Cladoceran Analyses Research Articles

Latitudinal patterns of shifts in cladoceran communities throughout the Holocene: A paleoecological case study of northwestern Russia

Paleolimnology is a rapidly expanding field within the natural sciences. To date, many scientific papers have been published focusing on studies of remains from single sediment cores in specific lakes, or a few cores from the same water body. However, few previous publications have provided a comprehensive comparative analysis of taphocenosis (and maternal community) changes in different water bodies from a large geographical region during whole Holocene using multivariate statistical methods. We conducted a joined statistical analysis of data obtained as a result of the cladoceran analysis of the sediment samples from six cores taken along the North-South transect from the Kola Peninsula to the Karelian Region (North-West Russia). Our aim was to identify, based on quantitative statistical methods, general whole-Holocene patterns in cladoceran taphocenosis changes. All taphocenoses in all cores from six lakes can be classified into six clusters based on their species composition. Our unexpected conclusion is that different taphocoenoses are formed by the same set of species, but their proportions vary significantly. This suggests that the same species may play different functional roles in different maternal communities. During whole Holocene, we observed a single taphocenosis cluster in the Holocene core from Lake Antyukh-Lambina, and four taphocenosis clusters in the Lake Medvedevskoe, with an intermediate number of clusters in the lakes between them. Furthermore, it can be asserted that the potential for cluster changes in the core is greater for the more southern studied water bodies (0–3 clusters for northern lakes vs. 4 clusters for southern lakes). Based on our data, we hypothesize that the diversity of cladoceran associations during the Holocene was lower in Arctic/Subarctic lakes, possibly due to their formation by ubiquitous species. Our study suggests that at least some Arctic lake ecosystems have remained unchanged since deglaciation times. Further studies are necessary to determine if this is a general rule.

The rise and fall of primary producers and consumers in a multiply-stressed shallow lake (Lake Qilu, China) over the last 200 years

In this multi-proxy palaeo study, the response of primary producers and consumers to anthropogenic disturbances in a large shallow lake was investigated. Overall, eutrophication and water-level changes (partly inferred by bisaccate pollen grains) are well-reflected in changes in sedimentation rates of pigments, diatom and cladoceran species composition and other proxies (e.g. Rhabdocoela oocytes). In particular, the stepwise decrease in relative abundance of Pediastrum simplex compared to P. boryanum/P. duplex proved to be a good indicator for eutrophication intensity. Furthermore, reductions in the body size (i.e. coenobia diameter) of Pediastrum simplex were clearly related to phases of low visibility that were caused by lake damming in the 1950 s and by accelerating eutrophication in the 1990 s. During the latter period, strong algal growth led to turbid conditions, which are indicated by the co-occurrence of the diatoms Fragilaria crotonensis, Aulacoseira ambigua and A. granulata, the green algae Staurastrum sp. as well as the cladoceran Anthalona cf. milleri. This study highlights that subfossil remains, which are often found in, for instance, standard cladoceran analysis (green algae such as Pediastrum spp. and Staurastrum spp. or bisaccate pollen grains), can add valuable information to the reconstruction of past environmental conditions and biotic response. Such better and more holistic understanding of freshwater ecosystems is crucial to meet future challenges in a rapidly changing world.

Reconstruction of the history of a thermokarst lake in the Mid-Holocene based on an analysis of subfossil Cladocera (Siberia, Central Yakutia)

This paper presents the results of a cladoceran analysis of a sediment core with a lenght of 382 cm collected from a pingo in alas Khara Bulgunnyakh located in Central Yakutia. Based on the Cladocera analysis results, the formation of the lake had started during the Holocene climatic optimum ~6600 cal. yrs. BP. The analysis of changes in the species composition of subfossil cladoceran communities made it possible to identify, on the basis of cluster analysis, four statistically significant ecological zones. The period of optimal conditions for the Cladocera community is defined by a complex evened community structure and numerous cladoceran remains in the sediments accumulated between 6500 and 6000 cal. yrs. BP. The history of the thermokarst water body development and existence reconstructed on the basis of the subfossil cladoceran analysis was rapid and short.

Fossil cladoceran record from Lake Piramide Inferiore (5067 m asl) in the Nepalese Himalayas: biogeographical and paleoecological implications

We investigated 2500 years of community succession in Cladocera from the sediments of a mountain lake (Lake Piramide Inferiore) located in the Khumbu Valley close to Mt. Everest in the Nepalese Himalayas. Our objective was to determine late Holocene changes in cladoceran species composition and abundance in a biogeographical context and with respect to previous proxy-based paleolimnological data (algal pigments and organic content). The results suggested that cladoceran fauna of Lake Piramide Inferiore was species-poor and dominated by Chydorus cf. sphaericus throughout the sequence. The sediment profile recorded the occurrence of Alona guttata type individuals, which were attributed to Alona werestschagini Sinev 1999 based on their morphology and the species' current distributional range, and this was the first record of its presence in the Himalayas. In addition, a periodic long-term succession of melanic Daphnia (Ctenodaphnia) fusca Gurney, 1907 and non-melanic D. (Daphnia) dentifera Forbes 1893 was observed in the sediments. The millennia-long cladoceran community changes, although subtle due to the C. cf. sphaericus dominance, were in general agreement with the previous proxy-data of lake productivity following the regional paleoclimatic development and apparently partly driven by bottom-up mechanisms. The periodic occurrence and success of D. fusca and D. dentifera throughout the late Holocene in Lake Piramide Inferiore, combined with the knowledge of their phenotypic properties (i.e. carapace melanization) and previous investigations on their contemporary and past distribution in Khumbu Valley, suggested that they may have responded to altered underwater UV radiation regimes. Furthermore, they may have even periodically excluded each other subsequent to changes in the underwater UV environment. The results indicated the usefulness of fossil cladoceran analysis as a tool in biogeographical research, since the occurrence of species in space and time can be observed through sediment records and taxonomic identity of the remains may be resolved with the help of regional faunal distribution.

Multiproxy environmental archaeology of Neolithic settlements at Osłonki, Poland, 5500–4000 BC

Archaeological research on Neolithic settlements (ca. 5500–4000 cal BC) at and near Osłonki, Poland, is complemented by palaeoenvironmental investigations in three basins with biogenic sediments adjacent to the archaeological sites. Research included sedimentology, palynology, malacology and cladoceran analysis. Complementary lines of evidence indicate that Linear Pottery pioneer farmers of the late 6th millennium BC caused minimal environmental impact, but intensive settlement and land use by the Brześć Kujawski Group during the 5th millennium BC triggered pronounced human-induced effects on the local landscape. Of particular significance is the evidence for erosion and aeolian ablation of exposed soil in the vicinity of the Neolithic settlements, presumably reflecting widespread land clearance, agricultural activity and settlement construction.

The application of palaeolimnology to evidence‐based lake management and conservation: examples from UK lakes

ABSTRACT To help meet the requirements of water legislation, palaeolimnology has been widely used to establish ‘reference conditions’ and restoration targets for lakes. However, its potential for assessing the necessity and appropriateness of different lake management activities has been less publicized. With reference to selected case studies covering consultancy projects commissioned by UK conservation agencies, this study highlights the important applied role of palaeolimnology. Using varying combinations of diatom, plant macrofossil and cladoceran analysis, the degree, timing and in many cases the likely drivers of ecological change were inferred for several lake sites. From this basis advice was given on a range of lake management issues, including the need for sediment removal to combat eutrophication and/or the necessity of other nutrient reduction measures (Case study 1), the depth of sediment to be removed to maximize restoration potential through exposure of dormant banks of characean oospores (Case study 2), the requirement for fish management (Case study 3), and advice regarding fish farm expansion and licensing (Case study 4). Where possible management responses to the recommendations are outlined including any major outcomes. All case studies illustrate the advantages, for lake management and conservation decision‐making, of placing current lake ecological conditions in the context of long‐term change. Copyright © 2012 John Wiley & Sons, Ltd.

Younger Dryas Cladocera assemblages from two valley mires in central Poland and their potential significance for climate reconstructions

Two sections of sediment from small oxbow-lake infillings located in different river valleys in central Poland were studied by cladoceran analysis in order to examine the response of aquatic ecosystems to the Younger Dryas. Lithological and geochemical records, as well as chydorid (Chydoridae) ephippia analysis were also used to reconstruct Younger Dryas climate trends. A high concentration of cladocerans, as well as the presence of Cladocera taxa preferring warmer water, was found. It is likely that local processes in the oxbow lakes were important, because the presence of warmpreferring taxa was also related to their habitats and their development. Yet local environmental forces, such as the influence of the rivers, habitat modification, macrophyte abundance, and eutrophication, were not only major factors to affect the Cladocera diversity in the Younger Dryas. The observation of changes in the composition and concentration of Cladocera in oxbow-lake infillings indicates that most of the changes occurred in response to climate changes.

Cladoceran remains in lake sediments: a comparison between plankton counts and sediment records

To evaluate the comparability of neo- and paleo-limnology, we made year-to-year as well as seasonal comparisons of contemporary zooplankton data and cladoceran remains in thick (9–42 mm) annual laminations in sediment of Lake Vesijarvi, southern Finland. We calculated the expected annual exuviae production of nine planktonic taxa in the water column using contemporary zooplankton records, and compared the value to the observed net accumulation of their remains in deep sediment for 7 years. Although all of the species studied occur commonly in the lake pelagic zone, deposition of remains differed significantly among taxa. The observed accumulation of three Bosmina species and Chydorus sphaericus was similar to or exceeded expected values, suggesting good preservation of their remains as well as focusing of sediment into the deepest part of the lake. The accumulation of Limnosida and Leptodora remains exceeded expected values several fold, suggesting under-representation of these species in pelagic plankton samples, as well as efficient transportation and spatial averaging of their remains in the sediment. Daphnia, Diaphanosoma, and Ceriodaphnia were clearly under-represented in the sediment due to poor preservation of their remains and use of a 50-μm sieve in sediment processing. Thus, sieving should be taken into account as a possible source of bias. Correlation between relative abundances of all species in the sediment and in the plankton was weak (rs = 0.54, P < 0.001), but for well-preserved species, the correlation was strong (rs = 0.91, P < 0.001). Inter-annual variation in the deposition of remains suggested that resuspension and sediment focusing may vary between years, thus making it difficult to interpret absolute abundances, even though the deepest part of the basin shows clear varve formation and seasonality is well recorded. Detailed study of the uppermost lamination showed the seasonal succession of a cladoceran community within an annual varve as well as differences in the seasonality and intensity of ephippia production among the species. We recommend that results of cladoceran analyses be expressed in several ways (relative abundances, per unit dry weight, per unit organic matter, and as net accumulation values) before drawing final conclusions, as each approach may reveal a different aspect of the deposition process. In addition, sedimentation differences between epilimnetic and hypolimnetic species should be considered in stratified lakes.

Abrupt and consistent responses of aquatic and terrestrial ecosystems to the 8200 cal. yr cold event: a lacustrine record from Lake Arapisto, Finland

A 8400—7700 yr cal. BP section of the sediments of a small lake in southern Finland was studied by high-resolution pollen and cladoceran analyses to examine the response of terrestrial and aquatic ecosystems to the 8200 cal. yr BP cold event. Furthermore, a pollen-based Tann reconstruction and proportions of chydorid ephippia were used to determine changes in temperature and in the length of open-water season during the event. The pollen data, with abrupt decreases of the early-flowering Alnus, Corylus and Ulmus at c. 8350 cal. yr BP, may partly reflect vegetation dynamics but possibly also decreased pollen productivity and reproduction caused by cold winters and springs. The reconstructed Tann indicated a rapid temperature fall and a subsequent recovery. Proportions of chydorid ephippia suggested a considerable reduction in the length of open-water season at the beginning of the event, followed by periodically shorter open-water seasons. In the aquatic ecosystem only one species, the dominant planktonic cladoceran Bosmina longirostris, responded by decreasing dramatically and almost became extinct during the coldest period. However, we were unable to reconstruct the causative link between the inferred climate change and its decrease. The response of both aquatic and terrestrial proxies at c. 8350 cal. yr BP was consistent, indicating an abrupt start of the event and also an abrupt end at c. 8100 cal. yr BP.

Reinvestigation of the classic late‐glacial Bølling Sø sequence, Denmark: chronology, macrofossils, Cladocera and chydorid ephippia

AbstractThe late‐glacial Bølling period was first identified by Johs. Iversen on the basis of pollen results from Lake Bølling Sø in Denmark. Because there were no radiocarbon dates from the sequence the Bølling Chronozone (12 000–13 000 14C yr BP) was later established on the basis of dates from other sites. A new project is reinvestigating the sediments from the Bølling Sø sequence with AMS radiocarbon dating and multiproxy analyses. Here we present results of AMS radiocarbon dating, macrofossil analyses, cladoceran analyses (Cladocera concentrations and chydorid ephippia) and Pediastrum analyses (concentrations). The AMS dates on land plant remains show that the lower part of the sequence is around 12 500 14C yr BP, and thus clearly pre‐dates the Allerød chronozone. However, construction of a chronology for the sequence was problematic, partly because of reworking of macroscopic plant remains. The climate ameliorated after glacial conditions to such an extent that growth of plants could begin at ca. 12 500 14C yr BP, but the results of multiproxy analyses show little evidence for a further warming period during the pre‐Allerød part of the sequence. Lake productivity was low, and tree birch rare or maybe absent. This may reflect widespread occurrence of dead ice, unstable soils, heavy in‐wash of minerogenic matter to the lake, resulting in turbid water and rapid sedimentation. The early pioneer vegetation was characterised by Salix polaris and Dryas octopetala, and by herbs. The Allerød Chronozone, and especially its initial part, appears to have been relatively warm but reduced cladoceran concentrations and increased proportion of chydorid ephippia suggest that climate cooled in the middle Allerød and that the late Allerød was colder than the early part. The early Younger Dryas was probably colder than the late Younger Dryas. Clear warming is apparent at the beginning of the Holocene, where the first macrofossil evidence of trees (Betula pubescens, Populus tremula) is found. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Chydoid ephippia as indicators of environmental change biostratigraphical evidence from two lakes in southern Finland

This study presents a new proxy method for studying past environmental change. The method is based on the relative abundance of ephippia of chydorid Cladocera (Chydoridae). Ephippia are a modification of the carapace that protects the resting eggs against, for example, freezing and desiccation. Holocene records of chydorid ephippia and other gamogenetic remains (male headshields and postabdomens, and headshields of ephippial females) from two lakes in southern Finland (Rutikka and Kaksoislammi) are presented. Results of pollen, diatom and cladoceran analyses from Rutikka Lake are also described. Results from this study suggest that chydorid ephippia are valuable indicators of the environmental stresses occurring in lakes. In particular, ephippia were abundant at both sites during the late Pleistocene/early Holocene transition when the climate was still severe and the open-water season was short. In the later-Holocene record, the relative abundance of the ephippia also reflected the environmental stress during profound changes in predator-prey relationships in Kaksoislammi Lake. In contrast, a change in the relative abundance of ephippia of only one species (Alona affinis) occurred in the late Holocene in Rutikka Lake when prehistoric cultivation took place and affected the water chemistry.