Analysis of pesticide runoff from mid-Texas estuaries and risk assessment implications for marine phytoplankton

During 1993, estuarine surface water samples were collected from the mid-Texas coast (Corpus Christi to Port Lavaca, TX). Agricultural watershed areas as well as tidal creeks immediately downstream were chosen as sampling sites along with adjoining bay sampling stations. Collections were made throughout the growing season (February to October 1993) before and after periods of significant (> 1.25 cm) rainfall. All samples were initially screened for the presence of pesticides using enzyme-linked immunosorbent assay (ELISA) test kits (EnviroGard) for triazine herbicides and carbamate insecticides. All samples were extracted and then analyzed using gas chromatography (GC) for quantification of atrazine. Only samples testing positive for carbamate insecticides via ELISA were further extracted for GC analysis to quantify aldicarb and carbofuran. Additionally, laboratory toxicity tests using phytoplankton were examined from published, peer-reviewed literature and compared with the atrazine field levels found in Texas. Results of ELISA screening indicated the presence of triazine herbicides in nearly all samples (>93%). GC analysis further confirmed the presence of atrazine concentrations ranging from <0.01-62.5 microg/L. Screening tests also found detectable levels of carbamate insecticides (aldicarb and carbofuran) that were also confirmed and quantified by GC. Comparison of measured concentrations of atrazine compared with published toxicity tests results indicated that there was a potential environmental risk for marine/estuarine phytoplankton in surface waters of Texas estuaries, particularly when the chronic nature of atrazine exposure is considered.     

A framework for understanding climate change impacts on coral reef social–ecological systems

Corals and coral-associated species are highly vulnerable to the emerging effects of global climate change. The widespread degradation of coral reefs, which will be accelerated by climate change, jeopardizes the goods and services that tropical nations derive from reef ecosystems. However, climate change impacts to reef social–ecological systems can also be bi-directional. For example, some climate impacts, such as storms and sea level rise, can directly impact societies, with repercussions for how they interact with the environment. This study identifies the multiple impact pathways within coral reef social–ecological systems arising from four key climatic drivers: increased sea surface temperature, severe tropical storms, sea level rise and ocean acidification. We develop a novel framework for investigating climate change impacts in social–ecological systems, which helps to highlight the diverse impacts that must be considered in order to develop a more complete understanding of the impacts of climate change, as well as developing appropriate management actions to mitigate climate change impacts on coral reef and people.     

Identifying important species that amplify or mitigate the interactive effects of human impacts on marine food webs

Some species may have a larger role than others in the transfer of complex effects of multiple human stressors, such as changes in biomass, through marine food webs. We devised a novel approach to identify such species. We constructed annual interaction-effect networks (IENs) of the simulated changes in biomass between species of the southeastern Australian marine system. Each annual IEN was composed of the species linked by either an additive (sum of the individual stressor response), synergistic (lower biomass compared with additive effects), or antagonistic (greater biomass compared with additive effects) response to the interaction effect of ocean warming, ocean acidification, and fisheries. Structurally, over the simulation period, the number of species and links in the synergistic IENs increased and the network structure became more stable. The stability of the antagonistic IENs decreased and became more vulnerable to the loss of species. In contrast, there was no change in the structural attributes of species linked by an additive response. Using indices common in food-web and network theory, we identified the species in each IEN for which a change in biomass from stressor effects would disproportionately affect the biomass of other species via direct and indirect local, intermediate, and global predator–prey feeding interactions. Knowing the species that transfer the most synergistic or antagonistic responses in a food-web may inform conservation under increasing multiple-stressor impacts.     

The changing sociocultural context of wildlife conservation

We introduced a multilevel model of value shift to describe the changing social context of wildlife conservation. Our model depicts how cultural-level processes driven by modernization (e.g., increased wealth, education, and urbanization) affect changes in individual-level cognition that prompt a shift from domination to mutualism wildlife values. Domination values promote beliefs that wildlife should be used primarily to benefit humans, whereas mutualism values adopt a view that wildlife are part of one's social network and worthy of care and compassion. Such shifts create emergent effects (e.g., new interest groups) and challenges to wildlife management organizations (e.g., increased conflict) and dramatically alter the sociopolitical context of conservation decisions. Although this model is likely applicable to many modernized countries, we tested it with data from a 2017–2018 nationwide survey (mail and email panel) of 43,949 residents in the United States. We conducted hierarchical linear modeling and correlational analysis to examine relationships. Modernization variables had strong state-level effects on domination and mutualism. Higher levels of education, income, and urbanization were associated with higher percentages of mutualists and lower percentages of traditionalists, who have strong domination values. Values affected attitudes toward wildlife management challenges; for example, states with higher proportions of mutualists were less supportive of lethal control of wolves (Canis lupus) and had lower percentages of active hunters, who represent the traditional clientele of state wildlife agencies in the United States. We contend that agencies will need to embrace new strategies to engage and represent a growing segment of the public with mutualism values. Our model merits testing for application in other countries.     

A pre/post evaluation of fatigue,stress and vigilance amongst commercially licensed truck drivers performing a prolonged driving task

Purpose. The main purpose of this research study was to evaluate changes in fatigue, stress and vigilance amongst commercially licensed truck drivers involved in a prolonged driving task. The secondary purpose was to determine whether a new ergonomic seat could help reduce both physical and cognitive fatigue during a prolonged driving task. Two different truck seats were evaluated: an industrial standard seat and a new truck seat prototype. Methods. Twenty male truck drivers were recruited to attend two testing sessions, on two separate days, with each session randomized for seat design. During each session, participants performed two 10-min simulated driving tasks. Between simulated sessions, participants drove a long-haul truck for 90 min. Fatigue and stress were quantified using a series of questionnaires whereas vigilance was measured using a standardized computer test. Results. Seat interactions had a significant effect on fatigue patterns. Conclusion. The new ergonomic seat design holds potential in improving road safety and vehicle accidents due to fatigue-related accidents.     

Subject Index

Subject Index

Subject Index     

Definition of an airworthiness certification framework for civil unmanned aircraft systems

The development of effective safety regulations for unmanned aircraft systems (UAS) is an issue of paramount concern for industry. The development of this framework is a prerequisite for greater UAS access to civil airspace and, subsequently, the continued growth of the UAS industry. The direct use of the existing conventionally piloted aircraft (CPA) airworthiness certification framework for the regulation of UAS has a number of limitations. The objective of this paper is to present one possible approach for the structuring of airworthiness regulations for civilian UAS. The proposed approach facilitates a more systematic, objective and justifiable method for managing the spectrum of risk associated with the diversity of UAS and their potential operations. A risk matrix is used to guide the development of an airworthiness certification matrix (ACM). The ACM provides a structured categorisation that facilitates the future tailoring of regulations proportionate to the levels of risk associated with the operation of the UAS. As a result, an objective and traceable link may be established between mandated regulations and the overarching objective for an equivalent level of safety to CPA. The ACM also facilitates the systematic consideration of a range of technical and operational mitigation strategies. For these reasons, the ACM is proposed as a suitable method for the structuring of an airworthiness certification framework for civil or commercially operated UAS (i.e., the UAS equivalent in function to the Part 21 regulations for civil CPA) and for the further structuring of requirements on the operation of UAS in un-segregated airspace.     

Seasonal changes in habitat structure underpin shifts in macroalgae-associated tropical fish communities

Habitat shifts play an important role in structuring faunal assemblages; however, research has focused on the influence of random disturbance events and information on how regular seasonal changes to habitat affect marine fauna remains largely unexplored, especially in the tropics. We recorded seasonal changes in the structure of tropical macroalgae fields within the Ningaloo lagoon (Western Australia) and related this to the density, biomass and species richness of fishes that represent key processes: juveniles, predators of juveniles and herbivores. The extent and direction of seasonal changes in macroalgae were inconsistent among sites, creating a highly dynamic habitat matrix across time and space. Species richness and density of fishes were largely maintained where density of holdfasts from canopy-forming macroalgae and/or cover was high across seasons, but shifted markedly in areas of macroalgae habitat loss: suggesting stable habitat structure is critical for the persistence of macroalgae-associated fishes. Our results demonstrate that macroalgae fields that maintain high structural complexity across different seasons are more likely to preserve key ecological processes and therefore warrant greater conservation attention within a spatial management framework.