Insights from barium variability in a Siderastrea siderea coral in the northwestern Gulf of Mexico.

Coral Ba/Ca is a proxy for seawater barium concentration that varies with upwelling, terrigenous input, and marine productivity whereas coral Sr/Ca varies with temperature. We examine monthly coral Ba/Ca and Sr/Ca before and during offshore oil exploration in a Siderastrea siderea coral from West Flower Garden Bank located on the continental shelf edge in the Gulf of Mexico. Coral Ba/Ca variations lack pulses driven by upwelling or river outflow and are not in sync with coral Sr/Ca that exhibit a different seasonal pattern. Seasonal variations in chlorophyll-a concentration negatively correlate with coral Ba/Ca explaining 25% of that variability. A significant increase in mean coral Ba/Ca of 1.76 µmol/mol between 1931-1944 and 1976-2004 corresponds to the increase in the United States barite production and consumption primarily used in offshore oil drilling, which escalated in the 1970s, suggesting oil drilling operations are increasing seawater Ba concentration in the Gulf of Mexico.

Winter is (not) coming: Warming temperatures will affect the overwinter behavior and survival of blue crab.

Understanding how increases in water temperature may affect winter dormancy period duration and overwinter survival are important for the effective conservation and management of estuarine species in the face of a warming climate. In this study, we determined the length of the overwintering period and the probability of overwinter survival of blue crab (Callinectes sapidus), an ecologically and economically important estuarine crustacean. Overwintering period length and probability of overwinter survival were determined using projected water temperatures up to the year 2100, derived from a harmonic model that utilized air temperatures from multi-model ensemble of regional-scale climate projections. Our estimates of warming water temperatures by 2100 in Chesapeake Bay indicate that winters will be up to 50% shorter and overwinter survival will increase by at least 20% compared to current conditions. The warmer conditions will lead to faster and prolonged seasonal growth, which, when combined with lower winter mortality, will lead to increased population productivity. The level of expression of this increased productivity will depend on the response of other elements of the Chesapeake Bay food web, as well as possible changes to fishery management policies over the same time period.

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

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 change and natural variability, 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 decades. 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 region) 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.

Identification of correlates of physical activity among Latino adults.

127 Latino adults responded to a survey concerning physical activity. Respondents over-represented well educated and middle class Latinos. Subjects reported a mean of 48 minutes/week of walking for exercise. This sample reported less than two episodes per week of vigorous physical activity, again below the recommended 3/wk needed to insure cardiovascular fitness. We expect more representative samples to engage in less physical activity. Stepwise multiple regression analyses were conducted using 24 variables based on Social Learning Theory. A multiple R of 0.66 accounted for over 27% of the variance in walking for exercise (p less than 0.001). Older adults, those with a history of childhood injury, and those who reported friend support were more likely to walk for exercise. Respondents who participated in physical activity during childhood and adolescence (including formal physical education in school) and, paradoxically, those who had models for exercise in childhood were less likely to walk for exercise. A multiple R of 0.75 accounted for 43% of the variance in vigorous physical activity and reached significance (p less than 0.001). Self-efficacy, friends' support, childhood physical activity, and eating a heart healthy diet were positively related to vigorous activity. These results suggest that different correlates influence walking versus vigorous activity, and that correlates of physical activity are different for Latinos compared to Anglos. The findings emphasize the need for larger scale investigations of the determinants of activity within the Latino population.

Effects of guanabenz in adolescent hypertension.

Fourteen adolescent patients, aged 12 to 21 years, with essential hypertension were treated on an open basis with guanabenz, a centrally acting antihypertensive agent. Guanabenz doses of 3-24 mg/day (0.08-0.20 mg/kg/day) given twice daily for 2 months effectively lowered mean supine blood pressure (p less than 0.05), standing blood pressure (p less than 0.01), and supine pulse rate (p less than 0.01). Body weight and standing pulse rate were unaffected. Adverse effects were mild, usually short lived, and did not interfere with therapy. No adverse effects were noted in laboratory test results or physical examinations. Baseline funduscopic photography revealed numerous but minor changes, including altered arteriovenous ratios and crossing changes. Prestudy echocardiograms revealed changes consistent with early hypertensive changes. Poststudy echocardiograms obtained in nine of the 14 subjects after 4-6 weeks of guanabenz therapy suggested that cardiac hypertrophy had regressed, but these changes did not reach statistical significance. These preliminary results suggest that guanabenz can be a safe and effective treatment for hypertensive children, that early hypertensive changes can be seen in the fundi and echocardiograms of mildly hypertensive adolescents, and that some echocardiographic changes may be reversed even after relatively short-term guanabenz therapy.

Guanabenz for adolescent hypertension.

Guanabenz, a centrally acting antihypertensive agent that acts through stimulation of central alpha-adrenergic receptors, appears to produce neither sodium retention nor clinically significant renal, cardiac, hepatic, or metabolic abnormalities. This 2-month open, uncontrolled dose-finding and short-term safety and efficacy trial was conducted in 11 male outpatients (12 to 21 years old) to establish the potential use of guanabenz in treating children with hypertension. Doses of 3 to 12 mg/day (0.07 to 0.17 mg/kg/day) given twice daily effectively lowered blood pressure in all patients. Mean supine blood pressure was significantly (P less than 0.05) reduced from 135/91/81 mmHg (phase I/IV/V) at baseline to 124/80/66 mmHg after approximately 2 months of treatment. Mean supine pulse rate also was significantly (P less than 0.05) reduced (10 beats/minute), while standing pulse rate and body weight were unaffected by guanabenz therapy. Adverse effects, the most common being headache, dry mouth, and drowsiness, were generally mild and did not interfere with continued therapy. No abnormal findings were noted in laboratory test results or physical examinations. These preliminary results suggest that guanabenz is safe and effective for the treatment of childhood hypertension.