Rapid Range Expansion of a Marine Ectotherm Reveals the Demographic and Ecological Consequences of Short-Term Variability in Seawater Temperature and Dissolved Oxygen.

AbstractThe distributions of marine ectotherms are governed by physiological sensitivities to long-term trends in seawater temperature and dissolved oxygen. Short-term variability in these parameters has the potential to facilitate rapid range expansions, and the resulting ecological and socioeconomic consequences may portend those of future marine communities. Here, we combine physiological experiments with ecological and demographic surveys to assess the causes and consequences of sudden but temporary poleward range expansions of a marine ectotherm with considerable life history plasticity (California market squid, Doryteuthis opalescens). We show that sequential factors related to resource accessibility in the core range-the buildup of large populations as a result of competitive release and climate-associated temperature increase and oxygen loss that constrain aerobic activity-may drive these expansions. We also reveal that poleward range expansion alters the body size-and therefore trophic role-of invading populations, with potential negative implications for socioeconomically valuable resident species. To help forecast rapid range expansions of marine ectotherms, we advocate that research efforts focus on factors impacting resource accessibility in core ranges. Determining how environmental conditions in receiving ecosystems affect body size and how body size is related to trophic role will help refine estimates of the impacts of future marine communities.

Exploring variability in the diet of depredating sperm whales in the Gulf of Alaska through stable isotope analysis.

Sperm whales interact with commercially important groundfish fisheries offshore in the Gulf of Alaska (GOA). This study aims to use stable isotope analysis to better understand the trophic variability of sperm whales and their potential prey, and to use dietary mixing models to estimate the importance of prey species to sperm whale diets. We analysed tissue samples from sperm whales and seven potential prey (five groundfish and two squid species). Samples were analysed for stable carbon and nitrogen isotope ratios, and diet composition was estimated using Bayesian isotopic mixing models. Mixing model results suggest that an isotopically combined sablefish/dogfish group, skates and rockfish make up the largest proportion of sperm whale diets (35%, 28% and 12%) in the GOA. The top prey items of whales that interact more frequently with fishing vessels consisted of skates (49%) and the sablefish/dogfish group (24%). This is the first known study to provide an isotopic baseline of adult male sperm whales and these adult groundfish and offshore squid species, and to assign contributions of prey to whale diets in the GOA. This study provides information to commercial fishermen and fisheries managers to better understand trophic connections of important commercial species.

Evidence for dietary time series in layers of cetacean skin using stable carbon and nitrogen isotope ratios.

RATIONALE: Stable isotope analysis integrates diet information over a time period specific to the type of tissue sampled. For metabolically active skin of free-ranging cetaceans, cells are generated at the basal layer of the skin and migrate outward until they eventually slough off, suggesting potential for a dietary time series. METHODS: Skin samples from cetaceans were analyzed using continuous-flow elemental analyzer isotope ratio mass spectrometry. We used ANOVAs to compare the variability of δ13 C and δ15 N values within and among layers and columns ("cores") of the skin of a fin, humpback, and sperm whale. We then used mixed-effects models to analyze isotopic variability among layers of 28 sperm whale skin samples, over the course of a season and among years. RESULTS: We found layer to be a significant predictor of δ13 C values in the sperm whale's skin, and δ15 N values in the humpback whale's skin. There was no evidence for significant differences in δ15 N or δ13 C values among cores for any species. Mixed-effects models selected layer and day of the year as significant predictors of δ13 C and δ15 N values in sperm whale skin across individuals sampled during the summer months in the Gulf of Alaska. CONCLUSIONS: These results suggest that skin samples from cetaceans may be subsampled to reflect diet during a narrower time period; specifically different layers of skin may contain a dietary time series. This underscores the importance of selecting an appropriate portion of skin to analyze based on the species and objectives of the study.

Using line acceleration to measure false killer whale (Pseudorca crassidens) click and whistle source levels during pelagic longline depredation.

False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015 a depredation event was recorded 14 m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15 Hz line vibration. Two similar line vibrations detected at earlier times permitted the animal's range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4-8 kHz) were estimated to be between 115 and 130 dB re 1 µPa2/Hz @ 1 m. Echolocation click source levels over 17-32 kHz bandwidth reached 205 dB re 1 µPa @ 1 m pk-pk, or 190 dB re 1 µPa @ 1 m (root-mean-square). Predicted detection ranges of the most intense whistles are 10 to 25 km at respective sea states of 4 and 1, with click detection ranges being 5 times smaller than whistles. These detection range analyses provide insight into how passive acoustic monitoring might be used to both quantify and avoid depredation encounters.

The implications of maternal grandmother coresidence and involvement for adolescent adjustment in South Africa.

Maternal grandmothers residing in 3-generation households often provide care and support to their grandchildren. However, the implications of grandmother coresidence and involvement for adolescent adjustment have been neglected in the South African literature. This study examined whether the involvement of maternal grandmothers who coreside with grandchildren and their parents differed from that of non-coresident grandmothers. In addition, we assessed the associations between maternal grandmother coresidence and involvement, and adolescents' internalising problems, externalising problems and prosocial behaviour. Self-report survey data were obtained from a sample of 384 "coloured" (mixed-race) and black African Grade 8 and Grade 9 students in Cape Town. The mean age of the participants was 13.96 years, 58% were females and 27% lived in 3-generation households. Results indicated that there was no significant difference in the involvement of coresident and non-coresident grandmothers, and that adolescents in 3-generation and 2-generation households displayed similar levels of adjustment. Hierarchical multiple regression analyses revealed that greater maternal grandmother involvement was associated with more adolescent prosocial behaviour (p < .001) regardless of household structure, and with fewer adolescent internalising problems in 3-generation households (p = .03). Findings underscore the need to move beyond the immediate family to consider how grandparents may influence adolescent development.

Direct and Indirect Effects of Caregiver Social Support on Adolescent Psychological Outcomes in Two South African AIDS-Affected Communities.

Caregiver social support has been shown to be protective for caregiver mental health, parenting and child psychosocial outcomes. This is the first known analysis to quantitatively investigate the relationship between caregiver social support and adolescent psychosocial outcomes in HIV-endemic, resource-scarce Southern African communities. A cross-sectional household survey was conducted over 2009-2010 with 2,477 South African adolescents aged 10-17 and their adult caregivers (18 years or older) in one urban and one rural community in South Africa's KwaZulu-Natal province. Adolescent adjustment was assessed using adult caregiver reports of the Strengths and Difficulties questionnaire (SDQ), which measures peer problems, hyperactivity, conduct problems, emotional symptoms and child prosocial behavior. Hierarchical linear regressions and multiple mediation analyses, using bootstrapping procedures, were conducted to assess for: (a) direct effects of more caregiver social support on better adolescent psychosocial wellbeing; and (b) indirect effects mediated by better parenting and caregiver mental health. Direct associations (p < .001), and indirect associations mediated through better parenting, were found for all adolescent outcomes. Findings reinforce the importance of social support components within parenting interventions but also point to scope for positive intervention on adolescent psychosocial wellbeing through the broader family social network.

Social support as a protective factor for depression among women caring for children in HIV-endemic South Africa.

Social support has been shown to be a protective resource for mental health among chronically ill adults and caregiver populations. However, to date no known studies have quantitatively explored the relationship between social support and depression among women caring for children in HIV-endemic Southern Africa, although they represent a high risk population for mental health conditions. Using data from a household survey with 2,199 adult female caregivers of children, living in two resource-deprived high HIV-prevalence South African communities, we conducted hierarchical logistic regression analysis with interaction terms to assess whether social support had a main effect or stress-buffering effect on depression. Findings provide evidence of stress-buffering of non-HIV-related chronic illness, but not HIV-related illness. Results reinforce the importance of social support for the mental health of chronically ill caregivers, and suggest that factors related to the specific nature of HIV/AIDS may be hindering the potential stress-buffering effects of social support among people living with the disease. Implications for future research and interventions are discussed.

A comparison of acoustic and visual metrics of sperm whale longline depredation.

Annual federal stock assessment surveys for Alaskan sablefish also attempt to measure sperm whale depredation by quantifying visual evidence of depredation, including lip remains and damaged fish. A complementary passive acoustic method for quantifying depredation was investigated during the 2011 and 2012 survey hauls. A combination of machine-aided and human analysis counted the number of distinct "creak" sounds detected on autonomous recorders deployed during the survey, emphasizing sounds that are followed by silence ("creak-pauses"), a possible indication of prey capture. These raw counts were then adjusted for variations in background noise levels between deployments. Both a randomized Pearson correlation analysis and a generalized linear model found that noise-adjusted counts of "creak-pauses" were highly correlated with survey counts of lip remains during both years (2012: r(10) = 0.89, p = 1e-3; 2011: r(39) = 0.72, p = 4e-3) and somewhat correlated with observed sablefish damage in 2011 [r(39) = 0.37, p = 0.03], but uncorrelated with other species depredation. The acoustic depredation count was anywhere from 10% to 80% higher than the visual counts, depending on the survey year and assumptions employed. The results suggest that passive acoustics can provide upper bounds on depredation rates; however, the observed correlation breaks down whenever three or more whales are present.

The relationship between social support and anxiety among caregivers of children in HIV-endemic South Africa.

Caring for children can be a source of joy and fulfilment, but also a source of stress, especially for caregivers living with illness and/or coping with difficult socio-economic conditions. Risks for poor caregiver mental health are especially salient in many parts of southern Africa affected by a generalised HIV-epidemic, high rates of physical illness, difficult livelihood conditions and an increasing number of orphaned and vulnerable children in need of care. Given limited availability and low uptake of formal mental health services in South Africa, the potential protective role of informal community or "social" resources for caregiver populations requires greater attention. To our knowledge, this is the first study to quantitatively assess the relationship between social support and symptomatic anxiety among caregivers of children living in HIV-endemic southern African communities. The data are from household survey interviews with 2477 adult primary caregivers of children aged 10-17 years living in two (urban and rural) resource-deprived HIV-endemic South African communities. Hierarchical logistic regression analysis with interaction terms was conducted to assess whether HIV and other illness were significant stressors for caregiver anxiety, whether social support had main or stress-buffering protective effects on anxiety and whether gender moderated the association between social support and anxiety. Our findings showed significant main effects of social support on caregiver anxiety, but no evidence of stress-buffering effects of support or of gender moderating the support-anxiety relationship. This suggests that social support is a general mental health resource for both male and female caregivers of children in these HIV-endemic communities, regardless of whether they are facing specific stressors related to HIV or other illness. Our results highlight the importance of paying greater attention to the social environment when designing and implementing caregiver health interventions, and indicate that social support could be a valuable component of such interventions.

"They give us hope": HIV-positive caregivers' perspectives on the role of social support for health.

A number of studies indicate that social support is associated with better health outcomes among HIV-positive caregivers of children, suggesting its potential importance for interventions aimed at safeguarding the well-being of this population. However, there is very little published literature assessing the support-health relationship or evaluating applied social support interventions with HIV-positive populations in HIV-endemic contexts of the developing world. The global literature on social support and health suggests that, in order to refine theory and improve interventions, greater attention should be paid to specific dimensions of support, such as types and sources, as well as the processes through which support may be affecting health outcomes. This article presents and discusses data from in-depth interviews with 12 HIV-positive primary caregivers of children living in an HIV-endemic, low-resourced, urban South African community. The primary aim of this qualitative work was to provide further insight into survey findings of a positive relationship between social support and self-reported general health and functioning, by exploring caregivers' personal experiences of being supported within their community, and their perceptions on how this "informal" support may be influencing their health. Our qualitative data highlight the importance of instrumental and emotional support for this population, the relevance of support provider characteristics and some of the processes or pathways that are likely explaining the support-health link. These processes include psychological factors such as mastery and hope, coping strategies and positive health behaviours. We provide recommendations for future research to further this work, and discuss implications for health interventions.

Effects and processes linking social support to caregiver health among HIV/AIDS-affected carer-child dyads: a critical review of the empirical evidence.

There is evidence to suggest that social support may be an important resource for the mental and physical health of caregivers and children affected by HIV/AIDS, especially in HIV-endemic areas of the developing world. Drawing from theory on social relations and health, in this paper we argue that it is important to assess not only the existence and direction of associations, but also the effects and processes explaining these. We refer to House et al's (in Annu Rev Sociol 14;293-318, 1988) theoretical framework on social support structures and processes as a guide to present and discuss findings of a systematic review of literature assessing the relationship between social support and health among caregivers living with HIV or caring for HIV/AIDS-affected children. Findings confirm the importance of social support for health among this population, but also expose the absence of empirical work deriving from the developing world, as well as the need for further investigation on the biopsychosocial processes explaining observed effects.

Evaluation of a school-based intervention programme for South African children of divorce.

OBJECTIVE: Parental divorce affects approximately 30 000 South African children annually. This pilot study aimed to evaluate the effectiveness of the Children of Divorce Intervention Programme (CODIP) at two South African schools. CODIP is a preventively oriented group programme which was developed to foster resilience by helping children cope more effectively with possible academic, behavioural, and emotional problems brought about by their parents' divorce. METHOD: Twenty-five 10- to 14-year-old boys from two primary schools were randomly assigned to 2 experimental groups and 1 delayed intervention control group. The experimental groups attended 12 one-hour weekly sessions; the control group received no intervention until after the study was completed. Children's understanding of divorce related events and social, emotional and behavioural adjustment was assessed one week before the intervention and three months thereafter using a battery of self-rated, teacher-rated and parent-rated questionnaires. RESULTS: One-way ANOVAs indicated no statistically significant decline in children's self-reported problematic beliefs about divorce or total difficulties. However, teachers' and parents' ratings indicated that compared to the control group, the combined experimental groups showed significant improvement in their general behavioural, emotional and social adjustment after programme participation. CONCLUSIONS: The results suggest that South African children who experience parental divorce may benefit from participation in CODIP.

Associations among sleep problems, learning difficulties and substance use in adolescence.

This study investigated the relationships among sleep problems, learning difficulties and substance use in adolescence. Previous research suggests that these variables share an association with executive functioning deficits, and are intertwined. The sample comprised 427 adolescents (M age = 16 years) attending remedial schools and 276 adolescents (M age = 15 years) attending a mainstream school in Cape Town, South Africa. Participants completed anonymous self-report questionnaires. Results indicated that adolescents without learning difficulties were more likely to use tobacco, methamphetamine and cannabis, whereas those with learning difficulties engaged in more inhalant use. Adolescents who had more sleep problems were more likely to use tobacco, alcohol, methamphetamine, cannabis, inhalants, cocaine, ecstasy and any other illegal drug. Adolescents with learning difficulties had more sleep problems than those without learning difficulties. However, sleep problems remained independently associated with tobacco, cannabis and inhalant use when learning difficulties were taken into account.

Family functioning and suicidal ideation/behaviour in adolescents: a pilot study.

OBJECTIVE: The main aim of this study was to explore the associations between specific aspects of family functioning and adolescent suicidal ideation/behaviour. METHOD: Participants were 87 high school students (43 male and 44 female) aged between 14 and 16 years of age. They completed a questionnaire measuring various aspects of family functioning and suicidal ideation/behaviour. The specific dimensions of family functioning assessed were: connection, psychological control and behavioural regulation in the parent-adolescent relationship, family conflict and family structure. RESULTS: The results of t-test and chi-square analyses indicated that adolescents who reported suicidal ideation or behaviour in the previous year experienced lower levels of connection and regulation and higher levels of conflict and psychological control in the parent-child relationship than non-suicidal adolescents. Family structure and interparental conflict were not significantly associated with suicidal ideation/behaviour. CONCLUSIONS: The quality of relationships between adolescents and both of their parents may be important in distinguishing South African adolescents with recent suicidal ideation/behaviour from non-suicidal controls.

Suicidal ideation and attempts in adolescents: associations with depression and six domains of self-esteem.

This study aimed to disentangle the influence of depression and self-esteem on suicidal behaviour in adolescence. Grades 8 and 11 students in Cape Town, South Africa (n = 939) completed questionnaires assessing suicidal ideation and behaviour, depression, and self-esteem with respect to family, peers, school, sports/athletics, body image and global self-worth. Data were analysed using a series of multinomial logistic regression models adjusted for gender, grade, race and the sampling strategy. Results indicated that depression and low self-esteem in the family context were independently associated with suicide ideation and attempts. Moreover, low family self-esteem significantly differentiated suicide attempters from ideators. Screening for depression and low self-esteem in the family context is discussed as a possible strategy for helping to identify adolescents at risk for suicide attempts.

Associations among adolescent risk behaviours and self-esteem in six domains.

BACKGROUND: This study investigated associations among adolescents' self-esteem in 6 domains (peers, school, family, sports/athletics, body image and global self-worth) and risk behaviours related to substance use, bullying, suicidality and sexuality. METHOD: A multistage stratified sampling strategy was used to select a representative sample of 939 English-, Afrikaans- and Xhosa-speaking students in Grades 8 and 11 at public high schools in Cape Town, South Africa. Participants completed the multidimensional Self-Esteem Questionnaire (SEQ; DuBois, Felner, Brand, Phillips, & Lease, 1996) and a self-report questionnaire containing items about demographic characteristics and participation in a range of risk behaviours. It included questions about their use of tobacco, alcohol, cannabis, solvents and other substances, bullying, suicidal ideation and attempts, and risky sexual behaviour. Data was analysed using a series of logistic regression models, with the estimation of model parameters being done through generalised estimation equations. RESULTS: Scores on each self-esteem scale were significantly associated with at least one risk behaviour in male and female adolescents after controlling for the sampling strategy, grade and race. However, specific self-esteem domains were differentially related to particular risk behaviours. After taking the correlations between the self-esteem scales into account, low self-esteem in the family and school contexts and high self-esteem in the peer domain were significantly independently associated with multiple risk behaviours in adolescents of both sexes. Low body-image self-esteem and global self-worth were also uniquely associated with risk behaviours in girls, but not in boys. CONCLUSIONS: Overall, the findings suggest that interventions that aim to protect adolescents from engaging in risk behaviours by increasing their self-esteem are likely to be most effective and cost-efficient if they are aimed at the family and school domains.

Substance abuse, suicidality, and self-esteem in South African adolescents.

Associations among six different domains of self-esteem (peers, school, family, sports/athletics, body image, and global self-worth) and risk behaviors related to substance use and suicidality were investigated in a sample of South African adolescents. Students enrolled in Grades 8 and 11 at independent secondary schools in Cape Town (N = 116) completed the Self-Esteem Questionnaire (SEQ) and a questionnaire that asked about their participation in a range of risk behaviors. Logistic regression analyses indicated that particular domains of self-esteem were differentially associated with indicators of alcohol, cigarette and drug use and suicidal ideation or behaviors in adolescents. Family self-esteem showed the strongest overall pattern of associations with the risk behaviors. Overall, the findings of this study suggest that interventions which aim to protect adolescents from engaging in risk behaviors by increasing their self-esteem are likely to be most effective and cost-efficient if they are aimed at the family and school domains.