The influence of dissolved organic carbon on primary production in northern lakes

Seekell, David A.; Lapierre, Jean‐François; Ask, Jenny; Bergström, Ann‐Kristin; Deininger, Anne; Rodríguez, Patricia; Karlsson, Jan

doi:10.1002/lno.10096

Cited by 212 publications

(296 citation statements)

References 58 publications

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“…Our results clearly show that the net effect of N fertilization on phytoplankton biomass declined with increasing DOC (cf. Our results take the whole lake model presented by Seekell et al (2015) one step further, in that increased limiting nutrient availability (i.e., inorganic N) has a greater impact on primary production in clearer lakes (here: low to medium DOC lakes), whereas in increasingly humic lakes (here: medium to high DOC lakes), light extinction has a greater impact on primary production than increasing the availability of the limiting nutrient. 2), i.e., simultaneous to the decrease in light:TP ratio.…”

Section: Effects Of N Fertilizationmentioning

confidence: 72%

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Deininger

Faithfull

Bergström

2017

Ecology

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Global change has increased inorganic nitrogen (N) and dissolved organic carbon (DOC; i.e., "browning") inputs to northern hemisphere boreal lakes. However, we do not know how phytoplankton in nutrient poor lake ecosystems of different DOC concentration respond to increased N availability. Here, we monitored changes in phytoplankton production, biomass and community composition in response to whole lake inorganic N fertilization in six boreal unproductive Swedish lakes divided into three lake pairs (control, N enriched) at three DOC levels (low, medium, high), with one reference year (2011) and 2 impact yr (2012, 2013). We found that phytoplankton biomass and production decreased with DOC concentration before N fertilization. Further, phytoplankton community composition also differed with respect to DOC, with a dominance of non-flagellated autotrophs at low DOC towards an increasing dominance of flagellated autotrophs with increased lake DOC concentration. The N fertilization increased phytoplankton biomass and production in all lakes, but did not affect phytoplankton community composition. However, the net response in biomass and production to N fertilization declined with increasing DOC, implying that the lake DOC concentration is critical in order to infer phytoplankton responses to N fertilization, and that the system switches from being primarily nutrient limited to becoming increasingly light limited with increased DOC concentration. In conclusion, our results show that browning will reduce phytoplankton production and biomass and influence phytoplankton community composition, whereas increased inorganic N loadings from deposition, forestry or other land use will primarily enhance phytoplankton biomass and production. Together, any change in the landscape that enhances inorganic N availability will increase phytoplankton production and biomass, but the positive effects of N will be much weaker or even neutralized in browner lakes as caused by light limitation.

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Section: Effects Of N Fertilizationmentioning

confidence: 72%

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Deininger

Faithfull

Bergström

2017

Ecology

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“…The impact of permafrost thaw on food webs and ecosystem functioning appear likely to be driven by changes in the inputs of nutrients, DOM, and sediments. Primary production is stimulated by nutrient input but can be hindered by light suppression following increasing input of CDOM or OC-rich sediments, particularly when DOM concentrations are great enough that the positive effect of increasing organic nutrients is overwhelmed by the negative effect of decreasing light penetration (Seekell et al, 2015). Benthic communities can be destabilized by high sediment loading but may thrive when slumping of mineral-rich sediment leads to increasing water clarity.…”

Section: Discussionmentioning

confidence: 99%

“…Alaska, Levine andWhalen, 2001 andO'Brien et al, 2005), yet input of sediments and DOM will decrease primary production if it leads to suboptimal conditions for photosynthesis, mainly affecting benthic algae but also planktonic algae when lakes are very turbid (northern Sweden, Ask et al, 2009;northern Québec, Roiha et al, 2015). In regions where thaw increases both nutrients and DOM we may expect stimulation of total primary production in clear and shallow lakes but suppression of primary production in more coloured or deeper lakes (Sweden and Alaska, Seekell et al, 2015). In regions where retrogressive thaw slumping delivers mineral-rich sediments to lakes (Mackenzie Delta uplands, Thompson et al, 2008 andMesquita et al, 2010), permafrost degradation has led to significantly greater dissolved ion content, lower DOC concentrations following mineral adsorption, and increased water transparency.…”

Section: Lakesmentioning

confidence: 99%

Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

et al. 2015

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Abstract. The Arctic is a water-rich region, with freshwater systems covering about 16 % of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can Published by Copernicus Publications on behalf of the European Geosciences Union. J. E. Vonk et al.: Effects of permafrost thaw on Arctic aquatic ecosystemsbe considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO 2 and CH 4 ), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to quantify how permafrost thaw is affecting aquatic ecosystems across diverse Arctic landscapes, and the implications of this change for further climate warming.

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“…Even though terrestrial organic matter can support the growth of individual consumers, it appears to reduce rather than increase whole lake secondary production (Kelly et al 2014; Karlsson et al 2015). Thus, the effects of increased humic levels acts over the whole year but in different ways depending on season, i.e., in winter by affecting the feeding success and survival of especially YOY fish, and in summer largely through lower primary production and resource supply to fish (Craig et al 2015; Karlsson et al 2015; Seekell et al 2015). …”

Section: Discussionmentioning

confidence: 99%

Brownification increases winter mortality in fish

et al. 2016

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In northern climates, winter is a bottleneck for many organisms. Low light and resource availability constrains individual foraging rates, potentially leading to starvation and increased mortality. Increasing input of humic substances to aquatic ecosystems causes brownification of water and hence a further decrease of light availability, which may lead to further decreased foraging rates and starvation mortality during winter. To test this hypothesis, we measured the effects of experimentally increased humic water input on consumption and survival of young-of-the-year three-spined stickleback (Gasterosteus aculeatus) over winter in large outdoor enclosures. Population densities were estimated in autumn, and the following spring and food availability and consumption were monitored over winter. As hypothesized, mortality was higher under humic (76%) as compared to ambient conditions (64%). In addition, body condition and ingested prey biomass were lower under humic conditions, even though resource availability was not lower under humic conditions. Light conditions were significantly poorer under humic conditions. This suggests that increased mortality and decreased body condition and ingested prey biomass were not due to decreased resource availability but due to decreased search efficiency in this visual feeding consumer. Increased future brownification of aquatic systems may, therefore, negatively affect both recruitment and densities of fish.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-016-3779-y) contains supplementary material, which is available to authorized users.

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The influence of dissolved organic carbon on primary production in northern lakes

Cited by 212 publications

References 58 publications

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

Brownification increases winter mortality in fish

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