Growth Reconstruction and Photosynthesis of Aquatic Mosses: Influence of Light, Temperature and Carbon Dioxide at Depth

Centimeter-large colonies of Nostoc zetterstedtii from a Swedish oligotrophic lake had the lowest growth and mortality rates of any studied temperate macrophyte. Annual growth rates at two shallow sites averaged 0.57-0.73 3 10 23 d 21 , corresponding to doubling times of colony dry weight in 2.6-3.3 yr. With such low growth rates, the largest colonies measuring 7 cm in diameter are 24-31 yr old. We found no mortality of incubated colonies and calculated the mortality rate to , 7.3 3 10 25 d 21 and the life span to . 24 yr in accordance with age of the largest colonies. The firm gelatinous tissue of high mass density, low nutrient content, and antibacterial property can account for the low growth and mortality rates. The measured daily surplus of photosynthesis minus respiration can support only small increments of the large mass per colony surface in accordance with the low growth rates. Growth and mortality rates of N. zetterstedtii correspond best with general allometric relationships for macroalgae using surface area to carbon biomass as the scaling parameter, but measurements are lower than predictions probably because of extra costs to sustain the substantial colony matrix. N. zetterstedtii is adapted to pristine Lobelia lakes with clear water and chronically low nutrient levels, but it is threatened by strong attenuation of light by brownification or eutrophication.

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“…Mortality risks include pathogens, grazing, and unsuitable environmental conditions. { Lake Grane Langsø (Riis and Sand-Jensen 1997).…”

Section: Discussionmentioning

confidence: 99%

Unprecedented slow growth and mortality of the rare colonial cyanobacterium, Nostoc zetterstedtii, in oligotrophic lakes

Sand‐Jensen

Møller

2011

Limnology & Oceanography

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“…The extinction coefficient was determined from light compensation values (about 30 µmol m −2 s −1 ) for Sphagnum mosses found in the literature (e.g. Riis and Sand-Jensen, 1997) and average depth of green (active biomass) layer in Siikaneva moss carpet (2.5 cm). Light intensity was calculated in 10 to 22 layers and the Guenther algorithm was applied to each of these.…”

Section: Resultsmentioning

confidence: 99%

Measurements of hydrocarbon emissions from a boreal fen using the REA technique

et al. 2006

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Abstract. Fluxes of biogenic volatile organic compounds (VOC) and methane were measured above a boreal fen. Vegetation on the fen is dominated by Sphagnum mosses and sedges. A relaxed eddy accumulation (REA) system with dynamic deadband was designed and constructed for the measurements. Methane, C 2 -C 6 hydrocarbons and some halogenated hydrocarbons were analysed from the samples by gas chromatographs equipped with FID and ECD. A significant flux of isoprene and methane was detected during the growing seasons. Isoprene emission was found to follow the common isoprene emission algorithm. Average standard emission potential of isoprene was 680 µg m −2 h −1 . Fluxes of other non-methane hydrocarbons were below detection limit.

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“…In contrast, dry periods are characterised by less surface runoff and the decreased diatom production creates clear lake water and good light conditions on the lake bottom. The aquatic mosses Sphagnum subsecundum and Drepanocladus exannulatus are more dependent on light conditions than on temperature (Riis and Sand-Jensen, 1997), and this could explain the increased moss abundance (mainly Drepanocladus exannulatus) with decreasing biogenic silica and clastic material content. It should be noted that some of the biogenic silica variability may also be related to temperature changes, but it is not possible to differentiate between the influence of temperature and precipitation on the lake sediment composition.…”

Section: Environmental Interpretationmentioning

confidence: 99%

Holocene climate changes in southern Greenland: evidence from lake sediments

Andresen

Björck

Bennike

et al. 2004

J Quaternary Science

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A Holocene lake sediment record is presented from Lake N14 situated on Angissoq Island 15 km off the main coast of southern Greenland. The palaeoclimatic development has been interpreted on the basis of flux and percentage content of biogenic silica, clastic material, organic material and sulphur as well as sedimentation rate, moss content and magnetic susceptibility. A total of 43 radiocarbon dates has ensured a reliable chronology. It is argued that varying sediment composition mainly reflects changing precipitation. By analogy with the present meteorological conditions in southern Greenland, Holocene climate development is inferred. Between 11 550 and 9300 cal. yr BP temperature and precipitation increase markedly, but this period is climatically unstable. From 9300 yr BP conditions become more stable and a Holocene climatic optimum, characterised by warm and humid conditions, is observed from 8000 to 5000 cal. yr BP. From 4700 cal. yr BP the first signs of a climatic deterioration are observed, and from 3700 cal. yr BP the climate has become more dry and cold. Superimposed on the climatic long-term trend is climate variability on a centennial time-scale that increases in amplitude after 3700 cal. yr BP. A climatic scenario related to the strength and position of the Greenland high-pressure cell and the Iceland low-pressure cell is proposed to explain the Holocene centennial climate variability. A comparison of the Lake N14 record with a terrestrial as well as a marine record from the eastern North Atlantic Ocean suggests that the centennial climate variability was uniform over large areas at certain times.

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Growth Reconstruction and Photosynthesis of Aquatic Mosses: Influence of Light, Temperature and Carbon Dioxide at Depth

Cited by 61 publications

References 34 publications

Unprecedented slow growth and mortality of the rare colonial cyanobacterium, Nostoc zetterstedtii, in oligotrophic lakes

Unprecedented slow growth and mortality of the rare colonial cyanobacterium, Nostoc zetterstedtii, in oligotrophic lakes

Measurements of hydrocarbon emissions from a boreal fen using the REA technique

Holocene climate changes in southern Greenland: evidence from lake sediments

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