Examining the effects of climate change, acidic deposition, and copper sulphate poisoning on long-term changes in cladoceran assemblages

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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“…and Bosmina spp. to increases in fish predation (Korosi and Smol, 2012). On the other hand, Bosmina spp.…”

Section: Discussionmentioning

confidence: 97%

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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“…Consequently, Glasgow Lake is considered a sentinel of widespread acidification that might have occurred in CBHNP if emission restrictions had not been implemented (Gerber et al 2008). Interestingly, an additional lake in the Park, Round Lake, experienced declines in the relative abundance of the acid-sensitive zooplankter Daphnia in the early 1900s (Korosi and Smol 2012c), consistent with the timing of diatominferred acidification in Glasgow Lake. This suggests that Round Lake may have experienced some early effects of acidification, although DI pH indicated that current lakewater pH is similar to that inferred for the pre-industrial sediment layer (Ginn et al 2007c).…”

Section: Fig 2 a Map Of The Study Lakes Examined In Recent Paleolimmentioning

confidence: 81%

“…In Pebbleogittch Lake (KNP), the appearance and increase in Holopedium corresponded to DI pH declines; but in Kejimkujik Lake (KNP), the increase in Holopedium occurred much later, postacidification (Korosi and Smol 2012b). Similarly, Holopedium appeared in Hirtle Lake (Bridgewater), a lake that never acidified, in the 1990s (Korosi and Smol 2012c). This suggests that the rise of Holopedium in Nova Scotia is related to multiple stressors, including, but not limited to, lakewater acidification.…”

Section: Fig 2 a Map Of The Study Lakes Examined In Recent Paleolimmentioning

confidence: 88%

“…Ca decline, then, has potentially severe implications for water quality and aquatic food web functioning in Nova Scotia lakes and elsewhere. Detailed sediment cores analyzed for Cladocera from two additional lakes near Bridgewater and one near Yarmouth showed no negative impact of declining Ca on Daphnia (Korosi and Smol 2012c), suggesting that Daphnia taxa historically present in Nova Scotia may be better adapted to low-Ca lakes than their counterparts in south-central Ontario, because most of these lakes are naturally very low in Ca. Nova Scotia contains fewer species of Daphnia than south-central Ontario (DeSellas et al 2011;Jeziorski et al 2012), and the most common daphniid in Nova Scotia is the acid-and low-Ca tolerant Daphnia catawba, while daphniids known to be sensitive to low Ca, like most of those in the D. longispina complex (Cairns 2010), have never been recorded in Nova Scotia (Hebert 1995).…”

Section: Acidic Deposition and Lakewater Calcium Declinementioning

confidence: 98%

“…Holopedium shows a clear preference for low-pH lakes (Hessen et al 1995;Korosi and Smol 2011), and this taxon's increase in KNP could be related to surface-water acidification. To assess the timing of the appearance of Holopedium and relate it to acidification, cladoceran subfossils were later analyzed in detailed sediment cores from three lakes in KNP (Korosi and Smol 2012b) and one lake in nearby Bridgewater (Korosi and Smol 2012c). In Pebbleogittch Lake (KNP), the appearance and increase in Holopedium corresponded to DI pH declines; but in Kejimkujik Lake (KNP), the increase in Holopedium occurred much later, postacidification (Korosi and Smol 2012b).…”

Section: Fig 2 a Map Of The Study Lakes Examined In Recent Paleolimmentioning

confidence: 99%

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Establishing past environmental conditions and tracking long-term environmental change in the Canadian Maritime provinces using lake sediments

et al. 2013

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Freshwater lakes in the Canadian Maritime provinces have been detrimentally influenced by multiple, often synergistic, anthropogenically-sourced environmental stressors. These include surface-water acidification (and a subsequent decrease in calcium loading to lakes); increased nutrient inputs; watershed development; invasive species; and climate change. While detailed studies of these stressors are often hindered by a lack of predisturbance monitoring information; in many cases, these missing data can be determined using paleolimnological techniques, along with inferences on the full extent of environmental change (and natural variability), the timing of changes, and linkages to probable causes for change. As freshwater resources are important for fisheries, agriculture, municipal drinking water, and recreational activities, among others, understanding longterm ecological changes in response to anthropogenic stressors is critical. To assess the impacts of the major water-quality issues facing freshwater resources in this ecologically significant region, a large number of paleolimnological studies have recently been conducted in Nova Scotia and southern New Brunswick. These studies showed that several lakes in southwestern Nova Scotia, especially those in Kejimkujik National Park, have undergone surface-water acidification (mean decline of 0.5 pH units) in response to local-source SO 2 emissions and the long-range transport of airborne pollutants. There has been no measureable chemical or biological recovery since emission restrictions were enacted. Lakewater calcium (Ca) decline, a recently recognized environmental stressor that is inextricably linked to acidification, has negatively affected the keystone zooplankter Daphnia in at least two lakes in Nova Scotia (and likely more), with critical implications for aquatic food webs. A consistent pattern of increasing planktonic diatoms and scaled chrysophytes was observed in lakes across Nova Scotia and New Brunswick, suggesting that the strength and duration of lake thermal stratification has increased since pre-industrial times in response to warming temperatures (ϳ1.5°C since 1870). These include three lakes near Bridgewater, Nova Scotia, that are among the last known habitat for critically endangered Atlantic whitefish (Coregonus huntsmani). Overall, these studies suggest that aquatic ecosystems in the Maritime Provinces are being affected by multiple anthropogenic stressors and paleolimnology can be effective for inferring the ecological implications of these stressors. Résumé :Les lacs d'eau douce des provinces maritimes canadiennes ont été influencés de façon néfaste par de multiples agents stressants environnementaux souvent synergiques et de sources anthropogènes, incluant l'acidification de l'eau de surface (avec une diminution subséquente de la charge en calcium dans les lacs), les apports accrus en nutriment, le développement des bassins versants, les espèces envahissantes ainsi que le changement climatique. Alors que les études détaillées de ces agents ...

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Long‐term dynamics of a cladoceran community from an early stage of lake formation in Lake Fukami‐ike, Japan

Otake

Ohtsuki

Urabe

et al. 2020

Ecology and Evolution

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An increase in nutrient levels due to eutrophication has considerable effects on lake ecosystems. Cladocerans are intermediate consumers in lake ecosystems; thus, they are influenced by both the bottom‐up and top‐down effects that occur as eutrophication progresses. The long‐term community succession of cladocerans and the effects cladocerans experience through the various eutrophication stages have rarely been investigated from the perspective of the early‐stage cladoceran community assemblage during lake formation. In our research, long‐term cladoceran community succession was examined via paleolimnological analysis in the currently eutrophic Lake Fukami‐ike, Japan. We measured the concentration of total phosphorus and phytoplankton pigments and counted cladoceran and other invertebrate subfossils in all layers of collected sediment cores, and then assessed changes in the factors controlling the cladoceran community over a 354‐year period from lake formation to the present. The cladoceran community consisted only of benthic taxa at the time of lake formation. When rapid eutrophication occurred and phytoplankton increased, the benthic community was replaced by a pelagic community. After further eutrophication, large Daphnia and high‐order consumers became established. The statistical analysis suggested that bottom‐up effects mainly controlled the cladoceran community in the lake's early stages, and the importance of top‐down effects increased after eutrophication occurred. Total phosphorus and phytoplankton pigments had positive effects on pelagic Bosmina, leading to the replacement of the benthic cladoceran community by the pelagic one. In contrast, the taxa established posteutrophication were affected more by predators than by nutrient levels. A decrease in planktivorous fish possibly allowed large Daphnia to establish, and the subsequent increase in planktivorous fish reduced the body size of the cladoceran community.

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Examining the effects of climate change, acidic deposition, and copper sulphate poisoning on long-term changes in cladoceran assemblages

Cited by 22 publications

References 46 publications

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)

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)

Establishing past environmental conditions and tracking long-term environmental change in the Canadian Maritime provinces using lake sediments

Long‐term dynamics of a cladoceran community from an early stage of lake formation in Lake Fukami‐ike, Japan

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