Continuous and high-frequency measurements in limnology: history, applications, and future challenges

Meinson, Pille; Idrizaj, Agron; Nõges, Peeter; Nõges, Tiina; Laas, Alo

doi:10.1139/er-2015-0030

Cited by 53 publications

(47 citation statements)

References 100 publications

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“…In particular, the short generation times of planktonic producers and consumers allow fast tracking of potentially complex trophic interactions, and the aquatic medium allows for straightforward measurements of ecosystem processes such as primary production and community respiration. Furthermore, technological developments have facilitated continuous depth-integrated measurements of basic lake characteristics (Meinson et al, 2015). Such high-frequency observations have fostered awareness of storm impacts on lake ecosystems (Jennings et al, 2012;Klug et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Thermocline deepening boosts ecosystem metabolism: evidence from a large‐scale lake enclosure experiment simulating a summer storm

Giling

Nejstgaard

Berger

et al. 2016

Global Change Biology

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Extreme weather events can pervasively influence ecosystems. Observations in lakes indicate that severe storms in particular can have pronounced ecosystem-scale consequences, but the underlying mechanisms have not been rigorously assessed in experiments. One major effect of storms on lakes is the redistribution of mineral resources and plankton communities as a result of abrupt thermocline deepening. We aimed at elucidating the importance of this effect by mimicking in replicated large enclosures (each 9 m in diameter, ca. 20 m deep, ca. 1300 m in volume) a mixing event caused by a severe natural storm that was previously observed in a deep clear-water lake. Metabolic rates were derived from diel changes in vertical profiles of dissolved oxygen concentrations using a Bayesian modelling approach, based on high-frequency measurements. Experimental thermocline deepening stimulated daily gross primary production (GPP) in surface waters by an average of 63% for >4 weeks even though thermal stratification re-established within 5 days. Ecosystem respiration (ER) was tightly coupled to GPP, exceeding that in control enclosures by 53% over the same period. As GPP responded more strongly than ER, net ecosystem productivity (NEP) of the entire water column was also increased. These protracted increases in ecosystem metabolism and autotrophy were driven by a proliferation of inedible filamentous cyanobacteria released from light and nutrient limitation after they were entrained from below the thermocline into the surface water. Thus, thermocline deepening by a single severe storm can induce prolonged responses of lake ecosystem metabolism independent of other storm-induced effects, such as inputs of terrestrial materials by increased catchment run-off. This highlights that future shifts in frequency, severity or timing of storms are an important component of climate change, whose impacts on lake thermal structure will superimpose upon climate trends to influence algal dynamics and organic matter cycling in clear-water lakes.

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Section: Introductionmentioning

confidence: 99%

Thermocline deepening boosts ecosystem metabolism: evidence from a large‐scale lake enclosure experiment simulating a summer storm

Giling

Nejstgaard

Berger

et al. 2016

Global Change Biology

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“…There are about 117 million lakes in the world [3], but only a small fraction of them is included in in situ monitoring networks and the frequency of in situ monitoring is often limited. Increasing amount of lakes has been equipped with automated monitoring systems [4,5] that provided data with sufficient frequency. However, the number of lakes with such systems is still rather small.…”

Section: Introductionmentioning

confidence: 99%

First Experiences in Mapping Lake Water Quality Parameters with Sentinel-2 MSI Imagery

et al. 2016

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Abstract:The importance of lakes and reservoirs leads to the high need for monitoring lake water quality both at local and global scales. The aim of the study was to test suitability of Sentinel-2 Multispectral Imager's (MSI) data for mapping different lake water quality parameters. In situ data of chlorophyll a (Chl a), water color, colored dissolved organic matter (CDOM) and dissolved organic carbon (DOC) from nine small and two large lakes were compared with band ratio algorithms derived from Sentinel-2 Level-1C and atmospherically corrected (Sen2cor) Level-2A images. The height of the 705 nm peak was used for estimating Chl a. The suitability of the commonly used green to red band ratio was tested for estimating the CDOM, DOC and water color. Concurrent reflectance measurements were not available. Therefore, we were not able to validate the performance of Sen2cor atmospheric correction available in the Sentinel-2 Toolbox. The shape and magnitude of water reflectance were consistent with our field measurements from previous years. However, the atmospheric correction reduced the correlation between the band ratio algorithms and water quality parameters indicating the need in better atmospheric correction. We were able to show that there is good correlation between band ratio algorithms calculated from Sentinel-2 MSI data and lake water parameters like Chl a (R 2 = 0.83), CDOM (R 2 = 0.72) and DOC (R 2 = 0.92) concentrations as well as water color (R 2 = 0.52). The in situ dataset was limited in number, but covered a reasonably wide range of optical water properties. These preliminary results allow us to assume that Sentinel-2 will be a valuable tool for lake monitoring and research, especially taking into account that the data will be available routinely for many years, the imagery will be frequent, and free of charge.

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“…, Meinson et al. ) and are using high‐frequency data to address important ecological research questions, including drivers of whole lake metabolism (Solomon et al. ), lake responses to extreme events (Jennings et al.…”

Section: Introductionmentioning

confidence: 99%

Analysis of high‐frequency and long‐term data in undergraduate ecology classes improves quantitative literacy

et al. 2017

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Abstract. Ecologists are increasingly analyzing long-term and high-frequency sensor datasets as part of their research. As ecology becomes a more data-rich scientific discipline, the next generation of ecologists needs to develop the quantitative literacy required to effectively analyze, visualize, and interpret large datasets. We developed and assessed three modules to teach undergraduate freshwater ecology students both scientific concepts and quantitative skills needed to work with large datasets. These modules covered key ecological topics of phenology, physical mixing, and the balance between primary production and respiration, using lakes as model systems with high-frequency or long-term data. Our assessment demonstrated that participating in these modules significantly increased student comfort using spreadsheet software and their self-reported competence in performing a variety of quantitative tasks. Interestingly, students with the lowest pre-module comfort and skills achieved the biggest gains. Furthermore, students reported that participating in the modules helped them better understand the concepts presented and that they appreciated practicing quantitative skills. Our approach demonstrates that working with large datasets in ecology classrooms helps undergraduate students develop the skills and knowledge needed to help solve complex ecological problems and be more prepared for a data-intensive future.

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Continuous and high-frequency measurements in limnology: history, applications, and future challenges

Cited by 53 publications

References 100 publications

Thermocline deepening boosts ecosystem metabolism: evidence from a large‐scale lake enclosure experiment simulating a summer storm

Thermocline deepening boosts ecosystem metabolism: evidence from a large‐scale lake enclosure experiment simulating a summer storm

First Experiences in Mapping Lake Water Quality Parameters with Sentinel-2 MSI Imagery

Analysis of high‐frequency and long‐term data in undergraduate ecology classes improves quantitative literacy

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