Predicting impacts of chemicals from organisms to ecosystem service delivery: A case study of endocrine disruptor effects on trout

We demonstrate how mechanistic modeling can be used to predict whether and how biological responses to chemicals at (sub)organismal levels in model species (i.e., what we typically measure) translate into impacts on ecosystem service delivery (i.e., what we care about). We consider a hypothetical case study of two species of trout, brown trout (Salmo trutta; BT) and greenback cutthroat trout (Oncorhynchus clarkii stomias; GCT). These hypothetical populations live in a high-altitude river system and are exposed to human-derived estrogen (17α‑ethinyl estradiol, EE2), which is the bioactive estrogen in many contraceptives. We use the individual based model in STREAM to explore how seasonally varying concentrations of EE2 could influence male spawning and sperm quality. Resulting impacts on trout recruitment and the consequences of such for anglers and for the continued viability of populations of GCT (the state fish of Colorado) are explored. in STREAM incorporates seasonally varying river flow and temperature, fishing pressure, the influence of EE2 on species-specific demography, and inter-specific competition. The model facilitates quantitative exploration of the relative importance of endocrine disruption and inter-species competition on trout population dynamics. Simulations predicted constant EE2 loading to have more impacts on GCT than BT. However, increasing removal of BT by anglers can enhance the persistence of GCT and offset some of the negative effects of EE2. We demonstrate how models that quantitatively link impacts of chemicals and other stressors on individual survival, growth, and reproduction to consequences for populations and ecosystem service delivery, can be coupled with ecosystem service valuation. The approach facilitates interpretation of toxicity data in an ecological context and gives beneficiaries of ecosystem services amore explicit role in management decisions. Although challenges remain, this type of approach may be particularly helpful for site-specific risk assessments and those in which trade offs and synergies among ecosystem services need to be considered

The role of the geophysical template and environmental regimes in controlling stream-living trout populations

The importance of multiple processes and instream factors to aquatic biota has been explored extensively, but questions remain about how local spatiotemporal variability of aquatic biota is tied to environmental regimes and the geophysical template of streams. We used an individual-based trout model to explore the relative role of the geophysical template versus environmental regimes on biomass of trout (Oncorhynchus clarkii clarkii). We parameterized the model with observed data from each of the four headwater streams (their local geophysical template and environmental regime) and then ran 12 simulations where we replaced environmental regimes (stream temperature, flow, turbidity) of a given stream with values from each neighboring stream while keeping the geophysical template fixed. We also performed single-parameter sensitivity analyses on the model results from each of the four streams. Although our modeled findings show that trout biomass is most responsive to changes in the geophysical template of streams, they also reveal that biomass is restricted by available habitat during seasonal low flow, which is a product of both the stream's geophysical template and flow regime. Our modeled results suggest that differences in the geophysical template among streams render trout more or less sensitive to environmental change, emphasizing the importance of local fish-habitat relationships in streams

Local Variability Mediates Vulnerability of Trout Populations to Land Use and Climate Change

Land use and climate change occur simultaneously around the globe. Fully understanding their separate and combined effects requires a mechanistic understanding at the local scale where their effects are ultimately realized. Here we applied an individual-based model of fish population dynamics to evaluate the role of local stream variability in modifying responses of Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) to scenarios simulating identical changes in temperature and stream flows linked to forest harvest, climate change, and their combined effects over six decades. We parameterized the model for four neighboring streams located in a forested headwater catchment in northwestern Oregon, USA with multi-year, daily measurements of stream temperature, flow, and turbidity (2007–2011), and field measurements of both instream habitat structure and three years of annual trout population estimates. Model simulations revealed that variability in habitat conditions among streams (depth, available habitat) mediated the effects of forest harvest and climate change. Net effects for most simulated trout responses were different from or less than the sum of their separate scenarios. In some cases, forest harvest countered the effects of climate change through increased summer flow. Climate change most strongly influenced trout (earlier fry emergence, reductions in biomass of older trout, increased biomass of young-of-year), but these changes did not consistently translate into reductions in biomass over time. Forest harvest, in contrast, produced fewer and less consistent responses in trout. Earlier fry emergence driven by climate change was the most consistent simulated response, whereas survival, growth, and biomass were inconsistent. Overall our findings indicate a host of local processes can strongly influence how populations respond to broad scale effects of land use and climate change

Predicting impacts of chemicals from organisms to ecosystem service delivery: A case study of endocrine disruptor effects on trout

We demonstrate how mechanistic modeling can be used to predict whether and how biological responses to chemicals at (sub)organismal levels in model species (i.e., what we typically measure) translate into impacts on ecosystem service delivery (i.e., what we care about). We consider a hypothetical case study of two species of trout, brown trout (Salmo trutta; BT) and greenback cutthroat trout (Oncorhynchus clarkii stomias; GCT). These hypothetical populations live in a high-altitude river system and are exposed to human-derived estrogen (17α‑ethinyl estradiol, EE2), which is the bioactive estrogen in many contraceptives. We use the individual based model in STREAM to explore how seasonally varying concentrations of EE2 could influence male spawning and sperm quality. Resulting impacts on trout recruitment and the consequences of such for anglers and for the continued viability of populations of GCT (the state fish of Colorado) are explored. in STREAM incorporates seasonally varying river flow and temperature, fishing pressure, the influence of EE2 on species-specific demography, and inter-specific competition. The model facilitates quantitative exploration of the relative importance of endocrine disruption and inter-species competition on trout population dynamics. Simulations predicted constant EE2 loading to have more impacts on GCT than BT. However, increasing removal of BT by anglers can enhance the persistence of GCT and offset some of the negative effects of EE2. We demonstrate how models that quantitatively link impacts of chemicals and other stressors on individual survival, growth, and reproduction to consequences for populations and ecosystem service delivery, can be coupled with ecosystem service valuation. The approach facilitates interpretation of toxicity data in an ecological context and gives beneficiaries of ecosystem services amore explicit role in management decisions. Although challenges remain, this type of approach may be particularly helpful for site-specific risk assessments and those in which trade offs and synergies among ecosystem services need to be considered

Forensic Engineering Analysis of Unintended Movement of Powered Industrial Trucks

Unintended movement of powered industrial trucks after operators have left the operating position has led to serious — and sometimes fatal — accidents. Even though operators are trained to prevent unintended movement of powered industrial trucks, they can forget to shut off the power source or activate systems to prevent the unintended movement when leaving the truck. Operators are known to make mistakes, especially if they are working in a fast-paced environment and are required to frequently leave the trucks. Engineershave designed electrical interlocks and other systems (e.g., automatically applied parking brakes) to prevent unintended movement; however, not all powered industrial trucks are equipped with them. Furthermore, some of these systems only disconnect the power source from the truck’s drivetrain. These trucks can continue traveling due to their initial momentum or by gravity if the truck was left on a slope. The purpose of this paper is to address the design of forklift operator presence detection systems and unintended movement of unoccupied forklifts through a safety and forensic engineering analysis, highlighting a brief case study to examine the concept of use and foreseeable misuse — and to review the legal concept of strict product liability.</jats:p

Stand-Up Forklift Egress Times as a Function of Operator Compartment Guarding

A significant hazard related to the use of stand-up lift trucks, or stand-up forklifts, is the hazard of a lower limb crush injury or foot crush due to the opening across the rear of the operator compartment. According to one lift truck manufacturer’s statistics, there have been over 500 accidents that resulted in an injury to the lower limb of the operator in the last 30 years that involved their stand-up lift trucks. [1] Other manufacturers have had similar accidents. The injuries have occurred to the lower limb of the operator due to the close proximity of the operator’s lower limbs to the exterior of the lift truck, and the confined areas that stand-up lift trucks operate in. The operator’s lower limb can become pinned and crushed between the moving lift and another fixed object such as a rack system, a column or another lift truck. Objects, such as a fork tine, can also intrude into the operator compartment, injuring the operator’s lower extremities. The ANSI/ITSDF B56.1, Safety Standard for Low Lift and High Lift Trucks, encourages stand-up lift trucks to be designed with an open compartment to permit easy ingress and egress. [2] According to the standard, the open design allows an operator a free and easy egress from the truck in the event of a tip-over or off-the-dock accident. However, the standard permits the use of additional guarding and enclosure of the operator compartment. Spring loaded doors (or spring assisted closing guards) have been designed, implemented and are available from many manufacturers, but no data has been published regarding the time to open and egress from the operator compartment. Latching doors have also been designed and manufactured, but are not currently available on the market except in the case of trucks equipped with freezer cabs, for operation in refrigerated environments. However, latched doors have been criticized for extending the egress time duration by approximately 1/2 second. This study shows that a spring loaded door can be implemented on a stand-up forklift while only increasing egress time by a negligible amount, 0.05 seconds over an open compartment configuration. Furthermore, this study shows that an optimized latching door, designed by Knott Laboratory engineers, can also be implemented for a stand-up forklift while only increasing egress time by 0.09 seconds. The latching door designed by Knott Laboratory decreases the change in egress time associated with a latched door by a factor of 5. Therefore, the addition of a spring loaded door, or a latching door will not significantly increase operator egress time and provide additional protection to the operator in the event of a collision while still maintaining quick egress.</jats:p

The role of the geophysical template and environmental regimes in controlling stream-living trout populations

The importance of multiple processes and instream factors to aquatic biota has been explored extensively, but questions remain about how local spatiotemporal variability of aquatic biota is tied to environmental regimes and the geophysical template of streams. We used an individual-based trout model to explore the relative role of the geophysical template versus environmental regimes on biomass of trout (Oncorhynchus clarkii clarkii). We parameterized the model with observed data from each of the four headwater streams (their local geophysical template and environmental regime) and then ran 12 simulations where we replaced environmental regimes (stream temperature, flow, turbidity) of a given stream with values from each neighboring stream while keeping the geophysical template fixed. We also performed single-parameter sensitivity analyses on the model results from each of the four streams. Although our modeled findings show that trout biomass is most responsive to changes in the geophysical template of streams, they also reveal that biomass is restricted by available habitat during seasonal low flow, which is a product of both the stream’s geophysical template and flow regime. Our modeled results suggest that differences in the geophysical template among streams render trout more or less sensitive to environmental change, emphasizing the importance of local fish–habitat relationships in streams. </jats:p

Local Variability Mediates Vulnerability of Trout Populations to Land Use and Climate Change

<div><p>Land use and climate change occur simultaneously around the globe. Fully understanding their separate and combined effects requires a mechanistic understanding at the local scale where their effects are ultimately realized. Here we applied an individual-based model of fish population dynamics to evaluate the role of local stream variability in modifying responses of Coastal Cutthroat Trout (<i>Oncorhynchus clarkii clarkii</i>) to scenarios simulating identical changes in temperature and stream flows linked to forest harvest, climate change, and their combined effects over six decades. We parameterized the model for four neighboring streams located in a forested headwater catchment in northwestern Oregon, USA with multi-year, daily measurements of stream temperature, flow, and turbidity (2007–2011), and field measurements of both instream habitat structure and three years of annual trout population estimates. Model simulations revealed that variability in habitat conditions among streams (depth, available habitat) mediated the effects of forest harvest and climate change. Net effects for most simulated trout responses were different from or less than the sum of their separate scenarios. In some cases, forest harvest countered the effects of climate change through increased summer flow. Climate change most strongly influenced trout (earlier fry emergence, reductions in biomass of older trout, increased biomass of young-of-year), but these changes did not consistently translate into reductions in biomass over time. Forest harvest, in contrast, produced fewer and less consistent responses in trout. Earlier fry emergence driven by climate change was the most consistent simulated response, whereas survival, growth, and biomass were inconsistent. Overall our findings indicate a host of local processes can strongly influence how populations respond to broad scale effects of land use and climate change.</p></div

Pairwise Comparisons for Differences in Total Summer Biomass between Scenario and Baseline.

<p>Pairwise comparisons of total biomass (g) of trout in summer for forest harvest (FH), climate change (CC), and combined (FH + CC) scenarios compared to baseline in modeled streams, including Gus Creek, Pothole Creek, Rock Creek, and Upper Mainstem (UM). Values of summer biomass by year were averaged for five replicate simulations and were analyzed using Wilcoxon signed rank test (V) with continuity correction resulting in a pseudomedian of difference between scenario and baseline (Δ) for the 1^st harvest period, 2^nd harvest period, and the entire study period. Scenarios include manipulations of stream temperature and flow regimes (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135334#sec002" target="_blank">Methods</a> for details). Significant p-values in bold (alpha ≤ 0.05) represent increasing or decreasing magnitudes in comparison to baseline.</p><p>Pairwise Comparisons for Differences in Total Summer Biomass between Scenario and Baseline.</p

Trends in Fry Emergence of Trout across Scenarios.

<p>DOY from five replicate simulations when median number of modeled fry had emerged over time in Gus Creek, Pothole Creek, Rock Creek, and Upper Mainstem (UM). Scenarios include manipulations of stream temperature and flow regimes (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135334#sec002" target="_blank">methods</a> narrative for detail). Only significant trends (P < 0.05) over time are listed and include the slope of the trend (days per decade). Negative values represent early fry emergence. Gaps in data are due to years with no fry emergence because model thresholds for spawning, egg development, or emergence were not met.</p