Optimizing best management practices to control anthropogenic sources of atmospheric phosphorus deposition to inland lakes

Excessive phosphorus loading to inland freshwater lakes around the globe has resulted in nuisance plant growth along the waterfronts, degraded habitat for cold-water fisheries, and impaired beaches, marinas, and waterfront property. The direct atmospheric deposition of phosphorus can be a significant contributing source to inland lakes. The atmospheric deposition monitoring program for Lake Simcoe, Ontario, indicates roughly 20% of the annual total phosphorus load (2010–2014 period) is due to direct atmospheric deposition (both wet and dry deposition) on the lake. This novel study presents a first-time application of the genetic algorithm (GA) methodology to optimize the application of best management practices (BMPs) related to agriculture and mobile sources to achieve atmospheric phosphorus reduction targets and restore the ecological health of the lake. The novel methodology takes into account the spatial distribution of the emission sources in the airshed, the complex atmospheric long-range transport and deposition processes, cost and efficiency of the popular management practices, and social constraints related to the adoption of BMPs. The optimization scenarios suggest that the optimal overall capital investment of approximately $2M, $4M, and $10M annually can achieve roughly 3, 4, and 5 tonnes reduction in atmospheric P load to the lake, respectively. The exponential trend indicates diminishing returns for the investment beyond roughly $3M per year and that focusing much of this investment in the upwind, nearshore area will significantly impact deposition to the lake. The optimization is based on a combination of the lowest cost, most beneficial and socially acceptable management practices that develops a science-informed promotion of implementation/BMP adoption strategy. The geospatial aspect to the optimization (i.e., proximity and location with respect to the lake) will help land managers to encourage the use of these targeted best practices in areas that will most benefit from the phosphorus reduction approach.

Implications: Excessive phosphorus loading to inland freshwater lakes around the globe has resulted in nuisance plant growth along the waterfronts, degraded habitat for cold water fisheries, and impaired beaches, marinas and waterfront property. This novel study presents a first-time application of the Genetic Algorithm methodology to optimize the application of best management practices related to agriculture and mobile sources to achieve atmospheric phosphorus reduction targets and restore the ecological health of the lake. The novel methodology takes into account the spatial distribution of the emission sources in the airshed, the complex atmospheric long-range transport and deposition processes, cost and efficiency of the popular management practices and social constraints related to the adoption of BMPs.     

Impact of trampling on sandy beach macrofauna

The effects of varying intensities of human trampling on sandy beach macrofauna were investigated at an exposed beach on the Eastern Cape coast. An experimental approach investigated the survival rates of four macrofaunal species which were subjected to human trampling at different intensities in a holiday-activity simulation. It was found that the clamDonax serra was slightly impacted at all trampling intensities whileDonax sordidus and the isopodEurydice longicomis were affected only at high trampling intensities. Vigorous beach games, such as volleyball, may have a damaging effect onD. serra. In a second experiment, the severe effects of human trampling onD. serra and the benthic mysidGastrosaccus psammodytes were investigated using numbered animals in enclosures. The results indicated that few members of the macrofauna were damaged at low trampling intensities but substantial damage occurred under intense trampling.     

Ambient ultraviolet radiation induces protective responses in soybean but does not attenuate indirect defense

We investigated the effects of ambient ultraviolet (UV) radiation on (i) the performance and chemistry of soybean plants, (ii) the performance of Spodoptera frugiperda and (iii) the foraging behavior of the herbivore's natural enemy Cotesia marginiventris which exploits herbivore-induced plant volatiles (VOC) for host location. The accumulation of protective phenolics was faster in plants receiving ambient UV than in controls exposed to sun light lacking UV. Accordingly, isorhamnetin- and quercetin-based flavonoids were increased in UV exposed plants. No UV effects were found on the performance and feeding behavior of S. frugiperda. Herbivore-damaged plants emitted the same VOC when grown under ambient or attenuated UV for 5, 10 or 30 days. Consequently, C. marginiventris was attracted but did not discriminate between exposed and unexposed soybeans. In summary, ambient UV radiation affected soybean morphology and physiology but did not destabilize interactions between trophic levels.     

Response to commentary on “The Driver Behaviour Questionnaire as a predictor of accidents: A meta-analysis”

A commentary on our previously published meta-analysis about the predictive validity of the Driver Behaviour Questionnaire (DBQ) raised a number of points. These points do not dispute the quantitative results as such, but suggest that our introduction and discussion overly favor the DBQ and are incomplete in a number of ways. The commentary targeted the following topics: common method variance, intercorrelations of different instruments, accident data validity, correcting for measurement error,

Common method variance

Our meta-analysis provided an extensive discussion of validity threats, including ones not treated before in the DBQ literature, such as common scale anchors and publication bias. We see little added value in the commentary when it informs the readership of common method variance (CMV), as we clearly did this in our article. It is widely understood that CMV can account for a large share of the variance when self-reported data are intercorrelated (see Podsakoff, MacKenzie, Lee, & Podsakoff, 2003

Intercorrelations of different instruments

The commentary reacts to an introductory sentence in which we stated that the DBQ is strongly situated in a network of other questionnaires and tests (such as Trait Anxiety, Cognitive Failures Questionnaire, and Sensation Seeking Scale), by asserting that we seem to interpret such correlations as a positive feature of the DBQ and by pointing out that correlations between the DBQ and other self-reports may have arisen spuriously because of CMV.We dispute the assertion that we regard correlations

Accident data validity

The commentary rejects our position that not only self-reported accident data are susceptible to biases, but recorded data too. Note that our remark applied to all types of recorded accidents, including police reports, hospital data, insurance data, as well as fleet data from professional drivers, and not just company data as in the work by af Wåhlberg, Dorn, and Kline (2011), which is mentioned in the commentary. The literature discusses several sources of bias for recorded accidents that are

Correcting for unreliability

The commentary pointed out that our correction for attenuation is unusual, a surprising claim considering the established importance of correction for measurement error in theory testing (Liu and Salvendy, 2009, Schmidt and Hunter, 1999). The available DBQ research provided almost no information on measurement error, so we did not apply a correction as part of the meta-analysis. Instead, we applied one afterwards, based on the raw data of the largest DBQ study available, and illustrated that

Exposure

The commentary points out that our results were not corrected for exposure in any way. First of all, this statement is false, because our meta-analysis did include effect sizes corrected for exposure. We used a special moderator category for effect sizes other than zero-order correlations. These effect sizes were derived from regression analysis, often with mileage as one of the predictors.Second, it may be noted that af Wåhlberg himself reported that the association between exposure and

Further references

The commentary attended us to 11 studies supposedly not included in our meta-analysis. We appreciate af Wåhlberg and Dorn's close scrutiny of our reference list for potential omissions on the DBQ-accident relationship. It may be noted that missing a small fraction of studies in a meta-analysis of this scope is almost inevitable.The samples of four of the studies (Dobson et al., 1999, Elliott et al., 2007, Parker, 1999, Stradling et al., 2005) identified in the commentary were already included

Discussion

The purpose of a meta-analysis is to provide a quantitative summary of a metric of interest, correlations between the DBQ, and external criteria in our case. af Wåhlberg and Dorn's commentary does not dispute the quantitative results in themselves (except with regard to the correction for exposure), but targets the qualitative introduction and discussion of our article.The commentary raises some valid points, albeit points already discussed in our article. We too believe that common method

     

Über den Einfluß der Nahrungskonzentration und anderer Faktoren auf Filtrierleistung und Nahrungsausnutzung der Muscheln Arctica islandica und Modiolus modiolus

Filtration rates and the extent of phagocytosed food particles were determined in the offshore lamellibranchs Artica islandica and Modiolus modiolus in relation to particle concentration, body size and temperature. Pure cultures of the algae Chlamydomonas sp. and Dunaliella sp. were used as food. A new method for determining filtration rates was developed by modifying the classical indirect method. The concentration of the experimental medium (100%) was kept constant to ±1%. Whenever the bivalves removed algae from the medium, additional algae were added and the filtration rate of the bivalves expressed in terms of percentage amount of algae added per unit time. The concentration of the experimental medium was measured continuously by a flow colorimeter. By keeping the concentration constant, filtration rates could be determined even in relation to different definite concentrations and over long periods of time. The amount of phagocytosed food was measured by employing the biuret-method (algae cells ingested minus algae cells in faeces). Filtration rates vary continuously. As a rule, however, during a period of 24 h, two phases of high food consumption alternate with two phases of low food consumption during which the mussels' activities are almost exclusively occupied by food digestion. Filtration rate and amount of phagocytosed algae increase with increasing body size. Specimens of A. islandica with a body length of 33 to 83 mm filter between 0.7 to 71/h (30–280 mg dry weight of algae/24 h) and phagocytose 21 to 122 mg dry weight of algae during a period of 24 h. The extent of food utilization declines from 75 to 43% with increasing body size. In M. modiolus of 40 to 88 mm body length, the corresponding values of filtration rate and amount of phagocytosed algae range between 0.5 and 2.5 l/h (20–100 mg dry weight of algae) and 17 to 90 mg dry weight of algae, respectively; the percentage of food utilization does not vary much and lies near 87%. Filtration rate and amount of phagocytosed algae follow the allometric equation y=a·x ^b. In this equation, y represents the filtration rate (or the amount of phagocytosed algae), a the specific capacity of a mussel of 1 g soft parts (wet weight), x the wet weight of the bivalves' soft parts, and b the specific form of relationship between body size and filtration rate (or the amount of phagocytosed algae). The values obtained for b lie within a range which indicates that the filtration rate (or the amount of phagocytosed algae) is sometimes more or less proportional to body surface area, sometimes to body weight. Temperature coefficients for the filtration rate are in Arctica islandica Q₁₀ (4°–14°C)=2.05 and Q₁₀ (10°–20°C)=1.23, in Modiolus modiolus Q₁₀ (4°–14°C)=2.33 and Q₁₀ (10°–20°C)=1.63. In A. islandica, temperature coefficients for the amount of phagocytosed algae amount to Q₁₀ (4°–14°C)=2.15 and Q₁₀ (10°–20°C)=1.55, in M. modiolus to Q₁₀ (4°–14°C)=2.54 and Q₁₀ (10°–20°C)=1.92. Upon a temperature decrease from 12° to 4°C, filtration rate and amount of phagocytosed algae are reduced to 50%. At the increasing concentrations of 10×10⁶, 20×10⁶ and 40×10⁶ cells of Chlamydomonas/l offered, filtration rates of both mollusc species decrease at the ratios 3:2:1. At 12°C, pseudofaeces production occurs in both species in a suspension of 40×10⁶, at 20°C in 60×10⁶ cells of Chlamydomonas/l. At 12°C and 10–20×10⁶ cells of Chlamydomonas/l, the maximum amount of algae is phagocytosed. At 40×10⁶ cells/l, the amount of phagocytosed cells is reduced by 26% as a consequence of low filtration rates and intensive production of pseudofaeces. At 20°C and 20–50×10⁶ cells of Chlamydomonas/l, the maximum amount of algae is sieved out and phagocytosed; the concentration of 10×10⁶ cells/l is too low and cannot be compensated for by increased activity of the molluscs. With increasing temperatures, the amount of suspended matter, allowing higher rates of filtration and food utilization, shifts toward higher particle concentrations; but at each temperature a threshold exists, above which increase in particle density is not followed by increase in the amount of particles ingested. Based on theoretical considerations and facts known from literature, 7 different levels of food concentration are distinguishable. Experiments with Chlamydomonas sp. and Dunaliella sp. used as food, reveal the combined influence of particle concentration and particle size on filtration rate. Supplementary experiments with Mytilus edulis resulted in filtration rates similar to those obtained for M. modiolus, whereas, experiments with Cardium edule, Mya arenaria, Mya truncata and Venerupis pullastra revealed low filtration rates. These species, inhabiting waters with high seston contents, seem to be adapted to higher food concentrations, and unable to compensate for low concentrations by higher filtration activities. Adaptation to higher food concentrations makes it possible to ingest large amounts of particles even at low filtration rates. Suspension feeding bivalves are subdivided into four groups on the basis of their different food filtration behaviour.     

The Steubenville comprehensive air monitoring program (SCAMP): overview and statistical considerations

Average concentrations of particulate matter with an aerodynamic diameter less than or equal to 2.5 microm (PM2.5) in Steubenville, OH, have decreased by more than 10 microg/m3 since the landmark Harvard Six Cities Study associated the city's elevated PM2.5 concentrations with adverse health effects in the 1980s. Given the promulgation of a new National Ambient Air Quality Standard (NAAQS) for PM2.5 in 1997, a current assessment of PM2.5 in the Steubenville region is warranted. The Steubenville Comprehensive Air Monitoring Program (SCAMP) was conducted from 2000 through 2002 to provide such an assessment. The program included both an outdoor ambient air monitoring component and an indoor and personal air sampling component. This paper, which is the first in a series of four that will present results from the outdoor portion of SCAMP, provides an overview of the outdoor ambient air monitoring program and addresses statistical issues, most notably autocorrelation, that have been overlooked by many PM2.5 data analyses. The average PM2.5 concentration measured in Steubenville during SCAMP (18.4 microg/m3) was 3.4 microg/m3 above the annual PM2.5 NAAQS. On average, sulfate and organic material accounted for approximately 31% and 25%, respectively, of the total PM2.5 mass. Local sources contributed an estimated 4.6 microg/m3 to Steubenville's mean PM2.5 concentration. PM2.5 and each of its major ionic components were significantly correlated in space across all pairs of monitoring sites in the region, suggesting the influence of meteorology and long-range transport on regional PM2.5 concentrations. Statistically significant autocorrelation was observed among time series of PM2.5 and component data collected at daily and 1-in-4-day frequencies during SCAMP. Results of spatial analyses that accounted for autocorrelation were generally consistent with findings from previous studies that did not consider autocorrelation; however, these analyses also indicated that failure to account for autocorrelation can lead to incorrect conclusions about statistical significance.