Winter A.

Ciguatera Toxins in the food chain revealed by Stable Isotopes

Winter A., Tosteson T.R. Ciguatera Toxins in the food chain revealed by Stable Isotopes. Bulletin de la Sociatie de Pathologie Exotique, Vol 85, Is 5 Pt 2, 1992 pp. 510-513.

A record of recent change in terrestrial sedimentation in a coral-reef environment, La Parguera, Puerto Rico: A response to coastal development?

Ryan, K. E., J. P. Walsh, D. R. Corbett, and A. Winter. 2008. A record of recent change in terrestrial sedimentation in a coral-reef environment, la parguera, puerto rico: A response to coastal development? Marine Pollution Bulletin 56 (6) (JUN): 1177-83.

Abstract: 
Increased sediment flux to the coastal ocean due to coastal development is considered a major threat to the viability of coral reefs. A change in the nature of sediment supply and storage has been identified in a variety of coastal settings, particularly in response to European colonization, but sedimentation around reefs has received less attention. This research examines the sedimentary record adjacent to a coastal village that has experienced considerable land-use change over the last few decades. Sediment cores were analyzed to characterize composition and sediment accumulation rates. Sedimentation rates decreased seaward across the shelf from 0.85 cm y1 in a nearshore bay to 0.19 cm y1 in a fore-reef setting. Data reflected a significant (up to 2) increase over the last 80 years in terrestrial sediment accumulating in the back-reef setting, suggesting greater terrestrial sediment flux to the area. Reef health has declined, and increased turbidity is believed to be an important impact, particularly when combined with additional stressors.

Seasonal changes in sea surface temperature and salinity during the little ice age in the caribbean sea deduced from Mg/Ca and O-18/O-16 ratios in corals

Watanabe, T., A. Winter, and T. Oba. 2001. Seasonal changes in sea surface temperature and salinity during the little ice age in the caribbean sea deduced from Mg/Ca and O-18/O-16 ratios in corals. Marine Geology 173 (1-4) (MAR 15): 21-35.

Abstract: 
The oxygen isotropic composition (delta 18O) of coral skeletons reflects a combination of sea surface temperature (SST) and the delta 18O of seawater, which is related to sea surface salinity (SSS). In contrast, the magnesium/Calcium (Mg/Ca) ratio of a coral skeleton reflects SST independent of Salinity. by using the relationships among coral Mg/Ca ratios, coral delta 18), seawater delta 18O and SST, it is possible to determine past SST and SS uniquely. Such determinations were made and calibrated using the Mg/Ca ratio and the delta 18O of the modern part of a 3 m long coral core (Monastrea faveolata) collected from the southwest coast of Puerto Rico in the Caribbean Sea where both SST and SSS changes seasonally and the seawater delta 18O measured at the coral site....

Paleoclimate proxy perspective on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability

Kilbourne, K. H., T. M. Quinn, R. Webb, T. Guilderson, J. Nyberg, and A. Winter. 2008. Paleoclimate proxy perspective on caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability RID A-5755-2008. Paleoceanography 23 (3) (SEP 19): PA3220.

Abstract: 
Annually resolved coral d18O and Sr/Ca records from southwestern Puerto Rico are used to investigate Caribbean climate variability between 1751 and 2004 C.E. Mean surface ocean temperatures in this region have increased steadily by about 2C since the year 1751, with Sr/Ca data indicating 2.1 ± 0.8C and d18O data indicating 2.7 ± 0.5C. Coral geochemical records from across the tropics demonstrate that regional variability is important for understanding climate variations at centennial time scales. A strong multidecadal salinity signal in the oxygen isotope data correlates with observed multidecadal temperature variations in the Northern Hemisphere. Instrumental wind and precipitation data indicate that the most recent coral isotopic variations are caused by expansion and contraction of the steep regional salinity gradient, forced by trade wind anomalies through meridional Ekman transport. The timing of the fluctuations suggests that the multidecadal-scale wind and surface circulation anomalies might play a role in Atlantic temperature variability and meridional overturning circulation, but further work is needed to confirm this suggestion.

Carbon and Oxygen Isotope Time Series From an 18-Year Caribbean Reef Coral

Abstract: 
Colonies of Montastrea annularis live near La Parguera, Puerto Rico, and maybe 799 years old. Time series from 1964 to 1982 of delta 13C and delta 18O from a continuous core of these corals are compared to an adjacent environmental record. At the intraannual level, delta 18O correlates well with water temperature. Changes in the amplitude of the delta 18O signal between 1967 and 1976 are attributed to sampling frequency but may be also due to environmental changes such as salinity. Average annual delta 18O, delta 13C and sea surface temperature show similar trends of the period from 1964 to 1982 but expecially from 1969 onwards. Changes in average annual values during this time interval are most likely due to water mass changes brough about by interannual variability of the North Atlantic circulation. Since water temperature at La Parguera are representative of changes occurring in the wider Caribbean, the isotope record from La Parquera corals could be used as a proxy for large-scale environmental changes beyond the historical record through the Little Ice Age.

Urban heat island effect analysis for San Juan, Puerto Rico

Velazquez-Lozada, A., Gonzalez, J. E., and Winter, A., 2006. Urban heat island effect analysis in San Juan,
Puerto Rico. Atmospheric Environment 40, 1731-1741.

Abstract: 
A climatological analysis of the differences of air temperature between rural and urban areas (dT(U–R)) corroborates the existence of an urban heat island (UHI) in the tropical coastal city of San Juan, Puerto Rico that has been increasing at a rate of 0.06 1Cyear1 for the last 40 years with predicted differences as high as 8 1C for the year 2050. The Regional Atmospheric Model System (RAMS) was used to validate the presence of this UHI and to simulate and compare three different land use scenarios consisting of potential natural vegetation, present, and projected future to quantify the impact of the urban development in the regional climate of Puerto Rico. RAMS simulated the UHI conditions at the lower and upper atmosphere revealing significant changes in sensible heat fluxes and sinks, and an increasing low turbulent-kineticenergy zone (LTKEZ) over the urbanized area of San Juan.

Paleoclimate proxy perspective on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability

Kilbourne, K. H., T. M. Quinn, R. Webb, T. Guilderson, J. Nyberg, and A. Winter (2008), Paleoclimate proxy perspective
on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability, Paleoceanography, 23,
PA3220, doi:10.1029/2008PA001598.

Abstract: 
Annually resolved coral delta O-18 and Sr/Ca records from southwestern Puerto Rico are used to investigate Caribbean climate variability between 1751 and 2004 C. E. Mean surface ocean temperatures in this region have increased steadily by about 2 degrees C since the year 1751, with Sr/Ca data indicating 2.1 +/- 0.8 degrees C and delta O-18 data indicating 2.7 +/- 0.5 degrees C. Coral geochemical records from across the tropics demonstrate that regional variability is important for understanding climate variations at centennial time scales. A strong multidecadal salinity signal in the oxygen isotope data correlates with observed multidecadal temperature variations in the Northern Hemisphere. Instrumental wind and precipitation data indicate that the most recent coral isotopic variations are caused by expansion and contraction of the steep regional salinity gradient, forced by trade wind anomalies through meridional Ekman transport. The timing of the fluctuations suggests that the multidecadal-scale wind and surface circulation anomalies might play a role in Atlantic temperature variability and meridional overturning circulation, but further work is needed to confirm this suggestion.

Low Atlantic hurricane activity in the 1970s and 1980s compared to the past 270 years

Nyberg, J., B. A. Malmgren, A. Winter, M. R.
Jury, K. H. Kilbourne, and T. M. Quinn
(2007), Low Atlantic hurricane activity in the
1970s and 1980s compared to the past 270
years, Nature, 447, 698–701.

Abstract: 
Hurricane activity in the North Atlantic Ocean has increased significantly since 1995 (refs 1, 2). This trend has been attributed to both anthropogenically induced climate change3 and natural variability1, but the primary cause remains uncertain. Changes in the frequency and intensity of hurricanes in the past can provide insights into the factors that influence hurricane activity, but reliable observations of hurricane activity in the North Atlantic only cover the past few decades2. Here we construct a record of the frequency of major Atlantic hurricanes over the past 270 years using proxy records of vertical wind shear and sea surface temperature (the main controls on the formation of major hurricanes in this region1,3–5) from corals and a marine sediment core. The record indicates that the average frequency of major hurricanes decreased gradually from the 1760s until the early 1990s, reaching anomalously low values during the 1970s and 1980s. Furthermore, the phase of enhanced hurricane activity since 1995 is not unusual compared to other periods of high hurricane activity in the record and thus appears to represent a recovery to normal hurricane activity, rather than a direct response to increasing sea surface temperature. Comparison of the record with a reconstruction of vertical wind shear indicates that variability in this parameter primarily controlled the frequency of major hurricanes in the Atlantic over the past 270 years, suggesting that changes in the magnitude of vertical wind shear will have a significant influence on future hurricane activity.
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