Extent and Causes of Chesapeake Bay Warming

Coastal environments such as the Chesapeake Bay have long been impacted by eutrophication stressors resulting from human activities, and these impacts are now being compounded by global warming trends. However, there are few studies documenting long-term estuarine temperature change and the relative contributions of rivers, the atmosphere, and the ocean. In this study, Chesapeake Bay warming, since 1985, is quantified using a combination of cruise observations and model outputs, and the relative contributions to that warming are estimated via numerical sensitivity experiments with a watershed–estuarine modeling system. Throughout the Bay’s main stem, similar warming rates are found at the surface and bottom between the late 1980s and late 2010s (0.02 +/- 0.02C/year, mean +/- 1 standard error), with elevated summer rates (0.04 +/- 0.01C/year) and lower rates of winter warming (0.01 +/- 0.01C/year). Most (~85%) of this estuarine warming is driven by atmospheric effects. The secondary influence of ocean warming increases with proximity to the Bay mouth, where it accounts for more than half of summer warming in bottom waters. Sea level rise has slightly reduced summer warming, and the influence of riverine warming has been limited to the heads of tidal tributaries. Future rates of warming in Chesapeake Bay will depend not only on global atmospheric trends, but also on regional circulation patterns in mid-Atlantic waters, which are currently warming faster than the atmosphere. Supporting model data available at: https://doi.org/10.25773/c774-a36

Gender-related differences in the effects of nitric oxide donors on neuroleptic-induced catalepsy in mice

It has been suggested that nigrostriatal dopaminergic transmission is modulated by nitric oxide (NO). Since there is evidence that gonadal hormones can affect extrapyramidal motor behavior in mammals, we investigated the effects of isosorbide dinitrate (ISD), linsidomine (SIN-1) and S-nitroso-N-acetylpenicillamine (SNAP), three pharmacologically different NO donors, on neuroleptic-induced catalepsy in 60- to 80-day-old male and female albino mice. Catalepsy was induced with haloperidol (1 mg/kg, ip) and measured at 30-min intervals by means of a bar test. Drugs (or appropriate vehicle) were injected ip 30 min before haloperidol, with each animal being used only once. ISD (5, 20 and 50 mg/kg) caused a dose-dependent inhibition of catalepsy in male mice (maximal effect 120 min after haloperidol: 64% inhibition). In the females only at the highest dose of ISD was an attenuation of catalepsy observed, which was mild and short lasting. SIN-1 (10 and 50 mg/kg) did not significantly affect catalepsy in female mice, while a significant attenuation was observed in males at the dose of 50 mg/kg (maximal inhibition: 60%). SNAP (20 mg/kg) significantly attenuated catalepsy in males 120 min after haloperidol (44% inhibition), but had no significant effect on females. These results basically agree with literature data showing that NO facilitates central dopaminergic transmission, although the mechanisms are not fully understood. They also reveal the existence of gender-related differences in this nitrergic modulation in mice, with females being less affected than males

Distribution and isotopic composition of lead in bottom sediments from the hydrographic system of Belém, Pará (western margin of Guajará Bay and Carnapijó River)

ABSTRACT: This study first aimed to evaluate the effect of human activities on the distribution of lead within the estuarine system of Belém, Pará. This was achieved by studying the concentration and isotopic signature of Pb in bottom sediments from the western margin of Guajará Bay and from Carnapijó River, an area removed from the influence of the city of Belém. Secondly, the contribution of suspended matter in the transportation of anthropogenic Pb in Guajará Bay was evaluated. Third, the content and background isotopic signature of Pb in the hydrographic system of Belém was determined. Isotopic signatures of sediments from the western margin of Guajará Bay confirm an anthropogenic contribution of Pb throughout the entire bay. The Pb accumulation process has become more efficient over the last 10 years, and this can be attributed to the rapid population growth of Belém city. Sediments in Carnapijó River are not affected by human activities, and the average concentration values (Pb = 19.6 ± 3.7 mg kg-1) and isotopic signatures (206Pb/207Pb = 1.196 ± 0.004) confirm the background Pb values previously proposed for the river system in the Belém region. The isotopic signatures of suspended matter on the eastern (206Pb/207Pb = 1.188) and western (206Pb/207Pb = 1.174) margins of Guajará Bay show that suspended matter is an efficient Pb transportation mechanism of domestic and industrial wastewater from Belém to the western margin of the Bay due to tidal effects at the confluence with Guamá River