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Temporal Variability in Nest Numbers of Rook (Corvus frugilegus) Colonies: Influence of Nearby Rookeries and Insights for Species Censuses

Gil-Gutiérrez Alejandro M., Olea Pedro P.

Polish Journal of Ecology

2023

Vol. 71, nr 4

141--152

While numerous censuses are conducted in Rook (Corvus frugilegus) populations, there is still a lack of comprehensive evaluations regarding the methodologies employed and factors influencing population estimates. Here, we assess patterns of nest number variation in colonies through the breeding season and examine some factors influencing this variability. We conducted four censuses in 18 colonies of the entire Spanish breeding population of Rook spread out over the breeding season, from 18th March to 11th April. The total population's nests count increased by 22% over the census period, with the highest count of 1,877 nests recorded on the last census date. Number nests within the rookeries exhibited fluctuations throughout the census period, with an average variation of 12%, predominantly decreasing over time; variations were higher during the second half of March compared to the first half of April. The temporal variability in rookery nest numbers was found to be independent of colony size, rookery type or census technique. However, it was positively influenced by the number of nests in nearby rookeries located within a 6 km radius, likely due to immigration and emigration processes. While most rookeries (72%) reached their peak nest numbers on the last census day (April 11th), the timing of this peak varied among colonies. This asynchrony leads to variations in the total population nest counts, depending on whether we base it on a single census date or select different dates when colonies reach their maximum nest numbers. Our results emphasize the importance of considering intra-colony temporal variations during the breeding period in census surveys to ensure robust comparisons among colonies and of the total population over time.

Testing Rhizobia for Natural and Anthropogenic Saline Soils and Subsoils

Skipin Leonid, Gaevaya Elena, Tarasova Svetlana

Journal of Ecological Engineering

2021

Vol. 22, nr 5

139--142

The area of naturally saline lands in Russia is approximately 30 million hectares. Currently, the growth of anthropogenic saline areas is associated with the extraction of minerals (agricultural ore) and the formation of drilling pits when drilling wells for the exploration and extraction of hydrocarbons. The number of drilling pits with high salt content in the Khanty-Mansi Autonomous Okrug is about 3 thousand. About the same number of them is found in the Yamalo-Nenets Autonomous Okrug. In the south of the Tyumen region, their number is increasing in the Uvat district. Reclamation of these areas includes the technical and biological phases of reclamation. The biological stage involves the use of phytomeliorant crops. Inclusion of the legume component in phytomeliorants implies its joint use with a preparation of active strain of nodule bacteria. The aim of the research was to identify the most salt-tolerant strain of lupine nodule bacteria under different chemistry and degree of salinity of the environment. In order to test lupine rhizobia for salt tolerance and salinity chemistry, laboratory experiments were set up in petri dishes. Lupine rhizobia strains 363a, 367a, and 375a were taken directly from the rhizotorphin preparations, and the degree of dilution was brought to a certain titer corresponding to about 80 colonies per Petri dish. The presented results of the experiments showed that the colonies of lupine rhizobia react extremely negatively to the concentration of salts in the nutrient medium of 0.3% or higher. This is true for both neutral and sodium salinity. Out of the three strains of rhizobia studied, sample 367a was the most salt tolerant. Strains 363a and 375a were less resistant to salinization. For the first time, strains of lupine rhizobia were tested for salt tolerance in relation to different chemistry and degree of salinity identical to anthropogenic soils and saline soils.

Method for Evaluating Germicidal Ultraviolet Inactivation of Biocontaminated Surfaces

Gorsuch E. L., Grinshpun S. A., Willeke K., Reponen T., Moss C. E., Jensen P. A.

International Journal of Occupational Safety and Ergonomics

1998

Vol. 4, No. 3

287--297

Safety issues related to work-site conditions often deal with potential worker exposure to infectious airborne microorganisms due to their dissemination in indoor air and contamination of surfaces. Germicidal ultraviolet (GUV) radiation is used in health-care settings and other occupational environments for microbial inactivation. In this study, a new methodology for determining the efficiency of GUV microbial inactivation of surfaces was developed and evaluated. The method utilizes identical chambers in which test microorganisms are irradiated on agar surfaces at different humidity and irradiation intensity levels. The effects of GUV intensity and exposure time on microbial inactivation were examined for Micrococcus luteus and Serratia marcescens. It was found that at low humidity levels (20-25%) both organisms can be inactivated with at least 95% efficiency if the GUV intensity exceeds 50 /zW/cm2 for at least 3-5 min (corresponding to a dose of ~ 1 0 mJ/cm2). The radiation dose needed for effective inactivation of S. marcescens, as measured by a UV meter near the microbial sample, was found not to be affected by the humidity level, whereas that of M. luteus increased at higher humidities. The findings of this study can be used to determine sufficient GUV inactivation doses for occupational environments with various microbial contaminations.