The phytobenthos of the Hornsund fiord, SW Spitsbergen

Abstract

The species composition and biomass of material collected in the summers 1981 and 1983 from 69 stations in the Hornsund fiord were analysed. 48 macroalgal taxa were found: 13 green algae, 18 brown algae and 17 red algae. 19 of these taxa were not reported from the nearby Isfjorden. The overall biomass for the littoral zone varied from 0 to 216gnT2 formalin d.w., although in J of samples the biomass was between 20 and 80 gm_z. The dominant species were Fucus distichus, Acrosiphonia duriusada and Pilayella littoralis. Using cluster analysis, an attempt was made to delimit regions with a characteristic species composition. The results obtained, however, do not permit this in the littoral zone of the Hornsund fiord.

Photosynthesis and respiration of some marine benthic algae from Spitsbergen

“…The compensation point was generally in the range of 100-200 Ix with a maximum of 350 Ix, while photosynthesis was saturated at 1 ,00& 2,000 Ix. These results correspond to those reported by Gorski (1962) for shade-tolerant plants. According to him, such plants exhibit a compensation point in the range of 100-300 lx and saturation at up to 2,000 Ix.…”

Continuous photoperiod of the Artic summer stimulates the photosynthetic response of some marine macrophytes

“…Our results for A. nodosum agree with those of Strömgren, (1978), using specimen from the North Sea and Norwegian Sea where A. nodosum, Fucus serratus and Pelvetia canaliculate increased its growth up to 24 h whereas F. vesiculosus only increased up to 20 h of daylight. The small increase in rETRmax of F. vesiculosus compared with the increase of A. nodosum and Z. marina at continuous daylight could explain their current presence in the high-Arctic (Florczyk and Latala, 1989;Hansen and Haugen, 1989). Other species such as Ulva lactuca and Porphyra umbilicalis from the North Sea did not increase their growth at photoperiods greater than 16 h (Fortes and Lüning, 1980).…”

“…As they expand northward, they will probably be able to successfully cope with 24 h of darkness during the Arctic winter since they are already present at 69.7º N (A. nodosum, reviewed by Marbà et al, 2017), 75º N (F. vesiculosus, Florczyk andLatala, 1989;Hansen and Haugen, 1989) and 70º N (Z. marina, reviewed by Olesen et al, 2015), and thus exposed to photoperiods of long daylight and darkness. Nevertheless, further research is needed on the interactive effects of day length and increased CO2 with nutrients availability, salinity and light intensities on photosynthesis of arctic and subarctic macrophyte.…”

“…Zostera marina has been reported in the Arctic up to 70ºN, although its presence is scarce (reviewed by Olesen et al, 2015). Intertidal belts of the macroalgae Ascophyllum nodosum are present up to 69.7º N (reviewed by Marbà et al, 2017) and Fucus vesiculosus has been found as far north of 75 °N as the Svalbard Archipelago (Florczyk and Latala, 1989;Hansen and Haugen, 1989).…”