Pub Date : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-0089
J. Vijverberg, Arve Doksæter, E. Donk
In a previous field study (Flik & Vijverberg 2003) we showed that in an oligotrophic-mesotrophic lake in the Netherlands (L. Maarsseveen) two co-occurring Daphnia species, Daphnia pulicaria and Daphnia galeata x hyalina performed distinct vertical migration behaviour during summer which is induced by a high fish biomass of young perch. During late spring and summer, D. galeata × hyalina exhibits diel vertical migration, whereas D. pulicaria is staying down day and night in the hypolim- nion. This difference in migration behaviour results in contrasting predation mortalities caused by fish, low for D. pulicaria and relatively high for D. galeata × hyalina. In the present study, we measured in the laboratory the effects of fish released infochemicals on five life history traits in four genetically distinct D. galeata × hyalina and three ge- netically distinct D. pulicaria clones collected during summer at day-time from the hypolimnion. We tested the hypothesis that the species which behaviour is providing the best protection against fish predation (i. e. D. pulicaria) is less protected by life his- tory traits induced by fish released infochemicals than the species which by its behav- iour is less well protected against fish predation (i. e. D. galeata × hyalina). Our results show that D. galeata × hyalina responded in three out of five traits differently to fish infochemicals than D. pulicaria. In all these three traits D. galeata × hyalina re- sponded significantly to fish-released infochemicals, whereas D. pulicaria did not show any significant response at all. We conclude that in D. pulicaria behavioural de- fences trade-off against life history defences.
{"title":"Contrasting life history responses to fish released infochemicals of two co-occurring Daphnia species that show different migration behaviour","authors":"J. Vijverberg, Arve Doksæter, E. Donk","doi":"10.1127/0003-9136/2006/0167-0089","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0089","url":null,"abstract":"In a previous field study (Flik & Vijverberg 2003) we showed that in an oligotrophic-mesotrophic lake in the Netherlands (L. Maarsseveen) two co-occurring Daphnia species, Daphnia pulicaria and Daphnia galeata x hyalina performed distinct vertical migration behaviour during summer which is induced by a high fish biomass of young perch. During late spring and summer, D. galeata × hyalina exhibits diel vertical migration, whereas D. pulicaria is staying down day and night in the hypolim- nion. This difference in migration behaviour results in contrasting predation mortalities caused by fish, low for D. pulicaria and relatively high for D. galeata × hyalina. In the present study, we measured in the laboratory the effects of fish released infochemicals on five life history traits in four genetically distinct D. galeata × hyalina and three ge- netically distinct D. pulicaria clones collected during summer at day-time from the hypolimnion. We tested the hypothesis that the species which behaviour is providing the best protection against fish predation (i. e. D. pulicaria) is less protected by life his- tory traits induced by fish released infochemicals than the species which by its behav- iour is less well protected against fish predation (i. e. D. galeata × hyalina). Our results show that D. galeata × hyalina responded in three out of five traits differently to fish infochemicals than D. pulicaria. In all these three traits D. galeata × hyalina re- sponded significantly to fish-released infochemicals, whereas D. pulicaria did not show any significant response at all. We conclude that in D. pulicaria behavioural de- fences trade-off against life history defences.","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":"79025503","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: 10.1127/0003-9136/2006/0167-0115
A. Sell
Changes in population dynamics and competitive outcome between Daphnia pulex and D. rosea in response to severe predation by Chaoborus larvae were investigated in a field experiment. In a nearly fishless lake with unusually high densities of Chaoborus flavicans and C. obscuripes, the two coexisting Daphnia species developed morphological defense structures to a different degree. An enclosure-exclosure setup was applied to investigate the population dynamics of both species in presence and absence of the predators. The field study followed the population growth of freshly hatched juveniles of D. pulex and D. rosea as they naturally emerged from ephippia in the lake's sediment during spring. Both Daphnia species have a large body size and, in enclosures with Chaoborus only, developed neckteeth and elongated tail spines as inducible defenses. Nevertheless, Chaoborus accounted for high mortality rates in ephippial neonates and strongly reduced the chance of individuals to reach maturity, especially in D. rosea, the dominant species in enclosures without Chaoborus. It is concluded that, in the first generation, when otherwise large and morphologically defended Daphnia are synchronized by ephippial origin to a population of only juveniles, a trophic cascade with Chaoborus may become highly effective.
{"title":"A trophic cascade with Chaoborus : population dynamics of ex-ephippial generations of Daphnia","authors":"A. Sell","doi":"10.1127/0003-9136/2006/0167-0115","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0115","url":null,"abstract":"Changes in population dynamics and competitive outcome between Daphnia pulex and D. rosea in response to severe predation by Chaoborus larvae were investigated in a field experiment. In a nearly fishless lake with unusually high densities of Chaoborus flavicans and C. obscuripes, the two coexisting Daphnia species developed morphological defense structures to a different degree. An enclosure-exclosure setup was applied to investigate the population dynamics of both species in presence and absence of the predators. The field study followed the population growth of freshly hatched juveniles of D. pulex and D. rosea as they naturally emerged from ephippia in the lake's sediment during spring. Both Daphnia species have a large body size and, in enclosures with Chaoborus only, developed neckteeth and elongated tail spines as inducible defenses. Nevertheless, Chaoborus accounted for high mortality rates in ephippial neonates and strongly reduced the chance of individuals to reach maturity, especially in D. rosea, the dominant species in enclosures without Chaoborus. It is concluded that, in the first generation, when otherwise large and morphologically defended Daphnia are synchronized by ephippial origin to a population of only juveniles, a trophic cascade with Chaoborus may become highly effective.","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":"77425692","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: 10.1127/0003-9136/2006/0167-0533
I. Trubetskova, J. Haney
The effects of differing concentrations of a microcystin-producing strain of Microcystis aeruginosa on the life history characteristics of adult Daphnia magna were studied in long-term experiments under controlled laboratory conditions. D. magna clones from a single female were grown at 2 mg C l -1 of Chlorella vulgaris. After producing the fifth clutch of eggs, D. magna were subjected to different concentrations of M. aeruginosa (0, 3, 6, 12, 25, 50, and 100%) in mixed suspensions with C. vulgaris at combined food concentrations of 2 mg C l -1 . After 6 days of exposure there was a decrease in survivorship, body weight, production of eggs and number of viable neonates with increasing Microcystis concentration. Neonate weights were significantly lower from mothers that had been exposed to pure Microcystis, compared to mothers fed pure Chlorella. The overall pattern showed an increase in neonate weight at low Microcystis concentrations (0-0.24 mg C l -1 ), but decreases at higher concentrations. At Microcystis concentrations above 0.5 mg C l -1 mortality, growth and reproduction were similar to the effects of starvation. Adult Daphnia recovery rate from exposure to toxic Microcystis was related to the exposure concentration of Microcystis. The effects were reversible at low concentrations of Microcystis, (0.06-0.5 mg C l -1 ), but above 0.5 mg C l -1 Microcystis animals did not recover and died. Continuous and linear losses in the body weight of Daphnia with concentration of Microcystis suggest the starvation-like effects on D. magna are caused by either cyanotoxin that is ingested or a chemical produced by Microcystis that inhibits feeding.
在严格控制的实验室条件下，通过长期实验研究了不同浓度的铜绿微囊藻毒素产生菌株对大水蚤成虫生活史特征的影响。小球藻(Chlorella vulgaris)的浓度为2mg c_1 -1。产完第5窝卵后，用不同浓度(0、3、6、12、25、50和100%)的铜绿假单胞菌与普通假单胞菌混合，饲料浓度为2 mg C l -1。暴露6天后，随着微囊藻浓度的增加，存活率、体重、产卵量和活产新生儿数量均下降。与喂食纯小球藻的母亲相比，接触纯微囊藻的母亲的新生儿体重明显较低。总体模式显示低微囊藻浓度(0-0.24 mg cl -1)下新生儿体重增加，但浓度较高时新生儿体重下降。微囊藻浓度高于0.5 mg C l -1时，死亡、生长和繁殖的影响与饥饿相似。成年水蚤暴露于有毒微囊藻后的恢复率与暴露浓度有关。低浓度的微囊藻(0.06 ~ 0.5 mg C l -1)对动物的影响是可逆的，但高于0.5 mg C l -1的微囊藻动物没有恢复并死亡。随着微囊藻浓度的增加，水蚤体重的持续和线性下降表明，对D. magna的饥饿样影响是由摄入的蓝藻毒素或微囊藻产生的抑制摄食的化学物质引起的。
{"title":"Effects of differing concentrations of microcystin-producing Microcystis aeruginosa on growth, reproduction, survivorship and offspring of Daphnia magna","authors":"I. Trubetskova, J. Haney","doi":"10.1127/0003-9136/2006/0167-0533","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0533","url":null,"abstract":"The effects of differing concentrations of a microcystin-producing strain of Microcystis aeruginosa on the life history characteristics of adult Daphnia magna were studied in long-term experiments under controlled laboratory conditions. D. magna clones from a single female were grown at 2 mg C l -1 of Chlorella vulgaris. After producing the fifth clutch of eggs, D. magna were subjected to different concentrations of M. aeruginosa (0, 3, 6, 12, 25, 50, and 100%) in mixed suspensions with C. vulgaris at combined food concentrations of 2 mg C l -1 . After 6 days of exposure there was a decrease in survivorship, body weight, production of eggs and number of viable neonates with increasing Microcystis concentration. Neonate weights were significantly lower from mothers that had been exposed to pure Microcystis, compared to mothers fed pure Chlorella. The overall pattern showed an increase in neonate weight at low Microcystis concentrations (0-0.24 mg C l -1 ), but decreases at higher concentrations. At Microcystis concentrations above 0.5 mg C l -1 mortality, growth and reproduction were similar to the effects of starvation. Adult Daphnia recovery rate from exposure to toxic Microcystis was related to the exposure concentration of Microcystis. The effects were reversible at low concentrations of Microcystis, (0.06-0.5 mg C l -1 ), but above 0.5 mg C l -1 Microcystis animals did not recover and died. Continuous and linear losses in the body weight of Daphnia with concentration of Microcystis suggest the starvation-like effects on D. magna are caused by either cyanotoxin that is ingested or a chemical produced by Microcystis that inhibits feeding.","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":"87919431","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: 10.1127/0003-9136/2006/0167-0245
J. Havel, J. Graham
During its invasion of North America, the exotic Daphnia lumholtzi has rap- idly colonized numerous reservoirs, natural lakes, and large rivers. In the current study, we examine the overlap between D. lumholtzi and native Daphnia species through analysis of two data sets: co-occurrence in reservoirs of the south-central United States and population dynamics in one reservoir. In 171 reservoirs and oxbow lakes, D. lumholtzi was among the most prevalent species and its distribution was independent of other Daphnia species. Over a 28-month period in Stockton Lake, Mis- souri, D. lumholtzi was abundant only in late summer, a period when the epilimnion was warm (25 - 30 uC) and cyanobacteria were common. Native Daphnia (D. mendo- tae, D. parvula, and D. retrocurva) complemented this pattern, being generally rare in summer and most abundant during winter and spring. Peak densities and average fecundities of native Daphnia during the cooler months were typically greater than densities and fecundities of D. lumholtzi in summer. The complementary population dynamics between native and exotic species may be significant for the food webs in warm reservoirs, with D. lumholtzi providing another food resource when the abun- dance of large zooplankton is ordinarily low.
{"title":"Complementary population dynamics of exotic and native Daphnia in North American reservoir communities","authors":"J. Havel, J. Graham","doi":"10.1127/0003-9136/2006/0167-0245","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0245","url":null,"abstract":"During its invasion of North America, the exotic Daphnia lumholtzi has rap- idly colonized numerous reservoirs, natural lakes, and large rivers. In the current study, we examine the overlap between D. lumholtzi and native Daphnia species through analysis of two data sets: co-occurrence in reservoirs of the south-central United States and population dynamics in one reservoir. In 171 reservoirs and oxbow lakes, D. lumholtzi was among the most prevalent species and its distribution was independent of other Daphnia species. Over a 28-month period in Stockton Lake, Mis- souri, D. lumholtzi was abundant only in late summer, a period when the epilimnion was warm (25 - 30 uC) and cyanobacteria were common. Native Daphnia (D. mendo- tae, D. parvula, and D. retrocurva) complemented this pattern, being generally rare in summer and most abundant during winter and spring. Peak densities and average fecundities of native Daphnia during the cooler months were typically greater than densities and fecundities of D. lumholtzi in summer. The complementary population dynamics between native and exotic species may be significant for the food webs in warm reservoirs, with D. lumholtzi providing another food resource when the abun- dance of large zooplankton is ordinarily low.","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":"91416586","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: 10.1127/0003-9136/2006/0167-0281
C. Harrod, J. Grey
Analysis of carbon and nitrogen stable isotopes has allowed freshwater ecologists to examine lake food webs in increasing detail. Many such studies have highlighted the existence of separate within-lake pelagic and benthic-littoral food webs but are typically conducted on large (> 10 km2) lakes, whereas the majority of lakes are actually relatively small. We used stable isotope analysis (δ13C & δ15N) to examine trophic interactions between fish and their prey in Plussee, as an example of a small, stratifying lake, and to determine whether separate pelagic/benthic-littoral food webs could be distinguished in such systems. Our results indicate that the Plussee food web was complicated, and due to extensive intra-annual isotopic variation in zooplankton (e.g.cladoceran δ13C annual range = 25.6‰), it may be impossible to definitively assign consumers from small, eutrophic stratified lakes to pelagic or benthic-littoral food webs. We present evidence that some components of the Plussee food web (large bream) may be subsidised by carbon of methanogenic origin.
{"title":"Isotopic variation complicates analysis of trophic relations within the fish community of Plußsee: a small, deep, stratifying lake","authors":"C. Harrod, J. Grey","doi":"10.1127/0003-9136/2006/0167-0281","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0281","url":null,"abstract":"Analysis of carbon and nitrogen stable isotopes has allowed freshwater ecologists to examine lake food webs in increasing detail. Many such studies have highlighted the existence of separate within-lake pelagic and benthic-littoral food webs but are typically conducted on large (> 10 km2) lakes, whereas the majority of lakes are actually relatively small. We used stable isotope analysis (δ13C & δ15N) to examine trophic interactions between fish and their prey in Plussee, as an example of a small, stratifying lake, and to determine whether separate pelagic/benthic-littoral food webs could be distinguished in such systems. Our results indicate that the Plussee food web was complicated, and due to extensive intra-annual isotopic variation in zooplankton (e.g.cladoceran δ13C annual range = 25.6‰), it may be impossible to definitively assign consumers from small, eutrophic stratified lakes to pelagic or benthic-littoral food webs. We present evidence that some components of the Plussee food web (large bream) may be subsidised by carbon of methanogenic origin.","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":"83906668","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: 10.1127/0003-9136/2006/0167-0447
N. Aberle, K. Wiltshire
Investigations on the littoral microphytobenthos populations of lakes are very rare. Based on new sampling techniques, allowing the undisturbed sampling of sublittoral sediments, we present information on limnic microphytobenthos populations of the Schohsee in Northern Germany (10° 26′ E, 54° 13′ N). Investigations on microphytobenthic communities at a sandy and a muddy site provided new insights into the community structure and seasonal variations of limnic benthic microalgae. The microphytobenthos was characterised by low chlorophyll-a contents (0.16 μg cm−2 to 0.74 μg cm−2) and low cell numbers (25 cells cm−2 to 266 cells cm−2). Both sites showed similar patterns in terms of algal biomass and seasonality; no site-specific characteristics were observed. The productivity of the sediment microflora in the Schohsee was low and most likely related to the mesotrophic lake character and to reduced light conditions in the near-shore sublittoral. The algal communities at both sites showed high diversity, distinct seasonality and succession patterns with shifts in community composition in spring, summer and autumn. The community was dominated by Fragilaria spp., Navicula spp., Nitzschia spp., and Stauroneis spp. in spring shifting to a Stauroneis spp.-dominated community in summer. In autumn the populations were dominated by Navicula spp., Nitzschia spp., and Stauroneis spp. Overall, the taxonomic composition showed a dominance of prostrate diatoms, whereas cyanobacteria, green algae and erect diatoms occurred rarely and with low abundance. Thus, the sediment microflora of the Schohsee can be characterized as a flat, two-dimensional community.
{"title":"Seasonality and diversity patterns of microphytobenthos in a mesotrophic lake","authors":"N. Aberle, K. Wiltshire","doi":"10.1127/0003-9136/2006/0167-0447","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0447","url":null,"abstract":"Investigations on the littoral microphytobenthos populations of lakes are very rare. Based on new sampling techniques, allowing the undisturbed sampling of sublittoral sediments, we present information on limnic microphytobenthos populations of the Schohsee in Northern Germany (10° 26′ E, 54° 13′ N). Investigations on microphytobenthic communities at a sandy and a muddy site provided new insights into the community structure and seasonal variations of limnic benthic microalgae. The microphytobenthos was characterised by low chlorophyll-a contents (0.16 μg cm−2 to 0.74 μg cm−2) and low cell numbers (25 cells cm−2 to 266 cells cm−2). Both sites showed similar patterns in terms of algal biomass and seasonality; no site-specific characteristics were observed. The productivity of the sediment microflora in the Schohsee was low and most likely related to the mesotrophic lake character and to reduced light conditions in the near-shore sublittoral. The algal communities at both sites showed high diversity, distinct seasonality and succession patterns with shifts in community composition in spring, summer and autumn. The community was dominated by Fragilaria spp., Navicula spp., Nitzschia spp., and Stauroneis spp. in spring shifting to a Stauroneis spp.-dominated community in summer. In autumn the populations were dominated by Navicula spp., Nitzschia spp., and Stauroneis spp. Overall, the taxonomic composition showed a dominance of prostrate diatoms, whereas cyanobacteria, green algae and erect diatoms occurred rarely and with low abundance. Thus, the sediment microflora of the Schohsee can be characterized as a flat, two-dimensional community.","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":"77411999","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: 10.1127/0003-9136/2006/0167-0077
J. Pijanowska, Piotr Dawidowicz, L. Weider
We studied the effects of predator exudates on evasion efficiency in two Daphnia magna clones that differed in their sensitivity to the kairomones. Pre-expo- sure to kairomones significantly increased the chances of survival of sensitive Daphnia when confronted with actively-foraging invertebrate and vertebrate predators, as com- pared to individuals which had not been pre-exposed to predator chemical cues. The induced response is adaptive: predators foraging on a mixture of sensitized and non- sensitized individuals, first removed those which had not been pre-exposed, or were non-sensitive to predator exudates. Predator-induced escape responses, therefore, can be a target for selection.
{"title":"Predator-induced escape response in Daphnia","authors":"J. Pijanowska, Piotr Dawidowicz, L. Weider","doi":"10.1127/0003-9136/2006/0167-0077","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0077","url":null,"abstract":"We studied the effects of predator exudates on evasion efficiency in two Daphnia magna clones that differed in their sensitivity to the kairomones. Pre-expo- sure to kairomones significantly increased the chances of survival of sensitive Daphnia when confronted with actively-foraging invertebrate and vertebrate predators, as com- pared to individuals which had not been pre-exposed to predator chemical cues. The induced response is adaptive: predators foraging on a mixture of sensitized and non- sensitized individuals, first removed those which had not been pre-exposed, or were non-sensitive to predator exudates. Predator-induced escape responses, therefore, can be a target for selection.","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":"82283990","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: 10.1127/0003-9136/2006/0167-0317
P. Deines, J. Grey
Previous analyses of larval chironomid δ13C have suggested that methanotrophic contribution to biomass is site-specific within lakes. We determined larval biomass, larval and methane gas stable carbon isotopes, and potential methane production from the sediments underlying different water column depths in Esthwaite Water, UK. Methane production increased whereas larval δ13C values typically became lighter with increasing lake depth. Reduced methane production at 15 m depth and correspondingly less13C-depleted larvae in the second year of study suggests that the rate of methane production influenced larval assimilation of methane-derived biomass. Larval distribution and other site-specific parameters, combined with two-source mixing models, were used to estimate potential methane-mediation via the abundant chironomid biomass to higher predators.
{"title":"Site-specific methane production and subsequent midge mediation within Esthwaite Water, UK","authors":"P. Deines, J. Grey","doi":"10.1127/0003-9136/2006/0167-0317","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-0317","url":null,"abstract":"Previous analyses of larval chironomid δ13C have suggested that methanotrophic contribution to biomass is site-specific within lakes. We determined larval biomass, larval and methane gas stable carbon isotopes, and potential methane production from the sediments underlying different water column depths in Esthwaite Water, UK. Methane production increased whereas larval δ13C values typically became lighter with increasing lake depth. Reduced methane production at 15 m depth and correspondingly less13C-depleted larvae in the second year of study suggests that the rate of methane production influenced larval assimilation of methane-derived biomass. Larval distribution and other site-specific parameters, combined with two-source mixing models, were used to estimate potential methane-mediation via the abundant chironomid biomass to higher predators.","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":"76974384","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: 10.1127/0003-9136/2006/0167-0183
A. Bohonak, M. Holland, B. Santer, M. Zeller, C. Kearns, N. Hairston
Prolonged diapause (extended dormancy) is thought to greatly influence evolution in freshwater invertebrates by lengthening generation time, promoting higher levels of dispersal among populations by wind or animal vectors, and increasing effective population size. However, empirical tests of these predictions are relatively rare. Comparative studies can be informative in this regard, if the comparisons involve sympatric, closely related species that differ only in the presence or absence of a dormant life history stage. We built upon a previous study by ZELLER et al. (2006), which used this approach to study patterns of microsatellite variation in Eudiaptomus copepods from northern Europe. E. graciloides possesses diapausing eggs and adults, whereas the closely related species E. gracilis is ecologically and trophically similar but lacks diapause. To separate further historical processes from recent anthropogenic influences, we examined mitochondrial DNA sequence variation in these species from three lakes in northern Germany where they are sympatric. Biotic and abiotic variation among contemporary and historical populations was minimized by focusing on hydro-logically linked lakes separated by less than 10km. E. gracilis and E. graciloides possess very different patterns of mtDNA variation. Both species possess significant population structure on small spatial scales, but E. graciloides has far fewer alleles despite a larger average divergence. Phylogeographic analyses and Bayesian skyline plots revealed evidence for historic population expansions in both species, with the growth phase beginning thousands of generations earlier in E. gracilis than in E. graciloides. Levels of genetic diversity suggest that effective population size may be an order of magnitude larger in E. gracilis than in E. graciloides, even though E. graciloides possesses a diapausing egg bank. Although this would seem to be an ideal system for quantifying the genetic role of diapause, we found no support for the assumption that freshwater invertebrates with diapause categorically possess larger effective population sizes and higher rates of gene flow than closely related species that lack diapause.
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Pub Date : 2006-09-01DOI: 10.1127/0003-9136/2006/0167-000V
M. Boersma, B. Santer
{"title":"Winfried Lampert: Natural selection is ecology in action","authors":"M. Boersma, B. Santer","doi":"10.1127/0003-9136/2006/0167-000V","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0167-000V","url":null,"abstract":"","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":"86776380","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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