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predator–prey interactions between fish and macrofauna in kelp (laminaria hyperboea) forest were examined. fish were caught in gill-nets and fish traps at two sites and throughout the diurnal cycle. their stomach contents were analysed. the most abundant fish species, except pollachius virens, were caught in larger numbers at night than during daytime. the examined fish fed throughout the diurnal cycle and kelp-associated fauna were found to be important prey. pollachius virens was caught in the same numbers throughout the diurnal cycle and contained mainly pelagic prey, in larger numbers during the day than at night. small labrids were specialists, feeding mainly on the two numerically dominant kelp-associated gastropods rissoa parva and lacuna vincta. the larger labrus bergylta, gadus morhua and myoxocephalus scorpius were generalists, feeding on a large range of kelp-associated invertebrates. some fish species showed preference for particular vertical levels when feeding in the kelp forest. the most mobile and/or the largest invertebrates were most heavily preyed upon.

The macrophytes Fucus serratus and Zostera marina form similar substrates for associated flora and fauna in shallow waters in Norway. While F. serratus forms a more or less continuous belt on rocky substrate along the coast, Z. marina forms disjunct populations on sandy or muddy bottoms. This study focused on the organisms associated with these two macrophytes in two localities in the Skagerrak region. In total, 130 taxa of epiphytic organisms were identified: 22 green algae, 41 red algae, 32 brown algae, eight diatoms and 27 sessile animals. One hundred and twenty-seven taxa of mobile macrofauna were registered. The dominant group was crustaceans, with amphipods as the order containing most species. Many species of both plants and animals preferred one or the other habitat. It is concluded that coastal macrophyte systems have high species diversity.

Changes in O2 concentration were measured during in situ incubation of whole, young Laminaria hyperborea and used to evaluate primary production and respiration over a 3-y period (1995–1998). The exudation of dissolved organic carbon (DOC) during incubation was also measured. Total carbohydrates and polyphenols in the exudates and the regional seawater were determined and fractionated into low molecular weight (LMW) and high molecular weight (HMW) species. Net production rates varied significantly, being highest during the growth phase (March), while respiration rates did not vary significantly. The exudation rates correlated with the plant strategy of growth and production in which high requirements for growth led to a lower proportion of fixed carbon being exuded. More fixed carbon was exuded during the non-growth phase. The annual exudation of DOC is estimated to be ∼26% of fixed carbon and amounts to ∼1·29 kgC m−2 y−1. The annual amount of carbon retained by the kelp (the difference between fixed and exuded carbon), assumed to contribute to growth, corresponds to a biomass increase of 3·0 kgC m−2 y−1, a value similar to those reported using direct measurements of biomass increase in the region. Carbohydrate concentrations in the exudates were lower during March than in other months, in accordance with the plant growth strategy. Phenols, on the other hand, which are assumed to function as predator deterrent, showed no significant variations in the exudate. The fraction is dominated by carbohydrates while phenols occurred mainly in the LMW fractions.

The invasive brown alga Sargassum muticum was first observed growing attached in Norway in 1988. Since then, the species has spread rapidly and is now an established member of the algal community in sheltered areas along the entire Skagerrak coast. In 1999, one population in the outer Oslofjord was investigated for epiphytic macroalgae, and evidence was found of a rich macroalgal community on S. muticum. A total of 82 different algal taxa were identified: 34 rhodophytes, 23 phaeophytes and 25 chlorophytes. The epiphytes found on S. muticum included more than 25% of the total number of algal species found in the Oslofjord area. A summary of all species recorded is given, with floristic notes on particular taxa.

The nutritional value of kelp Laminaria hyperborea (Gunn.) Foslie and the importance of bacterial degradation in making kelp available to consumers were tested by no-choice feeding experiments. Fresh and dead kelp material degraded in situ was sampled. In the laboratory, fresh kelp was degraded for 3, 14 and 44 d by kelp associated bacterial communities under aerobic and anaerobic conditions. The fresh and degraded kelp products were fed to the kelp associated amphipods Jassa falcata, Lembos websteri, Ampithoe rubricata and Gammarus locusta and the gas- tropod Rissoa parva. None of the amphipods tested could survive or grow on fresh kelp, but bacterial degradation decreased the C:N ratio and the phlorotannin content and made kelp available as food. In contrast, the gastropod survived on both fresh and degraded kelp. 13 C: 12 C and 15 N: 14 N isotope analysis of fauna and possible food items sampled in the field suggested that kelp derived particulate organic matter (POM) is an important food source for kelp epifauna.

Samples of kelp Laminaria hyperborea, various species of red algae, phytoplankton, material from sediment traps, invertebrates, fish and seabirds were collected on the west coast of Norway and the abundance of stable isotopes was analyzed. Canopy plants of L. hyperborea were most 13 C depleted in spring and there was a significant difference between the basal (δ 13 C: -16.65‰) and distal (δ 13 C: -18.67‰) parts of the lamina. Young kelp plants were more 13 C depleted (-23.59‰). The red algae fell into 2 groups: one in the same range as kelp plants (δ 13 C: -18.93 to -22.27‰) and the other highly depleted (δ 13 C: -32.85 to -34.38‰). Phytoplankton showed an average δ 13 C value of -24.44 ‰. δ 15 N values from L. hyperborea differed between the basal (δ 15 N: 5.54 ‰) and distal (δ 15 N: 3.54 ‰) part of lamina. δ 15 N values for all primary producers values were in the range of 3.52 to 5.78 ‰. Among the gastropods, Helcion pellucida proved to be a kelp plant grazer, Lacuna vincta probably fed on both kelp and various species of red algae, whereas Aplysia punctata grazed exclusively on the most 13 C-depleted red algae. δ 15 N values for 2 other gastropods, Gibbula sp. and Calliostoma zizyphinum (8.64 and 10.30%o, respectively), suggest that they belong to higher trophic levels. Filter feeders occupied lower trophic levels and received variable carbon inputs from kelp. The only group of animals with δ 13 C signals in the same range as phytoplankton were amphipods. Based on δ 15 N values, the fish varied from intermediate to top consumers (trophic level: 2.6 to 3.3). Two species of seabirds were included in the study and their δ 15 N values suggested 2 different trophic levels, which correspond to their known feeding preferences. A mixing model suggests that kelp-derived carbon plays an important role in this nearshore system and that kelp may serve as a carbon source for marine animals with several different types of feeding strategies.

Benthic algal vegetation was investigated at 10 sites in Isfjorden, Svalbard. Five sites were visited during summer 2010 and five during summer 2012. Both the littoral and sublittoral vegetation were sampled, the littoral by hand-picking and use of a throwable rake and the sublittoral using a triangular dredge. A total of 88 different taxa were registered, comprising 17 Chlorophyta, 40 Ochrophyta, 30 Rhodophyta and the Xantophyceae Vaucheria sp. The green algae Ulvaria splendens (Ruprecht) Vinogradova was recorded in Svalbard for the first time. Most of the sites consisted of hard bottom substrate, but one site, Kapp Wijk, consisted of loose-lying calcareous red algae (rhodoliths) and had species not recorded elsewhere. The sublittoral at the other sites was dominated by kelp. Molecular analysis confirmed the presence of the red alga Ceramium virgatum and a dwarf form of the brown alga Fucus vesiculosus . This study provides a baseline for future studies investigating changes in the vegetation due to environmental changes. Keywords: Arctic; Svalbard; Isfjorden; benthic algal diversity. (Published: 11 August 2015) To access the supplementary material for this article, please see supplementary files in the column to the right (under Article Tools). Citation: Polar Research 2015, 34 , 25994, http://dx.doi.org/10.3402/polar.v34.25994

Annual growth per plant and allocation of growth to the stipe were measured in 2- to 4-year-old plants of Laminaria hyperborea from five stations with different degrees of wave exposure and different amounts of canopy biomass. Low growth in plants with initial stipe lengths of less than about 40 cm suggested that the presence of canopy-forming plants suppresses growth of understorey plants, and this was supported by the high lamina growth rate of understorey plants after removal of the canopy-forming plants. Canopy biomass and wave exposure were found to exert a differential effect on the growth of the age groups examined. Average annual growth per plant in 2- to 3- year-old plants decreased with increasing canopy biomass; growth of 4 year-old plants was not significantly influenced by canopy biomass, but increased with increasing wave exposure of the sites, suggesting an influence of some factor connected with wave exposure. The allocation of annual growth to stipe and lamina was also found to be influen...

Interfertility has been demonstrated in vitro between isolates of G. pusillum from Norway, France and the British Isles, but anomalies in reproductive behaviour were observed in the two Norwegian isolates. In one of the latter (Fedje), female gametophytes were sterile. Carpogonia and nutritive filaments were differentiated, but further development was always disrupted and carposporangia never formed. On one occasion, bilocular ‘pseudo-cystocarps’ were formed in a self-cross, but no carpospores were produced. Male reproductive structures were functional and used in crossability tests. In the other Norwegian isolate (Solund), only a small percentage of the released tetraspores survived, and most of these had an aberrant dwarfed growth habit. Only a few of several thousand spores produced functional male and female gametophytes of normal appearance. In quantitative experiments, significantly higher sporeling survival was found in one of the French isolates (Cancale) than in the Solund isolate. Stages of the first meiotic division were observed and a haploid chromosome number of approximately n =15 − 20 was counted for the Solund isolate. During the second meiotic division, failure was frequently observed in that cytokinesis took place without completion of nuclear divison. In the French isolates of the same species (Cancale and Wimereux isolates), a haploid chromosome number of n = 20 or 21 was determined during meiosis in tetrasporocytes.

This paper focuses on the marine foundation eelgrass species, Zostera marina, along a gradient from the northern Baltic Sea to the north-east Atlantic. This vast region supports a minimum of 1480 km2 eelgrass (maximum >2100 km2), which corresponds to more than four times the previously quantified area of eelgrass in Western Europe.Eelgrass meadows in the low salinity Baltic Sea support the highest diversity (4–6 spp.) of angiosperms overall, but eelgrass productivity is low (

The seasonal growth pattern of canopy plants has been compared with that of first-year plants. Large, canopy-forming sporophytes grew between January and June. The seasonal variation in total carbon content of the lamina reflected the seasonal pattern of storage carbohydrates, with high content in the summer and autumn, and decreasing content after growth started in January. Vegetative and reproductive laminae contained similar percentages of carbon in dry weight in January, indicating that the process of sorus formation did not involve high consumption of stored carbohydrates in reproductive plants. The nitrogen content of the laminae of canopy plants was high during the growth period and low during the rest of the year. The high nitrogen content during spring may reflect storage in a period of excess ambient nitrate. The first-year plants grew until the end of September, with the highest relative growth rate during July. During the summer the nitrogen dry weight content of the first-year plants...

Lithophyllum crouanii and Titanoderma pustulatum have been found to be common epiphytes on Laminaria hyperborea stipes from western Norway. The two species were studied by light microscopy and SEM. The main character used to separate the two species macroscopically is that L. crouanii has immersed conceptacles seen as white circles on the thallus surface, whereas T. pustulatum has gradually raised conceptacies. Sporangial conceptacies are uniporate in both species. L. crouanii has zonately divided tetrasporangia and gametophytic plants were common. Only bisporangial plants were found in T. pustulatum. In vegetative specimens a cross section revealed that T. pustulatum has a unistratose hypothallium composed of oblique palisade cells and a bistratose margin. L. crouanii has horizontally aligned perithallial cells of more or less equal size and never has a bistratose margin.

Large areas of barren sea floor are found in northern Norway. These are limited to the inner coast: the outer coast is undisturbed with an intact kelp forest where the dominant species is Laminaria hyperborea. The kelp forest is an important spore source for the reforestation of barren areas, and its dispersal range is of vital importance. Experiment using sampling devices at varying distances from the kelp forest have shown the dispersal range of a populaiion of L. hyperborea plants to be at least 200 m. Large numbers of zoospores were found in samples taken from the water column at a depth of 5 m both within and 50 and 200 m from the kelp forest. Laboratory experiments have shown that spores probably swim as long as they can and thereafter sink passively out of the water column to settle.

Morphological development of Laminaria hyperborea was examined at localities with different degrees of wave exposure. Biomass data were converted to estimates of annual growth of lamina, stipe and hapteron. Allocation of annual growth to the hapteron constituted a small amount of the total production, but increased with increasing wave exposure. At the most sheltered locality, lamina growth amounted to between 80 and 95% of total growth in all age groups, and lamina to stipe ratios (fresh weight) were about 10. A higher portion of the annual growth was allocated to the stipe at the more wave-exposed localities. This resulted in lamina to stipe ratios of between 1 and 2 in old plants, but within these localities no gradual decrease in lamina to stipe ratio with increasing wave exposure was observed. At some localities a maximum of growth allocation to the stipe was found in the intermediate age groups. This was most pronounced at the locality with the highest density of canopy plants and intermediate wave exposure. Also, at this locallty the stipes were longer in relation to their weight than at the other localities. These results indicate that light environment, in additlon to wave exposure, Inay influence the stipe morphology and the relationship between stipe and lamina growth. At one station stipe growth was also calculated in individual tagged plants using the lengthweight relationship. The results agreed with those obtained by the biomass method. The highest allocation of growth to the stipes was found in 3 and 4 yr old plants. Maximum annual stipe growth (weight increase) occurred in 4 and 5 yr old plants and decreased in older plants, while maximum lamina growth was found in the oldest plants.

Copyright © 2011 Guri Sogn Andersen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. On the Skagerrak coast the kelp Saccharina latissima has suffered severe stand reductions over the last decade, resulting in loss of important habitats. In the present study, healthy kelp plants were transplanted into four deforested areas and their patterns of growth, reproduction, and survival were monitored through subsequent seasons. Our main objective was to establish whether the kelp plants were able to grow and mature in deforested areas. We observed normal patterns of growth and maturation at all study sites. However, heavy fouling by epiphytes occurred each summer, followed by high kelp mortality. The study shows that the seasonal variations and the life stage timing of S. latissima make formation of self-sustainable populations impossible in the present environment. Most noteworthy, we suggest that fouling by epiphytes is involved in the lack of kelp forest recovery in Skagerrak, Norway.

Unialgal isolates ofGelidium latifolium from northern Spain and western Norway were compared with respect to specific growth rate, when kept under different combinations of light (20, 50, 100, 200, 300 µmol m-2s-1) and temperature (17, 20, 24, 28, 31 °C.) The Norwegian isolate grew almost twice as fast as the Spanish isolate under all combinations tested. Maximum growth rate for the Norwegian and Spanish isolates was 6.71% d-1 and 3.64% d-1, respectively. The results show the existence of ecotypes and the importance of inoculum selection in the development of a mass cultivation system forGelidium.

Much evidence suggests that life originated in hydrothermal habitats, and for much of the time since the origin of cyanobacteria (at least 2.5 Ga ago) and of eukaryotic algae (at least 2.1 Ga ago) the average sea surface and land surface temperatures were higher than they are today. However, there have been at least four significant glacial episodes prior to the Pleistocene glaciations. Two of these (approx. 2.1 and 0.7 Ga ago) may have involved a 'Snowball Earth' with a very great impact on the algae (sensu lato) of the time (cyanobacteria, Chlorophyta and Rhodophyta) and especially those that were adapted to warm habitats. By contrast, it is possible that heterokont, dinophyte and haptophyte phototrophs only evolved after the Carboniferous-Permian ice age (approx. 250 Ma ago) and so did not encounter low (

The kelp Laminaria hyperborea is regularly harvested along the Norwegian coast. Kelp trawling is regulated by restricting this to every 5th year in specified areas. The kelp plants form dense forests, 1–2 m high, and house a large number of epiphytes and associated invertebrates. Kelp, epiphytes, and holdfast (hapteron) fauna were sampled at two different regions in untrawled kelp forest and at sites trawled different number of years ago. We have examined the rate of kelp regrowth after trawling, and in what time scale the associated flora and fauna colonize the trawled areas. The trawl removed all adult kelp plants (the canopy plants), while small understorey kelp plants were left undisturbed. These recruits, given improved light conditions, made the new generation of canopy-forming kelp plants, exceeding a height of 1 m within 2–3 y. The recruitment pattern of the kelp ensures maintenance of kelp forest dominance despite repeated trawling. Both percent cover, abundance and number of epiphytic species increased with time post trawling, but epiphytic communities were not totally re-established before the next trawling episode. Colonization of most species of fauna inhabiting the kelp holdfast were found as early as one year after trawling, but increasing size of the habitat by age of kelp gave room for increasing numbers of both individuals and species. Slow colonization rate by some species might be due to low dispersal potential. Due to a higher maximum age and size of kelp plants in the northernmost region studied, restoration of both kelp and kelp forest community was slower there.

Eight populations of Laminaria hyperborea from wave-exposed localities in Finnmark (70–71°N) were compared with two populations in Vega (65 °N). Standing stock in shallow water (3–5 m) was within the same range in the two areas (6–16 kg fr. wt. m-2). Both the highest and lowest value of standing stock were registered in Finnmark. Degree of wave-exposure was determined by the numbers of sectors exposed to open sea at each locality, with each sector given a relative wind force value. The most wave-exposed locality in Vega had a slightly higher annual biomass production as a function of plant age compared with the populations from Finnmark within a similar range of wave exposure. Of the two localities in Vega the most wave-exposed one had a higher annual biomass production per plant than the more sheltered one. The most wave-exposed locality examined was situated in Finnmark and exhibited the lowest annual biomass production per plant. Recruits (one-year-old plants) were found at all the localities except at one locality in Finnmark. The plants reached a higher age in Finnmark (13–18 years) than in Vega (8–9 years).

Two species of Gelidium, provisionally referred to as G. pusillum and G. latifolium, are included in the Scandinavian flora and reach their northern limit of distribution on the Norwegian west coast. Small frond sizes due to adverse growth conditions, extreme phenotypic variability and lack of sexual reproduction make identification of specimens very difficult. Both species were isolated into unialgal culture and were compared with cultured strains referable to G. pusillum from Ireland and France. Temperature and salinity requirements and tolerance ranges were determined and discussed in view of distribution along the Norwegian coast. Little or no growth occurs below 9 ° C, corresponding to a northern summer growth limit. On the Norwegian Skagerrak coast, low winter temperature rather than reduced salinity is the limiting factor.

G. latifolium from the Norwegian west coast was isolated into unialgal culture and growth responses to various regimes of temperature, light, and salinity were determined. The morphological variability in cultures of cloned material and of field-collected specimens is discussed in relation to species delineation. Comparisons with cultured strains referable to G. pusillum from Norway, France, and Ireland were undertaken. Enzyme electrophoresis provided supporting data for the distinction between the two entities from Norway. The distribution of G. latifolium along the Norwegian coast was recorded from examination of available herbarium specimens. The boundary near the entrance to the Skagerrak coast corresponds to lethal winter temperatures (< 0° C), while the northern boundary corresponds to a summer growth limit near the 10° C August isotherm, below which little or no growth occurs.