Sensory ecology in a changing world: salinity alters conspecific recognition in an amphidromous fish, Pseudomugil signifer

Group fission and fusion processes are driven by state dependence, risk and the availability of information from others. Yet the availability of information changes under different environmental conditions, thus aiding or inhibiting group formation and maintenance. Chemical cues provide information on the location of individuals and can act as a mechanism for individuals to group together, although they can be greatly affected by environmental conditions. Using a flow channel, we studied how one shoaling fish species, the Pacific blue-eye (Pseudomugil signifer), responds to conspecific chemical cues (CCCs) in different environmental conditions (salinities). This species lives in estuarine environments, ranging in salinity from fresh to fully marine. P. signifer responded to CCCs in freshwater but not in saltwater. Furthermore, P. signifer did not respond to saltwater with CCCs added from freshwater. It took significantly longer for fish in saltwater, than in freshwater, to locate and join a shoal when only CCCs from the shoal were present. Finally, fish formed more cohesive shoals in freshwater than in brackish or saltwater. These results suggest that these fish do not rely on chemical cues in saltwater to locate conspecific shoals. Furthermore, the reduced amounts of these cues in saltwater may inhibit the maintenance of tight shoal structures. We suggest that fish utilise different sensory modalities in fresh or saltwater in order to locate one another, or the social structure of these groups is fundamentally different between these two water types. The importance of this study in relation to understanding how animals utilise and change different sensory modalities in varying environmental conditions is discussed.     

Delays in DUI blood testing: Impact on cannabis DUI assessments

Objective: This study examined the time from law enforcement dispatch to the first blood draw in cases of driving under the influence (DUI) vehicular homicide and a subset of DUI vehicular assault cases in Colorado in 2012. Laboratory toxicology results were also examined to understand the implications of delays in blood draws in cases of driving while under the influence of marijuana's delta-9-tetrahydrocannabinol (THC).

Methods: Colorado court records were reviewed and information regarding charges, presence of alcohol and/or drugs, time of law enforcement contact and blood draw, crash location, and other contextual factors were identified. The distributions of first blood draw times were studied by charge and by responding law enforcement agency. Toxicology data from a different cohort of DUI traffic arrests in Colorado and Washington were examined to determine the proportion of blood tests for THC that were above specified legal limits in those states.

Results: The average time from law enforcement dispatch to blood draw in cases of vehicular homicide and vehicular assault was 2.32 h (SD ± 1.31 h), with a range of 0.83 to 8.0 h and a median of 2.0 h. Data from DUI traffic arrests found that between 42 and 70% of all cannabinoid-positive traffic arrests tested below 5 ng/ml THC in blood, which is the legal limit in Colorado and Washington.

Conclusion: Given the current delays to blood testing in cases of arrests for vehicular homicide and vehicular assault in Colorado, many blood tests are unlikely to confirm that drivers who are impaired from smoking marijuana have THC levels above established legal limits.     

Benefits and risks associated with consumption of Great Lakes fish containing omega-3 fatty acids and polychlorinated biphenyls (PCBs)

正Introduction Assessment of environmental health effects arising from exposure to multiple substances is often very challenging.This is particularly true when humans are exposed to a mixture that contains both beneficial and harmful substances.A good example relates to the risk and benefits of fish consumption.     

Modeling population effects of the Deepwater Horizon oil spill on a long-lived species

The 2010 Deepwater Horizon (DWH) oil spill exposed common bottlenose dolphins (Tursiops truncatus) in Barataria Bay, Louisiana to heavy oiling that caused increased mortality and chronic disease and impaired reproduction in surviving dolphins. We conducted photographic surveys and veterinary assessments in the decade following the spill. We assigned a prognostic score (good, fair, guarded, poor, or grave) for each dolphin to provide a single integrated indicator of overall health, and we examined temporal trends in prognostic scores. We used expert elicitation to quantify the implications of trends for the proportion of the dolphins that would recover within their lifetime. We integrated expert elicitation, along with other new information, in a population dynamics model to predict the effects of observed health trends on demography. We compared the resulting population trajectory with that predicted under baseline (no spill) conditions. Disease conditions persisted and have recently worsened in dolphins that were presumably exposed to DWH oil: 78% of those assessed in 2018 had a guarded, poor, or grave prognosis. Dolphins born after the spill were in better health. We estimated that the population declined by 45% (95% CI 14–74) relative to baseline and will take 35 years (95% CI 18–67) to recover to 95% of baseline numbers. The sum of annual differences between baseline and injured population sizes (i.e., the lost cetacean years) was 30,993 (95% CI 6607–94,148). The population is currently at a minimum point in its recovery trajectory and is vulnerable to emerging threats, including planned ecosystem restoration efforts that are likely to be detrimental to the dolphins’ survival. Our modeling framework demonstrates an approach for integrating different sources and types of data, highlights the utility of expert elicitation for indeterminable input parameters, and emphasizes the importance of considering and monitoring long-term health of long-lived species subject to environmental disasters. Article impact statement: Oil spills can have long-term consequences for the health of long-lived species; thus, effective restoration and monitoring are needed.     

The wild ancestors of domestic animals as a neglected and threatened component of biodiversity

Domestic animals have immense economic, cultural, and practical value and have played pivotal roles in the development of human civilization. Many domesticates have, among their wild relatives, undomesticated forms representative of their ancestors. Resurgent interest in these ancestral forms has highlighted the unclear genetic status of many, and some are threatened with extinction by hybridization with domestic conspecifics. We considered the contemporary status of these ancestral forms relative to their scientific, practical, and ecological importance; the varied impacts of wild–domestic hybridization; and the challenges and potential resolutions involved in conservation efforts. Identifying and conserving ancestral forms, particularly with respect to disentangling patterns of gene flow from domesticates, is complex because of the lack of available genomic and phenotypic baselines. Comparative behavioral, ecological, and genetic studies of ancestral-type, feral, and domestic animals should be prioritized to establish the contemporary status of the former. Such baseline information will be fundamental in ensuring successful conservation efforts.