Pub Date : 2006-05-01DOI: 10.1127/0003-9136/2006/0166-0079
H. Fischer, C. Mille-Lindblom, E. Zwirnmann, L. Tranvik
Bacteria and fungi dominate the decomposition of aquatic plants, a major process in the carbon and nutrient cycling in many aquatic systems. Although phylogenetically distant, bacteria and fungi often live in close proximity with each other. Since these microorganisms also have similar ecological functions, interactions have developed between them. This thesis explores the nature of such interactions, and the potential effects on key components of the decomposition process. The thesis includes a critical assessment of the ergosterol method for determination of fungal biomass, a survey of the environmental factors determining the distribution and taxa numbers of litter-decomposing bacteria and fungi in lakes, and a number of experiments on the interactions between bacteria and fungi. In all the experiments performed, fungi responded to bacterial presence through antagonism, although different fungal strains, bacterial communities and substrates were used. The antagonism seemed to be caused by interference competition for substrate. The fungal effect on bacteria was less consistent. Bacterial growth was suppressed, unaffected, or even enhanced by the presence of fungi. Fungi contributed more to extracellular enzyme production than bacteria, and bacteria were probably able to assimilate intermediate decomposition products formed through the activity of extracellular enzymes of fungal origin. Thus, the effect on bacteria from interacting with fungi was determined by the balance between competition and benefit from excreted enzymes. Bacteria and fungi also used different size fractions of the organic matter, according to their different enzymatic capacities. Hence, bacteria appeared to assimilate low-molecular-weight compounds, while high-molecular-weight compounds were utilized primarily by fungi. In brief, the ecological interactions influenced the growth and hence also the biomass development of bacteria and fungi, which affected enzyme activity as well as utilization of dissolved organic matter. Therefore, I suggest that interactions between bacteria and fungi influence degradation of plant litter in aquatic systems.
{"title":"Contribution of fungi and bacteria to the formation of dissolved organic carbon from decaying common reed (Phragmites australis)","authors":"H. Fischer, C. Mille-Lindblom, E. Zwirnmann, L. Tranvik","doi":"10.1127/0003-9136/2006/0166-0079","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0166-0079","url":null,"abstract":"Bacteria and fungi dominate the decomposition of aquatic plants, a major process in the carbon and nutrient cycling in many aquatic systems. Although phylogenetically distant, bacteria and fungi often live in close proximity with each other. Since these microorganisms also have similar ecological functions, interactions have developed between them. This thesis explores the nature of such interactions, and the potential effects on key components of the decomposition process. The thesis includes a critical assessment of the ergosterol method for determination of fungal biomass, a survey of the environmental factors determining the distribution and taxa numbers of litter-decomposing bacteria and fungi in lakes, and a number of experiments on the interactions between bacteria and fungi. In all the experiments performed, fungi responded to bacterial presence through antagonism, although different fungal strains, bacterial communities and substrates were used. The antagonism seemed to be caused by interference competition for substrate. The fungal effect on bacteria was less consistent. Bacterial growth was suppressed, unaffected, or even enhanced by the presence of fungi. Fungi contributed more to extracellular enzyme production than bacteria, and bacteria were probably able to assimilate intermediate decomposition products formed through the activity of extracellular enzymes of fungal origin. Thus, the effect on bacteria from interacting with fungi was determined by the balance between competition and benefit from excreted enzymes. Bacteria and fungi also used different size fractions of the organic matter, according to their different enzymatic capacities. Hence, bacteria appeared to assimilate low-molecular-weight compounds, while high-molecular-weight compounds were utilized primarily by fungi. In brief, the ecological interactions influenced the growth and hence also the biomass development of bacteria and fungi, which affected enzyme activity as well as utilization of dissolved organic matter. Therefore, I suggest that interactions between bacteria and fungi influence degradation of plant litter in aquatic systems.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89523407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-05-01DOI: 10.1127/0003-9136/2006/0166-0001
N. Usio, Kana Suzuki, M. Konishi, S. Nakano
In northern Japan, an alien crayfish species (signal crayfish; Pacifastacus leniusculus) is replacing Japan's only native crayfish species (Cambaroides japonicus) that is endemic to the country. We tested experimentally if these two crayfish species had similar roles in terms of ecosystem functioning in stream habitats. Experiments were performed to examine the impacts of alien and endemic crayfish on detritus-based food webs. During the experiment, neither crayfish species affected rates of breakdown of microbially conditioned oak leaves. In contrast, the amphipod Jesso-gammarus jesoensis, which dominated the non-crayfish invertebrate biomass, was significantly reduced in the presence of the two crayfish species. Thus, effects of crayfish on leaf breakdown were probably masked by the leaf processing activities of these large amphipods in the absence of crayfish. Overall, per-unit biomass impacts of Pacifastacus on leaf processing and invertebrate colonisation of leaves were comparable to those by Cambaroides. Laboratory experiments were performed to test whether rates of leaf processing of 10 riparian plant species, particulate organic matter (POM) production and nutrient excretion differed between crayfish species in the absence of other invertebrates. Although POM production rates did not differ between crayfish species, crayfish impacts on leaf processing differed depending on plant species reflecting differential leaf preference. Comparisons of individual nutrient excretion rates revealed that ammonia and phosphate excretion rates were higher in Cambaroides compared with Pacifastacus. Further, ammonia excretion rates were proportional to crayfish biomass in Cambaroides but not in Pacifastacus. Taken together, the two crayfish species had similar roles in stream food webs when biomass was similar. However, their roles as leaf processors and excretion rates of nutrients differed when there was a choice among different riparian species as sources of leaf litter. Species replacement between alien and endemic crayfish may therefore result in differential consequences for ecosystem processes.
{"title":"Alien vs. endemic crayfish: roles of species identity in ecosystem functioning","authors":"N. Usio, Kana Suzuki, M. Konishi, S. Nakano","doi":"10.1127/0003-9136/2006/0166-0001","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0166-0001","url":null,"abstract":"In northern Japan, an alien crayfish species (signal crayfish; Pacifastacus leniusculus) is replacing Japan's only native crayfish species (Cambaroides japonicus) that is endemic to the country. We tested experimentally if these two crayfish species had similar roles in terms of ecosystem functioning in stream habitats. Experiments were performed to examine the impacts of alien and endemic crayfish on detritus-based food webs. During the experiment, neither crayfish species affected rates of breakdown of microbially conditioned oak leaves. In contrast, the amphipod Jesso-gammarus jesoensis, which dominated the non-crayfish invertebrate biomass, was significantly reduced in the presence of the two crayfish species. Thus, effects of crayfish on leaf breakdown were probably masked by the leaf processing activities of these large amphipods in the absence of crayfish. Overall, per-unit biomass impacts of Pacifastacus on leaf processing and invertebrate colonisation of leaves were comparable to those by Cambaroides. Laboratory experiments were performed to test whether rates of leaf processing of 10 riparian plant species, particulate organic matter (POM) production and nutrient excretion differed between crayfish species in the absence of other invertebrates. Although POM production rates did not differ between crayfish species, crayfish impacts on leaf processing differed depending on plant species reflecting differential leaf preference. Comparisons of individual nutrient excretion rates revealed that ammonia and phosphate excretion rates were higher in Cambaroides compared with Pacifastacus. Further, ammonia excretion rates were proportional to crayfish biomass in Cambaroides but not in Pacifastacus. Taken together, the two crayfish species had similar roles in stream food webs when biomass was similar. However, their roles as leaf processors and excretion rates of nutrients differed when there was a choice among different riparian species as sources of leaf litter. Species replacement between alien and endemic crayfish may therefore result in differential consequences for ecosystem processes.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86243967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-05-01DOI: 10.1127/0003-9136/2006/0166-0041
Bishnu Simkhada, I. Jüttner
Diatoms were examined in twelve ponds and four small lakes of the Kathmandu Valley, Nepal, to assess their biodiversity, response to environmental conditions and potential use as bioindicators for water quality. They were investigated from different substrates and relationships with water chemistry and habitat character were assessed. In total 212 diatom species were found with 98 taxa at relative abundances > 1 %. The most species-rich genera were Navicula (42), Gomphonema (39), Achnanthes sensu lato (27), Nitzschia (27) and Fragilaria sensu lato (20). Species diversity was low (mean 0.95 ± 0.17 sd) and most assemblages were dominated by 1-3 taxa. Thirty percent of the taxa found could not be identified using relevant literature. Species richness, diversity and evenness were not related to water chemistry or habitat character, but varied significantly on different substrate types and were higher in the sediment compared to stones and macrophytes. At five of seven sites, where several substrates were collected, the most abundant species occurred on all substrates. Canonical correspondence analysis (CCA) revealed that changes in species composition were most strongly correlated with gradients in water chemistry. Achnanthidium minutissimum was characteristic at sites with higher Ca concentrations, while Eolimna minima, Nitzschia palea, Nitzschia palea cf. var. debilis and Gomphonema parvulum indicated higher concentrations of K, Cl, Na, As, Ni, Fe and Al. E. minima and N. palea were also typical at sites with higher concentration of SO 4 2- , Sr and Al. Assemblage composition was also significantly correlated with habitat character such as aquatic vegetation, substrate composition, bank character and land use.
在尼泊尔加德满都谷地的12个池塘和4个小湖泊中对硅藻进行了研究，以评估其生物多样性、对环境条件的反应以及作为水质生物指标的潜在用途。在不同基质上对它们进行了研究，并评价了它们与水化学和生境特征的关系。共发现硅藻212种，相对丰度> 1%的有98个分类群。种数最多的属为Navicula(42)、Gomphonema(39)、Achnanthes sensu lato(27)、Nitzschia(27)和Fragilaria sensu lato(20)。物种多样性较低(平均0.95±0.17 sd)，多数类群以1 ~ 3个类群为主。发现的分类群中有30%无法通过相关文献进行识别。物种丰富度、多样性和均匀度与水化学和生境特征无关，但在不同基质类型上差异显著，沉积物中物种丰富度、多样性和均匀度高于石料和大型植物。在收集到几种底物的7个地点中，有5个地点的所有底物上都有最丰富的物种。典型对应分析(Canonical correspondence analysis, CCA)表明，物种组成的变化与水体化学梯度的相关性最强。在Ca浓度较高的生境中，细粒棘球蚴(Achnanthidium mintissimum)表现出较高的特征，而极小依螨(Eolimna)、古尼氏菌(Nitzschia palea)、古尼氏菌(Nitzschia cfr . vars . depais)和小冈蚤(Gomphonema parvulum)表现出较高的K、Cl、Na、As、Ni、Fe和Al浓度，极小E. minima和古棘球蚴(gonphonema parvulum)在so42 -、Sr和Al浓度较高的生境中也表现出典型特征。银行性质及土地用途。
{"title":"Diatoms in ponds and small lakes of the Kathmandu Valley, Nepal – relationships with chemical and habitat characteristics","authors":"Bishnu Simkhada, I. Jüttner","doi":"10.1127/0003-9136/2006/0166-0041","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0166-0041","url":null,"abstract":"Diatoms were examined in twelve ponds and four small lakes of the Kathmandu Valley, Nepal, to assess their biodiversity, response to environmental conditions and potential use as bioindicators for water quality. They were investigated from different substrates and relationships with water chemistry and habitat character were assessed. In total 212 diatom species were found with 98 taxa at relative abundances > 1 %. The most species-rich genera were Navicula (42), Gomphonema (39), Achnanthes sensu lato (27), Nitzschia (27) and Fragilaria sensu lato (20). Species diversity was low (mean 0.95 ± 0.17 sd) and most assemblages were dominated by 1-3 taxa. Thirty percent of the taxa found could not be identified using relevant literature. Species richness, diversity and evenness were not related to water chemistry or habitat character, but varied significantly on different substrate types and were higher in the sediment compared to stones and macrophytes. At five of seven sites, where several substrates were collected, the most abundant species occurred on all substrates. Canonical correspondence analysis (CCA) revealed that changes in species composition were most strongly correlated with gradients in water chemistry. Achnanthidium minutissimum was characteristic at sites with higher Ca concentrations, while Eolimna minima, Nitzschia palea, Nitzschia palea cf. var. debilis and Gomphonema parvulum indicated higher concentrations of K, Cl, Na, As, Ni, Fe and Al. E. minima and N. palea were also typical at sites with higher concentration of SO 4 2- , Sr and Al. Assemblage composition was also significantly correlated with habitat character such as aquatic vegetation, substrate composition, bank character and land use.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76348544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-05-01DOI: 10.1127/0003-9136/2006/0166-0117
A. Steinman, R. Rediske, Rod Denning, L. Nemeth, X. Chu, D. Uzarski, Bopi Biddanda, M. Luttenton
The ecological health and integrity of watersheds throughout the world are being threatened by a variety of stressors. Often, restoration practices focus on single problems whereas comprehensive, multidisciplinary approaches are needed to address both the symptoms and underlying causes of impairment. A comprehensive assess- ment of a small, urbanized watershed in west Michigan, USA was conducted to evalu- ate the major stressors in the system. This assessment approach for the Mona Lake wa- tershed included analyses of land use/land cover change, water quality in both the major surface inflows and the receiving water body, and toxic inputs into a major in- flow. Because these issues are common to many watersheds, we developed a concep- tual model that spatially links these stressors and predicted impacts, allowing us to as- sess them in a comprehensive manner. Based on our results, we generated a set of re- commendations targeted for specific source or problem areas. This approach can be applied to other watersheds.
{"title":"An environmental assessment of an impacted, urbanized watershed: the Mona Lake Watershed, Michigan","authors":"A. Steinman, R. Rediske, Rod Denning, L. Nemeth, X. Chu, D. Uzarski, Bopi Biddanda, M. Luttenton","doi":"10.1127/0003-9136/2006/0166-0117","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0166-0117","url":null,"abstract":"The ecological health and integrity of watersheds throughout the world are being threatened by a variety of stressors. Often, restoration practices focus on single problems whereas comprehensive, multidisciplinary approaches are needed to address both the symptoms and underlying causes of impairment. A comprehensive assess- ment of a small, urbanized watershed in west Michigan, USA was conducted to evalu- ate the major stressors in the system. This assessment approach for the Mona Lake wa- tershed included analyses of land use/land cover change, water quality in both the major surface inflows and the receiving water body, and toxic inputs into a major in- flow. Because these issues are common to many watersheds, we developed a concep- tual model that spatially links these stressors and predicted impacts, allowing us to as- sess them in a comprehensive manner. Based on our results, we generated a set of re- commendations targeted for specific source or problem areas. This approach can be applied to other watersheds.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84101218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-05-01DOI: 10.1127/0003-9136/2006/0166-0099
S. Ormerod, Bethan R. Lewis, Renata A. Kowalik, J. Murphy, J. Davy-Bowker
Using data from 132 acid-sensitive streams in Wales and Scotland from two available data sets, we tested a recently proposed indicator system that uses aquatic invertebrates to detect acidification in British rivers, the Acid Water Indicator Community (AWIC). Although many sites held less than a quarter of AWIC scoring taxa, index values at sites in both data sets correlated significantly with acid-base variables including pH, calcium concentration, alkalinity and dissolved aluminium. Relationships with acid-base status during acid episodes were particularly strong in the more comprehensive test set. Strong correlations between the AWIC index and pH in a subset of sites from Scotland indicated potential for some extrapolation beyond the initial calibration regions of England and Wales. Despite considerable pH variability within AWIC classes, measured base-flow pH was within 0.5 pH units of values expected from invertebrates at over 55-70 % of test sites, and within 1 pH unit at 87-100 %. This compares favourably with direct pH measurement, where samples at fortnightly-monthly intervals are typically required to confidently estimate mean pH within 0.7-1.2 pH units. These data, drawn from a realistic application, illustrate the potential accuracy and integrating value of invertebrate bioassessment in acid-sensitive waters. Further developments should involve more specific identification and targeted calibration to i) improve discrimination between sensitive streams of contrasting acidity; ii) further improve the accuracy of pH determination based on invertebrates; iii) avoid the apparent over-estimation of pH in the lower AWIC classes; iv) clearly differentiate between acid-sensitive and acidified streams.
{"title":"Field testing the AWIC index for detecting acidification in British streams","authors":"S. Ormerod, Bethan R. Lewis, Renata A. Kowalik, J. Murphy, J. Davy-Bowker","doi":"10.1127/0003-9136/2006/0166-0099","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0166-0099","url":null,"abstract":"Using data from 132 acid-sensitive streams in Wales and Scotland from two available data sets, we tested a recently proposed indicator system that uses aquatic invertebrates to detect acidification in British rivers, the Acid Water Indicator Community (AWIC). Although many sites held less than a quarter of AWIC scoring taxa, index values at sites in both data sets correlated significantly with acid-base variables including pH, calcium concentration, alkalinity and dissolved aluminium. Relationships with acid-base status during acid episodes were particularly strong in the more comprehensive test set. Strong correlations between the AWIC index and pH in a subset of sites from Scotland indicated potential for some extrapolation beyond the initial calibration regions of England and Wales. Despite considerable pH variability within AWIC classes, measured base-flow pH was within 0.5 pH units of values expected from invertebrates at over 55-70 % of test sites, and within 1 pH unit at 87-100 %. This compares favourably with direct pH measurement, where samples at fortnightly-monthly intervals are typically required to confidently estimate mean pH within 0.7-1.2 pH units. These data, drawn from a realistic application, illustrate the potential accuracy and integrating value of invertebrate bioassessment in acid-sensitive waters. Further developments should involve more specific identification and targeted calibration to i) improve discrimination between sensitive streams of contrasting acidity; ii) further improve the accuracy of pH determination based on invertebrates; iii) avoid the apparent over-estimation of pH in the lower AWIC classes; iv) clearly differentiate between acid-sensitive and acidified streams.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79219856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-05-01DOI: 10.1127/0003-9136/2006/0166-0023
M. Riel, G. Velde, A. Vaate
Macroinvertebrate communities on the stones in the Rhine are dominated by the Ponto-Caspian amphipods Chelicorophium curvispinum (since 1987) and Dikerogammarus villosus (since 1995), which have invaded the Rhine through canals connecting the large rivers of Europe. Colonization of bare stones suspended in the water of the Rhine main channel was studied. At the same time the macroinvertebrates drifting in the water layer were sampled. Macroinvertebrate populations on the newly colonized stones were followed for two months (June - August 2002). Bare stones were colonized from the water layer, with D. villosus and C. curvispinum most numerous from the start. Species richness was highest after one month. D. villosus and C. curvispinum continued to dominate the macroinvertebrate community on the stones throughout the experiment, representing 70-95 % of the total number of macroinvertebrates. In the first period week of colonization, especially juveniles of both amphipod species settled on the bare stones. After one week, the number of adults of D. villosus increased. After one month, ovigerous females of D. villosus became abundant on the newly colonized substrate. The numbers of adult C. curvispinum increased after one month and ovigerous females were present after two months. Newly settled populations resembled the amphipod populations present in the water layer, but started to deviate as colonization time increased, indicating that development of populations on stones became increasingly autonomous and less dependent on new colonization by amphipods from the water layer. Ovigerous females of both amphipods were much more abundant on the stones than in the water layer. Juvenile C. curvispinum were smaller on the stones than in the water layer, indicating that the stone substrate is important for reproduction of at least C. curvispinum. Most juveniles of this species first grow to a certain body length on the stones before they start drifting off and swimming in the water layer. C. curvispinum and D. villosus densities were positively correlated in the early stages of colonization, but showed an inverse relationship after longer colonisation time. As both dominant amphipods colonize new stone substrate from the water layer where they drift or swim, they may not depend on extra vectors, such as shipping, for dispersal through the connecting canals and within the river.
{"title":"To conquer and persist : colonization and population development of the Ponto-Caspian amphipods Dikerogammarus villosus and Chelicorophium curvispinum on bare stone substrate in the main channel of the River Rhine","authors":"M. Riel, G. Velde, A. Vaate","doi":"10.1127/0003-9136/2006/0166-0023","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0166-0023","url":null,"abstract":"Macroinvertebrate communities on the stones in the Rhine are dominated by the Ponto-Caspian amphipods Chelicorophium curvispinum (since 1987) and Dikerogammarus villosus (since 1995), which have invaded the Rhine through canals connecting the large rivers of Europe. Colonization of bare stones suspended in the water of the Rhine main channel was studied. At the same time the macroinvertebrates drifting in the water layer were sampled. Macroinvertebrate populations on the newly colonized stones were followed for two months (June - August 2002). Bare stones were colonized from the water layer, with D. villosus and C. curvispinum most numerous from the start. Species richness was highest after one month. D. villosus and C. curvispinum continued to dominate the macroinvertebrate community on the stones throughout the experiment, representing 70-95 % of the total number of macroinvertebrates. In the first period week of colonization, especially juveniles of both amphipod species settled on the bare stones. After one week, the number of adults of D. villosus increased. After one month, ovigerous females of D. villosus became abundant on the newly colonized substrate. The numbers of adult C. curvispinum increased after one month and ovigerous females were present after two months. Newly settled populations resembled the amphipod populations present in the water layer, but started to deviate as colonization time increased, indicating that development of populations on stones became increasingly autonomous and less dependent on new colonization by amphipods from the water layer. Ovigerous females of both amphipods were much more abundant on the stones than in the water layer. Juvenile C. curvispinum were smaller on the stones than in the water layer, indicating that the stone substrate is important for reproduction of at least C. curvispinum. Most juveniles of this species first grow to a certain body length on the stones before they start drifting off and swimming in the water layer. C. curvispinum and D. villosus densities were positively correlated in the early stages of colonization, but showed an inverse relationship after longer colonisation time. As both dominant amphipods colonize new stone substrate from the water layer where they drift or swim, they may not depend on extra vectors, such as shipping, for dispersal through the connecting canals and within the river.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79630259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-04DOI: 10.1127/0003-9136/2006/0165-0469
J. Ortiz, E. Martí, M. Puig
We examined how community measures (density, biomass, and richness) and community composition were related to microhabitat variables (including hydraulic parameters, substrate, and food resources) in La Tordera stream in Catalonia (NE Spain). We collected macroinvertebrate samples on six dates between November 2001 and September 2002 upstream and downstream of a point source input. Macroinvertebrate density and biomass were positively correlated with food resources and complexity of habitat architecture (benthic organic matter, chlorophyll-a, vascular plants, and mosses) while taxa richness was negatively correlated with conventional (water velocity and depth) and complex hydraulic parameters (Froude number, Reynolds number, roughness shear velocity). Inorganic substrate exerted a minor influence on macroinvertebrate distribution. Ordination analysis revealed that the microhabitat variables of major significance at the two reaches were CPOM, chlorophyll-a, filamentous algae, and maximum velocity. Sand coverage was only relevant for macroinvertebrates at the upstream reach, and moss at the downstream reach. The number of significant correlations between macroinvertebrates and microhabitat variables was higher at the upstream reach than at the downstream reach mainly because of higher taxa richness.
{"title":"Influences of a point source on the microhabitat distribution of stream benthic macroinvertebrates","authors":"J. Ortiz, E. Martí, M. Puig","doi":"10.1127/0003-9136/2006/0165-0469","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0469","url":null,"abstract":"We examined how community measures (density, biomass, and richness) and community composition were related to microhabitat variables (including hydraulic parameters, substrate, and food resources) in La Tordera stream in Catalonia (NE Spain). We collected macroinvertebrate samples on six dates between November 2001 and September 2002 upstream and downstream of a point source input. Macroinvertebrate density and biomass were positively correlated with food resources and complexity of habitat architecture (benthic organic matter, chlorophyll-a, vascular plants, and mosses) while taxa richness was negatively correlated with conventional (water velocity and depth) and complex hydraulic parameters (Froude number, Reynolds number, roughness shear velocity). Inorganic substrate exerted a minor influence on macroinvertebrate distribution. Ordination analysis revealed that the microhabitat variables of major significance at the two reaches were CPOM, chlorophyll-a, filamentous algae, and maximum velocity. Sand coverage was only relevant for macroinvertebrates at the upstream reach, and moss at the downstream reach. The number of significant correlations between macroinvertebrates and microhabitat variables was higher at the upstream reach than at the downstream reach mainly because of higher taxa richness.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86087979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-01DOI: 10.1127/0003-9136/2006/0165-0433
K. Acharya, J. Jack, Allison S. Smith
Daphnia lumholtzi, a cladoceran native to Australia, South Africa and Asia, has been spreading through the rivers and reservoirs of the Southern and Midwestern US since its first detection in 1989 in Lake Texoma. Although several studies have documented D. lumholtzi dispersal in the US, there is little data linking its life history characteristics with its colonization success. In this study we investigated D. lumholtzi's body stoichiometry, growth and fecundity responses on natural seston vs. uni-algal cultures of Scenedesmus acutus (high and low quality and quantity). We also assessed resting egg production via a series of growth and population experiments to see if these life history parameters are linked with its invasion success. The first experiment examined the effect of diet quality and quantity on growth rates and fecundity of D. lumholtzi. The second experiment examined the growth performance of D. lumholtzi on ambient and lower concentrations of natural seston vs. uni-algae (S. acutus) treatments. In the third experiment, the relationship of D. lumholtzi population density and resting egg production was compared with two other widely distributed (Northern Hemisphere) species (D. pulicaria and D. magna). Growth rate, fecundity and body % P (dry mass) data from the quality-quantity experiment showed that D. lumholtzi performed best under P-rich, high food conditions and worst under P-deficient, low food conditions, exhibiting effects of both food quality and quantity. None of the life history characteristics we examined were significantly different from those of the tested native species of Daphnia. However, %RNA (dry mass) of D. lumholtzi was significantly higher than the tested native species (D. lumholtzi ≈10 %; D. pulicaria, D. magna <8%). The algae-seston experiment also showed that D. lumholtzi growth performance did not differ from that of the tested native species, but the population and resting egg production experiment showed that at similar food and environmental conditions D. lumholtzi produced significantly more resting eggs than either D. magna and D. pulicaria. The higher RNA levels in D. lumholtzi may facilitate quicker resting egg production, consistent with the Growth Rate Hypothesis. Higher resting egg production may be an important component in invasion success of D. lumholtzi in North America.
{"title":"Stoichiometry of Daphnia lumholtzi and their invasion success : Are they linked?","authors":"K. Acharya, J. Jack, Allison S. Smith","doi":"10.1127/0003-9136/2006/0165-0433","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0433","url":null,"abstract":"Daphnia lumholtzi, a cladoceran native to Australia, South Africa and Asia, has been spreading through the rivers and reservoirs of the Southern and Midwestern US since its first detection in 1989 in Lake Texoma. Although several studies have documented D. lumholtzi dispersal in the US, there is little data linking its life history characteristics with its colonization success. In this study we investigated D. lumholtzi's body stoichiometry, growth and fecundity responses on natural seston vs. uni-algal cultures of Scenedesmus acutus (high and low quality and quantity). We also assessed resting egg production via a series of growth and population experiments to see if these life history parameters are linked with its invasion success. The first experiment examined the effect of diet quality and quantity on growth rates and fecundity of D. lumholtzi. The second experiment examined the growth performance of D. lumholtzi on ambient and lower concentrations of natural seston vs. uni-algae (S. acutus) treatments. In the third experiment, the relationship of D. lumholtzi population density and resting egg production was compared with two other widely distributed (Northern Hemisphere) species (D. pulicaria and D. magna). Growth rate, fecundity and body % P (dry mass) data from the quality-quantity experiment showed that D. lumholtzi performed best under P-rich, high food conditions and worst under P-deficient, low food conditions, exhibiting effects of both food quality and quantity. None of the life history characteristics we examined were significantly different from those of the tested native species of Daphnia. However, %RNA (dry mass) of D. lumholtzi was significantly higher than the tested native species (D. lumholtzi ≈10 %; D. pulicaria, D. magna <8%). The algae-seston experiment also showed that D. lumholtzi growth performance did not differ from that of the tested native species, but the population and resting egg production experiment showed that at similar food and environmental conditions D. lumholtzi produced significantly more resting eggs than either D. magna and D. pulicaria. The higher RNA levels in D. lumholtzi may facilitate quicker resting egg production, consistent with the Growth Rate Hypothesis. Higher resting egg production may be an important component in invasion success of D. lumholtzi in North America.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79288090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-01DOI: 10.1127/0003-9136/2006/0165-0455
D. Fels
Daphnia magna selects different depths according to its genotype, its size or infection by a parasite. As a result, waterflea populations are often vertically structured. This vertical structure, i. e. different distances between waterfleas, might slow the progress of microparasite epidemics. This would enable avoidance behaviour to evolve. I tested in a set of experiments for both, distance effects and avoidance behaviour. The experiments were performed with the host-parasite system of D. magna and its microsporidian gut-parasite Glugoides intestinalis. Infection depended on spore loads in infected waterfleas. Transmission, however, was not affected by distance to infected animals. Avoidance behaviour was absent. The results suggest that the host's spatial structure does not influence the transmission of G. intestinalis in the populations of Daphnia magna living in shallow water. Rather, successful transmission depends on the dynamics of the water.
{"title":"Transmission of the microsporidian Glugoides intestinalis in relation to spatial structure of the host Daphnia magna","authors":"D. Fels","doi":"10.1127/0003-9136/2006/0165-0455","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0455","url":null,"abstract":"Daphnia magna selects different depths according to its genotype, its size or infection by a parasite. As a result, waterflea populations are often vertically structured. This vertical structure, i. e. different distances between waterfleas, might slow the progress of microparasite epidemics. This would enable avoidance behaviour to evolve. I tested in a set of experiments for both, distance effects and avoidance behaviour. The experiments were performed with the host-parasite system of D. magna and its microsporidian gut-parasite Glugoides intestinalis. Infection depended on spore loads in infected waterfleas. Transmission, however, was not affected by distance to infected animals. Avoidance behaviour was absent. The results suggest that the host's spatial structure does not influence the transmission of G. intestinalis in the populations of Daphnia magna living in shallow water. Rather, successful transmission depends on the dynamics of the water.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78965119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-04-01DOI: 10.1127/0003-9136/2006/0165-0493
Verónica Ferreira, M. Graça, J. Lima, R. Gomes
We evaluated the relative importance of current velocity and invertebrate activities in the breakdown rate of alder (Alnus glutinosa (L.) Gaertner) leaves. Decomposition experiments were carried out in artificial channels, where current velo- city and shredder presence were manipulated, and in a 4 th order stream, in both summer and autumn, where litter bags were incubated in several reaches differing in both depth and current velocity. Alder leaves incubated in artificial channels decomposed signifi- cantly faster in the presence of shredders than in their absence (k = 0.0368/d vs. k = 0.0210/d in low current and k = 0.0472/d vs. k = 0.0219/d in high current). However, cur- rent (up to 2.35 m/s) had no significant effect on decomposition rates. In channels with- out invertebrates, no significant differences in k values were found between coarse and fine mesh bags in high (0.20 m/s) and low (0.05 m/s) current. Leaves incubated in the stream during summer, in reaches with current velocity ranging from 0.003 to 1.185 m/s, did not differ in their decomposition rates (k = 0.0489/d to k = 0.0645/d). In autumn, leaves exposed to high current (1.228 m/s) had faster decomposition rate (k = 0.0417/d vs. k = 0.0136/d), which may be related to sediment transport during this time of the year or to the tendency for higher number of shredders in high current-shallow reaches.
我们评估了水流速度和无脊椎动物活动对桤木(Alnus glutinosa, L.)分解率的相对重要性。加特纳)树叶。在人工河道中进行了分解实验，其中控制了流速和碎纸机的存在，并在夏季和秋季在第4级河流中进行了分解实验，其中在几个深度和流速不同的河段孵育了垃圾袋。在人工通道中培养的桤木叶片，在有碎纸机的情况下，分解速度明显快于没有碎纸机的情况(k = 0.0368/d vs. k = 0.0210/d, k = 0.0472/d vs. k = 0.0219/d)。然而，电流(高达2.35 m/s)对分解速率没有显著影响。在无无脊椎动物的通道中，粗网袋和细网袋在高(0.20 m/s)和低(0.05 m/s)电流下的k值无显著差异。在流速为0.003 ~ 1.185 m/s的河段，夏季在溪流中孵育的叶片，其分解速率(k = 0.0489 ~ 0.0645/d)没有差异。在秋季，暴露在大电流(1.228 m/s)下的叶片分解速率更快(k = 0.0417/d vs. k = 0.0136/d)，这可能与秋季泥沙输运有关，也可能与大电流浅水河段碎纸机数量较多有关。
{"title":"Role of physical fragmentation and invertebrate activity in the breakdown rate of leaves","authors":"Verónica Ferreira, M. Graça, J. Lima, R. Gomes","doi":"10.1127/0003-9136/2006/0165-0493","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0493","url":null,"abstract":"We evaluated the relative importance of current velocity and invertebrate activities in the breakdown rate of alder (Alnus glutinosa (L.) Gaertner) leaves. Decomposition experiments were carried out in artificial channels, where current velo- city and shredder presence were manipulated, and in a 4 th order stream, in both summer and autumn, where litter bags were incubated in several reaches differing in both depth and current velocity. Alder leaves incubated in artificial channels decomposed signifi- cantly faster in the presence of shredders than in their absence (k = 0.0368/d vs. k = 0.0210/d in low current and k = 0.0472/d vs. k = 0.0219/d in high current). However, cur- rent (up to 2.35 m/s) had no significant effect on decomposition rates. In channels with- out invertebrates, no significant differences in k values were found between coarse and fine mesh bags in high (0.20 m/s) and low (0.05 m/s) current. Leaves incubated in the stream during summer, in reaches with current velocity ranging from 0.003 to 1.185 m/s, did not differ in their decomposition rates (k = 0.0489/d to k = 0.0645/d). In autumn, leaves exposed to high current (1.228 m/s) had faster decomposition rate (k = 0.0417/d vs. k = 0.0136/d), which may be related to sediment transport during this time of the year or to the tendency for higher number of shredders in high current-shallow reaches.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91075328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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