Mortality of US pentachlorophenol production workers through 2005

A cohort of 2122 US pentachlorophenol (PCP) production workers from four plants in the National Institute for Occupational Safety and Health Dioxin Registry was exposed to PCP and to polychlorinated dibenzo-p-dioxin and dibenzofuran contaminants of PCP production. A subcohort of 720 was also exposed to 2,3,7,8-tetrachlorodibenzodioxin, a contaminant of trichlorophenol (TCP) while using TCP or a TCP derivative. PCP and several production contaminants have been implicated as animal carcinogens. A priori hypotheses were that the cohort would have elevated standardized mortality ratios (SMRs) for aplastic anemia, soft-tissue sarcoma, and non-Hodgkin lymphoma, as suggested by human studies, and for leukemia and liver, adrenal, thyroid, and parathyroid cancer, as suggested by animal studies. From 1940 to 2005 1165 deaths occurred with an overall SMR of 1.01 [95% confidence limits (CI), 0.95-1.07]. Overall cancer mortality (326 deaths, SMR 1.17, CI 1.05-1.31) was in statistically significant excess. There were excess deaths for trachea, bronchus and lung cancers (126 deaths, SMR 1.36, CI 1.13-1.62), non-Hodgkin lymphoma (17 deaths, SMR 1.77, CI 1.03-2.84), chronic obstructive pulmonary disease (63 deaths, SMR 1.38, CI 1.06-1.77), and medical complications (5 deaths, SMR 3.52, CI 1.14-8.22). In race- and sex-specific analyses, white males had increased non-Hodgkin lymphoma mortality (17 deaths, SMR 1.98, CI 1.15-3.17) and males of other races had increased leukemia mortality (four deaths, SMR 4.57, CI 1.25-11.7). The excess of cancers of a priori interest, non-Hodgkin lymphoma and leukemia, provide some support for the carcinogenicity of PCP, however, further studies with more detailed exposure assessment are needed.     

Sea Otters (Enhydra lutris L.) of Bering Island, the Commander Islands: Age and Sex Composition of Dead Animals and Spatial Distribution

Animal censuses and assessment of mortality in the sea otter subpopulation of Bering Island (the Commander Islands) have shown that indices of seasonal mortality may be used as a criterion for estimating well-being of this animal group. In 1999, the subpopulation of Bering Island entered a phase of stabilization of its spatial, age, and sex structure, with the stabilization process proper taking approximately three years after a peak of mortality. Mortality in the course of this process proved to be relatively high in age groups older than eight years but insignificant among middle-aged reproductive animals. As the age and sex structure of the insular group varies during the year and in different coastal areas, the data obtained by collecting dead animals cannot be used for estimating the structure of the whole population.     

Learning to recognize novel predators under weakly acidic conditions: the effects of reduced pH on acquired predator recognition by juvenile rainbow trout

Summary. Recent studies have demonstrated that under weakly acidic conditions (pH 6.0), many prey fishes, including juvenile rainbow trout (Onchorhynchus mykiss), do not exhibit overt antipredator responses to conspecific chemical alarm cues. In laboratory trials, we investigated the potential effects of reduced pH on the ability of hatchery reared, predator naïve juvenile rainbow trout to acquire the recognition of a novel predator (yellow perch, Perca flavenscens). Initially, we exposed trout to the odour of a predatory yellow perch, buffered to pH 6.0 (weakly acidic) or pH 7.0 (neutral) paired with conspecific skin extracts (also buffered to pH 6.0 or 7.0) or a distilled water control. Juvenile trout exhibited significant increase in antipredator behaviour when exposed to neutral skin extract (pH 7.0). When retested 48 hours later to perch odour alone (pH 7.0), only trout initially conditioned with neutral skin extracts (pairs with either neutral or acidic perch odour) exhibited a learned recognition of perch odour as a predator risk. Those initially exposed to weakly acidic skin extract or the distilled water control did not show a learned response to predator odour. These results demonstrate that the ability to acquire the recognition of novel predators is impaired under weakly acidic conditions, as would occur in natural waterways affected by acidic precipitation.     

Conflict-related mortality: an analysis of 37 datasets

Mortality rates are among the main indicators of the human impact of armed conflict and many surveys have assessed this impact both for targeting and evaluating humanitarian aid programmes. Almost no epidemiological analysis such as calculating relative risk was performed nor were reference values clearly described. Here the aim is to review published mortality rates for a better understanding of age-specific mortality in armed conflict. Published mortality rates from conflict situations were collected and pre-conflict reference rates composed. We calculated the relative risk of dying in conflict compared to pre-conflict for children under 5 and people older than five years old. Although limited by reporting inadequacies, the results confirm the high vulnerability of children < 5 but identify a higher relative risk of dying among the > or = 5 year olds. Although not entirely new, this observation is not fully understood. Further systematic epidemiological research is needed to estimate and understand the impact of armed conflict on mortality.     

Correlated changes in breeding status and polyunsaturated cuticular hydrocarbons: the chemical basis of nestmate recognition in the burying beetle <Emphasis Type="Italic">Nicrophorus vespilloides</Emphasis>?

Nestmate recognition in eusocial insects has received a lot of attention in the last decades. Recognition in subsocial species, in contrast, has been ignored almost completely and consequently, and little is known about proximate mechanisms of recognition in subsocial systems. We studied one subsocial species, the biparental brood caring burying beetle Nicrophorus vespilloides, an interesting model organism for studies of recognition because of its ability to discriminate between breeding partners and conspecific competitors. Recognition appears to be based on a chemical cue closely linked to the breeding status of individuals. Breeding and non-breeding beetles consistently differ in their relative proportions of polyunsaturated cuticular hydrocarbons. To investigate the function of these polyenes in the burying beetles’ recognition system, we quantified their concentration on the cuticle during the early state of a breeding attempt and tested the response of breeding beetles in corresponding behavioural experiments. We observed a rapid increase in the proportion of polyunsaturated hydrocarbons of both males and females after they were provided with a carcass suitable for reproduction. Furthermore, we found that the relative amount of polyenes on an individual’s surface was closely correlated with its chance of being accepted as breeding partner. Our results support the idea that polyunsaturated hydrocarbons are involved in breeding partner recognition in N. vespilloides, functioning as a signal that conveys information about the individual’s breeding status. Breeding females have greater amount of polyenes than breeding males, and females ingest more carrion during the first days on the carcass, which supports our hypothesis that precursors for the respective polyenes are derived from ingested carrion.     

Disturbance cues in freshwater prey fishes: do juvenile convict cichlids and rainbow trout respond to ammonium as an ‘early warning’ signal?

Summary.  Several freshwater invertebrate and vertebrate prey species rely on chemosensory cues, including non-injury released disturbance cues, to assess and avoid local predation threats. The prevailing hypothesis is that a pulse of ammonia released by disturbed or stressed prey functions as the disturbance cue. Here, we test this hypothesis in two phylogenetically distant freshwater prey fishes, convict cichlids and rainbow trout. In our first experiment, we measured NH₄ ⁺ concentration in tanks containing shoals of cichlid or trout before and after exposure to a realistic model predator (or left undisturbed). We failed to find an increase in ambient NH₄ ⁺ concentration for either cichlids or trout. In our second experiment, we exposed cichlids or trout to NH₄ ⁺ at 0.1 or 0.5 mg L⁻¹ (or a distilled water control) and measured the change in antipredator behaviour (time moving, foraging rate and area use). We found no consistent increase in antipredator behaviour in response to NH₄ ⁺. In our third study, we exposed cichlids and trout to the disturbance cues of cichlids or trout (versus the odour of undisturbed donors). We found significant increases in antipredator behaviour, regardless of donor species, for both cichlids and trout. Thus, the results of our first two experiments do not support the hypothesis that ammonium functions as a disturbance cue in prey fishes. However, the results of our final experiment do confirm the use of disturbance cues in convict cichlids and rainbow trout and support that hypothesis that the disturbance cue is indeed some generalized metabolic byproduct.     

Critically evaluating best management practices for preventing freshwater turtle extinctions

Ex situ conservation tools, such as captive breeding for reintroduction, are considered a last resort to recover threatened or endangered species, but they may also help reduce anthropogenic threats where it is difficult or impossible to address them directly. Headstarting, or captive rearing of eggs or neonate animals for subsequent release into the wild, is controversial because it treats only a symptom of a larger conservation problem; however, it may provide a mechanism to address multiple threats, particularly near population centers. We conducted a population viability analysis of Australia's most widespread freshwater turtle, Chelodina longicollis, to determine the effect of adult roadkill (death by collision with motor vehicles), which is increasing, and reduced recruitment through nest predation from introduced European red foxes (Vulpes vulpes). We also modeled management scenarios to test the effectiveness of headstarting, fox management, and measures to reduce mortality on roads. Only scenarios with headstarting from source populations eliminated all risks of extinction and allowed population growth. Small increases in adult mortality (2%) had the greatest effect on population growth and extinction risk. Where threats simultaneously affected other life‐history stages (e.g., recruitment), eliminating harvest pressures on adult females alone did not eliminate the risk of population extinction. In our models, one source population could supply enough hatchlings annually to supplement 25 other similar‐sized populations such that extinction was avoided. Based on our results, we believe headstarting should be a primary tool for managing freshwater turtles for which threats affect multiple life‐history stages. We advocate the creation of source populations for managing freshwater turtles that are greatly threatened at multiple life‐history stages, such as depredation of eggs by invasive species and adult mortality via roadkill.     

Epidemiology of tornado destruction in rural northern Bangladesh: risk factors for death and injury

The epidemiology of tornado-related disasters in the developing world is poorly understood. An August 2005 post-tornado cohort study in rural Bangladesh identified elevated levels of death and injury among the elderly (≥ 60 years of age) (adjusted odds ratio (AOR) = 8.9 (95 per cent confidence interval (CI): 3.9-20.2) and AOR = 1.6 (95 per cent CI: 1.4-1.8), respectively), as compared to 15-24 year-olds, and among those outdoors versus indoors during the tornado (AOR = 10.4 (95 per cent CI: 5.5-19.9) and AOR = 6.6 (95 per cent CI: 5.8-7.5), respectively). Females were 1.24 times (95 per cent CI: 1.15-1.33) more likely to be injured than males. Elevated risk of injury was significantly associated with structural damage to the house and tin construction materials. Seeking treatment was protective against death among the injured, odds ratio = 0.08 (95 per cent CI: 0.03-0.21). Further research is needed to develop injury prevention strategies and to address disparities in risk between age groups and between men and women.     

氨氮胁迫下罗非鱼（GIFT Oreochromis niloticus）机体免疫力的变化及其对海豚链球菌易感性的影响

研究了不同作用时间（0、24、48、96和120 h）下不同质量浓度氨氮（对照组、1、3、5和10 mg·L-1）对罗非鱼（GIFT Oreochromis niloticus）血清SOD、AKP、溶菌酶和补体C3活性的影响,以及不同质量浓度氨氮（对照组、1、3、5和10 mg·L-1）胁迫下罗非鱼对海豚链球菌的易感性。结果显示：在1.0 mg·L-1氨氮质量浓度下,罗非鱼血清SOD活性在24 h受到诱导;在3.0、5.0和10.0 mg·L-1氨氮质量浓度下,罗非鱼血清SOD活性均受到抑制,最大抑制率分别达18.85%、23.47%和38.46%。在1.0 mg·L-1氨氮质量浓度下,罗非鱼血清AKP活性在0-96 h呈先降低后恢复的趋势;5.0和10.0 mg·L-1实验组的血清AKP活性在24-120 h则一直受到抑制。1.0 mg·L-1实验组的罗非鱼血清溶菌酶活性在24-120 h一直无显著变化,3.0、5.0和10.0 mg·L-1实验组的血清溶菌酶活性随着氨氮质量浓度的升高而降低。1.0 mg·L-1实验组的罗非鱼血清补体C3活性在各个采样时间下均大于对照组,而5.0和10.0 mg·L-1实验组补体C3活性始终受到抑制。罗非鱼对海豚链球菌的易感性实验研究显示,置于3.0、5.0和10.0 mg·L-1的罗非鱼的累积死亡率分别为43.33%、46.67%和63.33%,显著高于对照组和1.0 mg·L-1实验组,表明氨氮质量浓度超过3.0 mg·L-1能够增加罗非鱼对海豚链球菌的易感性。本实验认为,超过3 mg·L-1的氨氮质量浓度胁迫能够显著降低罗非鱼的免疫力,增加对海豚链球菌的易感性。因此在罗非鱼健康养殖中,调控并降低氨氮质量浓度非常重要。     

Male-biased predation of a cave fish by a giant water bug

Male-biased predation has been described from several epigean species, and in many cases, intrinsic differences between the sexes (such as male ornaments) have been suggested as an explanation. Here we report on male-biased predation of a cave fish (Poecilia mexicana) by an aquatic insect (Belostoma sp.) in a Mexican sulfur cave. P. mexicana use aquatic surface respiration (ASR) to survive in their sulfidic, hypoxic habitat. We found that males typically exhibit more ASR activity than females, which leads to increased exposure to the sit-and-wait predator that catches fish near the water surface. Our finding is novel, because male vulnerability to predation is not directly related to male traits involved in courtship, but rather due to other sexual differences in behavior and ultimately, oxygen demands.