Neighbourhood perceptions among inner-city adolescents: Relationships with their individual characteristics and with independently assessed neighbourhood conditions

We investigated relationships between adolescents’ perceptions of their neighbourhood, their mental health and independently assessed indicators of conditions in their residential neighbourhood. The Research with East London Adolescents Community Health Survey (RELACHS) provided information for 2370 adolescents on area perceptions (specifically alienation from/attachment to the area and satisfaction/dissatisfaction with local amenities and services), and on individual and family attributes including mental distress (measured by the Strengths and Difficulties Questionnaire). These were combined for this study with independently assessed small area geographical indicators proposed by government to measure local deprivation in England. A Bayesian regression analysis using Gibbs sampling investigated associations between the predictor variables and neighbourhood perception. Alienation from neighbourhood and dissatisfaction with local amenities was greater for girls than for boys and for the older adolescents sampled. Those of ‘Asian’ or ‘Black’ ethnicity, from relatively harmonious families, or with higher levels of social support were less likely to express negative area perceptions. While previously published research found no significant direct association between mental health and small area indicators, this analysis suggests that those with relatively high levels of distress did have worse area perceptions. Also, certain independently assessed area indicators were associated with adolescents’ views of their neighbourhood.     

Food availability and physiological state of sea urchin larvae (<Emphasis Type="Italic">Strongylocentrotus purpuratus</Emphasis>)

Food availability is highly variable in the ocean. Many species of marine invertebrates have a larval form that depends upon exogenous nutrients for growth, yet there are few biochemical and physiological indices for determining changes in the nutritional status of larvae. In this study, the effects of food availability on biochemical compositions and metabolic processes of larvae of the sea urchin, Strongylocentrotus purpuratus, were determined. Larvae were cultured under different food concentrations (fed-to-excess and unfed) and a suite of biological processes assayed, ranging from measurements at the level of the whole organism to that of specific molecules. These data were normalized to DNA content (an index of cell number) to allow comparisons of physiological rates in larvae of different sizes. Changes in the following were measured during larval growth: free amino acid pool, protein, lipid classes (cholesterol, free fatty acids, hydrocarbons, phospholipids, triacylglycerol), enzyme activities (Na⁺, K⁺-ATPase and citrate synthase), and respiration rates. In growing larvae, the two key components that showed differential cell-specific content relative to unfed larvae were glycine in the free amino acid pool and phospholipids. Additionally, several lipid classes were detectable only in fed larvae (cholesterols, free fatty acids, and hydrocarbons). While triacylglycerols were present in eggs and utilized during pre-feeding development, they were not re-accumulated at detectable levels in feeding larvae. Respiration rates, protein content, and enzyme activities were all similar on a cell-specific basis, showing that these variables did not provide useful indices of differences in physiological state between fed and unfed larvae. In contrast, measurements of the cell-specific content of glycine and certain lipid classes did provide useful indices of physiological state of larvae. Application of these indices could potentially allow for determinations of nutritional state of larvae in the ocean.     

Seasonal and decadal changes in distribution patterns of Halobates (Hemiptera: Gerridae) populations in the eastern tropical Pacific

Five species of the marine insect Halobates share similar ecology but have distinct biogeographic ranges in the eastern tropical Pacific, a region from approximately 75°W–160°W and 10°S–35°N. Between 2001 and 2010, the Sea Education Association collected Halobates from 682 neuston tows (surface net 1 m × 0.5 m, 335-μm mesh) during fifteen cruises between San Diego, USA, Mexico and Tahiti. Total Halobates spp. densities varied substantially from year to year, but our data do not show a sustained change from a data set collected 40 years earlier from 1967 to 1968 (Cheng and Shulenberger in Fish Bull 78(3):579–591, 1980). Halobates are sensitive to sea surface temperature and we observed significant differences in species distributions over time, but these were not due to differences in water temperature or climate change. Our analyses show that the patterns observed are attributable to substantial but previously undescribed seasonal shifts that occur each year in the ranges for both Halobates sobrinus and Halobates micans. There is substantial overlap in ranges during seasonal shifts, but very little co-occurrence of H. sobrinus and H. micans in individual net tows, suggesting biological mechanisms rather than physical factors are restricting distribution and co-occurrence of these two species.     

Higher trophic level prey does not represent a higher quality diet in a threatened seabird: implications for relating population dynamics to diet shifts inferred from stable isotopes

Diet quality is a key determinant of population dynamics. If a higher trophic level, more fish-based diet is of higher quality for marine predators, then individuals with a higher trophic level diet should have a greater body mass than those feeding at a lower trophic level. We examined this hypothesis using stable isotope analysis to infer dietary trophic level and foraging habitat over three years in eastern rockhopper penguins Eudyptes chrysocome filholi on sub-Antarctic Campbell Island, New Zealand. Rockhopper penguins are ‘Vulnerable’ to extinction because of widespread and dramatic population declines, perhaps related to nutritional stress caused by a climate-induced shift to a lower trophic level, lower quality diet. We related the stable nitrogen (δ¹⁵N) and carbon (δ¹³C) isotope values of blood from 70 chicks, 55 adult females, and 55 adult males to their body masses in the 2010, 2011, and 2012 breeding seasons and examined year, stage, age, and sex differences. Opposite to predictions, heavier males consumed a lower trophic level diet during incubation in 2011, and average chick mass was heavier in 2011 when chicks were fed a more zooplankton-based, pelagic/offshore diet than in 2012. Contrary to the suggested importance of a fish-based diet, our results support the alternative hypothesis that rockhopper penguin populations are likely to be most successful when abundant zooplankton prey are available. We caution that historic shifts to lower trophic level prey should not be assumed to reflect nutritional stress and a cause of population declines.