Interactive Effects of Anthropogenic, Environmental, and Biotic Stressors on Multiple Endpoints in Hyla chrysoscelis

Multiple stressors have been proposed as causative agents for declining populations and increased incidence of malformations in amphibians although few studies have examined possible interactions among these stressors. We measured interactive effects of UV radiation, three chemicals, and interspecific competition (with Rana 1phenocephala) on multiple endpoints in Hyla chrysoscelis using a center point- and chemical-free control-enhanced 24 factorial design. UV radiation was transmitted or filtered using OP-4 or OP-3 acrylite filters installed above 72, 500-liter mesocosms on 16 May 1997. Methyl mercury, chlorpyrifos, and atrazine were applied at levels of 0, 10, 50, and 100 % of 400 ppb, 30 ppb, and 192 ppb, respectively, on 8 June. Hatching success and larval mortality were assessed 1, 2, 4, 8, 16, and 32 days after chemical application. After sampling on day 32, chemicals were reapplied to 24 mesocosms, initial water levels were restored in 24 additional mesocosms, and the remaining mesocosms were unmanipulated. On day 33, we placed 25 Hyla eggs in each mesocosm to perform a complete larval assessment of interacting stressors on growth, development, metamorphosis, and incidence of malformations. Interactions among stressors affected hatching success, developmental time, number of metamorphs, and incidence of malformation. Single effects of stressors were uncommon in that only larval mortality was unaffected by potential stressor interactions. If interactive effects of stressors are not evaluated in experiments examining population declines and malformations, results may be misinterpreted leading to ineffective conservation efforts

Simultaneous changes of the spontaneous and stimulus-evoked cortical activity in rats acutely treated with mercuric chloride

In earlier studies of our laboratory and in several other reports, alterations in the electrical activity of the cortex of experimental animals on subchronic mercury (Hg) administration were described. In the present work, simultaneous changes in the spontaneous and stimulus-evoked cortical activity elicited by acute administration of inorganic Hg were evaluated with the aim of finding any correlation of the two, possibly giving insight into the mechanism of the alterations. In young adult male Wistar rats, spontaneous cortical, as well as stimulus-evoked cortical and peripheral nervous activity was recorded, before and after acute administration of 3.5 and 7.0 mg/kg Hg2+ ip. The effects of Hg2+ appeared within 10 min and most became significant over 3 h. On the cortex, slowed spontaneous activity, as well as increased amplitude and latency of the evoked potentials (EPs) was seen, and in the periphery, decreased nerve conduction velocity. These alterations seemed to be consistent with a separate cortical and peripheral axonal effect of Hg. Š 2003 Elsevier Inc. All rights reserved

Mobilization of Metals by Fungi in Historic Cemeteries

Interactions among fungi, soil, and metals are at the heart of nutrient cycling in terrestrial systems. Both major and trace elements are found in soils, but the degree to which they are biologically available is influenced by chemical weathering of soil minerals by fungi. In addition to contributing to weathering, mushrooms are known to bioaccumulate metals from soil, so edible mushrooms growing on soils contaminated with toxic metals can cause harm to those who eat them. This study focuses on metal content of mushrooms and soils from cemeteries that are suspected to be contaminated with arsenic as a result of late-19th Century embalming practices. Mushrooms and soil were collected from eight cemeteries and three control areas in Lewiston, Auburn, Sabattus, and Topsham, Maine and analyzed for metal content using acid digestion and ICP-OES. With particular focus on arsenic, concentrations of potassium, sodium, zinc, calcium, iron, magnesium, lead, and arsenic in mushrooms are compared to concentrations of those metals in the soil on which the mushrooms were growing

Maternal Vitamin D Status and the Relationship with Neonatal Anthropometric and Childhood Neurodevelopmental Outcomes: Results from the Seychelles Child Development Nutrition Study

Vitamin D has an important role in early life; however, the optimal vitamin D status during pregnancy is currently unclear. There have been recent calls for pregnant women to maintain circulating 25-hydroxyvitamin D (25(OH)D) concentrations >100 nmol/L for health, yet little is known about the long-term potential benefits or safety of achieving such high maternal 25(OH)D concentrations for infant or child health outcomes. We examined maternal vitamin D status and its associations with infant anthropometric and later childhood neurocognitive outcomes in a mother-child cohort in a sun-rich country near the equator (4.6° S). This study was conducted in pregnant mothers originally recruited to the Seychelles Child Development Nutrition Study. Blood samples (n = 202) taken at delivery were analysed for serum 25-hydroxyvitamin D (25(OH)D) concentrations. Multiple linear regression models assessed associations between maternal 25(OH)D and birth weight, infant head circumference, and neurocognitive outcomes in the children at age 5 years. Mothers were, on average, 27 years of age, and the children’s average gestational age was 39 weeks. None of the women reported any intake of vitamin D supplements. Maternal 25(OH)D concentrations had a mean of 101 (range 34–218 nmol/L) and none were deficient (<30 nmol/L). Maternal 25(OH)D concentrations were not associated with child anthropometric or neurodevelopmental outcomes. These findings appear to indicate that a higher vitamin D status is not a limiting factor for neonatal growth or neurocognitive development in the first 5 years of life. Larger studies with greater variability in vitamin D status are needed to further explore optimal cut-offs or non-linear associations (including for maternal health) that might exist among populations with sub-optimal exposure

Zastupljenost i specijacija žive u jadranskom planktonu, školjkašima i ribi – pregled

This article presents an overview of available research on mercury speciation in the most studied biota of the Adriatic Sea as a specific biogeochemical subunit of the Mediterranean. We present current knowledge about mercury concentration, speciation, spatial distribution and temporal changes in plankton, bivalves and fish from the Adriatic Sea. Results from mercury speciation studies in marine organisms are used to describe the extent of mercury bioaccumulation in the Adriatic Sea. Mercury biogeochemical cycle in the Adriatic is characterised by increased mercury concentrations from the water column, through plankton, bivalves and smaller fish to predator fish species. Although the Adriatic Sea has the highest mercury concentration in the whole Mediterranean Sea, fish species at the higher trophic levels have similar mercury concentrations everywhere in the Mediterranean, indicating incomplete understanding of the transfer mechanisms of mercury from seawater to upper trophic levels. As consumption of (contaminated) food is the main route of human exposure to mercury, it is of great importance to understand the influence of mercury contamination in the Adriatic Sea.Ovaj članak predstavlja pregled dostupnih istraživanja o specijaciji žive u najproučavanijoj bioti Jadranskog mora kao posebne biogeokemijske podjedinice Mediterana. Predstavljamo postojeće znanje o koncentraciji žive, specijaciji, prostornoj raspodjeli i vremenskim promjenama u planktonu, školjkašima i ribi Jadranskog mora. Rezultati studija o specijaciji žive u morskim organizmima su korišteni za opis razdiobe bioakumulacije žive u Jadranskom moru. Biogeokemijski ciklus žive u Jadranu karakterizira povećanje koncentracije žive od vodenog stupca, preko planktona, školjkaša i manjih riba do predatorskih ribljih vrsta. Iako Jadransko more sadrži najviše koncentracije žive u cijelom Mediteranu, riblje vrste na višim trofičkim razinama imaju slične koncentracije žive posvuda u Mediteranu, ukazujući na nepotpuno razumijevanje prijenosnih mehanizama žive iz morske vode na više trofičke razine. Budući da je konzumiranje (kontaminirane) hrane glavni put ljudske izloženosti živi, od iznimne je važnosti razumijevanje utjecaja kontaminacije živom u Jadranskom moru

U kojoj mjeri veličina zrna utječe na interpretaciju sastava zajednica planktonskih foraminifera - primjer iz južnog Jadrana

Study of planktonic foraminifera, sampled from two levels of a 26 cm thick core, recovered at 1,200 m water depth, sheds some lights on the composition of foraminiferal assemblages that occur in the Southern Adriatic. Altogether 15 planktonic species (including one referred as undeterminable and two species recorded for the first time in the eastern Adriatic Sea) identified from 0-2 cm and 24-26 cm sediment intervals, were grouped into two assemblages: >63 μm fraction Turborotalita quinqueloba and >125 μm fraction as Globigerina bulloides-Globigerinoides ruber. The differences in core-top and core-bottom assemblages lie in: a) change in the relative proportion of some species; and b) slight differences in diversity indices. The relative proportions of species are strongly controlled by sieve mesh size, whereas the slight increase in diversity follows the increase in sieve mesh size. The benthic foraminifera, although constituting a negligible quantitative factor, show a slight increase in abundance and diversity of species with age.Istraživanje planktonskih foraminifera iz dviju razina 26 cm duge jezgre izvađene sa 1,200 m dubine daje nove podatke o sastavu foraminiferskih zajednica u južnom dijelu Jadranskog mora. Ukupno 15 planktonskih vrsta (uključujući jednu neodredivu i dvije vrste koje su po prvi puta zabilježene u istočnom dijelu Jadranskog mora) određene su iz sedimentnih intervala 0-2 cm i 24-26 cm grupiranih u dvije zajednice: frakcija >63 μm nazvana Turborotalita quinqueloba, te frakcija >125 μm Globigerina bulloides -Globigerinoides ruber. Razlike između zajednica u vršnom i najdubljem dijelu jezge leže u: a) razlici u relativnim zastupljenostima nekih vrsta; b) blagim razlikama u indeksima raznolikosti. Relativni udio vrsta pod snažnim je utjecajem veličine otvora sita, gdje s povećanjem otvora sita lagano raste raznolikost. Bentičke foraminifere, iako čine neznatni kvantitativni faktor, pokazuju blago povećanje udjela i raznolikosti vrsta s dubinom sedimenta (sa starosti)