Pub Date : 2014-04-01DOI: 10.1127/1863-9135/2014/0591
Neil D Graham, S. Stoll, J. Loizeau
Colloids play a critical role in the transport of particle-bound contaminants. Knowledge of colloids and their aggregates provides insight into contaminant transport and fate within a given aquatic environment. Here, colloids and aggregates at the sediment-water interface of Vidy Bay, Lake Geneva, Switzerland, were characterized with a combination of analytical techniques to understand their structure, size distribution, concentration, and stability (the potential for aggregation). Vidy Bay is known to be the most contaminated part of Lake Geneva, being influenced by the effluents of a municipal wastewater treatment plant. Colloids were a heterogeneous mix of inorganic constituents (diatom fragments, quartz, clay, endogenic calcite, iron oxy-hydroxides) bridged together by rigid biopolymer strands or gels. The presence of rigid biopolymers was quite significant and they were typically found to have iron oxy-hydroxides embedded within their structure. Ion chromatographic data were comparable to previous values attained for the water column of Lake Geneva; however, single particle counting results indicated the presence of a nepheloid layer in Vidy Bay. In such, the stability of colloids was likely influenced by their proximity to the sediment-water interface. Zeta potential results inferred charge neutralization and destabilization of colloids and aggregates. Self-assembly of rigid biopolymers, along with cationic bridging between rigid biopolymers and inorganic constituents readily aggregated colloids. Taken together, colloids at the sediment water interface of Vidy Bay appeared to be unstable and to play a minor role in the transport of contaminants over long distances.
{"title":"Colloid characterization at the sediment-water interface of Vidy Bay, Lake Geneva","authors":"Neil D Graham, S. Stoll, J. Loizeau","doi":"10.1127/1863-9135/2014/0591","DOIUrl":"https://doi.org/10.1127/1863-9135/2014/0591","url":null,"abstract":"Colloids play a critical role in the transport of particle-bound contaminants. Knowledge of colloids and their aggregates provides insight into contaminant transport and fate within a given aquatic environment. Here, colloids and aggregates at the sediment-water interface of Vidy Bay, Lake Geneva, Switzerland, were characterized with a combination of analytical techniques to understand their structure, size distribution, concentration, and stability (the potential for aggregation). Vidy Bay is known to be the most contaminated part of Lake Geneva, being influenced by the effluents of a municipal wastewater treatment plant. Colloids were a heterogeneous mix of inorganic constituents (diatom fragments, quartz, clay, endogenic calcite, iron oxy-hydroxides) bridged together by rigid biopolymer strands or gels. The presence of rigid biopolymers was quite significant and they were typically found to have iron oxy-hydroxides embedded within their structure. Ion chromatographic data were comparable to previous values attained for the water column of Lake Geneva; however, single particle counting results indicated the presence of a nepheloid layer in Vidy Bay. In such, the stability of colloids was likely influenced by their proximity to the sediment-water interface. Zeta potential results inferred charge neutralization and destabilization of colloids and aggregates. Self-assembly of rigid biopolymers, along with cationic bridging between rigid biopolymers and inorganic constituents readily aggregated colloids. Taken together, colloids at the sediment water interface of Vidy Bay appeared to be unstable and to play a minor role in the transport of contaminants over long distances.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82766884","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 : 2013-12-01DOI: 10.1127/1863-9135/2013/0510
M. Juan, J. Casas, S. Bonachela, Irene Gallego, F. Fuentes-Rodríguez, E. Fenoy, M. Elorrieta
The study of fungi and fungus-like organisms in irrigation ponds has applied interest since waterborne phytopathogens can disperse through the irrigation system to the crop roots. We tested the hypothesis that manag- ing irrigation ponds to maintain high levels of biodiversity could entail agronomic benefits through the control of phytopathogens. The structure of assemblages of fungi and fungus-like taxa were characterized and compared us- ing samples taken from two strata depths (superficial and deep). This was done in four management/water source pond groups of southeastern Spain: groundwater-fed ponds with submerged aquatic vegetation stands (untreated SAV ponds); groundwater-fed ponds submitted to low and high doses of copper sulfate, and ponds fed with recy- cled urban wastewater bearing intermediate doses of copper sulfate. Higher density and diversity of fungi, besides a singular assemblage composition, were found in untreated SAV ponds compared to treated ponds, particularly for samples taken in the deep stratum. Phytopathogenicity of the main phytopathogens detected (Pythium isolates) was generally low and rather unaffected by the type of pond management. However, much evidence from poten- tial unsuitable hosts (submerged macrophyte species) and fungal composition (related to the presence of potential pathogen antagonists) suggests that managing ponds to preserve submerged vegetation might prove useful for controlling root rot diseases.
{"title":"Management effects on fungal assemblages in irrigation ponds: are biodiversity conservation and the control of phytopathogens compatible?","authors":"M. Juan, J. Casas, S. Bonachela, Irene Gallego, F. Fuentes-Rodríguez, E. Fenoy, M. Elorrieta","doi":"10.1127/1863-9135/2013/0510","DOIUrl":"https://doi.org/10.1127/1863-9135/2013/0510","url":null,"abstract":"The study of fungi and fungus-like organisms in irrigation ponds has applied interest since waterborne phytopathogens can disperse through the irrigation system to the crop roots. We tested the hypothesis that manag- ing irrigation ponds to maintain high levels of biodiversity could entail agronomic benefits through the control of phytopathogens. The structure of assemblages of fungi and fungus-like taxa were characterized and compared us- ing samples taken from two strata depths (superficial and deep). This was done in four management/water source pond groups of southeastern Spain: groundwater-fed ponds with submerged aquatic vegetation stands (untreated SAV ponds); groundwater-fed ponds submitted to low and high doses of copper sulfate, and ponds fed with recy- cled urban wastewater bearing intermediate doses of copper sulfate. Higher density and diversity of fungi, besides a singular assemblage composition, were found in untreated SAV ponds compared to treated ponds, particularly for samples taken in the deep stratum. Phytopathogenicity of the main phytopathogens detected (Pythium isolates) was generally low and rather unaffected by the type of pond management. However, much evidence from poten- tial unsuitable hosts (submerged macrophyte species) and fungal composition (related to the presence of potential pathogen antagonists) suggests that managing ponds to preserve submerged vegetation might prove useful for controlling root rot diseases.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87390630","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 : 2006-10-06DOI: 10.1127/0003-9136/2006/0167-0561
P. Fink, E. Elert, F. Jüttner
Lipoxygenase products (often called oxylipins) are degradation products of fatty acids. They are known to regulate many defensive and developmental pathways in plants. Among these lipoxygenase products are volatile aldehydes, that are released from wound activated diatom cells and that are potent inhibitors of mitotic prolifera- tion in sea urchin embryos. They have been shown to dramatically lower the hatching success of herbivorous copepods and therefore are considered to constitute an acti- vated defence strategy. Alternatively, lipoxygenase products might also serve as info- chemicals, especially in biofilms of benthic algae and cyanobacteria. Here, we demon- strate that the bouquet of volatile lipoxygenase products released from a benthic dia- tom (Achnanthes biasolettiana) is attractive to an herbivorous gastropod grazer (Radix ovata). The volatiles are released from the algae upon cell damage and can be utilized as food-finding cues by the herbivorous snails. In contrast to this observation, the odour bouquet from another benthic diatom species (Gomphonema parvulum) did not show any attractant activity to the snail, which is probably caused by differences in the bouquet of odorous substances released by the two diatom isolates. In contrast to G. parvulum, the odour bouquet of A. biasolettiana consisted of mono- and diunsaturated alcohols and ketones, primarily with a C8-skeleton. Most of the compounds have never before been described from diatoms. This study shows that diatom lipoxygenase prod- ucts cannot only be involved in activated defence, but can also be utilised as food-find- ing cues by herbivores. Thus, the ecological role of these volatile organic compounds can be very complex and will strongly depend on the ecological context of the chemi- cal interaction.
{"title":"Oxylipins from freshwater diatoms act as attractants for a benthic herbivore","authors":"P. Fink, E. Elert, F. Jüttner","doi":"10.1127/0003-9136/2006/0167-0561","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0561","url":null,"abstract":"Lipoxygenase products (often called oxylipins) are degradation products of fatty acids. They are known to regulate many defensive and developmental pathways in plants. Among these lipoxygenase products are volatile aldehydes, that are released from wound activated diatom cells and that are potent inhibitors of mitotic prolifera- tion in sea urchin embryos. They have been shown to dramatically lower the hatching success of herbivorous copepods and therefore are considered to constitute an acti- vated defence strategy. Alternatively, lipoxygenase products might also serve as info- chemicals, especially in biofilms of benthic algae and cyanobacteria. Here, we demon- strate that the bouquet of volatile lipoxygenase products released from a benthic dia- tom (Achnanthes biasolettiana) is attractive to an herbivorous gastropod grazer (Radix ovata). The volatiles are released from the algae upon cell damage and can be utilized as food-finding cues by the herbivorous snails. In contrast to this observation, the odour bouquet from another benthic diatom species (Gomphonema parvulum) did not show any attractant activity to the snail, which is probably caused by differences in the bouquet of odorous substances released by the two diatom isolates. In contrast to G. parvulum, the odour bouquet of A. biasolettiana consisted of mono- and diunsaturated alcohols and ketones, primarily with a C8-skeleton. Most of the compounds have never before been described from diatoms. This study shows that diatom lipoxygenase prod- ucts cannot only be involved in activated defence, but can also be utilised as food-find- ing cues by herbivores. Thus, the ecological role of these volatile organic compounds can be very complex and will strongly depend on the ecological context of the chemi- cal interaction.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91076394","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 : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0147
W. Kerfoot
Cladocerans in the genus Eubosmina exhibit spectacular and confusing morphological diversification in the Baltic region. The paleolimnological record suggests that lineages in regional lakes diverged recently from morphologically conservative E. longispina/coregoni-like ancestors and developed strong seasonal elongation of antennules, mucrones, or dorsal humps (cyclomorphosis). Allozyme studies on Schleswig-Holstein populations by DE MELO agree with this interpretation by demonstrating: 1) genetic difference between geographically distant E. longispina populations, 2) clustering of E. coregoni forms with local E. longispina lineages, and 3) great genetic similarity among regional E. coregoni forms, despite major morphological differences. Retention of distinguishing traits (shape of dorsal humps, antennule length) in common-garden experiments emphasizes that micro-evolutionary (genetic) differences underlie "form" phenotypes. However, regression of extreme summer forms towards a more conservative morphology in laboratory culture indicates that part of the seasonal variability is attributable to developmental plasticity. Split-clone laboratory experiments demonstrate that longer antennule lengths of an exuberant form, E. coregoni kessleri from the Grosser Ploner See, are increased (induced) in the presence of predatory cyclopoids. Induction responses strengthen the notion that long-term transformations involve evolutionary responses to invertebrate predators (cyclopoid copepods, Leptodora) which colonized large lakes during post-glacial periods, with the particulars of responses showing lineage and lake specificity.
{"title":"Baltic Eubosmina morphological radiation : Sensitivity to invertebrate predators (induction) and observations on genetic differences","authors":"W. Kerfoot","doi":"10.1127/0003-9136/2006/0167-0147","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0147","url":null,"abstract":"Cladocerans in the genus Eubosmina exhibit spectacular and confusing morphological diversification in the Baltic region. The paleolimnological record suggests that lineages in regional lakes diverged recently from morphologically conservative E. longispina/coregoni-like ancestors and developed strong seasonal elongation of antennules, mucrones, or dorsal humps (cyclomorphosis). Allozyme studies on Schleswig-Holstein populations by DE MELO agree with this interpretation by demonstrating: 1) genetic difference between geographically distant E. longispina populations, 2) clustering of E. coregoni forms with local E. longispina lineages, and 3) great genetic similarity among regional E. coregoni forms, despite major morphological differences. Retention of distinguishing traits (shape of dorsal humps, antennule length) in common-garden experiments emphasizes that micro-evolutionary (genetic) differences underlie \"form\" phenotypes. However, regression of extreme summer forms towards a more conservative morphology in laboratory culture indicates that part of the seasonal variability is attributable to developmental plasticity. Split-clone laboratory experiments demonstrate that longer antennule lengths of an exuberant form, E. coregoni kessleri from the Grosser Ploner See, are increased (induced) in the presence of predatory cyclopoids. Induction responses strengthen the notion that long-term transformations involve evolutionary responses to invertebrate predators (cyclopoid copepods, Leptodora) which colonized large lakes during post-glacial periods, with the particulars of responses showing lineage and lake specificity.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74084548","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 : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0547
J. F. Blom, H. I. Baumann, G. Codd, F. Jüttner
Planktothrix rubescens is a frequently found cyanobacterium in deep stratified mesotrophic lakes, and metalimnetic mass developments as well as surface blooms are frequently observed in these waterbodies. P. rubescens contains toxins, ([D-Asp 3 ,(E)-Dhb 7 ]microcystin-RR and oscillapeptin J), numerous other cyclic peptides and depsipeptides which are potent inhibitors of digestive proteases, and so far unknown infochemicals (deterrents) that are bound to the cell surface and allow grazers to discriminate between cyanobacteria and more suitable food particles. Purified [D-Asp 3 ,(E)-Dhb 7 ]microcystin-RR was toxic to all tested aquatic grazers, but the sensitivity varied. The selective feeder Eudiaptomus showed mortality (LC 50 ) at 1.2 μM, while Daphnia sp., Chironomus riparius and Brachionus calyciflorus were less sensitive (21.1 μM, 52μM and 157μM). Toxicity of oscillapeptin J was only found for crustacean grazers (Eudiaptomus sp. LC 50 = 58 μM, Daphnia sp. LC 50 = 203 μM). Toxicity of this compound to mice, when administered intraperitoneally, was not observed. The data characterize oscillapeptin J as a specific crustacean toxin directed against this most "dangerous" group of grazers for planktonic cyanobacteria. Oscillapeptin J is a very potent inhibitor of trypsin (IC 50 = 20nM) and a moderate inhibitor of chymotrypsin (IC 50 = 2.8 μM). Adaptation to this toxin was found when the sensitivity of Daphnia sp., collected from a lake with annual mass developments of P. rubescens (Lake Hallwilersee) and a lake virtually free of this cyanobacterium (Lake Walensee), were compared with each other. Daphnia sp. from Lake Walensee was significantly more sensitive than Daphnia sp. which has experienced P. rubescens.
{"title":"Sensitivity and adaptation of aquatic organisms to oscillapeptin J and [D-Asp3,(E)-Dhb7]microcystin-RR","authors":"J. F. Blom, H. I. Baumann, G. Codd, F. Jüttner","doi":"10.1127/0003-9136/2006/0167-0547","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0547","url":null,"abstract":"Planktothrix rubescens is a frequently found cyanobacterium in deep stratified mesotrophic lakes, and metalimnetic mass developments as well as surface blooms are frequently observed in these waterbodies. P. rubescens contains toxins, ([D-Asp 3 ,(E)-Dhb 7 ]microcystin-RR and oscillapeptin J), numerous other cyclic peptides and depsipeptides which are potent inhibitors of digestive proteases, and so far unknown infochemicals (deterrents) that are bound to the cell surface and allow grazers to discriminate between cyanobacteria and more suitable food particles. Purified [D-Asp 3 ,(E)-Dhb 7 ]microcystin-RR was toxic to all tested aquatic grazers, but the sensitivity varied. The selective feeder Eudiaptomus showed mortality (LC 50 ) at 1.2 μM, while Daphnia sp., Chironomus riparius and Brachionus calyciflorus were less sensitive (21.1 μM, 52μM and 157μM). Toxicity of oscillapeptin J was only found for crustacean grazers (Eudiaptomus sp. LC 50 = 58 μM, Daphnia sp. LC 50 = 203 μM). Toxicity of this compound to mice, when administered intraperitoneally, was not observed. The data characterize oscillapeptin J as a specific crustacean toxin directed against this most \"dangerous\" group of grazers for planktonic cyanobacteria. Oscillapeptin J is a very potent inhibitor of trypsin (IC 50 = 20nM) and a moderate inhibitor of chymotrypsin (IC 50 = 2.8 μM). Adaptation to this toxin was found when the sensitivity of Daphnia sp., collected from a lake with annual mass developments of P. rubescens (Lake Hallwilersee) and a lake virtually free of this cyanobacterium (Lake Walensee), were compared with each other. Daphnia sp. from Lake Walensee was significantly more sensitive than Daphnia sp. which has experienced P. rubescens.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81624363","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 : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0265
Petter Larsson, Ingrid Wathne
Surviving the winter is a special challenge for herbivorous aquatic inverte- brates in the alpine region due to the long period of ice cover and cessation of primary production. Since there can still be open water under the ice in lakes and ponds, aqua- tic invertebrates can be active if they have enough stored resources. Daphnids usually survive the difficult winter period by producing and depositing resting eggs (ephippia) at the end of the summer. Some daphnids in alpine lakes and ponds, however, have a mixed strategy by both producing ephippia and living active in the water during the winter. We ask why these two strategies coexist stably: Do individuals both produce ephippia and stay active during the winter or do they only have resources for one of the strategies? We studied this phenomenon by sampling of Daphnia umbra twice per month from June to September and monthly the rest of the year in an alpine pond at Finse, Norway, 1207 m a. s. l. The species reproduced parthenogenetically in August and early September, with sexual reproduction of ephippia starting in late August. Highest ephippia densities were found in October, with about 10 % females carrying such eggs. The remaining females did not carry eggs but stored large reserves of lipids. During the winter, population size decreased, as did accumulated lipids. In spring, very few winter-active daphnids had survived until the ice melted and active winter survival seemed not to be a successful strategy during the year of study. Accumulating lipid reserves is assumed to be a special adaptation to postpone reproduction until spring which is unusual in daphnids. It is in contrast to their food dependent reproduction tak- ing place during the summer, and it appears paradoxal that those specially adapted active winter survivors almost disappeared just before ice break-up. Most likely due to year to year variation in the conditions under the ice, the relative success of the two strategies varies. Parasitism, predators and available volume of open water under the ice might be the main factors. Ephippia producing females seem to have less lipids than those without ephippia, indicating that the two strategies compete for the animals resources and that the former might have problems with surviving the winter as active animals.
{"title":"Swim or rest during the winter - what is best for an alpine daphnid?","authors":"Petter Larsson, Ingrid Wathne","doi":"10.1127/0003-9136/2006/0167-0265","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0265","url":null,"abstract":"Surviving the winter is a special challenge for herbivorous aquatic inverte- brates in the alpine region due to the long period of ice cover and cessation of primary production. Since there can still be open water under the ice in lakes and ponds, aqua- tic invertebrates can be active if they have enough stored resources. Daphnids usually survive the difficult winter period by producing and depositing resting eggs (ephippia) at the end of the summer. Some daphnids in alpine lakes and ponds, however, have a mixed strategy by both producing ephippia and living active in the water during the winter. We ask why these two strategies coexist stably: Do individuals both produce ephippia and stay active during the winter or do they only have resources for one of the strategies? We studied this phenomenon by sampling of Daphnia umbra twice per month from June to September and monthly the rest of the year in an alpine pond at Finse, Norway, 1207 m a. s. l. The species reproduced parthenogenetically in August and early September, with sexual reproduction of ephippia starting in late August. Highest ephippia densities were found in October, with about 10 % females carrying such eggs. The remaining females did not carry eggs but stored large reserves of lipids. During the winter, population size decreased, as did accumulated lipids. In spring, very few winter-active daphnids had survived until the ice melted and active winter survival seemed not to be a successful strategy during the year of study. Accumulating lipid reserves is assumed to be a special adaptation to postpone reproduction until spring which is unusual in daphnids. It is in contrast to their food dependent reproduction tak- ing place during the summer, and it appears paradoxal that those specially adapted active winter survivors almost disappeared just before ice break-up. Most likely due to year to year variation in the conditions under the ice, the relative success of the two strategies varies. Parasitism, predators and available volume of open water under the ice might be the main factors. Ephippia producing females seem to have less lipids than those without ephippia, indicating that the two strategies compete for the animals resources and that the former might have problems with surviving the winter as active animals.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76262764","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 : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0055
P. Spaak, M. Boersma
We used Daphnia as a model to study the effect of predators on clonal and taxon coexistence within the same habitat. Different Daphnia species and their hybrids coexist in many lakes worldwide. We studied the potential influence of planktivorous fish on the maintenance of these species assemblages using 20 Daphnia clones, belonging to five hybrid and parental taxa of the Daphnia galeata-hyalina-cucullata complex originating from the Plussee (Northern Germany). With these clones, two competition experiments were conducted in two large-scale indoor mesocosms, the Plankton Towers in Plon, Germany. We varied the presence of fish and kairomones. Using allozyme electrophoresis we observed Diel Vertical Migration (DVM) of indi- vidual clones. Without fish, two clones belonging to the largest taxa (D. galeata and D. galeata × hyalina) became numerically dominant after three weeks. The mere presence of fish kairomones led to a significant decrease in the niche overlap between the five taxa. With fish present in the towers relative densities of smaller D. cucullata × ga- leata clones were highest. We observed that under different predation intensities differ- ent taxa showed the highest instantaneous rate of increase. Without fish and fish kairo- mones this rate was the highest for D. galeata, when fish kairomones were present D. galeata × hyalina had the highest relative r. With increasing fish predation D. cucul- lata and D. cucullata × galeata had the highest relative r, respectively, showing that changing predation pressure facilitates the co-occurrence of taxa in this species com- plex.
{"title":"Predator mediated coexistence of hybrid and parental Daphnia taxa","authors":"P. Spaak, M. Boersma","doi":"10.1127/0003-9136/2006/0167-0055","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0055","url":null,"abstract":"We used Daphnia as a model to study the effect of predators on clonal and taxon coexistence within the same habitat. Different Daphnia species and their hybrids coexist in many lakes worldwide. We studied the potential influence of planktivorous fish on the maintenance of these species assemblages using 20 Daphnia clones, belonging to five hybrid and parental taxa of the Daphnia galeata-hyalina-cucullata complex originating from the Plussee (Northern Germany). With these clones, two competition experiments were conducted in two large-scale indoor mesocosms, the Plankton Towers in Plon, Germany. We varied the presence of fish and kairomones. Using allozyme electrophoresis we observed Diel Vertical Migration (DVM) of indi- vidual clones. Without fish, two clones belonging to the largest taxa (D. galeata and D. galeata × hyalina) became numerically dominant after three weeks. The mere presence of fish kairomones led to a significant decrease in the niche overlap between the five taxa. With fish present in the towers relative densities of smaller D. cucullata × ga- leata clones were highest. We observed that under different predation intensities differ- ent taxa showed the highest instantaneous rate of increase. Without fish and fish kairo- mones this rate was the highest for D. galeata, when fish kairomones were present D. galeata × hyalina had the highest relative r. With increasing fish predation D. cucul- lata and D. cucullata × galeata had the highest relative r, respectively, showing that changing predation pressure facilitates the co-occurrence of taxa in this species com- plex.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78364626","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 : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0501
D. Müller-Navarra
Fatty acids of field caught Daphnia spp. (Phyllopoda) and Eudiaptomus spp. (Copepoda) representing a non-selective and a selective grazer were analyzed and compared to the respective fatty acids of their potential food, i. e. seston < 30 μm. In addition, values in daphniids from the field were compared to D. galeata fed cultured algae (Scenedesmus obliquus, Cryptomonas erosa, Nitzschia palea). In Daphnia spp. from the field their EPA content varied least among all ω3-polyunsaturated fatty acids (ω3-PUFA) and less than in their food. Hence, it can be considered to be more homeostatic than in the food. This becomes especially evident when comparing fatty acid profiles of D. galeata feeding on the cultured algae which had very different fatty acid compositions. However, the variation in daphniids' EPA and co3-PUFA content is much greater than what is observed for phosphorus (P) content in daphniids, owing the fact that PUFA and P are under different physiological constraints. Although the fatty acid pattern of D. galeata was greatly influenced when feeding on the algal cultures in the laboratory, no significant correlations were found between seston and Daphnia spp. and Eudiaptomus spp. for most PUFA and fatty acid ratios used as trophic markers. Thus, different to the laboratory situation when food was superfluous, a more homeostatic (03-PUFA profile occurred under limiting conditions in the field.
{"title":"The nutritional importance of polyunsaturated fatty acids and their use as trophic markers for herbivorous zooplankton : Does it contradict?","authors":"D. Müller-Navarra","doi":"10.1127/0003-9136/2006/0167-0501","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0501","url":null,"abstract":"Fatty acids of field caught Daphnia spp. (Phyllopoda) and Eudiaptomus spp. (Copepoda) representing a non-selective and a selective grazer were analyzed and compared to the respective fatty acids of their potential food, i. e. seston < 30 μm. In addition, values in daphniids from the field were compared to D. galeata fed cultured algae (Scenedesmus obliquus, Cryptomonas erosa, Nitzschia palea). In Daphnia spp. from the field their EPA content varied least among all ω3-polyunsaturated fatty acids (ω3-PUFA) and less than in their food. Hence, it can be considered to be more homeostatic than in the food. This becomes especially evident when comparing fatty acid profiles of D. galeata feeding on the cultured algae which had very different fatty acid compositions. However, the variation in daphniids' EPA and co3-PUFA content is much greater than what is observed for phosphorus (P) content in daphniids, owing the fact that PUFA and P are under different physiological constraints. Although the fatty acid pattern of D. galeata was greatly influenced when feeding on the algal cultures in the laboratory, no significant correlations were found between seston and Daphnia spp. and Eudiaptomus spp. for most PUFA and fatty acid ratios used as trophic markers. Thus, different to the laboratory situation when food was superfluous, a more homeostatic (03-PUFA profile occurred under limiting conditions in the field.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84233528","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 : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0021
E. Elert, H. Stibor
Daphnia responds to chemical cues released by fish with adaptive changes in life history traits, e. g. a reduction in size at first reproduction (SFR). We used effects on SFR of a clone of Daphnia magna to characterise the chemical nature of the kairomone released by Leuciscus idus. The kairomone was of low lipophilicity and was enriched from incubation water by C 18 -solid phase extraction. The chemical cue was an anion at neutral pH and was reversibly inactivated by acetylation. Ester bonds, olefinic bonds or glucuronic acid can be excluded as essential for the biological activity. The effects on SFR increased with increasing concentrations of enriched kairomone. HPLC yielded only two adjacent active fractions that differed in retention times from those obtained for the diel vertical migration inducing kairomones released by other cyprinid fish species.
{"title":"Predator-mediated life history shifts in Daphnia: enrichment and preliminary chemical characterisation of a kairomone exuded by fish","authors":"E. Elert, H. Stibor","doi":"10.1127/0003-9136/2006/0167-0021","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0021","url":null,"abstract":"Daphnia responds to chemical cues released by fish with adaptive changes in life history traits, e. g. a reduction in size at first reproduction (SFR). We used effects on SFR of a clone of Daphnia magna to characterise the chemical nature of the kairomone released by Leuciscus idus. The kairomone was of low lipophilicity and was enriched from incubation water by C 18 -solid phase extraction. The chemical cue was an anion at neutral pH and was reversibly inactivated by acetylation. Ester bonds, olefinic bonds or glucuronic acid can be excluded as essential for the biological activity. The effects on SFR increased with increasing concentrations of enriched kairomone. HPLC yielded only two adjacent active fractions that differed in retention times from those obtained for the diel vertical migration inducing kairomones released by other cyprinid fish species.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82907960","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 : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0515
I. D. Zellmer, M. T. Arts, V. Šustr
In shallow subarctic ponds Daphnia and their algal food are often exposed to solar ultraviolet radiation (UVR). It was previously demonstrated that direct exposure of Daphnia to UVR may result in sublethal damage to Daphnia's intestinal system. This led to the hypothesis that, as consequences of such exposures, Daphnia may be experiencing a situation similar to starvation. We examined, in controlled experiments, the indirect effect of UVR-treated food algae on Daphnia pulex which, themselves, were also exposed to UVR. We specifically tested whether exposure of D. pulex to solar UVR affects food transport and enzymatic digestion. As expected, the UVR-exposed food and UVR-treated Daphnia combination produced the strongest effects on intestinal damage, and mortality. Some of these effects, as well as the grazer-related effects, were similar to those observed during starvation. The total activities of digestive enzymes (amylase and cellulase) were somewhat reduced in UVR treated D. pulex, but the function of enzymes is not seriously damaged as is clear from the increasing trend of protein-specific activities. We conclude that, in some ways, Daphnia undergoing sublethal UVR exposures may be experiencing a condition similar to what they would experience under very low food or even fasting conditions.
{"title":"Food chain effects of sublethal ultraviolet radiation on subarctic Daphnia pulex - : a field and laboratory study","authors":"I. D. Zellmer, M. T. Arts, V. Šustr","doi":"10.1127/0003-9136/2006/0167-0515","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0515","url":null,"abstract":"In shallow subarctic ponds Daphnia and their algal food are often exposed to solar ultraviolet radiation (UVR). It was previously demonstrated that direct exposure of Daphnia to UVR may result in sublethal damage to Daphnia's intestinal system. This led to the hypothesis that, as consequences of such exposures, Daphnia may be experiencing a situation similar to starvation. We examined, in controlled experiments, the indirect effect of UVR-treated food algae on Daphnia pulex which, themselves, were also exposed to UVR. We specifically tested whether exposure of D. pulex to solar UVR affects food transport and enzymatic digestion. As expected, the UVR-exposed food and UVR-treated Daphnia combination produced the strongest effects on intestinal damage, and mortality. Some of these effects, as well as the grazer-related effects, were similar to those observed during starvation. The total activities of digestive enzymes (amylase and cellulase) were somewhat reduced in UVR treated D. pulex, but the function of enzymes is not seriously damaged as is clear from the increasing trend of protein-specific activities. We conclude that, in some ways, Daphnia undergoing sublethal UVR exposures may be experiencing a condition similar to what they would experience under very low food or even fasting conditions.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78955328","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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