Mosses in High-Arctic lakes: in situ measurements of annual primary production and decomposition

Abstract

Aquatic mosses are important primary producers in High-Arctic lakes, but little information is available on their contribution to the overall production in these lakes. In order to predict effects of climate change on whole-lake ecosystem characteristics, more knowledge is needed on the role of moss in primary production, the extent of nutrient limitation of moss primary production and whether moss serves as food resource for secondary producers. In this study, we conducted an in situ growth experiment of an aquatic moss in a High-Arctic lake in NE Greenland and used these data to determine annual net production of this moss in the whole lake. We also measured tissue-N and tissue-P in order to assess nutrient limitation of moss production, measured in situ decomposition rates by litter bag experiments over 1 year and assessed the role of moss as food source by analysing stable isotope 15 N and 13 C of relevant organism groups in the lake. Net primary production of moss was 1.3 gC m -2 year -1 and constituted 23 % of the total benthic primary production and 18 % of the total lake primary production. Stoichiometric assessments suggested N and P limitation of moss growth. On average, 15 % of the standing biomass was decomposed per year. Our results also indicate that moss is not directly used as food resource by herbivores, but the most abundant herbivore, Lepidurus arcticus, is feeding on the epiphytic biofilm on the moss. Moss biomass is instead incorporated into the microbial decomposer pathway. All together, the study shows that moss plays an important ecological role as primary producer in High-Arctic lakes and functions as substrate for periphytic biofilm that serves as food resource for important herbivore invertebrates.

Polish Polar Research

“…However, the content of SOC in the surface horizon at site 6 is much higher than in the abovementioned study due to the locally better developed heath tundra. The high content of SOC in A and organic horizons in profiles from sites 7 and 8 (Table 2) under wet moss tundra was associated with the high wetness of these sites and low decomposability of moss-derived litter (Gerdol et al 2007;Osono et al 2012;Riis et al 2016). A study conducted by Szymański (2017) in the eastern part of the Fuglebergsletta shows a slightly higher content of SOC (with a mean value of 20.26%) than results obtained in the present study.…”

“…The presence of a thin H horizon in these soils most likely was connected with the high wetness of these sites. Furthermore, mosses, which were the main part of the vegetation at these sites, are resistant to decomposition (Gerdol et al 2007;Osono et al 2012;Riis et al 2016). The morphology of the studied soils indicates an early stage of formation, which is typical of soils occurring in Spitsbergen, e.g., in Hornsund (Szymański et al 2015), on the Bellsund coast (Klimowicz et al 1999), and in Recherchefjorden (NW part of Wedel Jarlsberg Land) (Hanaka et al 2019).…”

Aquatic and Terrestrial Plant Contributions to Sedimentary Plant Waxes in a Modern Arctic Lake Setting

“…mosses found in other Arctic regions and at lower latitudes (Bush & McInerney, 2013; Nichols et al., 2009; Pancost et al., 2002). Aquatic mosses can grow submerged in thick mats on Arctic lake beds (Riis et al., 2016; Sand‐Jensen et al., 1999), likely providing a direct pathway for waxes to the lake sediments. However, some Arctic shrubs also produce high concentrations of mid‐chain waxes (C 22 and C 24 n ‐alkanoic acids) (Daniels et al., 2017; Dion‐Kirschner et al., 2020).…”

Changes in food web dynamics of low Arctic ponds with varying content of dissolved organic carbon

“…Macrophytes can also play a role in contributing to the carbon pool, and can outcompete benthic and pelagic algae for space and light while providing important refugia for zooplankton (Grosbois, del Giorgio, and Rautio 2017). In Arctic freshwaters, ice scouring and a short growing season keep macrophytes low; however, zooplankton have been shown to feed on periphyton growing on macrophytes, such as mosses (Riis, Christoffersen, and Baattrup-Pedersen 2015).…”