Establishing reliable minimum count sizes for cladoceran subfossils sampled from lake sediments

Kurek, Joshua; Korosi, Jennifer B.; Jeziorski, Adam; Smol, John P.

doi:10.1007/s10933-010-9440-6

Cited by 124 publications

(76 citation statements)

References 45 publications

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“…We counted and identified remains from a minimum of 90 individual cladocerans per sample [31,32], of which a mean of 78 and 61% were pelagic taxa in the Ontario and Nova Scotia lakes, respectively. This count is sufficient to characterize the taxonomic assemblage accurately [33]. We tested whether the contribution of Holopedium to planktonic cladoceran assemblages had changed since pre-industrial times using paired t-tests comparing Holopedium relative abundance in the pre-industrial versus recent lakewater Ca decline?…”

Section: Methodsmentioning

confidence: 99%

The jellification of north temperate lakes

et al. 2015

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Calcium (Ca) concentrations are decreasing in softwater lakes across eastern North America and western Europe. Using long-term contemporary and palaeo-environmental field data, we show that this is precipitating a dramatic change in Canadian lakes: the replacement of previously dominant pelagic herbivores (Ca-rich Daphnia species) by Holopedium glacialis, a jelly-clad, Ca-poor competitor. In some lakes, this transformation is being facilitated by increases in macro-invertebrate predation, both from native (Chaoborus spp.) and introduced (Bythotrephes longimanus) zooplanktivores, to which Holopedium, with its jelly coat, is relatively invulnerable. Greater representation by Holopedium within cladoceran zooplankton communities will reduce nutrient transfer through food webs, given their lower phosphorus content relative to daphniids, and greater absolute abundances may pose long-term problems to water users. The dominance of jelly-clad zooplankton will likely persist while lakewater Ca levels remain low.

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Section: Methodsmentioning

confidence: 99%

The jellification of north temperate lakes

et al. 2015

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“…Taxonomical identification was based on Flössner (2000), Margaritora (1983) and Szeroczyńska and Sarmaja-Korjonen (2007). Three to six slides were counted for each sample in order to obtain a minimum of 100 Cladocera individuals (Kurek et al, 2010). This minimum was not achieved in a few samples with extremely scarce Cladocera remains.…”

Section: Subfossil Cladoceramentioning

confidence: 99%

Combining sediment Cladocera remains and geochemistry to reveal the role of a large catchment in driving changes in a small subalpine lake (Lake Ledro, N-Italy)

2016

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Sediment Cladocera remains and geochemistry were analyzed at Lake Ledro, a small subalpine lake with a large catchment area located in northern Italy. The aim of the study was to investigate human, climate and hydrological impacts on the Cladocera community and on the geochemical components during the last few centuries. A sediment core was collected from the deepest point of Lake Ledro and radiometrically dated. Cladocera remains were analyzed to track the trophic lake evolution. The core bottom section revealed the dominance of Bosminidae in concomitance with nutrient pulses entering into the lake during major flood events. The abundance of species preferring cold water temperatures confirmed the deposition of this core section during the Little Ice Age. The flood event occurred in the first half of the 19th century produced a drastic increase in littoral species, due to the development of new habitats. The decrease in Cladocera densities during the following lake stage was followed by a rapid increase in planktonic species during the nutrient enrichment after the 1960s. Statistical analyses revealed a clear response of Cladocera community to climate variability during oligotrophic periods, while no relation to temperature changes was recorded during high nutrient levels. A preliminary study on Bosminidae and Daphnidae body size and appendages length was carried out to reconstruct major changes in the lake food web. Only Bosminia spp. revealed clear body size changes: minor shifts were recorded before the 1930s in relation to the low nutrient concentrations, while the major changes occurred during the 1980s were interpreted as related to the appearance of Cladocera invertebrate predators. Geochemical components were studied using X-ray fluorescence spectroscopy (XRF) analysis in order to recognize the impact of the large catchment area and from the lake-level regulations on the lake hydrology. Moreover the Si:Al ratios profile confirmed the increase in lake productivity after the 1960s. Although both Cladocera and geochemical analysis indicate major changes since the 1960s, they also revealed diverse responses to common external and local forcing, thus confirming the value of a multi-proxy approach for disentangling the lake responses to different environmental stressors. Moreover, it outlined the importance of larger catchment areas on small lakes as they are to a larger extent influenced by the modifications occurring in the drainage basin.

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“…Kurek et al (2010) examined the effect of cladoceran count sizes on species richness and the relative abundances of dominant taxa, and they showed that counts of at least 70-100 individuals were required for accuracy. Reavie and Juggins (2011) explored the effects of training-set size on the performance of diatom-based inference models that predict limnetic total phosphorus.…”

Section: Transfer Function Models: Improvements and Qualificationsmentioning

confidence: 99%