Gelatin embedding and diagnostic ultrasound in the examination of the fetal and neonatal brain

We describe a new method for the post-mortem examination of the fetal central nervous system. The brain is immobilized in gelatin prior to ultrasonic examination. Correlation with prenatal ultrasound is excellent and subsequent pathological examination is enhanced and facilitated.     

Mercury in feathers of Squacco Heron (Ardeola ralloides) chicks in relation to age, hatching order, growth, and sampling dates

We studied the relationships between mercury content of Squacco Heron (Ardeola ralloides) chick body-feathers and nestling age, hatching order (seniors-juniors) and growth parameters, and the date of feather sampling in the Axios Delta, northern Greece, in 1993 (n = 75 chicks) and 1994 (n = 80). Mercury levels were not significantly correlated with chick age in either year of the study. Most of the variability in mercury (90%) was found among broods, attributable to differential prey selection and/or foraging habitat and patch utilization by parents. Within broods, juniors had significantly higher mercury loads than seniors in 1993, but there was no significant difference between the two in 1994. Correlations of nestling weight and linear measurements corrected for chick age and mercury concentrations were never significant and explained small amounts of variability in chick growth. However, linear measurements corrected for age were significantly higher among seniors in 1993, when those nestlings had lower mercury loads than their siblings. Mercury levels were unaffected by the date of feather collection in 1993, but exhibited a significant increase over time in 1994. This can be attributed to a shift towards more highly contaminated habitats and prey types by foraging parents, resulting from seasonal changes in water level and vegetation cover in important foraging habitats. Feather collection from Squacco Heron nestlings late in the breeding season seems to be an appropriate method for biomonitoring mercury pollution in the Axios Delta.     

Mercury levels in the plumage of red-billed gulls Larus novaehollandiae scopulinus of known sex and age

Samples of 4-8 small body feathers were taken from 27 chicks and 35 adult red-billed gulls caught at their nests on the Kaikoura Peninsula, New Zealand, in December 1988. The adults had been ringed as chicks and were of known ages from 2 to 15 years old. Analysis of total mercury in the feather samples showed that levels were independent of sex and age in adults. Mean fresh weight concentration in adult body feathers was 2.4 microg g(-1). The lack of age accumulation of mercury in gull feathers contrasts with the well known age related accumulation of mercury in tissues of fish and marine mammals, but agrees with predictions of recent studies on mercury dynamics in birds. Mercury levels in chick feathers were about 80% of levels in adult feathers.     

Energy budgets reveal equal benefits of varied migration strategies in northern gannets

We investigated migration and wintering of adult northern gannets (Morus bassanus) breeding in east Scotland, North Sea, by deploying geolocation loggers over three winters. The wintering ranges of these birds varied from the North Sea to the Atlantic off West Africa. Flight time was taken as a proxy for migration and foraging effort. Gannets wintering off Africa had higher total flight times during migration than birds wintering further north. Total flight times in different wintering regions were generally low. Birds off West Africa consistently spent < 25 % of daylight hours in flight, but birds further north showed more variable values that may reflect more variable weather or food availability. Winter sea surface temperatures ranged from 9 °C (North Sea) to 16 °C (West Africa). Thermostatic costs in winter as estimated by measuring thermal conductance in carcasses in still air and water were 28 % higher in North Sea than off West Africa. This effect is aggravated by higher thermostatic costs caused by stronger wind chills in the North Sea compared to the conditions off West Africa. Birds wintering close to the UK arrived at the colony on average 12 days earlier than birds wintering off West Africa. We conclude that the net cost-benefit analysis may be similar for all wintering areas investigated.     

Metal concentrations in seabirds of the New Zealand region

Concentrations of the heavy metals cadmium, copper, lead, zinc, mercury and, in some individuals, methyl mercury were determined in a range of tissues of 64 tropical, subtropical, subantarctic and antarctic seabird taxa mostly from the New Zealand region. Although apparently natural, levels of cadmium and mercury in some species greatly exceed those known to have toxic effects in some terrestrial birds. Copper and zinc levels exhibited less inter-species variation than the non-essential metals cadmium and mercury. Cadmium concentrations were highest in kidney tissues but uniformly low in feathers. Total mercury concentrations showed most inter-species variation. Mean methyl mercury levels in liver tissues of several large procellariiforms represented less than 5% of the corresponding mean total mercury level. Lead concentrations were generally low or below the limits of detection, but elevated levels were measured in some coastal or scavenging species. In a significant number of species, mean concentrations of liver cadmium and mercury and kidney cadmium were greater in adults than in young birds. The reverse was true for copper. Mean zinc levels in liver did not differ between adults and young. High levels of cadmium in some species seem likely to be due to diet, whereas high levels of mercury probably reflect more closely the moult intervals which constrain the ability of birds to eliminate methyl mercury.     

The Influence of Age on Cadmium Concentrations in Seabirds

The effects of age on cadmium concentrations was investigated in Cory's shearwater, Calonectris diomedea, Lesser black-backed gull, Larus fuscus, and great skuas, Catharacta skua. There was no evidence for the continued accumulation of cadmium with increasing adult age. Adult shearwaters did have higher concentrations of cadmium compared to young fledglings, but there was no significant difference between cadmium concentrations in adult and sub-adult gulls. In addition, the sample of great skuas were of known age (3–22 yrs old) and showed no evidence of increasing cadmium concentrations with adult age in liver or kidney. However, it is possible that age accumulation of cadmium in great skuas was masked by individual dietary preferences overriding the effects of increasing age. It is often assumed that cadmium concentrations continue to accumulate with increasing adult age, but seabirds may have evolved some as yet unknown mechanism for excretion or more rapid turnover of cadmium than previously thought. The implications of this for the use of seabirds as biomonitors is discussed.     

Mercury levels and health parameters in the threatened Olrog��s Gull (Larus atlanticus) from Argentina

Mercury (Hg) exposure was investigated through feathers of Olrog's Gull and related to health parameters in adults (hematocrit, total plasma proteins, morphometric measures, sex) and chicks (hematocrit, total plasma proteins, immunoglobulins G and M) from a colony located in estuary of Bahía Blanca, Argentina. Mercury concentrations were 5.50 ± 2.59 μg g?1 (n = 44) in live adults, 1.85 ± 0.45 μg g?1 (n = 45) in live chicks and 1.81 ± 0.41 μg g?1 (n = 41) in dead chicks. Large differences were observed between live adults and live or dead chicks and small differences between live and dead chicks. In the adults, the sex of the birds was the variable that best explained Hg concentrations. Male birds had higher concentrations than females; this suggests that the clutch provides a sink for mercury during egg laying. Hg concentrations in both adults and live chicks were associated with higher hematocrits. This could be associated with upregulated erythropoiesis to compensate for increased rate of destruction of prematurely senescent, Hg-contaminated erythrocytes. Based on our results, on the levels of Hg pollution in the past in the study area, and on the dietary specialization of Olrog's Gull, we must be vigilant about potential negative effects of Hg pollution on this population and recommend continued monitoring on this threatened species.     

Changing priorities: the effect of pre-migratory fattening on the trade-off between foraging and vigilance

Summary Many birds accumulate fat reserves prior to departure on long distance migration. Since there will be an increased food requirement during the pre-migratory period, it is to be expected that more time will be invested in foraging, at the expense of other activities. The allocation of time to anti-predatory behavior in migratory ruddy turnstones (adults) was found to decrease prior to migration (Fig. 1); non-migratory individuals (juveniles) showed no decrease over the same time period (Fig. 2). This is interpreted as a change in the optimal adult behavior, the cost of a reduced rate of resource accumulation outweighing the additional risk of predation which results from the decrease in vigilance.     

The chemical form of mercury stored in South Atlantic seabirds

Concentrations of total mercury and organic (methyl) mercury were measured in the liver tissue of adults of 12 seabird species collected at colonies on Gough Island, South Atlantic Ocean. Total mercury levels showed both great intra- and interspecies variation, ranging from a mean of 1343.0 microg g(-1) dry weight in wandering albatrosses to a mean of 0.8 microg g(-1) dry weight in broad-billed prions. Organic mercury levels were less variable both between, but especially within, species. Organic mercury levels, expressed as a percentage of total mercury levels, ranged from a mean of 2.6% in wandering albatrosses up to a mean of 92.6% in littee shearwaters. Within each species, individuals with the highest total mercury levels tended to have the lowest percentage organic mercury, this trend being statistically significant in several species. Two species exhibited a significant positive correlation between organic mercury levels, in absolute terms, and total mercury levels. When all 12 species were considered, a highly significant negative correlation between mean percentage organic mercury and mean total mercury was found (rs = -0.888, P < 0.001). These results provide evidence to suggest that some seabirds may be capable of demethylating organic mercury in a species-dependent and that eliminatory pathways for the excretion of dietary mercury may influence the mode of response of a particular species.     

Food access,food security and community gardens in Rockford,IL

Urban agriculture projects seek to ameliorate issues of food access and food security for people living in areas with low access to fresh foods, including food deserts. Within this discourse, community gardens have been promoted as vehicles to reclaim unused urban space, produce food locally and connect populations to their food sources and larger community. A variety of community garden models exist; in the Midwestern city of Rockford, Illinois, many community gardens grow food for donation to food pantries as part of a programme to benefit socioeconomically disadvantaged persons in the city. However, the ability of these gardens to involve neighbourhood participants and provide the social capital-related benefits attributed to community gardens in the literature is uncertain. Here we examine community gardens in Rockford, IL to assess the extent to which they contribute to residents’ ability to obtain fresh produce as well as other social benefits. Data for this project come from a combination of interviews with gardeners, focus groups with food pantry users and a survey of pantry users. We find that while non-gardening community members are benefitting from the increased produce that the gardens provide, they are not receiving all of the social and communal benefits associated with actively participating in a garden.