Mean Crowding Research Articles

Environmental and geographical factors influencing the spread of SARS-CoV-2 over 2 years: a fine-scale spatiotemporal analysis.

Since its emergence in late 2019, the SARS-CoV-2 virus has led to a global health crisis, affecting millions and reshaping societies and economies worldwide. Investigating the determinants of SARS-CoV-2 diffusion and their spatiotemporal dynamics at high spatial resolution is critical for public health and policymaking. This study analyses 194,682 georeferenced SARS-CoV-2 RT-PCR tests from March 2020 and April 2022 in the canton of Vaud, Switzerland. We characterized five distinct pandemic periods using metrics of spatial and temporal clustering like inverse Shannon entropy, the Hoover index, Lloyd's index of mean crowding, and the modified space-time DBSCAN algorithm. We assessed the demographic, socioeconomic, and environmental factors contributing to cluster persistence during each period using eXtreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP), to consider non-linear and spatial effects. Our findings reveal important variations in the spatial and temporal clustering of cases. Notably, areas with flatter epidemics had higher total attack rate. Air pollution emerged as a factor showing a consistent positive association with higher cluster persistence, substantiated by both immission models and, to a lesser extent, tropospheric NO2 estimations. Factors including population density, testing rates, and geographical coordinates, also showed important positive associations with higher cluster persistence. The socioeconomic index showed no significant contribution to cluster persistence, suggesting its limited role in the observed dynamics, which warrants further research. Overall, the determinants of cluster persistence remained across the study periods. These findings highlight the need for effective air quality management strategies to mitigate air pollution's adverse impacts on public health, particularly in the context of respiratory viral diseases like COVID-19.

Assessment of wild prey of mammalian carnivores in Barda Wildlife Sanctuary, Gujarat, India

The Barda Wildlife Sanctuary (Barda WLS) is a semi-arid ecosystem that plays an important role in the conservation of mammalian carnivores. It is essential to evaluate the population of important wild prey species in Barda, which has conservation implications for mammalian predators and themselves. We assessed the density, biomass, and population structure of wild prey species by surveying road (n = 10) and trail (n = 8) transects using the distance sampling framework method. We used male-to-female sex ratios and the percent contribution of each age class to assess population structure. Mean group size (MGS), median group size (Mdgs), and mean crowding (Mc) were calculated to analyze group size. Of the species studied, Indian peafowl had the highest density (51.61 ± 7.08 individuals/km2), followed by wild pig (10.77 ± 4.59), blue bull (3.50 ± 0.51), Indian hare (3.03 ± 0.73), and spotted deer (0.62 ± 0.04). The male-to-adult female sex ratio was biased towards females, except for Indian peafowl. All species had small group sizes except wild pigs. The results of this study can aid in its development as one of the important protected areas in Gujarat for the conservation of mammalian predators, along with framing conservation strategies for Barda WLS.

Patterns in the Distribution and Abundance of the Post-Outbreak Population of the Coconut Leaf Beetle, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae) in Albay, Philippines

Field monitoring of the coconut leaf beetle (CLB) population in old stands (more than 7 years old) and young stands of coconut (3-5 years old) was conducted in Albay Philippines where an outbreak of the pest occurred in 2006. The study was conducted to characterize the changes in the population of the CLB over time and space and to relate these changes to the infestation pattern, age of palms, development and reproduction of the pest, growth, and development of the coconut leaf. The spatial distribution of the CLB population as well as the infested palms were aggregated throughout the monitoring period based on the Index of dispersion and Lloyd’s mean crowding. Development time and reproduction of CLB is inferred to be synchronous with the emergence of each leaflet in the spear of coconut which has an average of 23 days before another leaflet emerges. This complemented the biology studies where CLB was able to complete from egg to adult in 34.33±2.59 and 32.00±0.93 days in females for both laboratory and greenhouse studies. The infestation of CLB was shown not to spread even if there was an increase in the population.

Interrelationships and properties of parasite aggregation measures: a user’s guide

Aggregation of macroparasites among hosts is nearly universal among parasite-host associations. Researchers testing hypotheses on origins of parasite aggregation and its importance to parasite and host population ecology have used different measures of aggregation that are not necessarily measuring the same thing, potentially clouding our understanding of underlying epidemiological processes. We highlight these differences in meanings by exploring properties and interrelationships of six common measures of parasite aggregation, and provide a “user’s guide” to inform researchers’ decisions regarding their application. We compared the mathematical expressions of the different measures of aggregation, and ran two series of simulations and analyses. The first simulations tested the effect of random removals of parasites on aggregation levels under different conditions, while the second explored interrelationships between the measures, as well as between other individual parasitological sample measures (i.e. mean abundance, prevalence) and aggregation. Results of simulations and analyses showed that the six measures of aggregation could be separated readily into three groups: the variance-to-mean ratio (VMR) together with mean crowding, patchiness with k of the negative binomial, and Poulin’s D with Hoover’s index. These three pairs of measures showed differing responses to random parasite removals and differing relations with mean abundance and/or prevalence, highlighting that metrics capture different variation in other sample measures and different attributes of aggregation. We used results of our simulations and analyses, and a literature review, to list the properties, advantages, and disadvantages of each aggregation metric. We provide a comprehensive exploration of what is assessed by each metric, as a guide to metric choice. We implore researchers to provide enough information such that aggregation measures from each group are reported or can be readily calculated. Such steps are needed to allow large-scale analyses of variation in degrees of aggregation within and among parasite-host associations, to uncover epidemiological processes shaping parasite distributions.

Comparative Spatial Distribution of Sucking Insect-Pest-Complex in Summer and Monsoon Cowpea [Vigna unguiculata (L.) Walp.

Background: Pulse crops are known as an important dietary source of proteins for a major part of the vegetarian population across the globe; especially in India. Legume crops help restoration of soil fertility through symbiotic nitrogen fixation. Spatial distribution is an important aspect as it interprets the interaction between individuals of the species and their habitat. The biological reason of aggregation is highly unpredictable and it depends on behavioural pattern of the insect; therefore, spatial distribution accounts for informative description of organisms. Methods: In order to study the spatial distribution of sucking pests of cowpea, a field trial was laid out during Zaid and Kharif separately at the Instructional Farm of Rajasthan College of Agriculture, Udaipur in 2019 and 2020. Cowpea variety Pusa Komal was cultivated in 6 plots each of 3 m x 3 m with the row to row and plant to plant spacing of 50 cm and 10 cm, respectively. Different distribution pattern were used to determine spatial distribution pattern of species of insect fauna associated with cowpea during the summer and monsoon season. Result: The spatial distribution for most the insect pest complex was contagious during both the respective seasons. All positive IDM (index of clumping) values confirmed the clumping of the pest during the season. The mean crowding index was more than unity, indicated clumped interaction.

Spatial distribution of <i>Aphidius matricariae</i> (Haliday) and <i>Myzus persicae</i> (Sulzer) in bell pepper under polyhouse conditions

The spatial distribution of Aphidius matricariae and Myzus persicae was studied in bell pepper under polyhouse conditions. In the present study, M. persicae and its parasitoid, A. matricariae populations followed negative binomial distribution throughout the season. The variance to mean ratio (σ2/X), mean crowding (X*), ratio of mean crowding to mean (X*/X), ‘k’ of negative binomial, Taylor’s power equation for M. persicae and A. matricariae were σ² = 6.97X1.531 (R2 = 0.931), and σ² = 4.29X1.282 (R2 = 0.90) during 2018-2019, respectively. Iwao’s patchiness regression was X* = 45.12 + 1.333X (R2 = 0.853), and X* = 5.406 + 1.195X (R2 = 0.767) during 2018-2019, respectively. Optimum number of samples required for the green peach aphid, M. persicae and A. matricariae were 261.1 and 474 at 20% precision level. The present study will be useful for developing a sampling plan of M. persicae and its parasitoid, A. matricariae in bell pepper for its monitoring and management.

Group size, crowding, and age class composition of the threatened Sambar Rusa unicolor (Kerr, 1792) (Mammalia: Cetartiodactyla: Cervidae) in the semi-arid regions of northeastern Rajasthan, India

Grouping characteristics and population growth dynamics of Sambar were studied in Bir Jhunjhunu Conservation Reserve (BJCR) and Bairasar Johad (BJ) in Rajasthan, India from July 2018 to June 2019. Following the scan sampling method, a total of 117 sightings of Sambar (N= 488 individuals) were recorded in BJCR, and 106 in BJ (N= 389 individuals), during 24 fortnightly visits. The data revealed that besides solitary sightings of Sambar, groups ranging from 2–11 and 2–12 individuals were observed in BJCR and BJ, respectively. The overall mean group size and mean crowding of Sambar were 4.2±0.2 S.E. and 5.3 respectively in BJCR, and 3.7±0.2 S.E. and 5.0 respectively in BJ. The sex ratio was skewed towards females. The overall adult male: adult female: fawn ratio was 74.4: 100: 47.1 (N= 488 individuals) in BJCR while the ratio was 92.6: 100: 41.1 (N= 389 individuals) in BJ. As far as the social organization of Sambar is concerned, six types of herds were recorded in the present study. It is urged that sambar populations outside protected area also need simultaneous strategies for conservation attention.

Does the micro land snail, Kaliella barrakporensis (Mollusca: Gastropoda), exhibit plant preference and aggregation? A spatial scale analysis

The spatial scale occurrence of the micro land snail Kaliella barrakporensis (L. Pfeiffer, 1852) in the host plants was assessed in selected sites of West Bengal, India. In course of a survey, the collection of K. barrakporensis from randomly selected plants was accomplished for the purpose of highlighting – (a) distribution in host plants, (b) variation in abundance in different height and (c) the dispersion pattern. Although the snails were observed in seven different plants, the presence was more prominent in the lemon plant (Citrus limon), with an average of about 24 individuals / 100 leaves. The logit based principal component regression indicated significant differences in the choice of the host plants with abundance in C. limon followed by Hibiscus rosa sinensis and Nyctanthes arbor-tristis, which was further substantiated through ANOVA (F(1),6, 69 = 10.918; P < 0.001). The heterogeneity in the distribution of K. barrakporensis at different heights of the plant C. limon was also observed with maximum abundance at about 90cm height with least number of snails at the ground level (F(1)6,139 = 3.797;P < 0.0001). On the basis of the variance to mean ratio (s2/m = 1.847±0.161SE), negative binomial aggregation parameter k (1.034± 0.33 SE) and Lloyd mean crowding (ṁ) (1.083 ± 0.16SE) the dispersion of the snail appeared to comply with the clumped distribution in host plants. Apparently, the micro land snail K. barrakporensis exhibited clumped distribution in selected plant species that serve as the preferred resource and complies with the arboreal adaptation. However, further studies should be initiated on the resource preferences of the micro snail K. barrakporensis, to support conservation initiative and spread beyond native habitats.

<p><strong>Spatial distribution and sequential sampling of aphid and their natural enemies on wheat</strong></p>

Although many pests attack wheat, the damage due to wheat aphids has been on rise due to climate change phenomenon. Population of aphids increases during February to March and so the ladybird beetles to devour on aphids. With the aim of facilitating conservation of ladybird beetles, predator conditioned sampling plans were worked out. Wheat aphids, Rhopalosiphum padi L. and Sitobion avenae F. were observed infesting wheat. Major predatory coccinellid beetles, Cheilomenes sexmaculata (Fabricius) and Coccinella septempunctata (Linnaeus) were also found feeding on the wheat aphids. Spatial distribution of mixed population of the aphids and coccinellid beetles was analyzed using variance-mean ratio and regression models such as Taylor’s power law and Iwao’s mean crowding regression. The aphids and its predatory beetles were counted at different crop age. The mean population for wheat aphid was 7.88/plant and 0.72/ plant at 75 and 106 days after sowing (DAS), respectively. Variance-mean ratio indicated regular to aggregated distribution of aphids on the crop. Taylor’s power law aggregation parameter (b = 2.62) and density contagiousness co-efficient (β = 1.20) of Iwao’s mean crowding regression also revealed aggregated distribution of the wheat aphids. The mean population of coccinellid beetles varied from 0.72 to 1.43/plant during 68 to 100 DAS. Taylor’s power law aggregation parameter (b = 3.64) and density contagiousness co-efficient (β = 2.09) of Iwao’s mean crowding regression revealed aggregated distribution of the predators on the wheat crop. Sequential sampling plans were developed for wheat aphid management with and without predator’s effect through Taylor’s power law and Iwao’s mean crowding regression. Inclusion of predator effect in the regression models increased aphid population levels which necessitates need for management measures at higher population levels. Thus, the sequential sampling plans with predator effect are useful in avoiding unnecessary pesticide application on wheat crop for the aphid management.

闽南渔场游泳动物优势种种群聚集特性

基于2016年4月和10月闽南渔场渔业资源的专项调查数据，运用相对性重要指数、平均拥挤度指数、聚块指数、Cassie指标、Mrisita指数等方法分析闽南渔场游泳动物优势种组成及其种群聚集特性，比较不同的季节、类群和种类及其相互间的聚集状态，探究种群聚集驱动因子，旨在发现闽南渔场游泳动物优势种种群聚集的特征、内在规律和形成机制。结果表明，闽南渔场游泳动物优势种共17种，其中鱼类6种、虾类3种、蟹类4种、头足类4种；鱼类中六指马鲅（Polydactylus se-xfilis）聚集强度最强，头足类中火枪乌贼（Loligo beka）聚集强度最强；虾类和蟹类中春季以哈氏仿对虾（Parapenaeopsis hardwickii）和拥剑梭子蟹（Portunus gladiator）的聚集强度最强，而秋季以鹰爪虾（Trachypenaeus curvirostris）和日本蟳（Charybdis japonica）的聚集强度最强；鱼类、虾类、蟹类和头足类中春季分别以二长棘犁齿鲷（Evynnis cardinali）、鹰爪虾、三疣梭子蟹（P. trituberculatus）和火枪乌贼的平均拥挤度最高，而秋季分别以带鱼（Trichiurus lepturus）、鹰爪虾、拥剑梭子蟹和杜氏枪乌贼（Loligo duvaucelii）的平均拥挤度最高；闽南渔场游泳动物优势种的平均拥挤度呈现出秋季高于春季，虾类、蟹类种群聚集强度大于鱼类、头足类的特点。;The relative importance index, mean crowding index, patchiness index, Cassie index and Mrisita index were used to analyze the composition and aggregation characteristics of the dominant species of nekton in Minnan Fishing Ground using the special investigation data of fishery resources in Minnan Fishing Ground in April and October 2016. The results showed that there were 17 dominant species of nektons in Minnan Fishing Ground, including 6 species of fish, 3 species of shrimp, 4 species of crab and 4 species of cephalopod. Polydactylus se-xfilis had the strongest aggregation intensity among fishes, and Loligo beka had the strongest aggregation intensity among cephalopods in spring and autumn. Parapenaeopsis hardwickii had the largest aggregation intensity among shrimps, and Portunus gladiator had the largest aggregation intensity among crabs in spring. Trachypenaeus curvirostris had the largest aggregation intensity among shrimps, and Charybdis japonica had the largest aggregation intensity among crabs in autumn. In spring, Evynnis cardinali, Trachypenaeus curvirostris, Portunus trituberculatus, Loligo beka had the highest mean crowding among fishes, shrimps, crabs and cephalopods, respectively. In autumn, Trichiurus lepturus, Trachypenaeus curvirostris, P. gladiator and Loligo duvaucelii had the highest mean crowding among fishes, shrimps, crabs and cephalopods, respectively. The average crowding of main dominant species of nekton in autumn was higher than that in spring, and the aggregation intensity of shrimp and crab was higher than that of fish and cephalopod in the Minnan Fishing Ground.

The spatial niche and differentiation of major fish species in the waters east of the Zhoushan Islands in spring and autumn

Based on data from the fishery resources survey in the waters east of the Zhoushan Islands in April (spring) and October (autumn) in 2018, the index of relative importance was used to determine the importance of various fish species in the survey area. The niche breadth and overlap of major fish species were examined using the mean crowding, Shannon, and Pianka indices. Our results showed that there were 10 and 12 major fish species in spring and autumn, respectively. The niche breadth of major fish species in spring and autumn were 0.06–2.01 and 0.34–2.19, respectively, indicating differences between the two seasons. <italic>Larimichthys polyactis</italic> was the only wide-niche species (<italic>B</italic>_{<italic>i</italic>}≥2.0) in spring, whereas four were found in autumn: <italic>Johnius grypotus</italic>, <italic>Miichthys miiuy</italic>, <italic>Larimichthys polyactis,</italic> and <italic>Amblychaeturichthys hexanema</italic>. There were six medium-niche species (2.0&gt;<italic>B</italic>_{<italic>i</italic>}≥1.0) in both spring and autumn, whereas there were three narrow-niche species (1.0&gt;<italic>B</italic>_{<italic>i</italic>}&gt;0) in spring and two in autumn. The degree of niche overlap was unbalanced in the two seasons. There were 20 pairs of species with significant overlap in the spring niche, accounting for 44.44% of the total number of pairs, with a relatively high degree of overlap. Conversely, the major fish species overlap in autumn was low, with 16 pairs of species with significant overlap, accounting for only 24.24% of the total number of pairs. Redundancy analysis (RDA) showed that temperature and salinity were the factors directly affecting the distribution of the major fish species, though depth was also an important factor affecting the obvious niche differentiation of major fish species in spring and autumn.

Spatiotemporal characteristics and restoration potentiality of seed banks of aquatic plants in Dabokou wetland in Lake Dianchi, southwest China

以滇池典型生态修复区——大泊口水域为研究对象，研究了富营养化高原湖泊种子库时空特征、种子库与地表覆盖水生植被及水环境的相关关系和恢复潜力.利用高密度样方原位观测与温室控制种子萌发实验相结合，基于2014-2016共3年的长期定位研究，分析湖泊平均种子库密度、分布格局及与覆盖水生植物Sørensen相似性关系，结果显示：年平均种子库形成率在20.35%~34.13%之间，种子库密度2014年为546.67粒/m²，2015年为826粒/m²，2016年为1682粒/m²，眼子菜科的篦齿眼子菜（Potamogeton pectinatus L.）、金鱼藻科的金鱼藻（Ceratophyllum demersum L.）等耐污种属对种子库构成和年增长率贡献较大；垂直方向上种子主要分布于深层底泥（5~30 cm）.随着在时间尺度上的延长，种子库分布更为广泛，且规模越来越大（其中500粒/m²以上规模的分布频率显示增多）.离散系数（V/m）与Lloyd平均拥挤指数（m^*）分析显示主要优势群丛（篦齿眼子菜等）为聚集分布，其余为均匀空间分布格局；种子库与水生植被关系评价指标Sørensen相似性系数（SC）研究显示，滇池大泊口平均SC=（0.3628±0.0265），在湖泊湿地类型和草本群落植被类型属性上处于较低水平，即显示目前植物群落演替过程发生较快，耐污先锋种属在恢复进程上占据优势生态位，而历史优势种和对水环境要求较高的物种却未能规模萌发，一定程度上揭示了高原富营养化湖泊种子库中历史优势植被可恢复性的特征及难点.;Based on long-term dynamics and recent in situ observations across three consecutive years, combined with soil seed samples and greenhouse controlled seedling-emergence methods, this study comprehensively analyzed the scale heterogeneity and spatial-temporal characteristics of seed banks under eutrophic and damaged ecosystems in Dabokou wetland, Lake Dianchi. Seventy-five soil cores were collected from sampling sites within the water area. The sites were systematically distributed using the line-transect method. Investigations were completed a total of 3 times from 2014 to 2016. Species-area relationships were then modeled for pattern detection using seed banks density and characteristics; variance/mean ratio (V/m); and Lloyd's index of mean crowding(m^*). Relationships between seed banks and extant vegetation were also evaluated using Sørensen similarity coefficient(SC). Results showed that the seed density increased significantly accounting for 27.24%. Across the three year period, the mean seed bank densities were:546.67 ind./m², 826 ind./m² and 1682 ind./m², respectively for 2014, 2015 and 2016. Additionally, seven species were detected from seed banks, and most of them were distributed in the deeper bottom sludge as compared to the topsoil(0-5 cm). Over the course of time, there were more and more seed banks dispersal and large-scale density amounting to a distribution frequency of 500 ind./m². The seed pattern of Potamogeton pectinatus L. was aggregated while other extant vegetation was evenly distributed as indicated by aforesaid indices of pattern detection. The mean Sørensen similarity coefficient of Dabokou wetland was 0.3628, a low value for a lake wetland and herbosa-ecosystem. Overall, the succession of aquatic plant communities occurred intensely at Lake Dianchi.

Do species display characteristic intraspecific levels of patchiness in a given habitat type? The case of intertidal seagrass macrobenthos

Intertidal macrobenthic assemblages associated with monospecific stands of Zostera muelleri, Cymodocea serratula, Halodule uninervis and Halophila ovalis seagrasses are known to display uniform spatial patchiness on the Moreton Bay coast of North Stradbroke Island, Queensland, as do those in Z. capensis in the Knysna estuarine bay, South Africa. Thirty-seven historical datasets of these macrobenthic assemblages were re-analysed to assess variation of local patchiness in each of the 18 most common individual assemblage components at each of these localities in terms of three metrics: overall patchiness (Lloyd's index of patchiness), levels of unoccupancy, and variation in abundance across occupied samples (Lloyd's index of mean crowding). Within-site patchiness was not caused by a restriction of individual species to specific subareas but by variation in their local density, particularly by the extent of unoccupied ‘interstitial’ spaces within patches. Especially in the more uniform Queensland conditions, the more common species occurred relatively widely across the whole locality; individual samples from which a given species was absent never themselves formed patches, the number of such samples conforming to points on truncated normal curves of the frequency of occurrence. Of the 36 species investigated, the two most abundant and widespread both in Queensland and in South Africa displayed significant or near-significant uniformity of levels of local patchiness, whilst five showed significantly uniform mean crowding and ten significantly uniform unoccupancy. This is the first demonstration that some species may display a characteristic level of patchiness in a given habitat type.

Interspecific relationship of patchiness to occupancy and abundance, as exemplified by seagrass macrobenthos

The macroecological abundance-occupancy relationship is well known; not so the potential one of patchiness with either or both. Following earlier work on the intertidal seagrass Zostera capensis in South Africa, interspecific macrofaunal patchiness-occupancy and patchiness-abundance relationships were investigated within each of a number of other seagrass systems (intertidal Cymodocea serratula, Halodule uninervis, Halophila ovalis, Zostera muelleri and Z. noltei, and subtidal Z. capensis) where faunal assemblages were markedly different in their overall abundance and species richness, and where the beds differed in their latitude, longitude, and other variables, including one in an artificial canal in a residential marina. Notwithstanding these differences, in all cases the more abundant and widespread the macrobenthic species, the less was its Lloyd's Ip patchiness, the more clearly so in respect of occupancy than of abundance. Correlation of Ip and mean crowding (Ic) values was relatively poor, and often not significant. This suggests that patchiness of a species is more influenced by unoccupancy levels than by even marked variation in abundance at occupied sites (e.g. Ic values of <0.3–>380). Indeed, values of Ip were closely correlated with the expression [a.unoccupancy + (1−a).Ic], where a is >0.80. In all cases, component macrofaunal species displayed a significant or near significant negative patchiness-occupancy relationship in the form of a power-law with a mean scaling coefficient across sites of −0.76, although data points appeared highly scattered. There was little uniformity amongst the component species in the life-style of the most patchy, most widespread or most abundant.

Measuring aggregation in parasite populations

Aggregation, a fundamental feature of parasite distributions, has been measured using a variety of indices. We use the definition that parasite-host system A is more aggregated than parasite-host system B if any given proportion of the parasite population is concentrated in a smaller proportion of the host population A than of host population B. This leads to indices based on the Lorenz curve such as the Gini index (Poulin's D), coefficient of variation and the Hoover index, all of which measure departure from a uniform distribution. The Hoover index is particularly useful because it can be interpreted directly in terms of parasites and hosts. An alternative view of aggregation is degree of departure from a Poisson (or random) distribution, as used in the index of dispersion and the negative binomial k. These and Lloyd's mean crowding index are reinterpreted and connected back to Lorenz curves. Aggregation has occasionally been defined as the slope from Taylor's law, although the slope appears unrelated to other indices. The Hoover index may be the method of choice when data points are available, and the coefficient of variation when only variance and mean are given.

Spatial niche of major fish species in spring in the coastal waters of central and southern Zhejiang Province, China

The relative importance index (IRI), mean crowding, niche breadth, and niche overlap (Qik) of major fish species were calculated based on two fishery resource surveys from April to May 2016 (spring) in the coastal waters of central and southern Zhejiang Province. The results showed that there were 24 major fish species (IRI:100), the niche breadth values of which differed greatly and were positively correlated with IRI. The niche overlaps of fishes were extremely low in spring. The total amount of species pairs with niche overlap 0.6 (Qik :0.6) were six in April and five in May, which represented 3.9% and 4.8% of the total pairs, respectively. Results from the redundancy analysis showed that the distribution of major fish species were mainly affected by temperature, salinity, water depth, and dissolved oxygen, which caused ecological differentiation of fish species.

FEATURES OF USING STATISTICAL METHODS IN INVESTIGATIONS OF THE BLACK SEA SANDY COAST MACROINVERTEBRATES

Relevance. The feature of the sandy beaches as the marginal biotope complex is that most of the environmental gradients act across the coastline. The low amplitude of the tides and the non-periodic wind tides determine the dynamics and specificity of these zones in the north-western Black Sea (NWBS). Because of this, the macroinvertebrate sampling design in the NWBS and the statistical processing of the results need special attention.Aim. The purpose of this paper is to review the methods of statistical data processing that will allow us to clarify and extend our understanding of the structure of macro-invertebrate sand beach communities of NWBS and the features of their use.Main results. The shape of the sampling device slightly affects the catch of macrofauna. It is acceptable to use both transects and randomized stratified sampling.A reliable estimation of quantity is provided by kriging methods and recalculation of density per length of the coastline.The coefficient b of the Taylor equation and the regression of mean crowding characterize species-specific aggregation. For estimation of distribution it is recommended to use spatial autocorrelation coefficients (Moran's I, Geary’s C), Ripley’s K function, JCA (for binary data) and SADIE.The relationship between the spatial distributions of species from one sampling station can be detected by the Mantel test.The biological diversity of macroinvertebrates of NWBS sandy beaches is relatively low, so unspecific fauna can significantly affect the value of indices.Influence of environmental factors on macroinvertebrates, their groups and communities can be measured using regression analysis or more specific methods.Suggestions. It is recommended to use a randomized stratified sampling design. Species-specific aggregation parameters should be evaluated by density-independent indices. Geostatistical methods are recommended for estimating the spatial distribution. It is suggested to estimate the number by the results, interpolated by kriging methods. For calculation of biodiversity, it is recommended to exclude randomly introduced species from the sample. It is recommended to use logistic, multiple linear regression and Mantel test to evaluate the impact of environmental factors. The analysis should evaluate the effect of factors at different time scales and use beach indices to characterize beaches.

Distribution pattern and sequential sampling plan for chilli thrips, Scirtothrips dorsalis Hood (Thripidae: Thysanoptera)

Spatial distribution and sequential sampling plan for chilli thrips, Scirtothrips dorsalis Hood were analyzed through Taylor’s power law (TPL) and Iwao’s mean crowding regression (IMC) for rainy and summer seasons during 2016–17 on chilli crop. The results revealed that the mean number of thrips in the field was low (1.07 thrips/plant) at early crop growth stages (32 days after transplanting (DAT)) and increased gradually with a peak (21.53 thrips/plant) at 56 DAT. Inconsistency in the mean number of thrips with shifting variance was noticed. The variance of thrips population increased with increase in its density with the best variance (122.41) observed at 56 DAT. Samples of thrips showed variance to mean ratio (S2/X), Lloyd’s patchiness index (X*/X), as well as Morisita Index more than one, revealing clumped distribution. The data on thrips population was best fit to TPL (a = 0.184, b = 1.27, R2 = 0.66) and the IMC (α = 0.93, β = 1.14, R2 = 0.94). Larger variability in sample size vis-a-vis mean population density was also achieved at 10 and 20% precision levels. Considering TPL parameters, the decisive lines of sequential sampling for S. dorsalis was chosen at d = 13n ± 8.07√n. The sequential sampling plan will thus help in reducing the costs for an effective and efficient management of S. dorsalis on chilli.

Unveiling the Hidden Dimension of Pedestrian Crowds: Introducing Personal Space and Crowding into Simulations

Models for the automated analysis and simulation of the complex phenomena observable in built environment crowded by pedestrians have been studied for over thirty years. Nonetheless, one of the commonly agreed upon rules guiding regulation of distance among pedestrian, i.e. proxemics, was defined a nd discussed in static settings, whereas scenarios of interest generally deal with individual and collective movements in crowds. The present paper presents a systemic perspective on the research aimed at defining a dynamic form of proxemics. The paper firstly reports the results of an experiment focused on proxemics and pedestrians personal space, as the hidden dimension of human spatial behavior in crowded environments. We propose a representation of personal space through discrete potentials and an innovative crowding estimation method (i.e. Cumulative Mean Crowding), going beyond simple perceived density evaluation. The experimental setting is introduced and applied to appraise the potential impact of this novel pedestrian perception mechanism on innovative simulation models.

Crowding, group size and population structure of the Blackbuck Antilope cervicapra (Linnaeus, 1758) (Mammalia: Cetartiodactyla: Bovidae) in the semi-arid habitat of Haryana, India

To understand the population growth dynamics and life history parameters of the Blackbuck, 24 fortnightly visits were made in and around Lalpur Jheel, Dobhi Village of district Hisar (Haryana) from March 2017 to February 2018. Scan sampling method was used to record the Blackbuck population. In the present study, a total of 68 sightings of Blackbuck were made including a minimum of one sighting per visit to a maximum of seven sightings per visit with group size varying from one individual to a maximum of 58 individuals per sighting. The overall mean group size and crowding of the Blackbuck population were 13.84 ± 1.89 S.E. and 31.31 (N=941 individuals), respectively. The population structure of Blackbuck revealed six different age and sex classes, namely, adult male, adult female, sub-adult male, sub-adult female, yearling male, and fawn. As far as the social organization of the Blackbuck is concerned, six different types of social grouping were recorded, namely lone territorial male (adult male), unimale-unifemale (adult male and adult female), bachelor herd (adult male(s)/ sub-adult male(s)/ yearling male(s)), mixed herd (adult male(s)/ sub-adult male(s)/ yearling male(s)/ adult female(s)/ sub-adult female(s)/ fawn(s)), harem herd (1 adult male/ adult female(s)/ sub-adult female(s)/ fawn(s)), and female herd (adult female(s)/ sub-adult female(s)/ fawn(s)). It was concluded that Blackbuck shows partial social organization as both the solitary and herd were observed during the present study.