A framework for understanding ecological traps and an evaluation of existing evidence

When an animal settles preferentially in a habitat within which it does poorly relative to other available habitats, it is said to have been caught in an "ecological trap." Although the theoretical possibility that animals may be so trapped is widely recognized, the absence of a clear mechanistic understanding of what constitutes a trap means that much of the literature cited as support for the idea may be weak, at best. Here, we develop a conceptual model to explain how an ecological trap might work, outline the specific criteria that are necessary for demonstrating the existence of an ecological trap, and provide tools for researchers to use in detecting ecological traps. We then review the existing literature and summarize the state of empirical evidence for the existence of traps. Our conceptual model suggests that there are two basic kinds of ecological traps and three mechanisms by which traps may be created. To this point in time, there are still only a few solid empirical examples of ecological traps in the published literature (although those few examples suggest that both types of traps and all three of the predicted mechanisms do exist in nature). Therefore, ecological traps are either rare in nature, are difficult to detect, or both. An improved library of empirical studies will be essential if we are to develop a more synthetic understanding of the mechanisms that can trigger maladaptive behavior in general and the specific conditions under which ecological traps might occur.     

Microscale analytical methods for the quantitative detection of PCBs and PAHs in small tissue masses

Microscale methods (MM) were evaluated and compared to traditional methods (TM) for measuring polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in spiked and standard reference fish and mussel tissues. MMs are advantageous because they use small tissue masses (ca. 100 mg), and maintain sensitivity through reducing final extract volume (traditionally 1 ml) by an order of magnitude or more (40 μl—PCBs; 100 μl—PAHs). Procedural losses occurred in the MMs’ combined cleanup/primary evaporation step (19% PAHs; 6% PCBs), and the final extract concentration (14% PAHs; 22% PCBs). The PAH MM performed comparably to the TM. Although most PCBs had recoveries >50%, the PCB MM generally yielded lower recoveries than the TM. Average method detection limits were 0.6 μg/kg (TM) and 1.0 μg/kg (MM) for PCBs and 25.7 μg/kg (TM) and 27.7 μg/kg (MM) for PAHs. MMs described for PCB and PAH tissue samples are potentially viable alternatives to TMs, and could lead to cost savings in bioaccumulation/toxicity tests.     

Developmental and behavioral effects of embryonic exposure to the polybrominated diphenylether mixture DE-71 in the killifish (Fundulus heteroclitus)

Exposures to penta polybrominated diphenylether (PeBDE) cause neurobehavioral toxicity in developing mice and rats. As levels of these ubiquitous contaminants are increasing in the environment, this raises concern that wildlife may also suffer such effects, with consequences for their ability to catch prey and avoid predators. PeBDE levels in wild-caught fish have been steadily escalating over the past fifteen years. To our knowledge, behavioral consequences of piscine embryonic exposure to PeBDE has not yet been studied. The objectives of this investigation were to characterize effects on development in an environmentally relevant fish model, and test for latent behavioral effects following cessation of exposure. Embryos from the estuarine minnow, Fundulus heteroclitus, were exposed from day 0-7 post fertilization to the industrial PeBDE mixture, DE-71 (0.001 to 100 microg l(-1)). Embryos were assayed for hatching success, development, and microsomal enzyme cytochrome P4501A (CYP1A) activity, which was determined by analysis of in ovo ethoxy-resorufin-O-deethylase (EROD) activation in embryos. Larval fish were assayed for predation ability, activity level, and fright response to a simulated predator. Juvenile fish were assayed for learning ability in a three-chambered fish maze. No induction of embryonic EROD activity was observed, nor was a high dose of DE-71 able to inhibit EROD activity induced by beta-naphthoflavone. No deformities were detected, but a subtle developmental asymmetry with respect to tail curvature direction was observed, and a hatching delay of up to 4.5 days was noted. Behavioral test results suggest that embryonic exposure to DE-71 may alter activity level, fright response, predation rates, and learning ability in subsequent life stages.     

Predicting Gran alkalinity and calcium concentrations in river waters over a national scale using a novel modification to the G-BASH model

Monthly stream water calcium and Gran alkalinity concentration data from 11 sub-catchments of the Nether Beck in the English Lake District have been used to appraise the transferability of the Scottish, River Dee-based G-BASH model. Readily available riparian zone geochemistry and flow paths were used initially to predict minimum and mean stream water concentrations at the Nether Beck, based on calibration equations from the River Dee catchment data. Predicted values significantly exceeded observed values. Differences in runoff between the two areas, leading to a dilution effect in the Nether Beck, explained most of the difference between observed and predicted values. Greater acid deposition in the Lake District also reduced stream water Gran alkalinity concentrations in that area. If regional differences in precipitation, evapotranspiration and pollutant deposition are incorporated into the model, it may then be used reliably to predict catchment susceptibility to acidification over a wide regional (national) scale.     

Sources of fine particulate species in ambient air over lake Champlain Basin, VT

This study is a part of an ongoing investigation of the types and locations of emission sources that contribute fine particulate air contaminants to Underhill, VT. The air quality monitoring data used for this study are from the Interagency Monitoring of Protected Visual Environments network for the period of 2001-2003 for the Underhill site. The main source-receptor modeling techniques used are the positive matrix factorization (PMF) and potential source contribution function (PSCF). This new study is intended as a comparison to a previous study of the 1988-1995 Underhill data that successfully revealed a total of 11 types of emission sources with significant contributions to this rural site. This new study has identified a total of nine sources: nitrate-rich secondary aerosol, wood smoke, East Coast oil combustion, automobile emission, metal working, soil/dust, sulfur-rich aerosol type I, sulfur-rich aerosol type II, and sea salt/road salt. Furthermore, the mass contributions from the PMF identified sources that correspond with sampling days with either good or poor visibility were analyzed to seek possible correlations. It has been shown that sulfur-rich aerosol type I, nitrate aerosol, and automobile emission are the most important contributors to visibility degradation. Soil/dust and sea salt/road salt also have an added effect.     

Impacts from control operations on a recreationally hunted feral swine population at a large military installation in Florida

Feral swine were targeted for control at Avon Park Air Force Range in south-central Florida to avert damage to sensitive wetland habitats on the 40,000-ha base. We conducted a 5-year study to assess impacts from control to this population that had been recreationally hunted for many years. Control was initiated in early 2009. The feral swine population was monitored from 2008 to 2012 using a passive tracking index (PTI) during the dry and wet seasons and using recreational hunter take rates from the dry season. All three indices showed substantial feral swine declines after implementing control, with indices leveling for the final two study years. Military missions and recreational hunting seasons impacted temporal and spatial consistency of control application, thereby limiting further impacts of control efforts on the feral swine population. The PTI was also able to monitor coyotes, another invasive species on the base, and detect Florida black bear and Florida panther, species of particular concern.     

Subjectivity and social-ecological systems: a rigidity trap (and sense of place as a way out)

The fundamental point of this paper is that constructs such as system identity stability and changes (tips, transitions, transformations from one identity to another), are subjectively perceived, and acted upon by the social actors that occupy these systems. However, social-ecological systems (SES) research has not yet adequately engaged this subjectivity. I argue, here, that this relative lack of recognition of subjectivity has become a “rigidity trap” for SES scholars. Subjectivity is messy and difficult, and does not fit particularly well within the systems perspectives that characterize resilience work. As such, this lack of engagement has led to self-reinforcing perspectives that emphasize some elements and de-emphasize others, creating a systematic neglect of some principles that might productively challenge existing notions and expand our thinking. Sense of place theory, which emphasizes the creation of meaning as systematically distributed throughout society, is offered as a mechanism for helping SES researchers more fully engage subjectivity.     

Approaches to studying the genomic architecture of complex birth defects

Every year nearly 6 percent of children worldwide are born with a serious congenital malformation, resulting in death or lifelong disability. In the United States, birth defects remain one of the leading causes of infant mortality. Among the common structural congenital defects are conditions known as neural tube defects (NTDs). These are a class of malformation of the brain and spinal cord where the neural tube fails to close during the neurulation. Although NTDs remain among the most pervasive and debilitating of all human developmental anomalies, there is insufficient understanding of their etiology. Previous studies have proposed that complex birth defects like NTDs are likely omnigenic, involving interconnected gene regulatory networks with associated signals throughout the genome. Advances in technologies have allowed researchers to more critically investigate regulatory gene networks in ever increasing detail, informing our understanding of the genetic basis of NTDs. Employing a systematic analysis of these complex birth defects using massively parallel DNA sequencing with stringent bioinformatic algorithms, it is possible to approach a greater level of understanding of the genomic architecture underlying NTDs. Herein, we present a brief overview of different approaches undertaken in our laboratory to dissect out the genetics of susceptibility to NTDs. This involves the use of mouse models to identify candidate genes, as well as large scale whole genome/whole exome (WGS/WES) studies to interrogate the genomic landscape of NTDs. The goal of this research is to elucidate the gene-environment interactions contributing to NTDs, thus encouraging global research efforts in their prevention.