Loosdrecht Lakes, origin, eutrophication, restoration and research programme

Liere, Louis Van

doi:10.1007/bf02291146

Cited by 46 publications

(22 citation statements)

References 6 publications

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“…1A) is situated 20 km south-east of Amsterdam, The Netherlands. The lakes originated because of peat dredging, and erosion by wind and wave action ( VAN LIERE, 1966). The site of the present study was the main lake (A -----9.8 kin2; ~-= 1.9 m) -the Loosdrecht Lakes proper-formerly consisting of five lakes, now partly separated by islands.…”

Section: Introductionmentioning

confidence: 99%

Effects of wind on a shallow lake ecosystem: Resuspension of particles in the Loosdrecht Lakes

Gons¹,

Veeningen²,

Keulen³

1986

Hydrobiological Bulletin

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Horizontal variation of seston concentration in the shallow, eutrophic Loosdrecht Lakes (A = 9.8 km2; ~" =1.9 m) was studied in relation to windspeed and effective fetch. Simple wave theory was applied in order to predict resuspension using wind data from a nearby meteorological station. Most results were consistent with the theory, but a clear limit for the occurrence of resuspension could not be established. Generally, changes in epipelon -the particles at the sediment-water interface -were not directly related to computed frequency of resuspension at the sampling station. The frequency was estimated for 37 grid points over the entire lake. Resuspension was computed to affect high Percentages of the lake area in winter. In summer the frequency was much lower, but in June and July 1984 there were days with nearly 50 % of the lake area subject to resuspension. The resulting input of particulate organic carbon into the water column during these days was estimated to equal 12-25 times the daytime phytoplankton carbon fixation. Most of the resuspended matter appeared to be redeposited rapidly. The computed frequency of resuspension for the 37 locations of the lake varied between 7 and 48 days in 1984.

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Section: Introductionmentioning

confidence: 99%

Effects of wind on a shallow lake ecosystem: Resuspension of particles in the Loosdrecht Lakes

Gons¹,

Veeningen²,

Keulen³

1986

Hydrobiological Bulletin

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“…Until recently eutrophication problems were being primarily tackled by reducing external nutrient loading (Hosper & Meijer, 1986;Van Liere, 1986). Improvement of water quality, however, seems to be retarded by the present structure of the food chain, i.e.…”

Section: Introductionmentioning

confidence: 99%

Whole-lake food-web manipulation as a means to study community interactions in a small ecosystem

Donk¹,

Grimm²,

Gulati³

et al. 1990

Hydrobiologia

104

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Whole-lake food-web manipulation was carried out in the hypertrophic Lake Zwemlust (The Netherlands), with the aim of studying the effects on the lake's trophic status and to gain an insight into complex interactions among lake communities. Before manipulation this small (1.5 ha) and shallow (1.5 m) lake was characterized by Microcystis blooms in summer and high chlorophyll-a concentrations were common (ca. 250/~g 1-1). In March 1987 the planktivorous and benthivorous fish species in the lake were completely removed (ca. 1000 kg ha-1 ), a new simple fish community (pike and rudd) was introduced and artificial refuges were created. The effects of this manipulation on the light climate, nutrient concentrations, phytoplankton, zooplankton, fish, macrophytes, and macrofauna were monitored during 1987, 1988 and 1989. Community interactions were investigated in phytoplankton bioassays and zooplankton grazing experiments. After the manipulation, despite the still high P and N loads to the lake (ca. 2.2 g P m 2 y -l and ca. 5.3 g N m -2 y ~ ), the phytoplankton density was low (Chl-a < 5 lug 1-~), due to control by large-sized zooplankton in spring and N-limitation in summer and autunm. A marked increase in the abundance ofmacrophytes and filamentous green algae in 1988 and 1989, as well as N loss due to denitrification, contributed to the N limitation of the phytoplankton. Before manipulation no submerged macro-vegetation was present but in 1988, the second year after manipulation, about 50~ of the lake bottom was covered by macrophytes increasing to 80~0 in 1989. This led to substantial accumulation of both N and P, namely 76~o and 73~o respectively of the total nutrients in the lake in particulate matter. Undesirable features of the increase in macrophytes were: 1)direct nuisance to swimmers; and, 2) the large scale development of snails, especially L. peregra, which may harbour the parasite causing 'swimmers' itch'. But harvesting of only about 3 ~o of the total macrophyte biomass from the swimmers' area, twice a year, reduced the nuisance for swimmers without adversely affecting the water clarity. 276

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“…The biological consequences in the Rhine delta range from an increased phytoplankton production and incidence of flagellate blooms in coastal waters (CADEE and HEGEMAN, 1986) to an overall degradation of biologically diversb freshwater systems and to uniformly turbid waters, dominated by cyanobacteria (cf. VAN LIERE, 1986).…”

Section: Introductionmentioning

confidence: 95%

Impact of eutrophication on the silicate cycle of man-made basins in the Rhine delta

Admiraal¹,

Vlugt²

1990

Hydrobiological Bulletin

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The impact of eutrophication on the biogeochemical cycle of silicate in the Rhine delta was analysed by 1) comparing the seasonal variation in river water, stagnant fresh water and coastal seawater and 2) observations in well-controlled experimeneral reservoirs subjected to different regimes of phosphate precipitation. The high input of dissolved silicate from Rhine water was rapidly depleted in receiving water systems through vigorous phytoplankton (diatom) growth. In reservoirs ca. 50% of the silicate input was retained over a seven years' observation period. Regeneration of silicate immobilized by diatoms was accelerated by very dense blooms of phytoplankton in reservoirs and in Lake IJssel that increased the pH value over 9.The prevailing low ratios of Si/N and Si/P in Rhine water entail the risk of massive blooms of flagellates or cyanobacteria in receiving waters. The 50% reduction in nitrogen and phosphate emission agreed upon in the Rhine Action Plan may reduce but not eliminate this risk.

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Loosdrecht Lakes, origin, eutrophication, restoration and research programme

Abstract: The Loosdrecht Lakes area is briefly described, light has been shed on its morphology, history, the process of eutrophication with its concomitant phenomena, as well as the planned restoration and research programme.

Cited by 46 publications

References 6 publications

Effects of wind on a shallow lake ecosystem: Resuspension of particles in the Loosdrecht Lakes

Effects of wind on a shallow lake ecosystem: Resuspension of particles in the Loosdrecht Lakes

Whole-lake food-web manipulation as a means to study community interactions in a small ecosystem

Impact of eutrophication on the silicate cycle of man-made basins in the Rhine delta

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