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| Cronin, Tm; Dwyer, Gs; Kamiya, T; Schwede, S; Willard, Da. |
| We present paleoclimate evidence for rapid (< 100 years) shifts of similar to 2-4 degreesC in Chesapeake Bay (CB) temperature similar to 2100, 1600, 950, 650, 400 and 150 years before present (years BP) reconstructed from magnesium/calcium (Mg/Ca) paleothermometry. These include large temperature excursions during the Little Ice Age (similar to 1400-1900 AD) and the Medieval Warm Period (similar to 800-1300 AD) possibly related to changes in the strength of North Atlantic thermohaline circulation (THC). Evidence is presented for a long period of sustained regional and North Atlantic-wide warmth with low-amplitude temperature variability between similar to450. and 1000 AD. In addition to centennial-scale temperature shifts, the existence of numerous... |
| Tipo: Text |
Palavras-chave: Paleoclimatology; Holocene; Medieval Warm Period; Little Ice Age; 20th century climate; North Atlantic Oscillation. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00225/33648/32092.pdf |
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| Cronin, Tm; Thunell, R; Dwyer, Gs; Saenger, C; Mann, Me; Vann, C; Seal, Rr. |
| We reconstructed paleoclimate patterns from oxygen and carbon isotope records from the fossil estuarine benthic foraminifera Elphidium and Mg/Ca ratios from the ostracode Loxoconcha from sediment cores from Chesapeake Bay to examine the Holocene evolution of North Atlantic Oscillation (NAO)-type climate variability. Precipitation-driven river discharge and regional temperature variability are the primary influences on Chesapeake Bay salinity and water temperature, respectively. We first calibrated modern delta(18)O(water) to salinity and applied this relationship to calculate trends in paleosalinity from the delta(18)O(foram), correcting for changes in water temperature estimated from ostracode Mg/Ca ratios. The results indicate a much drier early Holocene... |
| Tipo: Text |
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| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00229/34072/32537.pdf |
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| Vann, Cd; Cronin, Tm; Dwyer, Gs. |
| Population ecology and shell chemistry were studied in the phytal ostracode Loxoconcha matagordensis (Swain 1955) collected from Zostera marina seagrass beds in the Chesapeake Bay to provide seasonal constraints on shell secretion time for paleothermometry. Population density and age structure were defined by two main breeding cycles that occurred between 01 to 15 June and 02 to 16 August 2001. The time interval between breeding cycles was similar to2 months and total juvenile standing crop increased almost three-fold between the first and second breeding cycles. Dark brown over-wintered adults comprised the majority of the population between March and April 2001, while newly secreted translucent adults were predominant between June and September. Seasonal... |
| Tipo: Text |
Palavras-chave: Ostracoda; Paleoclimatology; Ecology; Minor elements; Holocene; Seagrass. |
| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/00229/33995/32356.pdf |
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