algae species investigated. Based on the distribution of these algae in the Arctic environment, Dictyosiphon foeniculaceus and Laminaria saccharina may be important sources for VHOC because of high release and high biomass. Release of VHOC could be detected from all parts of the thallus of the macroalga. This may provide some evidence for a possible role of VHOC production as a chemical protection mechanism in algae.

Haloperoxidase activities in Arctic macroalgae

Haloperoxidase activities were assayed in 21 species of Arctic green, red and brown macroalgae collected in the Kongsfjord at Ny-Alesund (Svalbard). The enzymes were specific for bromide and/or iodide, but not for chloride. Highest bromoperoxidase activities were found in the brown seaweads Laminaria saccharina and L. digitata, whereas highest iodoperoxidase activities were measured in the green species Acrosiphonia sonderi and Enteromorpha compressa. Optimum pH for bromination ranged between pH 4 and 7.

Temperature Requirements and Biogeography of Antarctic, Arctic and Amphiequatorial Seaweeds

The temperature requirements for growth and survival of cold water seaweeds from both Hemispheres are compared and discussed in relation to the climatic history of the various regions and in relation to the origin of amphiequatorial distribution patterns. Endemic Antarctic species are most strongly adapted to low temperatures. In contrast, endemic Arctic macroalgae show higher temperature demands and correspond in their temperature responses to many Antarctic cold-temperate species. Arctic cold-temperate species show similar temperature requirements to cold-temperate species from southernmost South America. The temperature requirements of cold-temperate N. Atlantic species are somewhat higher than those of cold-temperate N. E. Pacific species. These differences are the result of the different times of exposure of these groups to low temperatures. The first steps in the adaptation of macroalgae to low temperatures are an increase in cold tolerance and an increase of growth and reproduction rates at low temperatures. Later, the ability to grow and reproduce at greater-than-or-equal-to 15 to 20-degrees-C and to survive temperatures greater-than-or-equal-to 20-degrees-C is lost. This temperature response type is exemplified in endemic Arctic and Arctic cold-temperate seaweeds exposed to low temperatures since about 3 My. The last steps in the adaptation to low temperatures include the loss of ability to grow and reproduce at greater-than-or-equal-to 5 or 10-degrees-C and a strong reduction in the upper survival temperatures (UST) down to 10-13-degrees-C. This temperature response type is typical for endemic Antarctic species exposed to cold waters for at least 14 My. Amphiequatorial filamentous green and brown algal taxa and microthalli of amphiequatorial brown algae mostly show UST's of 23 to 28.5-degrees-C, significantly higher compared to single Hemisphere taxa from the same regions. These findings strongly favour a migrationist jump across the equator to the other Hemisphere during Pleistocene lowering of the water temperatures in the tropics. Reproduction and growth during the passage across the equator would not have been possible in all species except Ectocarpus siliculosus due to the narrow temperature-reproduction and temperature-growth windows.

Effects of Experimental Releases of Oil and Dispersed Oil on Arctic Nearshore Macrobenthos. III. Macroalgae

An experimental subsurface release of chemically dispersed oil at Cape Hatt, northern Baffin Island, resulted in short-term relatively high oil concentrations in the water of two adjacent bays. Untreated oil released onto the surface of the third bay could not be detected in the water below a depth of 1 m. Both releases, however, resulted in measurable contamination of sediments in shallow water. Macroalgae at 3 m depth were sampled by a diver-operated airlift sampler in three treatment bays and in a fourth (reference) bay during the open water seasons of 1980-83 (two pre-spill and four post-spill sampling periods). Biomass, number of species and reproductive condition of the dominant understory algae at 3 m depth did not seem to be adversely affected wither by oil in subtidal sediments or by chemically dispersed oil in the water column. No oil effects were detected in data on the biomasses of total algae or of two of the three species analyzed (Stictyosiphon tortilis and Pilayella littoralis). In the third species, Dictyosiphon foeniculaceus, growth increased in the year following the oil release, either stimulated by low levels of oil in sediments or through natural annual variability. The lack of major effects on macroalgae may have been partly attributable to the lack of effects on herbivores and the vegetative mode of reproduction in the dominant macroalgal species.Key words: arctic macroalgae, oil effects, dispersed oil effects, experimental oil releases, Baffin Island, macrobenthos, Stictyosiphon tortilis, Pilayella littoralis, Dictyosiphon foeniculaceus