Cyclomorphosis inEubosmina longispina in a small North American pond

The cyclomorphosis exhibited by a population ofEubosmina longispina in Bullhead Pond, Rhode Island is documented and compared to that reported for similar species of Bosminidae. Cyclomorphosis inEubosmina longispina involves the same morphological characters that exhibit seasonal changes in related species, but the temporal patterns of these changes are quite distinct. We suggest that the cyclomorphosis exhibited byEubosmina longispina is caused by simultaneous, but very different selective predation by planktivorous copepods and fish.     

The use of life-tables for evaluating the chronic toxicity of pollutants toMysidopsis bahia

This study examines the application of population statistics to laboratory-derived toxicological data for the purpose of developing a predictive model that assesses the population consequences of pollutant and environmentally-induced stress. Life tables are used to calculate age-specific survivorship, fecundity, intrinsic rate of population increase (r), and reproductive value (V_a), for populations ofMysidopsis bahia chronically exposed, in separate tests, to mercury and nickel. The population statistics, r, and V_a, and pollutant dose are defined quantitatively, and the critical value (r = 0) for the intrinsic rate of population increase is compared with traditional toxicological measures of acute and chronic toxicity.The effects of an environmental variable, predation, significantly reduce the critical value (r = 0) for the intrinsic rate of growth and demonstrate the interactions of multiple stressors. The use of the population statistic, r, is recommended for estimating the ecological significance of toxicological data and for facilitating the assessment of interactions between pollutant-stressed populations and dynamic environmental pressures.Contribution No. 258 of the U.S. Environmental Protection Agency.     

The evolution of competing species of terrestrial salamanders: niche partitioning or interference?

Summary One of the central assumptions of evolutionary ecology is that interspecific competition is a potent evolutionary force acting on coexisting species. There are few animal species that provide an opportunity for an experimental analysis of the evolutionary consequences of the phenomenon. We have taken advantage of the fact that two species of terrestrial salamander,Plethodon glutinosus andP. jordani, have different altitudinal distributions on two mountain ranges in North Carolina. Field removal experiments showed that interspecfic competition was much stronger in the Great Smoky Mountains than in the Balsam Mountains, and transplant experiments between the two mountain ranges showed that neither species from the Balsam Mountains had a measurable effect on its congener in the Smokies, although both species from the Smokies had strong negative effects on the Balsam congeners. Other experiments were conducted on the behavioral and ecological changes that have (or have not) evolved in the two areas. Our studies show that increased interspecific interference was the major evolutionary response of these largePlethodon species to interspecific competition, and that partitioning of food or microhabitat was not involved.     

Measurement of biological aerosol with a fluorescent aerodynamic particle sizer (FLAPS): correlation of optical data with biological data

Biological aerosol measurement in real time is anurgent military requirement that also has manypotential non-military applications. Such detectioncapabilities will be useful in environmentalmonitoring, for example, in gathering information inperceived hazardous areas like housing developmentsdownwind of sewage treatment plants.Experience gained from measuring fluorescence signalsof single bacterial spores under flow cytometry usingUV excitation at 340--360 nm, was applied to concepttesting of a prototype instrument, built to do thesame for aerosols. This machine was capable ofresolving particle size as well as fluorescenceintensity of each particle under laboratory and fieldconditions; it was called the fluorescent aerodynamicparticle sizer (FLAPS). A second generation FLAPS(FLAPS2) was designed to be smaller, power efficientand field portable. FLAPS2 was challenged underrefereed conditions in blind trials to determine if itcould detect biological aerosols in natural fieldenvironment. This paper describes practical aspects ofmeasuring biological aerosols when the results must becompared to reference samplers that provide culturableor ``live' data. Treatment of particle size andfluorescence information is discussed with respect toFLAPS and reference data fidelity. Finally, anobjective method is introduced to evaluate FLAPS datacorrelation to reference data. The measurementssuggest that there is positive correlation betweenFLAPS measurements and live biological aerosolparticles.