Temporal scales of water-level fluctuations in lakes and their ecological implications

Hofmann, Hilmar; Lorke, Andreas; Peeters, Frank

doi:10.1007/s10750-008-9474-1

Cited by 108 publications

(57 citation statements)

References 44 publications

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“…A myriad of environmental factors shape habitat structure (Dodds, 2002;Hofmann et al, 2008). Aquatic and near-shore faunal distribution depends largely on the environment, with high diversity of habitats and food resources generating correspondingly diverse littoral communities (Wallace, 1996;Weatherhead & James, 2001;Schindler & Scheuerell, 2002;Stendera & Johnson, 2008;Tolonen & H€ am€ al€ ainen, 2010).…”

Section: Discussionmentioning

confidence: 99%

Water‐level fluctuations regulate the structure and functioning of natural lakes

2015

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1. Despite becoming one of the main pressures on aquatic ecosystems globally, understanding of the ecological impacts of altered water-level regimes in lakes lags far behind that of other human disturbances (e.g. eutrophication, acidification). 2. We employed a multifaceted approach to explore the potential importance of water-level fluctuations (WLF) for the structure and functioning of littoral zones and multiple trait responses of primary producers and benthic consumers across a range of natural lakes. 3. We found that lakes with high WLF had significantly more coarse littoral substrata with less coverage of macrophyte vegetation in the shallows than in lakes with low WLF. Lakes with high WLF also had greater proportions of motile diatom species and omnivorous benthic invertebrates in shallow waters, altered taxonomic and trophic structure of benthic consumers and more homogeneous algal and benthic invertebrate assemblages. 4. Variation along the littoral depth gradient needs to be examined when assessing the impacts of hydrological pressures in lakes. We found that depth interacted with WLF in its effects on habitat structure and mediated the response of both producer and consumer benthic assemblages to WLF. 5. Our results indicate that amplified WLF significantly affect both the structure and functioning of lake ecosystems. Given the growing importance of WLF as an increasingly pervasive pressure on lake ecosystems worldwide, our findings have important implications for the conservation and management of global aquatic biodiversity. Inclusion of both biological traits and sampling along a depth gradient in existing and in future monitoring programmes could improve significantly the ability to detect and predict effects of altered patterns of WLF on lake ecosystems.

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Section: Discussionmentioning

confidence: 99%

Water‐level fluctuations regulate the structure and functioning of natural lakes

2015

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“…Such events are particularly pronounced if the lake additionally experiences short-or long-term lake water-level fluctuations (Coops et al 2003;Hofmann et al 2008). …”

Section: Discussionmentioning

confidence: 99%

Effects of ice cover on sediment resuspension and phosphorus entrainment in shallow lakes: Combining in situ experiments and wind‐wave modeling

Kleeberg

Freidank

Joehnk

2013

Limnology & Oceanography

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In situ experiments on sediment resuspension were carried out along a depth transect in shallow polytrophic Lake Langer See, northeast Germany (area 5 1.27 km 2 , Z max 5 3.8 m), in winter under ice and in summer 2006, using a hydrodynamically calibrated erosion chamber (diameter 20 cm). Shear velocity U * was incrementally increased 11 times for 10 min each (0-2.57 cm s 21 ) to initiate resuspension. Entrainment rates (E) of suspended particulate matter (E SPM ) and total P (E TP ) were determined by a mass balance. Sandy nearshore sediments at 1-2 m depth showed low E SPM (0.01-6.64 g m 22 h 21 ) and E TP (0.2-2.96 mg m 22 h 21 ). There was no difference in critical shear velocity (U * crit ) of incipient resuspension between winter and summer. Muddy offshore sediments at 2-3.8 m depth showed higher E SPM (0.09-106.1 g m 22 h 21 ) and E TP (0.06-532.3 mg m 22 h 21 ). Under ice, U * crit was 0.9-1.1 cm s 21 higher than in summer, indicating that the wave-unaffected sediment had ample time for consolidation and biostabilization. Wind-wave modeling, using measured E SPM and E TP , revealed that resuspension is primarily (90%) restricted to the nearshore sediments (17% lake area). Our scenarios show that annual entrainment of SPM and TP increased linearly with the duration of ice-free period. Since ice coverage increased shear resistance, climate-driven absence or shortening of ice-cover would reduce the period for settling of particles and their integration into sediments, lowering their biostabilization, thus facilitating resuspension and phytoplankton recruitment in spring after ice thaw.Shallow lakes, without aquatic macrophytes, often demonstrate enhanced sediment resuspension induced by wind and/or benthic fishes. Particles are resuspended from the bottom if a critical shear stress of erosion is exceeded, leading to sediment-related water quality problems such as reduced water clarity, enhanced nutrient cycling, and high phytoplankton biomass (Bloesch 1995).Due to wind-driven resuspension, considerable quantities of particulate and interstitial phosphorus (P) can be entrained and distributed into the water column. At any given time, this physical upward transport of P may be orders of magnitude greater than other P inputs, from external or internal loading, including diffusion and bioturbation (Havens et al. 2007). However, resuspension may be not only a source (Reddy et al. 1996) but also a sink (Havens et al. 2007), or has no effect on water column P concentration (Peters and Cattaneo 1984). Hence, resuspension needs to be studied, particularly in lakes subject to wind and associated wave-current interactions with the lake bed.Because of its growth-stimulating effect on phytoplankton, P resuspension in shallow lakes was quantified by quite different approaches. There are numerous whole lake studies (Istvá novics et al. 2004;Havens et al. 2007), enclosure experiments (Ogilvie and Mitchell 1998), combinations of in situ and laboratory experiments (Qin et al. 2004), and exclusively laboratory experime...

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“…In lakes for example, water level changes are often caused by changes in the inflow of rivers on a timescale of days to weeks (Hofmann et al, 2008b;Jöhnk et al, 2004;Wilcox et al, 2007). In large lakes that have sufficient fetch length for wind energy input, seiches and propagating surface waves can generate short-term pressure fluctuations (Hamblin and Hollan, 1978).…”

Section: Timescale Of Forcing In Other Aquatic Systemsmentioning

confidence: 99%

Pumping methane out of aquatic sediments – ebullition forcing mechanisms in an impounded river

2014

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Abstract. Freshwater systems contribute significantly to the global atmospheric methane budget. A large fraction of the methane emitted from freshwaters is transported via ebullition. However, due to its strong variability in space and time, accurate measurements of ebullition rates are difficult; hence, the uncertainty regarding its contribution to global budgets is large. Here, we analyze measurements made by continuously recording automated bubble traps in an impounded river in central Europe and investigate the mechanisms affecting the temporal dynamics of bubble release from cohesive sediments. Our results show that the main triggers of bubble release were pressure changes, originating from the passage of ship lock-induced surges and ship passages. The response to physical forcing was also affected by previous outgassing. Ebullition rates varied strongly over all relevant timescales from minutes to days; therefore, representative ebullition estimates could only be inferred with continuous sampling over long periods. Since ebullition was found to be episodic, short-term measurement periods of a few hours or days will likely underestimate ebullition rates. Our results thus indicate that flux estimates could be grossly underestimated (by up to~50%) if the correct temporal resolution is not used during data collection.

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Temporal scales of water-level fluctuations in lakes and their ecological implications

Cited by 108 publications

References 44 publications

Water‐level fluctuations regulate the structure and functioning of natural lakes

Water‐level fluctuations regulate the structure and functioning of natural lakes

Effects of ice cover on sediment resuspension and phosphorus entrainment in shallow lakes: Combining in situ experiments and wind‐wave modeling

Pumping methane out of aquatic sediments – ebullition forcing mechanisms in an impounded river

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