Using morphological characters of subfossil daphniid postabdominal claws to improve taxonomic resolution within species complexes

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

doi:10.1007/s10750-011-0779-0

Cited by 19 publications

(12 citation statements)

References 36 publications

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“…Daphniids were merged into two groups, the Daphnia longispina species complex (herein referred to as D. longispina spp., comprised of D. longispina , D. ambigua , D. mendotae , D. dentifera , D. dubia , and D. longiremis ) and the Daphnia pulex species complex (herein referred to as D. pulex spp., comprised of D. pulex , D. pulicaria , D. catawba , and D. minehaha ), as postabdominal claws are often the only well‐preserved daphniid remain in the sediment record and can only be broadly grouped based on morphology (e.g. Korosi et al., 2011). The original research projects referred to either Holopedium gibberum or Holopedium glacialis depending on publication date, due to taxonomic revisions based upon genetic analyses (Rowe et al., 2007); however, as these taxa cannot be differentiated visually in the sedimentary record, they were combined as Holopedium spp.…”

Section: Methodsmentioning

confidence: 99%

Environmental drivers of cladoceran assemblages at a continental scale: A synthesis of Alaskan and Canadian datasets

et al. 2021

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Cladocera serve as important bio‐ and paleo‐indicators of lake food webs and environmental conditions. The ecological optima of cladocerans are often established by regional‐scale calibration sets, with subsequent comparisons to limnological variables. However, due to logistical constraints when sampling large numbers of lakes, this approach often limits the length of the environmental gradients that can be examined. To extend spatial and limnological gradients, we combined 20 datasets (388 lakes) containing both cladoceran and environmental data, spanning multiple ecoregions across Canada and Alaska. These data were collected over c. 20 years using similar techniques in a single laboratory. Our continental‐scale analysis examined the main chemical and physical variables that influenced cladoceran assemblages, and identified critical environmental thresholds structuring assemblages. Multivariate analyses were used to examine the influences of six environmental variables (depth [either maximum depth or coring depth, which are very similar], surface area, pH, calcium [Ca], total phosphorus [TP], and dissolved organic carbon) and ecoregion classifications on cladoceran assemblages. Gradients of pH and Ca were strongly related. Daphnia longispina spp. and Chydorus brevilabris/biovatus were associated with higher pH and Ca concentrations, while Bosmina spp. and Holopedium spp. were more common in lakes with lower pH and Ca. Dissolved organic carbon was highly correlated with TP. Chydorus brevilabris/biovatus was associated with higher‐nutrient systems. Littoral chydorids, D. longispina spp., Holopedium spp., and Daphnia pulex spp. were associated with intermediate TP and dissolved organic carbon concentrations, and Bosmina spp. was more closely associated with oligotrophic systems. Physical limnological variables influenced taxonomic composition on a continental scale. For example, D. longispina spp., D. pulex spp., Bosmina spp., and Holopedium spp. were associated with larger and/or deeper systems, and littoral chydorids were associated with smaller and/or shallower lakes. A multivariate regression tree identified two thresholds important for structuring assemblages based on pH (<7 and ≥7, probably closely tied to lakewater Ca concentrations) and depth (<6.45 m and ≥6.45 m at pH < 7, and <4.75 m and ≥4.75 m at pH ≥ 7). Our results highlight the sensitivity of several cladoceran taxa to multiple chemical and physical gradients. We demonstrate that the ecological responses of cladocerans to environmental variables—often established through regional‐scale surveys—are applicable across ecoregions and broad limnological gradients, reinforcing the value of cladocerans as bioindicators of key chemical and physical variables in freshwaters and as paleoindicators for assessing human impacts on aquatic systems through time.

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Section: Methodsmentioning

confidence: 99%

Environmental drivers of cladoceran assemblages at a continental scale: A synthesis of Alaskan and Canadian datasets

et al. 2021

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“…The PCL of Daphnia community was measured for each layer of two sediment core samples (Lim2 and Mac3) as an index of fish predation pressure following Korosi et al. (2011), using photographs taken by a digital camera (ARTCAM‐130MI) at 200× magnification ( n = 1,097).…”

Section: Methodsmentioning

confidence: 99%

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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“…Daphniid remains were attributed to a particular species complex based on the presence/absence of stout spines on the middle comb of the postabdominal claw (Korosi et al 2011): in this geographic region the D. pulex complex (stout spines present) can include D. pulex, D. pulicaria, D. catawba and D. minehaha; and the D. longispina complex (stout spines absent) can include D. ambigua, D. mendotae, D. longiremis, D. dentifera, D. dubia, D. parvula and D. retrocurva (Hebert 1995;Yan et al 2008b). …”

Section: Sample Preparation and Cladoceran Analysismentioning

confidence: 99%

“…The application of daphniids to questions regarding environmental Ca decline is complicated by the lack of taxonomic resolution among the sedimentary remains of daphniid species (Szeroczyńska and Sarmaja-Korjonen 2007;Korosi et al 2011), and the apparent tolerance for low Ca concentrations of at least one species (i.e. D. catawba) among the members of the D. pulex species complex Shapiera et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Changes since the onset of acid deposition among calcium-sensitive cladoceran taxa within softwater lakes of Ontario, Canada

2012

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Aqueous calcium (Ca) concentrations are currently decreasing in many softwater lakes on the Boreal Shield. As the onset of these declines often predate direct monitoring programs, indirect techniques are required to examine the impacts of reduced Ca availability on aquatic communities with relatively high Ca demands such as the Cladocera (Class: Branchiopoda). Among the Cladocera, the family Daphniidae has been identified as a taxonomic group potentially useful for inferring past Ca concentrations due to their high Ca demands and preservation in lake sediments. Here, we use a ''top/bottom'' paleolimnological analysis to compare present-day cladoceran communities preserved in the surface sediments of 36 softwater lakes in south-central Ontario, Canada, which are potentially vulnerable to Ca decline (i.e. small headwater systems with present-day lakewater [Ca] \ 3 mg L -1 ), with the communities present in lake sediments deposited prior to the onset of regional acid deposition. To distinguish the potential impacts of lake acidification from those of Ca availability (as Ca and pH trends are strongly correlated in this region), the study lakes were chosen to be evenly distributed about a present-day lakewater pH of 6 and Ca concentration of 1.5 mg L -1 (threshold values). Despite the importance of pH as an explanatory variable for the present-day assemblages, a comparison of the sedimentary remains from the two time periods indicate there have been large declines since pre-industrial times in the relative abundances of Ca-rich Daphnia spp. (particularly of the Daphnia longispina species complex), regardless of presentday pH, accompanied by increases in the Ca-poor species Holopedium glacialis. These observations suggest that recent declines in Ca concentration may have already fallen below baseline conditions, with marked implications for ecosystem function due to the differential responses among cladoceran taxa.

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Using morphological characters of subfossil daphniid postabdominal claws to improve taxonomic resolution within species complexes

Cited by 19 publications

References 36 publications

Environmental drivers of cladoceran assemblages at a continental scale: A synthesis of Alaskan and Canadian datasets

Environmental drivers of cladoceran assemblages at a continental scale: A synthesis of Alaskan and Canadian datasets

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

Changes since the onset of acid deposition among calcium-sensitive cladoceran taxa within softwater lakes of Ontario, Canada

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