The Contribution of Marsh Zones to Water Quality in Dutch Shallow Lakes: A Modeling Study

Abstract

Many lakes have experienced a transition from a clear into a turbid state without macrophyte growth due to eutrophication. There are several measures by which nitrogen (N) and phosphorus (P) concentrations in the surface water can be reduced. We used the shallow lake model PCLake to evaluate the effects of three measures (reducing external nutrient loading, increasing relative marsh area, and increasing exchange rate between open water and marsh) on water quality improvement. Furthermore, the contribution of different retention processes was calculated. Settling and burial contributed more to nutrient retention than denitrification. The model runs for a typical shallow lake in The Netherlands showed that after increasing relative marsh area to 50%, total phosphorous (TP) concentration in the surface water was lower than the Maximum Admissible Risk (MAR, a Dutch government water quality standard) level, in contrast to total nitrogen (TN) concentration. The MAR levels could also be achieved by reducing N and P load. However, reduction of nutrient concentrations to MAR levels did not result in a clear lake state with submerged vegetation. Only a combination of a more drastic reduction of the present nutrient loading, in combination with a relatively large marsh cover (approximately 50%) would lead to such a clear state. We therefore concluded that littoral marsh areas can make a small but significant contribution to lake recovery.

How to combat cyanobacterial blooms: strategy toward preventive lake restoration and reactive control measures

“…Deep lakes are similar to shallow lakes at low and high nutrient loading in terms of planktonic biomass dominance. The influence of fish and macrophytes, though, might be very limited if the littoral zones are marginal compared to the epilimnetic volume of water in the pelagic zone (Jeppesen et al 1997;Sollie et al 2008). This minor influence of the littoral food web is the main reason why hardly any nutrient-related hysteresis effects are observed in many deep lakes (Scheffer 2001;Sachse et al 2014).…”

The ecology of ditches : a modeling perspective

“…In addition to reporting on the published and unpublished analyses (Table 5.3) -where the figures show only analyses resulting from DATM-implementations -we point to powerful framework tools that come within reach through using DATM. Janse et al (2001), 18 Witteveen + Bos (2008a), 19 Witteveen + Bos (2008b), 20 Witteveen + Bos (2009), 21 Witteveen + Bos (2010a), 22 Witteveen + Bos (2010b), 23 Janse and van Puijenbroek (1998), 24 Sollie et al (2008), 25 Witteveen + Bos (2013a), 26 Witteveen + Bos (2013b), 27 Witteveen + Bos (2013c) , 28 Broers (2012) …”

Making eco logic and models work : an integrative approach to lake ecosystem modelling

“…Besides inducing the above mentioned changes in external forcings and the food web, humans tend to alter the physical characteristics of lakes: surrounding marsh areas are converted into agricultural land, natural banks are turned into steep concrete banks and the water table is regulated by dams and wires for e.g. water storage or flood control Sollie et al, 2008). These modifications may corrode the resilience of the system to withstand and recover from stress .…”

“…For example, Janse et al (2008) used the model to study how general lake features, such as depth, fetch and sediment type determine the resilience of shallow lakes. Likewise, PCLake has been used to evaluate the importance of rising temperatures (Mooij et al, 2009(Mooij et al, , 2007 littoral-pelagic coupling (Sollie et al, 2008), allochthones carbon , tube-dwelling invertebrates (Holker et al 2015) and herbivory by birds . Summarizing, it may be concluded that PCLake embodies the right order of complexity: simple enough to maintain a connection with ecological theory and sufficiently complex to link up with the daily practice of ecosystem managers.…”

“…The apparent success of the model has attracted many new users, and since its development in the early eighties of the past century, the model has been applied in a much wider context than the eutrophication studies for which the model was originally developed and calibrated. These applications include studies on climate change (Mooij et al, 2007;Nielsen et al, 2014), the impact of marsh zones (Sollie et al 2008), water level fluctuations and the impact of allochthonous carbon inputs to lakes . Moreover, the model was used in studies that zoom in on a specific component of or process in the ecosystem, such the effect of herbivory .…”