@misc{NixdorfRueckerDolmanetal., author = {Nixdorf, Brigitte and R{\"u}cker, Jacqueline and Dolman, Andrew M. and Wiedner, Claudia and Hilt, Sabine and Kasprzak, Peter and K{\"o}hler, Antje and Weyer, Klaus van de and Sandrock, Stephan and Scharf, Eva-Maria and Willmitzer, Hartmut}, title = {Prozessverst{\"a}ndnis als Grundlage f{\"u}r die Gew{\"a}sserbewirtschaftung - Fallbeispiele f{\"u}r Limitation, Konkurrenz, Gew{\"a}sserstruktur und Nahrungsnetzsteuerung}, series = {Korrespondenz Wasserwirtschaft}, volume = {6}, journal = {Korrespondenz Wasserwirtschaft}, number = {12}, issn = {1865-9926}, pages = {693 -- 701}, language = {de} } @misc{SachsePetzoldtBlumstocketal., author = {Sachse, Ren{\´e} and Petzoldt, Thomas and Blumstock, Maria and Moreira, Santiago and P{\"a}tzig, Marlene and R{\"u}cker, Jacqueline and Janse, Jan H. and Mooij, Wolf M. and Hilt, Sabine}, title = {Extending one-dimensional models for deep lakes to simulate the impact of submerged macrophytes on water quality}, series = {Environmental Modelling \& Software}, volume = {61}, journal = {Environmental Modelling \& Software}, issn = {1364-8152}, doi = {10.1016/j.envsoft.2014.05.023}, pages = {410 -- 423}, language = {en} } @misc{HiltHenschkeRueckeretal., author = {Hilt, Sabine and Henschke, Ingo and R{\"u}cker, Jacqueline and Nixdorf, Brigitte}, title = {Can submerged macrophytes influence turbidity and trophic state in deep lakes? Suggestions from a case study}, series = {Journal of Environmental Quality}, volume = {39}, journal = {Journal of Environmental Quality}, number = {2}, issn = {0047-2425}, doi = {10.2134/jeq2009.0122}, pages = {725 -- 733}, language = {en} } @misc{HiltAliranguesNunezBakkeretal., author = {Hilt, Sabine and Alirangues Nu{\~n}ez, Marta M. and Bakker, Elisabeth S. and Blindow, Irmgard and Davidson, Thomas A. and Gillefalk, Mikael and Hansson, Lars-Anders and Janse, Jan H. and Janssen, Annette B. G. and Jeppesen, Erik and Kabus, Timm-Alexander and Kelly, Andrea and K{\"o}hler, Jan and Lauridsen, Torben L. and Mooij, Wolf M. and Noordhuis, Ruurd and Phillips, Geoff and R{\"u}cker, Jacqueline and Schuster, Hans-Heinrich and S{\o}ndergaard, Martin and Teurlincx, Sven and Weyer, Klaus van de and Donk, Ellen van and Waterstraat, Arno and Willby, Nigel and Sayer, Carl D.}, title = {Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes}, series = {Frontiers in plant science}, volume = {9}, journal = {Frontiers in plant science}, issn = {1664-462X}, doi = {10.3389/fpls.2018.00194}, pages = {24}, language = {en} } @misc{GonsiorczykHupferHiltetal., author = {Gonsiorczyk, Thomas and Hupfer, Michael and Hilt, Sabine and Gessner, Mark O.}, title = {Rapid eutrophication of a clearwater lake : trends and potential causes inferred from phosphorus mass balance analyses}, series = {Global change biology}, volume = {30}, journal = {Global change biology}, number = {11}, publisher = {Wiley}, address = {Hoboken}, issn = {1354-1013}, doi = {10.1111/gcb.17575}, pages = {1 -- 15}, abstract = {Many clearwater lakes increasingly show symptoms of eutrophication, but the underlying causes are largely unknown. We combined long-term water chemistry data, multi-year sediment trap measurements, sediment analyses and simple mass balance models to elucidate potential causes of eutrophication of a deep temperate clearwater lake, where total phosphorus (TP) concentrations quadrupled within a decade, accompanied by expanding hypolimnetic anoxia. Discrepancies between modeled and empirically determined P inputs suggest that the observed sharp rise in TP was driven by internal processes. The magnitude of seasonal variation in TP greatly increased at the same time, both in surface and deep water, partly decoupled from deep water oxygen conditions. A positive correlation between annual P loss from the upper water column and hypolimnetic P accumulation could hint at a short-circuited P cycle involving lateral TP transport from shallow-water zones and deposition and release from sediments in deep water. This hypothesis is also supported by P budgets for the upper 20 m during stable summer stratification, suggesting that sediments in shallow lake areas acted as a P net source until 2018. These changes are potentially related to shifts in submerged macrophytes from wintergreen charophyte meadows ( Nitellopsis obtusa ) to annual free-floating hornwort ( Ceratophyllum demersum ) and to increased sulfide formation, promoting iron fixation in the sediments. Iron bound to sulfur is unavailable for binding P, resulting in a positive feedback between P release in shallow lake areas, primary productivity, macrophyte community structure and redox-dependent sediment biogeochemistry. Overall, our results suggest that relationships more complex than the commonly invoked increase in internal P release under increasingly anoxic conditions can drive rapid lake eutrophication. Since the proportion of littoral areas is typically large even in deep stratified lakes, littoral processes may contribute more frequently to the rapid lake eutrophication trends observed around the world than is currently recognized.}, language = {en} } @misc{HiltvandeWeyerMeisetal., author = {Hilt, Sabine and van de Weyer, Klaus and Meis, Sebastian and P{\"a}zolt, Jens and Gessner, Mark O. and Gonsiorczyk, Thomas and Alirangues-Nu{\~n}ez, Marta Maria and Hupfer, Michael}, title = {Facilitation of lake eutrophication by altered feedback loops between submerged macrophyte vegetation and phosphorus retention}, series = {Freshwater biology}, volume = {70}, journal = {Freshwater biology}, number = {5}, publisher = {Wiley}, address = {Oxford}, issn = {0046-5070}, doi = {10.1111/fwb.70051}, pages = {1 -- 11}, abstract = {Charophytes (stoneworts) often dominate the submerged vegetation in nutrient-poor hardwater lakes, where they support high benthic phosphorus (P) retention. As a consequence, epilimnion P concentrations remain low and water clarity high, resulting in a positive feedback. When perennial charophytes, retaining P all year round, are replaced by vascular macrophytes, P is retained only during summer but rapidly released during decomposition in the autumn and winter. Epilimnion P thus becomes available to phytoplankton in the following growing season, reducing lake water clarity and further shifting plant dominance from bottom-dwelling charophytes to taller vascular species. We tested the hypothesis that changes in lake P concentrations may be partly related to changes in the structure of submerged macrophytes in a deep hardwater lake that experienced a dramatic increase in total P (TP) concentrations over a decade with no evidence of changes in external P loading. We repeatedly measured water transparency, macrophyte maximum colonisation depth (MCD) and abundance between 2008 and 2022 and determined macrophyte tissue P content in 2020 to test whether changes in submerged vegetation could explain gaps in the lake's P budget and shifts in P sink/source functions of littoral areas. In 2008, charophyte communities were dominated by wintergreen Nitellopsis obtusa . The subsequent decline of the species was negatively correlated with the spring TP concentration in the upper water layer (0-20 m) of the lake and positively correlated with Secchi depth and macrophyte MCD, which decreased from 13.5 to 9.5 m. In contrast, the cover of annual vascular macrophytes (mainly rootless hornwort, Ceratophyllum demersum ) increased and was positively correlated with P losses from the upper water layer in summer and negatively correlated with Secchi depth and MCD. Budget calculations showed that the littoral zone was a P source during the period when N. obtusa declined. Despite the relatively low contribution of P directly released from lost charophyte biomass, declines of N. obtusa partly explained the temporary P source function of the littoral zone and the increasing P concentrations in the upper water layer at the beginning of May. This was most probably due to the positive effects of charophytes on particle retention and the negative effects on sediment resuspension. Conversely, the growth of C. demersum can explain P losses from the upper water layer, turning the littoral zone into a temporal P sink during summer. However, most of this P is likely to return to the upper water layer during the decomposition of plant biomass after the growing season. In conclusion, our data indicate that replacement of charophytes by submerged vascular plants can facilitate rapid lake eutrophication due to changes in the feedback loop between submerged vegetation, benthic P retention, epilimnion P availability, water transparency, and MCD.}, language = {en} }