High interannual variability in connectivity and genetic pool of a temperate clingfish matches oceanographic transport predictions

Adults of most marine benthic and demersal fish are site-attached, with the dispersal of their larval stages ensuring connectivity among populations. In this study we aimed to infer spatial and temporal variation in population connectivity and dispersal of a marine fish species, using genetic tools and comparing these with oceanographic transport. We focused on an intertidal rocky reef fish species, the shore clingfish Lepadogaster lepadogaster, along the southwest Iberian Peninsula, in 2011 and 2012. We predicted high levels of self-recruitment and distinct populations, due to short pelagic larval duration and because all its developmental stages have previously been found near adult habitats. Genetic analyses based on microsatellites countered our prediction and a biophysical dispersal model showed that oceanographic transport was a good explanation for the patterns observed. Adult sub-populations separated by up to 300 km of coastline displayed no genetic differentiation, revealing a single connected population with larvae potentially dispersing long distances over hundreds of km. Despite this, parentage analysis performed on recruits from one focal site within the Marine Park of Arrabida (Portugal), revealed self-recruitment levels of 2.5% and 7.7% in 2011 and 2012, respectively, suggesting that both long-and short-distance dispersal play an important role in the replenishment of these populations. Population differentiation and patterns of dispersal, which were highly variable between years, could be linked to the variability inherent in local oceanographic processes. Overall, our measures of connectivity based on genetic and oceanographic data highlight the relevance of long-distance dispersal in determining the degree of connectivity, even in species with short pelagic larval durations

Comparing the Invasibility of Experimental “Reefs” with Field Observations of Natural Reefs and Artificial Structures

Natural systems are increasingly being modified by the addition of artificial habitats which may facilitate invasion. Where invaders are able to disperse from artificial habitats, their impact may spread to surrounding natural communities and therefore it is important to investigate potential factors that reduce or enhance invasibility. We surveyed the distribution of non-indigenous and native invertebrates and algae between artificial habitats and natural reefs in a marine subtidal system. We also deployed sandstone plates as experimental ‘reefs’ and manipulated the orientation, starting assemblage and degree of shading. Invertebrates (non-indigenous and native) appeared to be responding to similar environmental factors (e.g. orientation) and occupied most space on artificial structures and to a lesser extent reef walls. Non-indigenous invertebrates are less successful than native invertebrates on horizontal reefs despite functional similarities. Manipulative experiments revealed that even when non-indigenous invertebrates invade vertical “reefs”, they are unlikely to gain a foothold and never exceed covers of native invertebrates (regardless of space availability). Community ecology suggests that invertebrates will dominate reef walls and algae horizontal reefs due to functional differences, however our surveys revealed that native algae dominate both vertical and horizontal reefs in shallow estuarine systems. Few non-indigenous algae were sampled in the study, however where invasive algal species are present in a system, they may present a threat to reef communities. Our findings suggest that non-indigenous species are less successful at occupying space on reef compared to artificial structures, and manipulations of biotic and abiotic conditions (primarily orientation and to a lesser extent biotic resistance) on experimental “reefs” explained a large portion of this variation, however they could not fully explain the magnitude of differences

Shorter Food Chain Length in Ancient Lakes: Evidence from a Global Synthesis

Food webs may be affected by evolutionary processes, and effective evolutionary time ultimately affects the probability of species evolving to fill the niche space. Thus, ecosystem history may set important evolutionary constraints on community composition and food web structure. Food chain length (FCL) has long been recognized as a fundamental ecosystem attribute. We examined historical effects on FCL in large lakes spanning >6 orders of magnitude in age. We found that food chains in the world’s ancient lakes (n = 8) were significantly shorter than in recently formed lakes (n = 10) and reservoirs (n = 3), despite the fact that ancient lakes harbored much higher species richness, including many endemic species. One potential factor leading to shorter FCL in ancient lakes is an increasing diversity of trophic omnivores and herbivores. Speciation could simply broaden the number of species within a trophic group, particularly at lower trophic levels and could also lead to a greater degree of trophic omnivory. Our results highlight a counter-intuitive and poorly-understood role of evolutionary history in shaping key food web properties such as FCL

Measuring hypoxia induced metal release from highly contaminated estuarine sediments during a 40 day laboratory incubation experiment

Nutrient inputs to estuarine and coastal waters worldwide are increasing and this in turn is increasing the prevalence of eutrophication and hypoxic and anoxic episodes in these systems. Many urbanised estuaries are also subject to high levels of anthropogenic metal contamination. Environmental O2 levels may influence whether sediments act as sinks or sources of metals. In this study we investigated the effect of an extended O2 depletion event (40 days) on fluxes of trace metals (and the metalloid As) across the sediment–water interface in sediments from a highly metal contaminated estuary in S.E. Tasmania, Australia. We collected sediments from three sites that spanned a range of contamination and measured total metal concentration in the overlying water using sealed core incubations. Manganese and iron, which are known to regulate the release of other divalent cations from sub-oxic sediments, were released from sediments at all sites as hypoxia developed. In contrast, the release of arsenic, cadmium, copper and zinc was comparatively low, most likely due to inherent stability of these elements within the sediments, perhaps as a result of their refractory origin, their association with fine-grained sediments or their being bound in stable sulphide complexes. Metal release was not sustained due to the powerful effect of metal-sulphide precipitation of dissolved metals back into sediments. The limited mobilisation of sediment bound metals during hypoxia is encouraging, nevertheless the results highlight particular problems for management in areas where hypoxia might occur, such as the release of metals exacerbating already high loads or resulting in localised toxicity

Cannabis use, time perspective and risk perception: Evidence of a moderating effect.

International audienceThis study explores the relationship between time perspective (TP), cannabis use and risk perceptions associated to this substance. A sample of French students (n=198) were provided with a valid French version of the ZTPI scale. Risk perceptions linked to cannabis consumption were evaluated from a list of 22 items referring to different risks. Respondents were asked to declare how frequently they consumed this substance. Data analysis was based on firstly, ZTPI scores, secondly, declared consumption and finally, two risk perception indices which were established after factorial analysis. Results showed that TP acted as a significant predictor of both psychoactive substance use and of cannabis consumption frequency. Significant links between consumption and risk perception also appeared. A second series of analyses showed that TP acted as a moderating variable in this link between cannabis consumption and risk perception. These findings indicate that TP must be considered as a significant variable when analysing the complexity of contemporary cannabis use and suggests that further research in this area should be carried out

Time orientation and health-related behaviour: measurement in general population samples

Research on health behaviour and time orientation has been hindered by a lack of consensus about appropriate measurement. Study 1 assessed the reliability of the Consideration of Future Consequences Scale (CFC) and the Zimbardo Time Perspective Inventory (ZTPI) in a general population sample (n = 300). Although more reliable, the CFC was less readable. Study 2 assessed the validity of a shortened ZTPI, measuring future and present orientation, and the full CFC. The measures had good discrimination to distinguish interpersonal differences. Construct validity of present, but not future, orientation as measured by the ZTPI, was evidenced by its mediation of the association between socioeconomic status and expectations of participating in diabetes screening. The CFC mediated this relationship more weakly. Further investigation of present orientation in understanding health-related behaviour is warrante

Time perspective, personality and psychopathology: Zimbardo's time perspective inventory in psychiatry

Time perspective theory assumes that behaviour is influenced by how individuals link their behaviour to their past, present, and future. This paper explores the concept of time perspective (Zimbardo and Boyd, 1999) within a psychiatric context. We compared 76 individuals, in treatment (n = 32) or not in treatment (n = 44). The participants completed the time perspective questionnaire ZTPI, the NEO-PI-R (personality traits), an instrument to measure personality problems SIPP-118, and the BDI-II (depression). We found correlations between measures of psychopathology and Past Positive, Past Negative and Present Fatalistic time perspectives. Particularly Past Negative appeared to be indicative for psychiatric problems. © 2011, SAGE Publications. All rights reserved

Unemployment and its association with health-relevant actions: investigating the role of time perspective with German census data

Schunck R, Rogge B. Unemployment and its association with health-relevant actions: investigating the role of time perspective with German census data. International Journal of Public Health. 2010;55(4):271-278.Objective In this study, we seek to explain how unemployment is related to an increase in health-damaging actions. A short time perspective, that is an orientation towards the present rather than the future, is hypothesised to account for this effect. The concept of time perspective is located within an action theoretical framework and the hypothesis is tested empirically. Methods We investigated the unemployed people’s smoking behaviour and body-mass index (BMI) using German microcensus data from 2003. Data from 77,766 respondents (88.60% employed and 11.40% unemployed) were analysed. Multivariate regression analysis was applied to test our hypotheses. Results Unemployment is associated with a 46% higher probability to smoke and with a 0.37 unit increase in BMI compared to employment. The likelihood of smoking steadily increases with the duration of unemployment, while only unemployment spells of 4 years and longer are significantly related to BMI. Yet, the smoking probability of those unemployed who have a long time perspective is 74% lower and their BMI is 1.81 lower than those who do not have a long time perspective. Conclusion Unemployment is negatively associated with health-relevant actions. This effect varies according to persons’ time perspectives. Our approach delivers an innovative view on why unemployed individuals exercise more health-damaging actions than the employed