Dutch Inland Waters Research Articles

Field sensitivity distribution of macroinvertebrates for phosphorus in inland waters

The magnitude of ecological damage caused by elevated phosphorus concentrations (C(P) ) in Dutch inland waters is expressed as the fraction of disappeared macroinvertebrate genera. We used field observations of species occurrence from 1980 to 2005 that were stored in the Limnodata Neerlandica to derive the presence of 867 aquatic macroinvertebrate genera in the water column of freshwater bodies with total phosphorus (P(tot) ) concentrations ranging from 0.001 to 40 mg/L. At concentrations > 0.3 mg/L, which is considered to cause nutrient enrichment of freshwater bodies, the disappeared fraction (DF) of macroinvertebrate genera can be described as a logistic function of the C(P) : DF = 1/(1 + 4.07/C( P)¹·¹¹). The logistic function suggests that half of the macroinvertebrate genera that potentially occur in the freshwater column in the Netherlands would disappear at a C(P) = 3.5 mg/L. This field-based effect expression resembles the cumulative sensitivity distribution function for a toxic substance based on the species sensitivity distribution (SSD) concept and exposure data. Whereas an SSD for a toxic chemical is derived from laboratory sensitivity data for a small number of species, our DF is derived from field observations of many macroinvertebrate genera at numerous C(P) levels. By applying this damage function to measured phosphorus in the rivers Rhine, Meuse, and Scheldt, we found that the observed C(P) values in 1975 imply diversity losses of 15% for the Rhine and Meuse, and 20% for the Scheldt. For 2000, the calculated diversity losses are 3% (Rhine), 6% (Meuse), and 9% (Scheldt). The cumulative genera sensitivity distribution function for phosphorus from national freshwater monitoring data can be applied in various environmental screening systems, such as multistress impact assessment of surface waters, and in life cycle impact assessment of products.

Pesticide concentrations in air and precipitation in the Netherlands.

Atmospheric deposition may be an important source of persistent organic compounds (POP) and pesticides for the Dutch coastal and inland waters. Current estimates of the atmospheric input have been made using atmospheric dispersion models. The uncertainty is however large. A project was defined with the aim to assess the input on the basis of measurements. For a period of two years (1999-2001) a monitoring network was operated. At eighteen stations, located across the whole country, air and precipitation samples were taken on a weekly and monthly basis. In these samples the concentrations of pesticides, PCB's and PAH's were determined. Up to 50 different pesticides were observed in precipitation and air. The concentration of 17 of these in precipitation exceeded the maximum permissible level for surface water and 22 exceeded the standard for drinking water of 100 ng l(-1). The input from the atmosphere to Dutch inland waters appeared to be as large as the input of pesticides by other sources such as spray drift. Model calculations were also carried out to identify the sources of these compounds. The occurrence of atrazine could be related to emissions outside the Netherlands.

Optical classification of Dutch inland waters

Optical classification of Dutch inland waters

The attenuation of ultraviolet and visible radiation in Dutch inland waters

The vertical attenuation coefficients (Kd) of downward ultraviolet (UV) and visible irradiance (PAR) were measured in 19 different inland waters in the Netherlands using a scanning spectroradiometer. Water chemistry variables such as dissolved organic carbon (DOC), absorbance of dissolved matter (ad), chlorophyll-a, and particulate matter were measured to determine the relative contribution of dissolved and particulate components in explaining the variation in Kd. In addition to the field measurements, laboratory measurements were performed to test the relationships between water properties and light attenuation. The attenuation properties of Dutch inland waters vary. In most systems the penetration of UV-B radiation (280–320 nm) is limited to the upper decimetres. Lake Maarsseveen was the clearest waterbody in this study, with KdUVB of 9.1 (m−1). The DOC concentration had limited power in predicting UV attenuation in this study (r2=0.33), because of the large differences in carbon-specific absorption. Ad300 was a much better predictor of UV attenuation (r2=0.75). The relationships obtained in the laboratory experiments can be used to give a good prediction of in situKd values, based on 3 variables (chlorophyll-a, ash weight, and absorption of dissolved matter).

Ecological objectives for management purposes: applying the Amoeba approach

Dutch integral water management aims to restore and maintain healthy aquatic ecosystems, which can sustain most human uses. Clear ecological objectives are necessary. Sustainability of fundamental ecological values (production and yield, species diversity, and self-regulation) is assumed to be best preserved in the reference situation. This is the situation, in which human influence is minimal. A general method to present ecological information, the Amoeba approach is discussed. This approach uses selected species as representatives for the ecosystem. Criteria for the selection of species are discussed. For each species (target variable) the current situation, the reference situation, and estimated effects of measures can be found and plotted in an amoeba-like figure. The presentation is a simplification and is therefore easily understood by managers, politicians, and the public. It's application for some Dutch inland waters is discussed.

Drastic changes in the amphipod fauna (Crustacea) of Dutch inland waters during the last 25 years

After the introduction of Gammarus tigrinus in The Netherlands some 25 years ago and of other recently invading amphipods (Crangonyx pseudogracilis and Corophium curvispinum) the native species decreased, the invaders increased. The success of these invaders and its impact on the local amphipod fauna is discussed. Electrophoretic tests give evidence that a second invasion of Gammarus tigrinus, this time from Germany, is taking place. Some predictions about future developments are made.

Ecological assessment of Dutch inland waters: Philosophy and preliminary results

(1991). Ecological assessment of Dutch inland waters: Philosophy and preliminary results. SIL Proceedings, 1922-2010: Vol. 24, No. 4, pp. 2104-2106.

PCDDs and PCDFs in Dutch inland waters

The occurence of PCDDs and PCDFs in selected relevant waste-water discharges and sediments in the Dutch aquatic environment was investigated. The load of PCDDs and PCDFs to the aquatic environment via the studied waste-water discharges appeared to be of minor importance compared to other (diffusive) sources. PCDDs and PCDFs commonly occured in sediments at 0.01 to 0.10 ng/g levels. Two sediments had a concentration over 1 ng/g. Further research on the degree and extent of the contamination of these two sediments is carried out. In general the contamination of sediments is related to diffusive sources and the border crossing loads of the rivers Rhine and Meuse.

Factors Affecting the Migration of the Silver Eel in Dutch Inland Waters

Factors Affecting the Migration of the Silver Eel in Dutch Inland Waters