AN IN SITU COMPARISON OF THE EFFECTIVENESS OF FOUR ALGICIDES1

ABSTRACT: Four algicides (copper citrate, copper ethanolamine, simazine, and diuron) were tested for effectiveness using in situ bio-assays. Bioassays were conducted in clear polyethylene bags and algicide effectiveness measured by chlorophyll a, productivity, and algal counts. The body of water where this testing took place had a high pH (9.2), and high levels of total dissolved solids (610 mg/l) and nutrients. The order of effectiveness found in this study was simazine > diuron > copper ethanolamine > copper citrate.     

APPLICABILITY OF THE GREEN AND AMPT INFILTRATION EQUATION TO RANGELANDS1

ABSTRACT: The objective of this study was to investigate the use of Green and Ampt infiltration equation parameters (determined by least squares fitting of field infiltration data or predicted from soil texture properties) to characterize infiltration on spatially varying rangeland sites. It was found that a least squares regression approach reduces the physically based parameters in the Green and Ampt to empirical coefficients since negative coefficients are obtained, particularly on plots with low infiltration rates. Green and Ampt parameters predicted from soil texture data describe infiltration rates less than 3 cm/hr. The applicability of these Green and Ampt parameters appears limited to sites with lower infiltration rates. Results indicate that soil texture predictive triangles, developed to describe infiltration on agricultural soils, need revision to adequately describe infiltration patterns on rangelands.     

The organizational tenure — Job involvement relationship: A job-career experience explanation

Research on the job involvement-organizational tenure relationship has shown no consistent relationship, but recent job and career experience models suggest that a relationship should be found. Using data from three organizations (n = 216), polynomial regression analysis revealed a curvilinear job involvement-organizational tenure relationship. This finding is discussed with reference to changes in workplace sensemaking that occur as work experience is accumulated.     

Are bison exotic in the Wrangell-St. Elias National Park and Preserve?

The effect of past distributions of animal populations now extinct in an area from unknown causes is considered relative to their status as exotic or native in national parks. The example is the bison (Bisonbison) on the Copper and Chitina river drainages in Alaska in the USA which was introduced prior to establishment of Wrangell-St. Elias National Park and Preserve. The fossil record suggests that bison were present as recently as 500 years ago in Alaska. The policy of the US National Park Service to maintain natural ecosystems and restrict or eliminate exotic species raises the issue of whether this species should be treated as exotic or native.     

Quantifying Targets for Rehabilitating Degraded Areas of the Great Lakes

/ One attempt to quantify targets for rehabilitating degraded aquatic ecosystems has been through a United States-Canada program to develop and implement comprehensive remedial action plans (RAPs) to restore beneficial uses in 42 Great Lakes Areas of Concern. The International Joint Commission has facilitated agreement on listing/delisting guidelines for determining when use impairments exist in areas of concern and when uses have been restored, while federal/state/provincial governments and local stakeholders have provided leadership in establishing quantitative targets for restoring uses and in determining how to achieve them. The listing/delisting guidelines have been instrumental in helping reach agreement on problem definition (lack of agreement on problem definition has historically been used as a reason to delay action) and reaching agreement on quantitative targets for restoring uses. Quantitative, ecosystem-based targets are being used to drive the RAP process, help organizations pursue a common mission of restoring uses, and help achieve greater accountability. As a priority, the target-setting process must also recognize the importance of establishing both short- and long-term milestones in order to measure and celebrate incremental progress in restoring uses.KEY WORDS: Use impairments; Restoring uses; Quantitative targets     

Pup guarding by greater spear-nosed bats

Alloparental care poses an evolutionary dilemma because effort is expended on non-filial offspring. Thus, instances of alloparental care have been attributed to either mistaken identity, (i.e., recognition errors) or active cooperation. In greater spear-nosed bats (Phyllostomus hastatus), reproductive females roost together in stable long-term social groups in cave ceilings. Non-volant pups frequently fall from roost sites to the cave floor where they can die unless retrieved by an adult. In this study, we examined the function of adult female visits to non-filial young and tested whether visits were attributable to recognition errors or to cooperation. We found that females visited non-filial pups from their own social group more than expected. Females from different social groups attacked and sometimes killed pups, and male pups were attacked more frequently than female pups. Visits by group mates benefited fallen pups by reducing the likelihood of attack by females from other groups. In contrast to the mistaken identity hypothesis, we found that some females leave their own pups to approach and remain with group mates’ pups. We used microsatellite markers to estimate relatedness and test whether kinship could explain this alloparental care and found that females were unrelated to the pups they guard. We conclude that females who reside in highly stable social groups exhibit cooperative behavior that cannot be explained by kinship and is unlikely to be due to direct or generalized reciprocity. Instead, our data suggest that alloparental care likely involves a complex interplay between group membership and cooperative foraging.     

Predicting constant decay rates of coarse woody debris—A meta-analysis approach with a mixed model

The aim of the study is the estimation of decay rates for coarse woody debris in large forest regions. These rates, together with estimations of the amount of deadwood, can be used to calculate the release of carbon from that pool into the atmosphere. The model can be used for predictions of decomposition rate constants in a wide range of forest areas (e.g. in process based ecological models, reporting of GHG-emissions), as only easily available predictor variables were used in the regression.Based on an intensive literature research a meta-analysis on influencing factors controlling the constant decay rate of coarse woody debris was set up. The included studies differed significantly in the survey methods as well as in the geographical origin. 39 studies were collected, 30 appeared in North America and nine in Europe. Based on these studies 291 observations of the remaining fraction of coarse woody debris were collected.To quantify the effects that influence the decomposition rates a nonlinear mixed effects model was constructed. Only physiologically interpretable variables were included. With this approach it was possible to determine influencing effects from mean temperature in July, annual rainfall (as quadratic term), diameter of woody material and grouping into hardwoods or conifers and mass- or density loss were significant variables. The mixed effects model also allowed an estimation of the species-specific effects on the decomposition process. These random effects are given for 42 tree species. The degrees of freedom were used efficiently. The model explains 79.6% of the variance and is superior to a comparable multiple regression model.     

Public mosquito abatement

Mosquito abatement is a public good for which there is a long history of operating expenditures and measured performance. A simultaneous model of mosquito abundance and abatement response is developed. Parameters are estimated using time-series, cross-section data from 30 districts. Both insecticides and ditching have contributed to reduced mosquito populations. There is evidence that district managers may have invested in excess permanent control (ditching) relative to use of insecticides, and that present abatement expenditures for the average district are excessive.     

Beach macro-litter monitoring on southern Baltic beaches: results,experiences and recommendations

Major objectives were to provide a comprehensive dataset on beach macro-litter for parts of the southern Baltic Sea and to analyse if the methodology is fully applicable and a suitable monitoring method in the Baltic. We carried out a regular macro litter beach monitoring (OSPAR methodology, 4 time a year) on 35 beaches along the German and Lithuanian Baltic coast over 2–5 years. Additional experiments addressed the subjectivity of the field surveys and spatio-temporal variability on different scales. We observed no seasonality of the data and a monthly compared to a 3-monthly sampling resulted in 3 times higher annual item numbers. Along the Lithuanian coast, the average number of items per survey varied between 138 and 340 and along the German Baltic coast between 7 and 404, with a median value of 47. All data showed a very high spatio-temporal variability. Using the Matrix Scoring Technique we assessed beach litter sources. With 50% tourism and recreation was the most important source. 3D–transport simulations helped to explain the minor role of shipping as a source and, compared to the North Sea, the low numbers of items on German Baltic beaches. Floating litter had a short duration time in the western Baltic Sea and offshore drift dominated. Further, the common regular beach cleanings reduced the potential for local litter accumulation and translocation. We suggest a monitoring system on 14 Baltic beaches in Germany and 2 in Lithuania and provide cost calculations. The analysis of macro-litter in cormorant nesting material and the search for beached dead animals did not show any result. We can conclude that the macro-litter beach monitoring method is less suitable for Baltic beaches and should only serve as a complementary method in combination with others.