Habitat, not resource availability, limits consumer production in lake ecosystems

Craig, Nicola; Jones, Stuart; Weidel, Brian C.; Solomon, Christopher T.

doi:10.1002/lno.10153

Cited by 52 publications

(74 citation statements)

References 53 publications

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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%

“…Still, brownification not only decrease intake rates but may also strengthen the negative effects on fish performance further by decreasing benthic resource densities during winter. This is because negative effects of increased humic levels during summer are especially pronounced on benthic primary productions and invertebrate production (Karlsson et al 2009; Craig et al 2015), i.e., the main resource for fish during winter (Byström et al 2006). Hence, future climate-change affects both productivity during summer and survival of YOY fish during winter.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Brownification increases winter mortality in fish

et al. 2016

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“…Vertical structure of heat in small lakes (< 0.5 km 2 ) is typically driven by molecular diffusion and the attenuation of light (Read and Rose 2013), and as small lakes dominate globally (Downing et al 2006), the recent browning phenomenon likely has strongly affected the temperature regime in many lakes worldwide. Thermocline and z mix control habitat use for phytoplankton, zoobenthos, and fish, and as such, may adversely affect consumer productivity in many lakes due to a reduction in suitable habitat as shown in previous studies (Kelly et al 2014;Craig et al 2015).…”

Section: Physiochemical Responsesmentioning

confidence: 91%

Metabolic and physiochemical responses to a whole-lake experimental increase in dissolved organic carbon in a north-temperate lake

et al. 2015

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Over the last several decades, many lakes globally have increased in dissolved organic carbon (DOC), calling into question how lake functions may respond to increasing DOC. Unfortunately, our basis for making predictions is limited to spatial surveys, modeling, and laboratory experiments, which may not accurately capture important whole-ecosystem processes. In this article, we present data on metabolic and physiochemical responses of a multiyear experimental whole-lake increase in DOC concentration. Unexpectedly, we observed an increase in pelagic gross primary production, likely due to a small increase in phosphorus as well as a surprising lack of change in epilimnetic light climate. We also speculate on the importance of lake size modifying the relationship between light climate and elevated DOC. A larger increase in ecosystem respiration resulted in an increased heterotrophy for the treatment basin. The magnitude of the increase in heterotrophy was extremely close to the excess DOC load to the treatment basin, indicating that changes in heterotrophy may be predictable if allochthonous carbon loads are well-constrained. Elevated DOC concentration also reduced thermocline and mixed layer depth and reduced whole-lake temperature. Results from this experiment were quantitatively different, and sometimes even in the opposite direction, from expectations based on cross-system surveys and bottle experiments, emphasizing the importance of whole-ecosystem experiments in understanding ecosystem response to environmental change.Many northern hemisphere lakes have experienced a gradual increase in dissolved organic carbon (DOC) concentration over the past several decades, a phenomenon termed "global browning" (Evans et al. 2006;Roulet and Moore 2006;Monteith et al. 2007). The increase in DOC concentration has been attributed to a recovery from acidification (Evans et al. 2006;Monteith et al. 2007), increased catchment terrestrial primary production (Freeman et al. 2004), high nitrogen loads affecting soil decomposition (Findlay 2005), ecosystem effects of climate change (Urban et al. 2011), and changes in catchment hydrology (Evans et al. 2005). Although the mechanism for global browning is important to understand and currently still debated, the ecological consequences of increased DOC concentration on lake processes are poorly understood. DOC has both abiotic and biotic effects on lake ecosystems, and comparative studies suggest DOC as a master variable in structuring aquatic ecosystems . Abiotic effects of DOC on lake ecosystems are expressed through its light attenuating properties, as the absorption of solar radiation affects the vertical distribution of light and heat, and in turn, affects a host of other lake ecosystem functions. For example, highly colored north-temperate lakes had reduced epilimnetic depth, temperature, and irradiance compared with clearer lakes (Houser 2006). Additionally, modeling of a north-temperate bog lake showed that a 50% reduction in DOC concentration caused a deepening of the mi...

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“…These bacteria are known to occur in environments where both oxygen and CH 4 are available, and they have been suggested to contribute to the zooplankton diet (Jones, 2000;northern Finland, Kankaala et al, 2006). Permafrost thaw may stimulate this C pathway but it is not clear if this could override the likely negative effect on higher consumers by oxygen depletion (Craig et al, 2015;Karlsson et al, 2015).…”

Section: J E Vonk Et Al: Effects Of Permafrost Thaw On Arctic Aquamentioning

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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Habitat, not resource availability, limits consumer production in lake ecosystems

Cited by 52 publications

References 53 publications

Brownification increases winter mortality in fish

Brownification increases winter mortality in fish

Metabolic and physiochemical responses to a whole-lake experimental increase in dissolved organic carbon in a north-temperate lake

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

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