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Crustacean zooplankton occupy a key position as primary consumers within lake food webs, acting as early indicators of wider ecosystem shifts that can cascade to higher trophic levels. Their communities can be assessed via water column net hauls or via sediment samples containing preserved subfossil remnants from various time periods; the latter probably integrate multiple years of data, habitats within lakes, and seasonal patterns. The degree to which such samples do or do not correspond has never been assessed across a wide variety of lake types and gradients.As part of a larger sampling of over 600 lakes across lake‐rich Canada, 85 lakes were selected along a gradient of human impact, according to contemporary catchment land use, to analyse cladoceran zooplankton assemblage relatedness among snapshot water column, contemporary and pre‐industrial sediment samples.We used a combination of ordinations and matrix correlations (RV coefficients), along with partial redundancy analyses, to determine the degree to which the different sample types were comparable and whether they responded similarly to >30 environmental variables. We also compared conclusions obtained using the full cladoceran assemblages versus pelagic‐only taxa and whether our results varied according to degree of human impact.Overall, while all sample types were correlated, congruence was highest between contemporary and pre‐industrial sediment sample types. This result could arise from the under‐representation of littoral taxa in water column samples relative to those from the sediment. In high impacted catchments, however, we observed greater similarity between water column and contemporary sediment samples, as water quality stressors potentially structure assemblages in parallel directions over time. In these modern‐day sample types and among measured variables, we identified lake depth and pH as the most important structuring variables across Canada.In this first study comparing cladoceran assemblages in water column, contemporary and pre‐industrial sediments across many lakes, we conclude that water column and sediment samples respond similarly to environmental drivers but should not be considered entirely analogous or redundant. [ABSTRACT FROM AUTHOR]

Subfossil remains of aquatic invertebrates found in lacustrine sediments are useful paleoenvironmental indicators. Strongly scleroticized chitinous body parts from the exoskeleton or exuviae from invertebrates are often the most resistant to degradation during syn- and post-depositional processes. Invertebrate mandibles and body parts that superficially resemble mandibles, such as claw-like appendages and pygopodia, are frequently found in sieved Quaternary lacustrine, palustrine, and deltaic sediments. Guides, catalogs and atlases have been published that are well suited for the identification of subfossil remains for several invertebrate groups, such as chironomids, cladocerans, and ostracods, among others. However, aquatic invertebrate remains of several ecologically important invertebrate groups continue to be underused in paleoenvironmental studies, in part, because there are few visual keys or other documentation sources (e.g. descriptions, catalogs or atlases) that increase awareness and facilitate identification. Here we present sets of digital photomicrographs of pre-identified aquatic invertebrate specimens collected from streams, lakes and ponds that have been chemically cleared to preserve structures that are observed in subfossil remains in sieved sediment samples, commonly the > 100 μm size fractions. In addition, we present examples of these structures from Quaternary lake-sediment samples and cite the dispersed literature that demonstrate that these remains are preserved and remain identifiable in the fossil record. We document mandibles from several taxonomic groups that include Crustacea: Amphipoda, Isopoda, Ostracoda, and Notostraca; and Insecta orders: Coleoptera, Diptera, Ephemeroptera, Hemiptera, Odonata, Lepidoptera, Megaloptera, Plecoptera, and Trichoptera. The compilation of microphotographs also includes pygopodia and claw appendages of Plecoptera and Trichoptera, with additional images of other common invertebrate mouthpart and head remains. We describe several types of fossilizing structures that are, to our knowledge, not previously described in the paleoecological literature (e.g. mandibles of amphipods or plecopterans) but also show that some structures are considerably more variable than expected based on available descriptions, such as the mandibles of Ephemeroptera or Trichoptera, and that these can potentially be separated into different morphotypes useful for identification of subfossil material. We also discuss the potential of analyzing and interpreting the additional remains together with the remains of more commonly analyzed invertebrate groups (e.g. Chironomidae) to contribute to paleoenvironmental interpretations, which will allow assessments of functional groups (e.g. predators, shredders, grazers) or habitat types (e.g. littoral, profundal or lotic environments) that aquatic invertebrate remains originate from. [ABSTRACT FROM AUTHOR]

Aim: While it is now well accepted that human activities are having pronounced effects on natural ecosystems, regional variation in the rate and magnitude of various human impacts is unclear. Moreover, the effects of land use change on natural aquatic communities have only relatively recently begun to be explored. Our goal was to understand how and where assemblages of a central food web component of freshwater lakes have changed over the course of industrialization in relation to land use. Location: Canada. Time period: Pre‐1880 AD to present. Major taxa studied: Cladoceran zooplankton. Methods: As part of the Natural Sciences and Engineering Research Council (NSERC) Canadian Lake Pulse Network, we selected 101 lakes across Canada along a gradient of human impact to analyse subfossil cladoceran assemblages from sediment cores. We examined relationships between taxonomic and functional indicators of cladoceran assemblage change among lakes and through time. Results: Contemporary assemblages were taxonomically and functionally less diverse locally relative to pre‐industrial assemblages (α‐diversity) and were structured by the degree of human impact in watersheds. Local α‐diversity losses were greatest in highly impacted lakes where agriculture and pasture are prevalent. While spatial homogenization (spatial β‐diversity) did not increase since pre‐industrial times as expected, temporal turnover (temporal β‐diversity) showed a non‐significant but increasing trend in highly impacted lakes, especially in urbanized watersheds. Main conclusions: Cladoceran assemblages have changed significantly over the course of the Industrial period, and especially in more highly impacted watersheds, underscoring the important role of watershed land use in shaping diversity. However, indicators of cladoceran function have remained relatively conserved over time and land use change showed little impact on β‐diversity, despite important environmental variation. Overall, this research furthers our understanding of the health status of Canadian lakes and the consequences of human activities, especially agriculture and urbanization, on lake zooplankton. [ABSTRACT FROM AUTHOR]

We present a dataset of subfossil chironomid assemblages in the MUT-10 sediment core obtained from the high alpine lake Mutterbergersee in the Austrian Alps in 2010. The data were presented in the research article by Ilyashuk et al. (2019) “The Little Ice Age signature in a 700-year high-resolution chironomid record of summer temperatures in the Central Eastern Alps”. In addition to the results of the chironomid analysis of 100 sediment samples presented in this article, we also include chironomid assemblage data from an additional 48 sediment samples that complement this dataset. The data includes raw chironomid counts, percent abundance of chironomid taxa, as well as mean July air temperature estimates derived from the chironomid record based on a chironomid-temperature transfer function. We also provide information on age-dating of the sedimentary sequence. Given the high temporal resolution and the robust age-depth model of the record, the chironomid-based reconstruction of temperature since AD 1300 provides a detailed documentation of climate change in the Eastern Alps from the Little Ice Age onwards and can be used for comparison with other independent proxy-based climate reconstructions. In addition to the data, we detail the sample processing for subfossil chironomid analysis and provide a detailed description of the reconstruction technique used for producing chironomid-based quantitative temperature inferences.

Improved multibeam swath bathymetry allows targeted coring of glacial landforms aiming at improving our understanding of sedimentary facies that developed in glacimarine settings during the post‐Last Glacial Maximum (LGM) deglaciation. Coupled with radiocarbon dates, we explore foraminiferal records from 18 sediment cores from the western Ross Sea largely from sites near paleo–grounding lines. We investigate post‐LGM foraminiferal assemblages from glacimarine environments, including those proximal and more distal to paleo–grounding lines, including environments influenced by subglacial meltwater outflow and further removed from direct glacial influence and subject to different oceanographic conditions. Agglutinated benthic foraminiferal assemblages dominate open marine facies deposited under the presence of High Salinity Shelf Water and significant primary production, while calcareous foraminiferal assemblages characterize grounding line‐proximal settings, some of which were potentially influenced by Modified Circumpolar Deep Water. Rapid deposition of meltwater plume deposits inhibited and, in some cases, significantly altered foraminifera abundance and diversity. Broadly in the Ross Sea, it appears that the high bathymetric gradient of grounding zone wedges is a key factor promoting rich benthic foraminiferal communities in habitats proximal to grounding lines. Therefore, we demonstrate that paleo–grounding line settings may archive high quality in situ foraminiferal data, which is imperative for paleoenvironmental and geochemical studies on glaciated continental margins worldwide. Key Points: High quality in situ calcareous foraminiferal material for radiocarbon and paleoenvironments may be obtained GZW foresets and toesOnly largest GZWs supported thick water column between ice sheet and the seafloor, providing favorable habitats for calcareous foraminiferaThin‐walled, calcareous foraminiferal specimens in western Ross Sea suggest only ocasional and limited food supply [ABSTRACT FROM AUTHOR]

Caribbean coral reefs have transformed into algal‐dominated habitats over the past half‐century, but the role of specific anthropogenic drivers is unresolved due to the lack of ecosystem‐level data predating human disturbance. To better understand the extent and causes of long‐term Caribbean reef declines, we produced a continuous 3000‐yr record of the ecosystem state of three reefs in Bocas del Toro, Caribbean Panama. From fossils and sediments obtained from reef matrix cores, we tracked changes in reef accretion rates and the taxonomic and functional group composition of fish, coral, urchin, bivalve and benthic foraminifera. This dataset provided a comprehensive picture of reef community and environmental change. At all sites, reefs shifted from systems with greater relative abundance of herbivorous fish, epifaunal suspension feeding bivalves and Diadema urchins to systems with greater relative abundance of micropredator fish, infaunal bivalves and Echinometra urchins. These transitions were initiated a millennium ago at two less‐degraded reefs fringing offshore islands and ~250 yr ago at a degraded patch reef near the continental coast. Ecosystem shifts were accompanied by a decline in reef accretion rates, and at the patch reef, a decline in water quality since the 18th century. Within all cores, synchronous increases in infaunal bivalves and declines in herbivorous fish regardless of water quality suggest a loss of hard substrate and increasingly hypoxic sediment conditions related to herbivore loss. While the early timing of ecosystem transitions at the fringing reefs implicates large‐scale hydrological change, the more recent timing of change and loss of water quality at the patch reef implicates terrigenous runoff from land‐clearing. Our whole‐ecosystem reconstruction reveals that reef ecosystem deterioration appears to follow a predictable trajectory whether driven by natural or anthropogenic disturbances and that historical local human activities have quickly unraveled reefs at a scale similar to longer‐term natural environmental change. [ABSTRACT FROM AUTHOR]

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Natural areas near human-modified landscapes experience factors that may affect local biodiversity at levels commensurate with natural environmental factors. The land snails of the Canary Islands provide excellent opportunities to evaluate the importance of anthropogenic agents in mediating the diversity and distribution of species. Land snails are particularly sensitive to disturbance and are an integral part of terrestrial ecosystems. This study analyzed the distributions and abundances of terrestrial macrosnail shell assemblages at 60 localities throughout the coastal scrub biome of the Canary Islands. This was accomplished using data on natural and anthropogenic variables to assess their relative importance in governing land snail diversity. A total of 34,801 dead shells represented a diverse malacofauna with highly localized endemism. Due to uncertain species identifications, samples from the 18 sites from the two easternmost islands are described, but excluded from statistical analyses. Regression tree analysis indicated that proximity to agricultural sites was the most important predictor of species diversity. Sites with no or very little agricultural area (≤ 0.167 km) within a 1 km radius had significantly higher richness and diversity. These results have implications for Canary Islands conservation. Protected areas that are patchworks of natural and agricultural landscapes are still subject to native biodiversity loss because of anthropogenic impacts even when the footprint of agriculture is small. [ABSTRACT FROM AUTHOR]

Over the last decade, protocols aimed at reproducibly sequencing reduced-genome subsets in non-model organisms have been widely developed. Their use is, however, limited to DNA of relatively high molecular weight. During the last year, several methods exploiting hybridization capture using probes based on RAD-sequencing loci have circumvented this limitation and opened avenues to the study of samples characterized by degraded DNA, such as historical specimens., Here, we present a major update to those methods, namely hybridization capture from RAD-derived probes obtained from a reduced eXome template (hy RAD-X), a technique applying RAD sequencing to messenger RNA from one or few fresh specimens to elaborate bench-top produced probes, that is, a reduced representation of the exome, further used to capture homologous DNA from a samples set. In contrast to previous hybridization capture methods, the reference catalogue on which reads are aligned does not rely on de novo assembly of anonymous RAD-sequencing loci, but on an assembled transcriptome obtained from RNAseq data, thus increasing the accuracy of loci definition and single-nucleotide polymorphisms ( SNP) call, and targeting, specifically, expressed genes. Finally, the capture step of hy RAD-X relies on RNA probes, increasing stringency of hybridization, making it well suited for low-content DNA samples. As a proof of concept, we applied hy RAD-X to subfossil needles from the coniferous tree Abies alba, collected in lake sediments ( Origlio, Switzerland) and dating back from 7200 to 5800 years before present ( bp). More specifically, we investigated genetic variation before, during and after an anthropogenic perturbation that caused an abrupt decrease in A. alba population size, 6500-6200 years bp., Hy RAD-X produced a matrix encompassing 524 exome-derived SNPs. Despite a lower observed heterozygosity was found during the 6500-6200 years bp time slice, genetic composition was nearly identical before and after the perturbation, indicating that re-expansion of the population after the decline was most likely driven by local specimens., To the best of our knowledge, this is the first time a population genomic study incorporating ancient DNA samples of tree subfossils is conducted at a moderate cost using reproducible exome-reduced complexity. [ABSTRACT FROM AUTHOR]

Numerous tree trunks are present in the Late Weichselian deposits on the low terrace of the Warta river valley, in central Poland. This study concerns the well preserved tree remnants as well as accompanying depositional series and their sedimentary environments in relation to the geological position. The depositional sequence presented covers periods from the Middle Weichselian onwards. The riparian forest dates at the Younger Dryas. Environmental changes connected with rapid cooling were responsible for its destruction.

Background: To date, there is a substantial lack of information about gastropods from the Tuscan-Emilian Apennine in the north of Italy, notwithstanding the availability of detailed and comprehensive literature on this molluscan class. We present a gastropod fauna from the Natural Reserve of the Pliocene Mountain Spur: to our knowledge, this is the first investigation of the extant gastropod fauna in the Tuscan-Emilian Apennine and one of the few in the Apennine's mountain chain as a whole., New Information: We describe a gastropod fauna comprised by 25 species, belonging to 18 genera and 10 families: the general figure which is emerging is an assemblage of European and Mediterranean-European species, with a single Asian contribution. Several shells were collected as embedded in sandy-clayey soils and showed fossilisation traces: therefore, we regard these shells as subfossil samples. Namely, subfossil shells are from the species Pomatiaselegans , Granariafrumentum , Retinellaolivetorum , Xerolentaobviaobvia , Oxychiluscf.draparnaudi, Monachacartusiana and Monachacantiana . The present checklist is the first report in the Tuscan-Emilian Apennine and Emilia-Romagna areas for six taxa: Morlinaglabraglabra , Oxychiliusalliarius , Xerosectacespitum , Fruticicolafruticum , Xerogyraspadae and Xerolentaobviaobvia ., (Federico Plazzi, Guido Pedroni.)

Climate change is one of the key drivers of changes in the biodiversity of the planet. There is, however, a general lack of long-term data sets showing trends in taxonomic diversity of aquatic insects in high mountain environments particularly vulnerable to climate change. Using palaeolimnological techniques, we explored the changes in subfossil chironomid assemblages from three remote water bodies in the Eastern Alps, with the main focus on taxonomic turnover over different intervals of the late Holocene., Major changes in the assemblages coincided with shifts between different climate regimes and were mainly associated with the taxonomic shifts indicating the crossing ecological thresholds related to the ice-cover duration in alpine lakes., Patterns of assemblage turnover through the past 2000 years differ between the study sites. Nevertheless, despite site-specific differences in the physical setting and taxonomic composition, the study sites reveal substantial chironomid assemblage turnover (>1.0 SD) since AD 1850. The highest chironomid turnover (0.87 SD) over the last 30 years ( AD 1980-2010), more than three times greater (0.26 SD) than in the previous 30 years, is observed in the lake situated at the highest elevation among the study lakes., Applying non-linear structural equation modelling, we found that cold-season (October-May) temperatures and therefore lake ice phenology are among the most important environment variables affecting the chironomid assemblages., The results of this study suggest that further climate warming will increase the risk of ecological alterations in remote Alpine freshwaters, including major shifts in chironomid fauna. [ABSTRACT FROM AUTHOR]

We present a dataset of subfossil chironomid assemblages in the MUT-10 sediment core obtained from the high alpine lake Mutterbergersee in the Austrian Alps in 2010. The data were presented in the research article by Ilyashuk et al. (2019) "The Little Ice Age signature in a 700-year high-resolution chironomid record of summer temperatures in the Central Eastern Alps". In addition to the results of the chironomid analysis of 100 sediment samples presented in this article, we also include chironomid assemblage data from an additional 48 sediment samples that complement this dataset. The data includes raw chironomid counts, percent abundance of chironomid taxa, as well as mean July air temperature estimates derived from the chironomid record based on a chironomid-temperature transfer function. We also provide information on age-dating of the sedimentary sequence. Given the high temporal resolution and the robust age-depth model of the record, the chironomid-based reconstruction of temperature since AD 1300 provides a detailed documentation of climate change in the Eastern Alps from the Little Ice Age onwards and can be used for comparison with other independent proxy-based climate reconstructions. In addition to the data, we detail the sample processing for subfossil chironomid analysis and provide a detailed description of the reconstruction technique used for producing chironomid-based quantitative temperature inferences., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 Published by Elsevier Inc.)

The diverse members of the cladoceran family Chydoridae are typically well preserved in lake sediments, although identifications of chydorids using subfossil remains still differ from identifications using whole animals. To address this issue, we analyzed and photographed chydorid subfossil remains from lakes in eastern Canada and northeastern USA and compiled this information into an illustrated identification guide for this region, which is characterized by high chydorid species richness. We provide detailed descriptions of commonly recovered body parts for each species, including headshields, carapaces, postabdomens, and postabdominal claws. We describe 29 chydorid taxa, discuss the distribution of these taxa within North America, and compare morphology with related species described from Alaska or northern Europe, the only other regions for which subfossil chydorid identification guides are available. [ABSTRACT FROM AUTHOR]

Cladocera identifications based on subfossil remains differ considerably from identifications based on whole animals, yet despite this very few subfossil Cladocera identification guides exist. In particular, taxa belonging to the families Daphniidae, Leptodoridae, Polyphemidae, Holopedidae, Sididae, and Macrothricidae tend to preserve poorly, with only a few, small body parts available for identification within the sediments. Since many of these taxa are important environmental indicators in lakes, subfossil identification guides that enable them to be recognized based on only a few body parts are critical for paleolimnological investigations utilizing Cladocera. In this illustrated identification guide, we provide detailed descriptions of subfossil remains commonly recovered for 14 species belonging to the families Daphniidae, Leptodoridae, Polyphemidae, Holopedidae, Sididae, Macrothricidae, and Bosminidae for lakes in eastern Canada and northeastern USA, where several recent subfossil Cladocera-based investigations of environmental change have been focused. It is our hope that this taxonomic guide will improve consistency in subfossil Cladocera taxonomy among laboratories, and help to stimulate additional research in this ecologically significant region. The diverse taxa belonging to the family Chydoridae are considered separately. [ABSTRACT FROM AUTHOR]

Larvae of the chironomid genus Propsilocerus Kieffer (Diptera: Chironomidae), known from the Palaearctic region and from subfossil larval head capsules in North America, have been found living in remote British Columbia, Canada. We review the morphology and ecology of the taxon in North America, and report and interpret the subfossil occurrences. Although the species appears to be undescribed, we refrain from a formal taxonomic description based on the larva alone pending discovery of the full life history. [ABSTRACT FROM AUTHOR]

To investigate the extent to which anthropogenic perturbations such as eutrophication and trace metal pollution (i.e., environmental stress sensu Odum 1985) influence the reproductive modes of cladoceran populations, we analyzed the abundance of subfossils of the chydorids Alonella nana (Baird, 1850) and Alona affinis (Leydig, 1860) in sediment cores from three Finnish lakes. Reconstruction of lakes' pollutant history and the biological response of chydorids indicate that in two of the lakes the proportion of individuals reproducing sexually increased with environmental stressors. More specifically, A. nana responded to eutrophication in Lake Hampträsk with greater production of ephippia, while A. affinis responded to aluminum pollution or acidification in Lake Pieni Majaslampi. In contrast, the reference lake, Lake Iso Lehmälampi, showed no radical changes in sexual reproduction over the twomillennium long sediment record. We conclude that chydorids may use sexual reproduction as a strategy for overcoming unexpected environmental stresses. [ABSTRACT FROM AUTHOR]

Abstract: Since the mid-19th century, the Malagasy subfossil macrofauna has been the object of numerous studies and publications, contrary to the microfauna. New fieldwork, initiated in 2001, in the North West of Madagascar (Province of Mahajanga) led to the discovery of sites rich in fossiliferous breccias, containing micromammals. In this article, we describe two new subfossil species of rodent: Brachytarsomys mahajambaensis, the smallest within the genus and Nesomys narindaensis, the largest within the genus. Most of the extant species of these two genera live in the tropical rainforests of the eastern and north-eastern areas of Madagascar, far away from the north-western part of the island where a dry deciduous forest occurs. The presence of the two taxa in the subfossil record in the Northwest of the country suggests the occurrence of wetter conditions in the past in this region. [Copyright &y& Elsevier]

Archeological evidence indicates that a dwarf fox ( Urocyon sp.) has inhabited Cozumel Island, Mexico at least since the arrival of Mayan peoples, but no taxonomic descriptions or morphological assessments of the animal exist. A recent field study indicates that this fox is on the verge of extinction and therefore it is critical to describe the population. Because no skins or complete skulls of the Cozumel fox exist in museum collections, we examined subfossils collected during archeological excavations of the human-waste middens of Mayans who inhabited the island c. 1500–500 years before present. Measurements of 37 bones from a minimum of 12 adult individuals suggest that this animal is diminutive (the body size was c. 60–80% of mainland specimens), similar to other Carnivora from Cozumel that are recognized as distinct species. Estimated rates of character differentiation for mainland and island foxes under a range of possible divergence periods (1000–130 000 years) suggest that the Cozumel fox population has been isolated for a minimum of 5000–13 000 years, and perhaps far longer. Colonization of the island by Urocyon therefore likely predates the colonization of Cozumel by humans. [ABSTRACT FROM AUTHOR]

This paper provides a critical analysis of archaeological small mammal collections in the Mediterranean area, from the Late Glacial to the first centuries AD, to validate the presence/absence of the house mouse through zooarchaeological criteria. The results have been synthesized through a diachronic map, whose chronological phases are related to socio-economic and cultural human evolution. The house mouse (Mus musculus domesticus) progression in the Mediterranean begins with a quick but limited diffusion in the Eastern Mediterranean Basin achieved around the 8th millennium BC. Until the 1st millennium BC, the invasive process seems to have stopped or drastically slowed, despite the increasing opportunities of passive transport during the Bronze Age. During the 1st millennium BC, there was mass colonization by the house mouse of the entire Western Mediterranean Basin and Northern Europe. We propose to explain this chronological gap in the colonization of the Eastern and Western Mediterranean using source-sink theory considering that the western environments acted like sinks until the first millennium BC. At that time the Western Mediterranean was fully opened to Eastern influences and migrations, and the human pressures on the environment drastically increased. This may have favoured definitively the adaptation of the house mouse to the Western commensal niches. © 2005 The Linnean Society of London,Biological Journal of the Linnean Society, 2005,84, 429–445. [ABSTRACT FROM AUTHOR]

Boreal forests at high latitudes are climate-sensitive ecosystems that respond directly to environmental forcing by changing their position according to latitude or by changing their abundance at local and regional scales. South of the arctic treeline, external forcing (warming, cooling, drought, fire) necessarily results in the changing abundance of the impacted forests; in particular, the deforestation of well-drained sites through fire is the most important factor. In this study, we examined the changing abundance of wetland forests located at the arctic treeline (northern Québec, Canada) during the last 1500 years, a period of known contrasting climatic conditions. Black spruce (Picea mariana) trees submerged in small lakes and peatland ponds and soil-peat stratigraphy were used concurrently to reconstruct the millennial-long developmental sequence of wetland stands associated with moisture changes and fire disturbance. Changing lake levels from AD 300 to the present were identified based on radiocarbon-dated submerged paleosols and tree- ring cross-dating of submerged trees distributed in three wetlands from the same watershed. Dead and living trees in a standing position below and above present water level of a small lake (LE Lake) showed direct evidence of past water levels from the 12th century to the present day. Submerged subfossil trees from another lake (LB Lake) and two peatland ponds (PB Peatland) also responded synchronously to changes in soil moisture during the last 1500 years. Regional-scale catastrophic flooding around AD 1150, inferred from paleosol and subfossil tree data, eliminated riparian peat and wetland trees growing at least since AD 300. Also, the coincidence of events such as the mass mortality of wetland spruce and post-fire deforestation of a small hill surrounding LE Lake during the late 1500s suggests the impact of local-scale flooding, probably attributable to greater snow transportation and accumulation on the lake surface after fire disturbance. Massive tree mortality climaxed at ca. 1750, when all wetland trees at LB Lake and PB Peatland died because of permafrost disturbance and soil upthrusting. Lower water levels from AD 300 to 1750 were associated with drier conditions, possibly caused by greater evaporation and/or reduced snow accumulation. Permafrost development in shallow waters occurred during the Little Ice Age, after 1600. It is concluded that the climate at the eastern Canadian treeline was warmer and drier from AD 300 to the onset of the Little Ice Age and promoted tree establishment. The highest water levels were recorded recently (19th and 20th centuries), causing lake and peatland expansion. Any future moisture changes at these subarctic latitudes will result in important spatial rearrangements of wetland ecosystems. [ABSTRACT FROM AUTHOR]

Preliminary report on Antsingiavo subfossils sites (Madagascar). Two new sites, Antsingiavo A & B, have been discovered in the Narinda peninsula, situated in the North-West of Madagascar, Province of Mahajanga. Breccias contain microfauna associated with subfossil lemurs of an average size (Archaeolemur) and small (Microcebus). Until now, the subfossil microfauna of Madagascar was practically unknown. The sample from Antsingiavo offers information on past environments in the Narinda peninsula. The new discoveries contribute to an understanding of the diversity Archaeolemur, with different forms in the different areas of Madagascar. To cite this article : D. Gommery et al., C. R. Palevol 2 (2003). [Copyright &y& Elsevier]

The concentrations of chironomid remains in lake sediments are very variable and, therefore, chironomid stratigraphies often include samples with a low number of counts. Thus, the effect of low count sums on reconstructed temperatures is an important issue when applying chironomid temperature inference models. Using an existing data set, we simulated low count sums by randomly picking subsets of head capsules from surface sediment samples with a high number of specimens. Subsequently, a chironomid temperature inference model was used to assess how the inferred temperatures are affected by low counts. The simulations indicate that the variability of inferred temperatures increases progressively with decreasing count sums. At counts below 50 specimens, a further reduction in count sum can cause a disproportionate increase in the variation of inferred temperatures, whereas at higher count sums the inferences are more stable. Furthermore, low count samples may consistently infer too low or too high temperatures and, therefore, produce a systematic error in a reconstruction. Smoothing reconstructed temperatures downcore is proposed as a possible way to compensate for the high variability due to low count sums. By combining adjacent samples in a stratigraphy, to produce samples of a more reliable size, it is possible to assess if low counts cause a systematic error in inferred temperatures. [ABSTRACT FROM AUTHOR]