The role of natural disaster in individual and relational adjustment in Sri Lankan mothers following the 2004 tsunami

The purpose of this study is to examine the associations between maternal mental health distress symptoms, including depression and post‐traumatic stress disorder, the extent to which the presence of a child's disaster‐related physical health problem(s) have interfered with daily functioning, and family cohesion over time among Sri Lankan mothers who survived the tsunami on 26 December 2004. Study variables were measured using a self‐report questionnaire administered approximately four months after the event and three years later in summer 2008. Univariate, bivariate, and multivariate analyses were conducted. Path analysis was employed to assess the relationships between the key variables over time and the correlations in the study variables at each time point. Among other findings, the results of the path analysis indicated that post‐traumatic stress symptom distress four months after the disaster significantly predicted variance in family cohesion three years later. Clinical and empirical research implications are presented and discussed.     

Aggressiveness and foraging mode of young-of-the-year brook charr,Salvelinus fontinalis (Pisces,Salmonidae)

Summary Young-of-the-year brook charr in streams use either an active or a sit-and-wait foraging tactic and exhibit a range of resource defense from territoriality to tolerating conspecifics. We use simple graphical models, based on encounter rate with drift and the theory of economic defendability, to predict qualitative changes in the aggressiveness and mobility of brook charr in relation to current velocity. Aggressiveness (percent of conspecifics eliciting an overt response) initially increases with increasing current velocity, as does drift rate and foraging rate. However, aggressiveness decreases at high current velocities, probably because of increased costs of defense at these velocities. In standing water areas, brook charr use primarily an active foraging tactic, but mobility (percent time spent moving) decreases rapidly as current velocity increases. These results are generally consistent with the simple graphical models. A literature survey suggests that the models can be generalized for most species of stream salmonids.     

Models of fish school size in relation to environmental productivity

A simple energy-balance model, relating energetic requirements of fish schools to food production, was used to predict shoal sizes. Lower limits to school size are unlikely to be set by food but rather by predation. Upper limits depend on both food and school behavior, being greater for schools that break up to feed than for schools that remain continuously cohesive. Faced with a decreasing food supply, a school could either break into smaller schools or change behavior, increasing the area available for foraging. The models suggest that environmental productivity needs to be considered when examining fishery statistics such as (catch per unit effort), where maximum catch may be limited by maximum school size.     

International competitive displacement from environmental control The quantitative gains from methodological refinement

This paper demonstrates empirically the gain from adopting more general equilibrium approaches in projecting the effects on domestic output and international trade of environmental controls. The suggested models include a partial equilibrium case where all industries are treated independently, an intermediate case incorporating effects in supplying industries, and general equilibrium formulations based on alternative macroeconomic conditions. U. S. data is used to evaluate these models. Under both pollutor pays and subsidy financing schemes, moving from the simplest case to the intermediate model results in quite different industry projections. Including macroeconomic factors appears particularly important in the classical setting.     

High connectivity among locally adapted populations of a marine fish (Menidia menidia)

Patterns of connectivity are important in understanding the geographic scale of local adaptation in marine populations. While natural selection can lead to local adaptation, high connectivity can diminish the potential for such adaptation to occur. Connectivity, defined as the exchange of individuals among subpopulations, is presumed to be significant in most marine species due to life histories that include widely dispersive stages. However, evidence of local adaptation in marine species, such the Atlantic silverside, Menidia menidia, raises questions concerning the degree of connectivity. We examined geochemical signatures in the otoliths, or ear bones, of adult Atlantic silversides collected in 11 locations along the northeastern coast of the United States from New Jersey to Maine in 2004 and eight locations in 2005 using laser ablation inductively coupled plasma mass spectrometry (ICP-MS) and isotope ratio monitoring mass spectrometry (irm-MS). These signatures were then compared to baseline signatures of juvenile fish of known origin to determine natal origin of these adult fish. We then estimated migration distances and the degree of mixing from these data. In both years, fish generally had the highest probability of originating from the same location in which they were captured (0.01-0.80), but evidence of mixing throughout the sample area was present. Furthermore, adult M. menidia exhibit highly dispersive behavior with some fish migrating over 700 km. The probability of adult fish returning to natal areas differed between years, with the probability being, on average, 0.2 higher in the second year. These findings demonstrate that marine species with largely open populations are capable of local adaptation despite apparently high gene flow.     

AIC model selection and multimodel inference in behavioral ecology: some background,observations, and comparisons

We briefly outline the information-theoretic (I-T) approaches to valid inference including a review of some simple methods for making formal inference from all the hypotheses in the model set (multimodel inference). The I-T approaches can replace the usual t tests and ANOVA tables that are so inferentially limited, but still commonly used. The I-T methods are easy to compute and understand and provide formal measures of the strength of evidence for both the null and alternative hypotheses, given the data. We give an example to highlight the importance of deriving alternative hypotheses and representing these as probability models. Fifteen technical issues are addressed to clarify various points that have appeared incorrectly in the recent literature. We offer several remarks regarding the future of empirical science and data analysis under an I-T framework.     

The ability of a benthic elasmobranch to discriminate between biological and artificial electric fields

To investigate the ability of elasmobranchs to distinguish between differing prey-type electric fields we examined the electroreceptive foraging behaviour of a model species, Scyliorhinus canicula (small-spotted catshark). Catshark preferences were studied by behaviourally conditioning them to swim through narrow tunnels, and on exit presenting them simultaneously with two different electric fields. Their subsequent choices of the following paired options were recorded; (i) Two artificial electric fields (dipole electrodes) with different magnitude direct current (D.C.), (ii) Two artificial electric fields, one D.C. and the other alternating current (A.C.), of the same magnitude, and (iii) similar magnitude, natural and artificial D.C. electric fields associated with shore crabs and dipole electrodes respectively. We found a highly significant preference for the stronger D.C. electric field and a less pronounced, but still significant, preference for the A.C. electric field rather than the D.C. electric field. No preference was demonstrated between the artificial and natural D.C. electric fields. The findings are discussed in relation to the animal’s diet and ecology and with regard to anthropogenic sources of electric fields within their habitat.     

Behavioural inertia places a top marine predator at risk from environmental change in the Benguela upwelling system

In variable environments, organisms are bound to track environmental changes if they are to survive. Most marine mammals and seabirds are colonial, central-place foragers with long-term breeding-site fidelity. When confronted with environmental change, such species are potentially constrained in their ability to respond to these changes. For example, if environmental conditions deteriorate within their limited foraging range, long-lived species favour adult survival and abandon their current breeding effort, which ultimately influences population dynamics. Should poor conditions persist over several seasons, breeding-site fidelity may force animals to continue breeding in low-quality habitats instead of emigrating towards more profitable grounds. We assessed the behavioural response of a site-faithful central-place forager, the Cape gannet Morus capensis, endemic to the Benguela upwelling system, to a rapid shift in the distribution and abundance of its preferred prey, small pelagic shoaling fish. We studied the distribution and the abundance of prey species, and the diet, foraging distribution, foraging effort, energy requirements, and breeding success of gannets at Malgas Island (South Africa) over four consecutive breeding seasons. Facing a rapid depletion of preferred food within their foraging range, Cape gannets initially increased their foraging effort in search of their natural prey. However, as pelagic fish became progressively scarcer, breeding birds resorted to scavenging readily available discards from a nearby demersal fishery. Their chicks cannot survive on such a diet, and during our 4-year study, numbers of breeding birds at the colony decreased by 40% and breeding success of the remaining birds was very low. Such behavioural inflexibility caused numbers of Cape gannets breeding in Namibia to crash by 95% following over-fishing of pelagic fish in the 1970s. In the context of rapid environmental changes, breeding-site fidelity of long-lived species may increase the risk of local or even global extinction, rendering these species particularly vulnerable to global change.