Curt Stager
Paul Smith's College, Biology, Faculty Member
Long-term monitoring of the spring and autumn phenology of five animal species, four plant species, phytoplankton communities, lake temperatures and ice cover on the Paul Smith’s College Phenology Trail in the uplands of the Adirondack... more
Long-term monitoring of the spring and autumn phenology of five animal species, four plant species, phytoplankton communities, lake temperatures and ice cover on the Paul Smith’s College Phenology Trail in the uplands of the Adirondack State Park (NY, USA) has produced time series spanning 1990–2020 for the biological and water temperature records and 1909–2020 for lake ice. In conjunction with climate records from three nearby weather stations these observations demonstrate that the ice on Lower Saint Regis Lake now thaws one week earlier, on average, than it did in 1909 while the region as a whole warmed by 1.7°C and received 19 cm more precipitation annually. Statistically significant warming trends between 1990 and 2020 were restricted to July and September and therefore contributed to a scarcity of temporal shifts in the spring phenologies of species and lake ice during that shorter time frame, but the lake surface warmed by 1.9°C on average in October. Although most of the phe...
Research Interests:
<p>a, b. Percent planktonic diatoms in Walden Pond cores WAL-3 and WAL-15, respectively. Data after ca. A.D. 1930 primarily represent increased cultural eutrophication rather than climate alone. c. Composite hydroclimate record... more
<p>a, b. Percent planktonic diatoms in Walden Pond cores WAL-3 and WAL-15, respectively. Data after ca. A.D. 1930 primarily represent increased cultural eutrophication rather than climate alone. c. Composite hydroclimate record derived from varved sediments of a lake and estuary in New York and Massachusetts, respectively [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0191755#pone.0191755.ref038" target="_blank">38</a>]. Horizontal bars represent drought periods at Little Pond, MA (upper)[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0191755#pone.0191755.ref036" target="_blank">36</a>] and the New England region (lower)[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0191755#pone.0191755.ref034" target="_blank">34</a>]. Vertical dotted lines #1–2 bracket the A.D. 1150–1300 interval, line #3 indicates approximate onset of cultural eutrophication. Asterisks indicate core-intervals with calibrated radiocarbon ages.</p
Research Interests:
Documenting whether a biotic taxon is native or alien to an ecosystem has theoretical value for ecological and evolutionary studies, and has practical value because it can potentially identify a taxon as a desirable component of an... more
Documenting whether a biotic taxon is native or alien to an ecosystem has theoretical value for ecological and evolutionary studies, and has practical value because it can potentially identify a taxon as a desirable component of an ecosystem or target it for removal. In some cases, however, such background information is inadequate or unavailable. Here we use paleo-DNA to re-evaluate the historical status of yellow perch in the 6 million acre Adiron-dack State Park of northern New York. Yellow perch DNA in a 2200-year sediment record reveals a long-term native status for these supposedly alien fish and challenges assump-tions that they necessarily exclude native trout from upland lakes. Similar approaches could be applied to other species with uncertain historical distributions and could help to identify unrecognized pockets of biodiversity.
Research Interests:
Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize... more
Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Paleoclimatic records from equatorial East Africa, Antarctica, and Greenland reveal that atmospheric circulation changed abruptly at the early to mid-Holocene transition to full postglacial conditions. A climatic reorganization occurred... more
Paleoclimatic records from equatorial East Africa, Antarctica, and Greenland reveal that atmospheric circulation changed abruptly at the early to mid-Holocene transition to full postglacial conditions. A climatic reorganization occurred at all three sites between 8200 and 7800 years ago that lasted 200 years or less and appears to have been related to abrupt transitions in both marine and terrestrial records around the world.
Research Interests:
Research Interests:
Research Interests:
... 5160 Illustrations copyright ©1998 by Anne E. Lacy All Rights Reserved First Edition 1998 98 99 00 01 02 03 6 4 5 4 3 2 1 This book is published with the assistance of a grant from the JohnBen Snow Foundation ... T Library of Congress... more
... 5160 Illustrations copyright ©1998 by Anne E. Lacy All Rights Reserved First Edition 1998 98 99 00 01 02 03 6 4 5 4 3 2 1 This book is published with the assistance of a grant from the JohnBen Snow Foundation ... T Library of Congress Cataloging-in-Publication Data Stager, Curt ...
Research Interests:
... Brian Cumming, Ellen Currano, Kathie Dello, Andrew Derocher, Mike Farrell, Andrei Ganopolski, Gordon Hamilton, Darden Hood, Mimi Katz, Joe Kelley, George Jacobson, Andrei Kurbatov, Marie-France Loutre, Kirk Maasch, Paul Mayewski,... more
... Brian Cumming, Ellen Currano, Kathie Dello, Andrew Derocher, Mike Farrell, Andrei Ganopolski, Gordon Hamilton, Darden Hood, Mimi Katz, Joe Kelley, George Jacobson, Andrei Kurbatov, Marie-France Loutre, Kirk Maasch, Paul Mayewski, Stacy McNulty, Mike Mead-ows ...
Research Interests:
Research Interests:
Research Interests:
Long-term, large-scale perspectives are necessary for understanding climate variability and its effects on ecosystems and cultures. Tree ring records of the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) have documented major... more
Long-term, large-scale perspectives are necessary for understanding climate variability and its effects on ecosystems and cultures. Tree ring records of the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) have documented major hydroclimatic variability during the last millennium in the American West, but fewer continuous, high-resolution hydroclimate records of the MCA-LIA period are available for eastern North America, particularly during the transition from the MCA to the LIA (ca. A.D. 1250–1400). Diatoms (micro-algae with silica cell walls) in sediment cores from three Adirondack (NY, USA) lakes and a hiatus in a wetland peat deposit in the Adirondack uplands provide novel insights into the late Holocene hydroclimate history of the Northeast. These records demonstrate that two of the region’s most extreme decadal-scale droughts of the last millennium occurred ca. A.D. 1260–1330 and ca. A.D. 1360–1390 during a dry-wet-dry (DWD) oscillation in the Adirondacks that contribut...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
A new diatom record from Lake Victoria’s Pilkington Bay, subsampled at 21- to 25-year intervals and supported by 20 AMS dates, reveals a ∼10,000 calendar year environmental history that is supported by published diatom and pollen data... more
A new diatom record from Lake Victoria’s Pilkington Bay, subsampled at 21- to 25-year intervals and supported by 20 AMS dates, reveals a ∼10,000 calendar year environmental history that is supported by published diatom and pollen data from two nearby sites. With their chronologies adjusted here to account for newly documented ancient carbon effects in the lake, these three records provide a coherent, finely resolved reconstruction of Holocene climate change in equatorial East Africa. After an insolation-induced rainfall maximum ca. 8800–8300 cal yr B.P., precipitation became more seasonal and decreased abruptly ca. 8200 and 5700 yr B.P. in apparent association with northern deglaciation events. Century-scale rainfall increases occurred ca. 8500, 7000, 5800, and 4000 yr B.P. Conditions after 2700 yr B.P. were generally similar to those of today, but major droughts occurred ca. 1200–600 yr B.P. during Europe’s Medieval Warm Period.
Research Interests: Archaeology, Geology, Oceanography, Climate Change, Quaternary, and 4 moreHolocene, Diatom, Bay, and Calendar year
An extreme megadrought occurred in the Afro-Asian monsoon region during an iceberg melting episode 50,000 years ago.
Research Interests:
Lake Nabugabo is widely known as the home of endemic cichlid fishes, but virtually nothing has been published regarding the limnological setting in which those species evolved during the late Holocene. Analysis of a 2.7 m long sediment... more
Lake Nabugabo is widely known as the home of endemic cichlid fishes, but virtually nothing has been published regarding the limnological setting in which those species evolved during the late Holocene. Analysis of a 2.7 m long sediment core collected near the center of the lake suggests that Nabugabo was first isolated from Lake Victoria ca. 5000 calendar years ago, which would make it ca. 1000 years older than was previously believed. The lake apparently shrank significantly around 2600 and 2000 years ago during century-scale droughts, but it did not dry out at any point in its history. The inferred lake-level history of Nabugabo is generally consistent with Holocene paleoclimate records from the adjacent Lake Victoria basin, and suggests that biota in this lake were subjected to at least two major environmental changes during the last 5 millenia.
Documenting whether a biotic taxon is native or alien to an ecosystem has theoretical value for ecological and evolutionary studies, and has practical value because it can potentially identify a taxon as a desirable component of an... more
Documenting whether a biotic taxon is native or alien to an ecosystem has theoretical value for ecological and evolutionary studies, and has practical value because it can potentially identify a taxon as a desirable component of an ecosystem or target it for removal. In some cases, however, such background information is inadequate or unavailable. Here we use paleo-DNA to re-evaluate the historical status of yellow perch in the 6 million acre Adirondack State Park of northern New York. Yellow perch DNA in a 2200-year sediment record reveals a long-term native status for these supposedly alien fish and challenges assumptions that they necessarily exclude native trout from upland lakes. Similar approaches could be applied to other species with uncertain historical distributions and could help to identify unrecognized pockets of biodiversity.
Research Interests:
ABSTRACT The late Holocene history of the South African summer rainfall zone offers insights into the effects of climate on ecosystems and human societies, as well as into the accuracy of model projections of the future. However, some... more
ABSTRACT The late Holocene history of the South African summer rainfall zone offers insights into the effects of climate on ecosystems and human societies, as well as into the accuracy of model projections of the future. However, some important aspects of this region’s climatic history remain unresolved. Here we present new high-resolution diatom records representing hydrological fluctuations at Lake Sibaya, KwaZulu-Natal, during the last 1800 years. The cores were dated with 14C, 210Pb, 137Cs, and exotic pollen, and were sampled at increments of 1e22 years. A low stand ending wAD 150 was followed by additional decadal to century-scale droughts, most notably wAD 1540e1760, and several periods of markedly wetter conditions wAD 220e290, AD 790e830, AD 1470e1540, and AD 1760e1860. The Medieval Climate Anomaly was generally wetter than average and the Little Ice Age was generally drier, but hydroclimate during both intervals was highly variable. These records confirm that local tree ring and stalagmite gray scale series represent rainfall variability, but they also show that widely cited stable isotope series from Makapansgat do not represent past climate as clearly. Because many interpretations of the climatic history of southern Africa have been influenced by those isotope data, we re-examine late Holocene precipitation variability in the summer rainfall zone, and also address model projections of future precipitation in the region.
Research Interests:
Sediment and microfossil analyses of a 7.5-m core from Lake Cheshi suggest that south-central Africa experienced late Quaternary climate changes similar to those in East Africa. The lake formed around 34,000 yr B.P., after a prelacustrine... more
Sediment and microfossil analyses of a 7.5-m core from Lake Cheshi suggest that south-central Africa experienced late Quaternary climate changes similar to those in East Africa. The lake formed around 34,000 yr B.P., after a prelacustrine phase of at least 6000 yr, from climatic or tectonic causes. Ratios of precipitation to evaporation were probably similar to those of today until a decline about 15,000-13,000 yr B.P. when the lake shrank and became chemically concentrated. Maximal lake levels occurred between 8000 and 4000 yr B.P., and were followed by a low stand under presumably arid conditions about 3500 yr B.P. Encroachment of sudd vegetation contributed to shallowing during the last 3000 yr. A phase of microfossil dilution may reflect human activity in the basin, or climatic or hydrological changes. Melosira valve morphology seems to reflect mixing regimes. Sponge and testate amoeba remains were most numerous relative to diatoms during low-water phases.
Research Interests:
The palynology of two overlapping Holocene cores from Lake Sibaya in KwaZulu-Natal elucidates the relationship between climate, vegetation and human impact in the region. By means of twenty-one AMS 14C dates, loss on ignition, and... more
The palynology of two overlapping Holocene cores from Lake Sibaya in KwaZulu-Natal elucidates the relationship between climate, vegetation and human impact in the region. By means of twenty-one AMS 14C dates, loss on ignition, and palynological results we established a composite profile. Pollen assemblages include elements of swamp forest (e.g. Rauvolfia, Macaranga), dune forest (e.g. Mimusops), mangrove vegetation (Bruguiera), palmveld
Research Interests: Geology and Palaeobotany
Research Interests:
... In this paper, we examine the late Holocene history of Lake Tanganyika through microfossil and ... collected with a 3 m long steel gravity sampler equipped with a polycarbonate liner. ... Sediments, plant remains, and hand-picked... more
... In this paper, we examine the late Holocene history of Lake Tanganyika through microfossil and ... collected with a 3 m long steel gravity sampler equipped with a polycarbonate liner. ... Sediments, plant remains, and hand-picked charcoal fragments for dating were immediately oven ...
Research Interests:
Lake Nabugabo is widely known as the home of endemic cichlid fishes, but virtually nothing has been published regarding the limnological setting in which those species evolved during the late Holocene. Analysis of a 2.7 m long sediment... more
Lake Nabugabo is widely known as the home of endemic cichlid fishes, but virtually nothing has been published regarding the limnological setting in which those species evolved during the late Holocene. Analysis of a 2.7 m long sediment core collected near the center of the lake suggests that Nabugabo was first isolated from Lake Victoria ca. 5000 calendar years ago,
Research Interests:
Paleolimnological techniques were used to establish baseline environmental conditions as guidelines for lake management and to evaluate water quality changes over the last 300 years in the north basin of Upper Saranac Lake (Adirondack... more
Paleolimnological techniques were used to establish baseline environmental conditions as guidelines for lake management and to evaluate water quality changes over the last 300 years in the north basin of Upper Saranac Lake (Adirondack Park, New York). Analysis of diatoms, bulk sedimentary characteristics and fossil pigments in a 30-cm core showed that the lake was once oligo- to mesotrophic but
Research Interests:
Research Interests:
Research Interests:
Research Interests:
... years, E. macrops was abundant in the deep channels during the dry season of 1978 ... flow among fish from different habitats, almost nothing is known about reproduction in E ... If it exists, competition among generalized carnivores... more
... years, E. macrops was abundant in the deep channels during the dry season of 1978 ... flow among fish from different habitats, almost nothing is known about reproduction in E ... If it exists, competition among generalized carnivores (includ-ing many characins, knifefishes, catfishes ...
Research Interests:
Research Interests:
An association of high sunspot numbers with rises in the level of Lake Victoria, East Africa, has been the focus of many investigations and vigorous debate during the last century. In this paper, we show that peaks in the ~11-year sunspot... more
An association of high sunspot numbers with rises in the level of Lake Victoria, East Africa, has been the focus of many investigations and vigorous debate during the last century. In this paper, we show that peaks in the ~11-year sunspot cycle were accompanied by Victoria level maxima throughout the 20th century, due to the occurrence of positive rainfall anomalies ~1 year before solar maxima. Similar patterns also occurred in at least five other East African lakes, which indicates that these sunspot-rainfall relationships were broadly regional in scale. Although irradiance fluctuations associated with the sunspot cycle are weak, their effects on tropical rainfall could be amplified through interactions with sea surface temperatures and atmospheric circulation systems, including ENSO. If this Sun-rainfall relationship persists in the future, then sunspot cycles can be used for long-term prediction of precipitation anomalies and associated outbreaks of insect-borne disease in much of East Africa. In that case, unusually wet rainy seasons and Rift Valley Fever epidemics should occur a year or so before the next solar maximum, which is expected to occur in 2011-2012 AD.
Research Interests:
Instructions for construction and use of a simple and inexpensive sediment coring device are presented. The sampler is suitable for use in high school and undergraduate science courses.
Research Interests:
Research Interests:
New sediment core data from a unique slow-sedimentation rate site in Lake Tanganyika contain a much longer and continuous record of limnological response to climate change than have been previously observed in equatorial regions of... more
New sediment core data from a unique slow-sedimentation rate site in Lake Tanganyika contain a much longer and continuous record of limnological response to climate change than have been previously observed in equatorial regions of central Africa. The new core site was first located through an extensive seismic reflection survey over the Kavala Island Ridge (KIR), a sedimented basement high that separates the Kigoma and Kalemie Basins in Lake Tanganyika. Proxy analyses of paleoclimate response carried out on core T97-52V include paleomagnetic and index properties, TOC and isotopic analyses of organic carbon, and diatom and biogenic silica analyses. A robust age model based on 11 radiocarbon (AMS) dates indicates a linear, continuous sedimentation rate nearly an order of magnitude slower here compared to other core sites around the lake. This age model indicates continuous sedimentation over the past 79 k yr, and a basal age in excess of 100 k yr. The results of the proxy analyses for the past ∼ 20 k yr are comparable to previous studies focused on that interval in Lake Tanganyika, and show that the lake was about 350 m lower than present at the Last Glacial Maximum (LGM). Repetitive peaks in TOC and corresponding drops in δ13C over the past 79 k yr indicate periods of high productivity and mixing above the T97-52V core site, probably due to cooler and perhaps windier conditions. From ∼ 80 through ∼ 58 k yr the δ13C values are relatively negative (−26 to −28 l) suggesting predominance of algal contributions to bottom sediments at this site during this time. Following this interval there is a shift to higher values of δ13C, indicating a possible shift to C-4 pathway-dominated grassland-type vegetation in the catchment, and indicating cooler, dryer conditions from ∼ 55 k yr through the LGM. Two seismic sequence boundaries are observed at shallow stratigraphic levels in the seismic reflection data, and the upper boundary correlates to a major discontinuity near the base of T97-52V. We interpret these discontinuities to reflect major, prolonged drops in lake level below the core site (393 m), with the lower boundary correlating to marine oxygen isotope Stage 6. This suggests that the previous glacial period was considerably cooler and more arid in the equatorial tropics than was the last glacial period.
Research Interests:
Research Interests:
Detailed, continuous paleoclimatic records of the late Holocene are relatively uncommon in the southern hemisphere, and the environmental interpretations of some important southern records remain unresolved. Such issues have hindered the... more
Detailed, continuous paleoclimatic records of the late Holocene are relatively uncommon in the southern hemisphere, and the environmental interpretations of some important southern records remain unresolved. Such issues have hindered the understanding of continental and hemispheric-scale climatic processes, including the roles of solar variability, ENSO, and latitudinal positions of key weather systems, in the long-term evolution of tropical climates. Sediment cores from two widely separated lakes on the South African coast now shed additional light on precipitation variability in the region as well as on the interpretation of existing records from other sites that are located farther inland. Lake Sibaya, in the northeastern sector, receives most of its rain during austral summers and can be influenced by latitudinal shifts in the position of the ITCZ; its climatic history may therefore be informative for the understanding of unusual precipitation patterns during the late Holocene that have been reported from equatorial East Africa. Verlorenvlei, in the southwestern sector, receives most of its rain during austral winters and is well situated to register latitudinal shifts in the positions of mid-latitude westerly storm tracks which, in turn, are sensitive to atmospheric and marine conditions around Antarctica. Comparing sedimentary records from these two sites can therefore be helpful in testing the hypothesis that synchronous changes in low- and mid-latitude weather systems have occurred during the late Holocene, presumably in response to solar variability or other disruptions of large-scale air and ocean circulation patterns. In this presentation, diatom, pollen, and sedimentological data from Sibaya and Verlorenvlei are used to address the nature and origins of climatic changes in tropical and southernmost Africa during the last 1500 years. In addition, because the variability of lacustrine conditions at these two sites appears to be primarily the result of rainfall fluctuations, their sedimentary records can shed useful light on the interpretation of paleoclimatic reconstructions from other sites in which the relative roles of temperature and precipitation are less clearly distinguished by the proxies under consideration.