Acid rain is one of the most imporEanE threats to the environment. The flrst ecological responses... more Acid rain is one of the most imporEanE threats to the environment. The flrst ecological responses \íere seen in Ehe early seventies in the very sensitive, poorly buffered, lakes of Scandinavia, although t.he at.mospheric deposition in Ehat. area is much less than in The NeEherlands. The results of the first invesEigations of the present author on Ehe impact of acid rain on poorly buffered vrat.ers, malnly moorland pools, in The Netherlands, demonstraEed thaE Èhese oligotrophic water bodies, wit.h a highly characteristic flora and fauna, were much more affected by acidification than Ehe Scandinavian lakes. Therefore, regular moniËoring of chemistry and diatoms in some moorland pools started in 1979. DiaÈoms were chosen as biological lndicators because they are very sensitive to changes in acidity and because a unique set of old samples, which could serve as a frame of reference, $ras avallable. The inÈernat.lonal value of Chis project was recognized by the European Comrunity, thaE funded a part of the research act.ivities. ïhis document is noE only a report of Ehe research acÈivities of the aut.hor, buË summarizes all the available knowledge on management, physiography, chemistry, and bot.any of Ehe study sltes. ïherefore, it is a base-line study for forthcorning monit.oring and modelling studies on Èhe inpact of acid precipitat,ion in shallow freshwater bodies.
Changes in chemistry, particularly pH, of a number of soft-water moorland pools in The Netherland... more Changes in chemistry, particularly pH, of a number of soft-water moorland pools in The Netherlands are described. Several groups of organisms, including diatoms, and direct measurements are used to infer past pH values. Diatoms were studied from preserved samples from the beginning of the 20th century, from recent samples and from sediment cores. Old data about chemistry, macrophytes and human impact were obtained from published and unpublished documents.In isolated pools in nature reserves the pH declined to c. 4 from initial values between 4 and 6 at the beginning of this century. Small inputs of nutrients by agriculture, fisheries or swimming retards acidification. The diversity and dissimilarity of diatom assemblages decrease by acidification, particularly in clear water pools. Acidification boosts the growth of the diatom Eunotia exigua .Sulphate concentrations were extremely high in 1977 and 1978 in two clear water pools where more than half of the bottom surface was exposed t...
kan leiden tot meer invloed van regionaal grondwater. Een goede monitoring van de buffercapacitei... more kan leiden tot meer invloed van regionaal grondwater. Een goede monitoring van de buffercapaciteit van ven-en grondwater (peilbuizen) is hier essentieel. Opnieuw oppompen van grondwater is een laatste redmiddel om te sterke verzuring te voorkomen. Eventueel kan het grondwater niet direct in het ven worden geleid, maar worden gebruikt om het inzijggebied te bevloeien, zodat de kwelstromen naar het ven minder zuur worden. Er lijken voldoende mogelijkheden aanwezig om de levensgemeenschap van zwak gebufferde vennen hier over grote oppervlakten verder te herstellen. Literatuur
ABSTRACT Luticola higleri nov. sp. is described from the Antarctic King George Island (South Shet... more ABSTRACT Luticola higleri nov. sp. is described from the Antarctic King George Island (South Shetland Islands). The detailed morphology of this taxon is examined using both light and scanning electron microscopy and compared with similar species. The main morphological features include the presence of a distinct number of poroid rows, the relatively simple raphe structure and the small stigma. This new taxon is so far only recorded from samples taken from both mosses and mud pools, near the Bellingshausen area on King George Island. Based on its typical features, the species clearly belongs to the genus Luticola although several characters might point to an intermediate or transitional position between Luticola and Diadesmis.
Obligate symbioses between specialized arboreal ants and plants have evolved independently in man... more Obligate symbioses between specialized arboreal ants and plants have evolved independently in many lineages 1,2. Ant-plants (myrmecophytes) typically provide hollow nest cavities and nutrition
SUMMARY1. Samples for the analysis of attached diatoms and surface water chemistry were taken at ... more SUMMARY1. Samples for the analysis of attached diatoms and surface water chemistry were taken at thirty‐five stations in sixteen soft‐water streams in the Netherlands during autumn 1990. Most were located in pine forest and heathland catchments, fed by deep groundwater (median residence time 87 years), with no direct influence of agricultural or urban drainage water.2. The chemical data from sixteen stations were compared with data collected in 1974 and 1981. There were no significant increases in pH (6.3 in 1974, 6–4 in 1990) or in sulphate (200 mmol m−3 in 1974, 229 mmol m−3 in 1990). Over the same period nitrate increased significantly from 17 to 158 mmol m−3, while alkalinity decreased significantly from 355 to 251 meq m−3.3. The most important correlates with the distribution of diatoms, as revealed by canonical correspondence analysis, were pH, nitrate, cross‐sectional area of the stream and the Ca/(Ca + Cl) ratio.4. Diatom assemblages of upstream stations indicated more acid ...
No part of this publication, apart from bibliographic data and brief quotations embodied in criti... more No part of this publication, apart from bibliographic data and brief quotations embodied in critical reviews, may be reproduced, re-recorded or published in any form including print, photocopy, microfilm, electronic or electromagnetic record without written permission from the publisher: Pudoc,
Liming experiments with powdered limestone (grain size < 3 mm) were conducted in eight aci... more Liming experiments with powdered limestone (grain size < 3 mm) were conducted in eight acid shallow moorland pools in the Tongerense Heide heathland area from February 1988 until November 1989. The effects on water chemistry, diatoms and fungal infection of the eggs of the moor frog were studied. After an initial treatment in March 1988, the pH increased from c. 4.0 to c. 5.0 in those pools which dried out in summer and to c. 6.0 in the permanent pools. Alkalinity increased from 0 to 20-200 microeq litre(-1) in temporary pools and from 0 to 300-500 microeq litre(-1) in permanent pools. As drying out of the pools caused reacidification, after refilling the temporary pools were relimed in March 1989. No significant changes were found in concentrations of phosphate and nitrogen compounds. Eunotia paludosa, which is characteristic for ologotrophic, very acid pools and bogs with a fluctuating water table, was the dominant diatom in the untreated pools. It was replaced by eutraphentic and saprophilous taxa, particularly in the permanent pools. Species from extremely soft waters, which are very sensitive to acidification, were found only occasionally in some samples from the treated permanent pools. After liming the proportion of infected moor frog eggs decreased from c. 95% in the untreated to c. 5% in the treated pools.
Diatoms are well-known indicators for acidification and recovery of lakes, as mainly with paleoli... more Diatoms are well-known indicators for acidification and recovery of lakes, as mainly with paleolimnological methods. However, from the last few decades, such studies are scarce, especially in Europe, and there is a poor insight into the interaction between the impact of the recovery from acidification and drought periods on diatoms. The surface water chemistry of Dutch moorland pools has shown strong signs of chemical recovery as a response to declines in sulphur and nitrogen deposition between 1978 and 2018. We expected that changes in water chemistry were associated with changes in diatom assemblages and that the diatom assemblages at the end of the monitoring period would be dissimilar to pre-acidification diatom assemblages due to the changed biogeochemical processes in the pools. To monitor the recovery from acidification, diatoms from plants and surficial sediments were sampled in 11 Dutch moorland pools from 1978 to 2018. As far as we know, this is the longest series of semi-annual diatom records in stagnant shallow waters recovering from acidification. Early 20th-century samples were retrieved from collections. Changes in the diatom assemblages were assessed by analyses of traits (including pH-preference) and ecological groups. Direct correspondence analysis revealed high correlations between the species composition and environmental variables (pH, sulphate, ammonium, dissolved organic carbon, calcium, and aluminium). Between 1916 and 1978, the greatest species composition changes occurred in pools with relatively flat banks exposed to the air in extremely dry summers. After the dry summer of 1921, the changes were insignificant, but after the extremely dry summer of 1976, the changes were dramatic due to acidification by oxidation of the reduced sulphur and nitrogen compounds stored in the moorland pool bottom. After 1980, the changes were consistent with chemical recovery from acidification. However, there was a significant interaction with climatic factors: drought episodes in the short term and temperature increase in the long term. Some species in the samples from the last decades indicate an acid, but eutrophic environment, due to internal eutrophication. The species composition did not return to the historical composition (1920 s), as the chemical dynamics due to the large stock of sulphur and nitrogen compounds are now entirely different from those a century ago.
Acid rain is one of the most imporEanE threats to the environment. The flrst ecological responses... more Acid rain is one of the most imporEanE threats to the environment. The flrst ecological responses \íere seen in Ehe early seventies in the very sensitive, poorly buffered, lakes of Scandinavia, although t.he at.mospheric deposition in Ehat. area is much less than in The NeEherlands. The results of the first invesEigations of the present author on Ehe impact of acid rain on poorly buffered vrat.ers, malnly moorland pools, in The Netherlands, demonstraEed thaE Èhese oligotrophic water bodies, wit.h a highly characteristic flora and fauna, were much more affected by acidification than Ehe Scandinavian lakes. Therefore, regular moniËoring of chemistry and diatoms in some moorland pools started in 1979. DiaÈoms were chosen as biological lndicators because they are very sensitive to changes in acidity and because a unique set of old samples, which could serve as a frame of reference, $ras avallable. The inÈernat.lonal value of Chis project was recognized by the European Comrunity, thaE funded a part of the research act.ivities. ïhis document is noE only a report of Ehe research acÈivities of the aut.hor, buË summarizes all the available knowledge on management, physiography, chemistry, and bot.any of Ehe study sltes. ïherefore, it is a base-line study for forthcorning monit.oring and modelling studies on Èhe inpact of acid precipitat,ion in shallow freshwater bodies.
Changes in chemistry, particularly pH, of a number of soft-water moorland pools in The Netherland... more Changes in chemistry, particularly pH, of a number of soft-water moorland pools in The Netherlands are described. Several groups of organisms, including diatoms, and direct measurements are used to infer past pH values. Diatoms were studied from preserved samples from the beginning of the 20th century, from recent samples and from sediment cores. Old data about chemistry, macrophytes and human impact were obtained from published and unpublished documents.In isolated pools in nature reserves the pH declined to c. 4 from initial values between 4 and 6 at the beginning of this century. Small inputs of nutrients by agriculture, fisheries or swimming retards acidification. The diversity and dissimilarity of diatom assemblages decrease by acidification, particularly in clear water pools. Acidification boosts the growth of the diatom Eunotia exigua .Sulphate concentrations were extremely high in 1977 and 1978 in two clear water pools where more than half of the bottom surface was exposed t...
kan leiden tot meer invloed van regionaal grondwater. Een goede monitoring van de buffercapacitei... more kan leiden tot meer invloed van regionaal grondwater. Een goede monitoring van de buffercapaciteit van ven-en grondwater (peilbuizen) is hier essentieel. Opnieuw oppompen van grondwater is een laatste redmiddel om te sterke verzuring te voorkomen. Eventueel kan het grondwater niet direct in het ven worden geleid, maar worden gebruikt om het inzijggebied te bevloeien, zodat de kwelstromen naar het ven minder zuur worden. Er lijken voldoende mogelijkheden aanwezig om de levensgemeenschap van zwak gebufferde vennen hier over grote oppervlakten verder te herstellen. Literatuur
ABSTRACT Luticola higleri nov. sp. is described from the Antarctic King George Island (South Shet... more ABSTRACT Luticola higleri nov. sp. is described from the Antarctic King George Island (South Shetland Islands). The detailed morphology of this taxon is examined using both light and scanning electron microscopy and compared with similar species. The main morphological features include the presence of a distinct number of poroid rows, the relatively simple raphe structure and the small stigma. This new taxon is so far only recorded from samples taken from both mosses and mud pools, near the Bellingshausen area on King George Island. Based on its typical features, the species clearly belongs to the genus Luticola although several characters might point to an intermediate or transitional position between Luticola and Diadesmis.
Obligate symbioses between specialized arboreal ants and plants have evolved independently in man... more Obligate symbioses between specialized arboreal ants and plants have evolved independently in many lineages 1,2. Ant-plants (myrmecophytes) typically provide hollow nest cavities and nutrition
SUMMARY1. Samples for the analysis of attached diatoms and surface water chemistry were taken at ... more SUMMARY1. Samples for the analysis of attached diatoms and surface water chemistry were taken at thirty‐five stations in sixteen soft‐water streams in the Netherlands during autumn 1990. Most were located in pine forest and heathland catchments, fed by deep groundwater (median residence time 87 years), with no direct influence of agricultural or urban drainage water.2. The chemical data from sixteen stations were compared with data collected in 1974 and 1981. There were no significant increases in pH (6.3 in 1974, 6–4 in 1990) or in sulphate (200 mmol m−3 in 1974, 229 mmol m−3 in 1990). Over the same period nitrate increased significantly from 17 to 158 mmol m−3, while alkalinity decreased significantly from 355 to 251 meq m−3.3. The most important correlates with the distribution of diatoms, as revealed by canonical correspondence analysis, were pH, nitrate, cross‐sectional area of the stream and the Ca/(Ca + Cl) ratio.4. Diatom assemblages of upstream stations indicated more acid ...
No part of this publication, apart from bibliographic data and brief quotations embodied in criti... more No part of this publication, apart from bibliographic data and brief quotations embodied in critical reviews, may be reproduced, re-recorded or published in any form including print, photocopy, microfilm, electronic or electromagnetic record without written permission from the publisher: Pudoc,
Liming experiments with powdered limestone (grain size < 3 mm) were conducted in eight aci... more Liming experiments with powdered limestone (grain size < 3 mm) were conducted in eight acid shallow moorland pools in the Tongerense Heide heathland area from February 1988 until November 1989. The effects on water chemistry, diatoms and fungal infection of the eggs of the moor frog were studied. After an initial treatment in March 1988, the pH increased from c. 4.0 to c. 5.0 in those pools which dried out in summer and to c. 6.0 in the permanent pools. Alkalinity increased from 0 to 20-200 microeq litre(-1) in temporary pools and from 0 to 300-500 microeq litre(-1) in permanent pools. As drying out of the pools caused reacidification, after refilling the temporary pools were relimed in March 1989. No significant changes were found in concentrations of phosphate and nitrogen compounds. Eunotia paludosa, which is characteristic for ologotrophic, very acid pools and bogs with a fluctuating water table, was the dominant diatom in the untreated pools. It was replaced by eutraphentic and saprophilous taxa, particularly in the permanent pools. Species from extremely soft waters, which are very sensitive to acidification, were found only occasionally in some samples from the treated permanent pools. After liming the proportion of infected moor frog eggs decreased from c. 95% in the untreated to c. 5% in the treated pools.
Diatoms are well-known indicators for acidification and recovery of lakes, as mainly with paleoli... more Diatoms are well-known indicators for acidification and recovery of lakes, as mainly with paleolimnological methods. However, from the last few decades, such studies are scarce, especially in Europe, and there is a poor insight into the interaction between the impact of the recovery from acidification and drought periods on diatoms. The surface water chemistry of Dutch moorland pools has shown strong signs of chemical recovery as a response to declines in sulphur and nitrogen deposition between 1978 and 2018. We expected that changes in water chemistry were associated with changes in diatom assemblages and that the diatom assemblages at the end of the monitoring period would be dissimilar to pre-acidification diatom assemblages due to the changed biogeochemical processes in the pools. To monitor the recovery from acidification, diatoms from plants and surficial sediments were sampled in 11 Dutch moorland pools from 1978 to 2018. As far as we know, this is the longest series of semi-annual diatom records in stagnant shallow waters recovering from acidification. Early 20th-century samples were retrieved from collections. Changes in the diatom assemblages were assessed by analyses of traits (including pH-preference) and ecological groups. Direct correspondence analysis revealed high correlations between the species composition and environmental variables (pH, sulphate, ammonium, dissolved organic carbon, calcium, and aluminium). Between 1916 and 1978, the greatest species composition changes occurred in pools with relatively flat banks exposed to the air in extremely dry summers. After the dry summer of 1921, the changes were insignificant, but after the extremely dry summer of 1976, the changes were dramatic due to acidification by oxidation of the reduced sulphur and nitrogen compounds stored in the moorland pool bottom. After 1980, the changes were consistent with chemical recovery from acidification. However, there was a significant interaction with climatic factors: drought episodes in the short term and temperature increase in the long term. Some species in the samples from the last decades indicate an acid, but eutrophic environment, due to internal eutrophication. The species composition did not return to the historical composition (1920 s), as the chemical dynamics due to the large stock of sulphur and nitrogen compounds are now entirely different from those a century ago.
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