scholarly journals Spatial distribution, abundance and habitat use of the endemic Mediterranean fan mussel Pinna nobilis in Gera Gulf, Lesvos (Greece): comparison of design-based and model-based approaches

2018 ◽  
Vol 19 (3) ◽  
pp. 642 ◽  
Author(s):  
ALEXANDROS TSATIRIS ◽  
VASILEIOS PAPADOPOULOS ◽  
DESPINA MAKRI ◽  
KONSTANSTINOS TOPOUZELIS ◽  
EVA MANOUTSOGLOU ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Population Density ◽  
Habitat Use ◽  
Additive Models ◽  
Mussel Population ◽  
Population Densities ◽  
Model Based ◽  
Pinna Nobilis ◽  
Eastern Aegean ◽  
Muddy Sediments

An important population of the endemic Mediterranean fan mussel Pinna nobilis thrives in the marine protected area of Gera Gulf (Lesvos island, north-eastern Aegean Sea, Greece), and was assessed for the first time. To estimate the abundance, spatial distribution and habitat use of fan mussels in Gera Gulf, a distance sampling underwater survey was conducted. Detectability was modelled to secure unbiased estimates of population density. Two approaches were applied to analyze survey data, a design-based and a model-based approach using generalized additive models. The first approach was based on stratified random sampling on two strata, an assumed ‘preferable’ zone close to the coastline and an assumed unsuitable habitat, with predominantly muddy sediments, in which low sampling effort was applied. For the needs of the model-based approach, a dedicated cruise was conducted to collect bathymetric data with a single-beam echo-sounder and map the bathymetry of the study area. A very high-resolution image from the Worldview-3 satellite was processed, based on an object-based image analysis, for mapping all main habitat types in the study area. The estimated abundance using the design-based approach was low-biased as the stratum of pre-assumed unsuitable habitat proved to include patches of suitable habitats with high population densities that were missed by sampling. The model-based approach provided an abundance estimate of 213300 individuals (95% confidence interval between 97600-466000 individuals), which renders the fan mussel population of Gera Gulf the largest recorded population in Greece. Population density peaked between 1.5-8 m depth and became practically zero at depths >15 m. A bathymetric segregation of fan mussel size classes was noted, with the density of small individuals peaking in shallow waters, while that of large individuals peaked deeper. The highest population densities were observed in Posidonia oceanica meadows, followed by mixed bottoms (with reefs, rocks and sandy patches), while densities were very low on sandy and zero on muddy sediments. The current assessment provides a baseline for future monitoring of the fan mussel population in Gera Gulf. In view of the current (2017-2018) ongoing mass mortality of the species in the western Mediterranean, continuous monitoring of the main fan mussel populations, such as the one in Gera Gulf, is of utmost importance.   

Sorghum-pigeonpea intercropping and the effects of plant population density

1980 ◽  
Vol 95 (1) ◽  
pp. 51-58 ◽  
Author(s):  
M. Natarajan ◽  
R. W. Willey
Keyword(s):  
Spatial Distribution ◽  
Population Density ◽  
Primary Objective ◽  
Plant Population ◽  
Population Densities ◽  
Sole Crop ◽  
Plant Population Density ◽  
Distribution Of Roots

SummaryAn intercropping experiment is described in which three plant population densities of an early sorghum (82 days) were factorially combined with three plant population densities of a later-maturing pigeonpea (173 days) in a standard 2 sorghum:1 pigeonpea row arrangement. Sorghum growth was not affected by the presence of pigeonpea, and the farmers' primary objective of maintaining a ‘full’ sorghum yield was achieved if the density of the intercropped sorghum was equivalent to the sole crop optimum.The spatial distribution of roots after 30 and 60 days of growth did not appear to be altered by intercropping, and roots of the two crops were found to intermingle freely.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

Population Densities Allowed Around Dutch SEVESO Establishments

2000 ◽  
Author(s):  
G. M. H. Laheij ◽  
B. J. M. Ale ◽  
J. G. Post
Keyword(s):  
Population Density ◽  
The Netherlands ◽  
Individual Risk ◽  
Population Densities ◽  
Planning Policy ◽  
Relative Contribution ◽  
Societal Risk ◽  
Dangerous Substances ◽  
The Individual ◽  
Uniform Population

Abstract In the Netherlands, the individual risk and societal risk are used in efforts to reduce the number of people exposed to the effect of an accident at an establishment with dangerous substances. To facilitate the societal risk planning policy an investigation was carried out for the Dutch SEVESO establishments to investigate the possibility of determining a generic uniform population density for the zone between the individual risk contours of 10−5 and 10−6 per year. The indicative limit for the societal risk at this density was not to be exceeded. Also there was to be enough space left for a significantly higher population density outside the individual risk contour of 10−6 per year. The RORISC methodology and the actual data for the 124 Dutch SEVESO establishments were used to determine the generic uniform population density. Based on the data available it can be concluded that the maximum allowed uniform population density in the zone between the individual risk contours of 10−5 and 10−6 per year is lower than one person per hectare. At this density there is no space left for a higher population density outside the individual risk contour of 10−6 per year. For uniform population densities the relative contribution to the societal risk has been found significant up to the individual risk contour of 10−7 per year.

scholarly journals Occurrence of tuberculosis cases in Crato, Ceará, from 2002 to 2011: a spatial analisys of specific standards

2015 ◽  
Vol 18 (2) ◽  
pp. 313-325 ◽  
Author(s):  
Mayrla Lima Pinto ◽  
Talina Carla da Silva ◽  
Lidiane Cristina Félix Gomes ◽  
Maria Rita Bertolozzi ◽  
Lourdes Milagros Mendoza Villavicencio ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Pattern ◽  
Urban Area ◽  
Temporal Trend ◽  
Kernel Method ◽  
Quantitative Approach ◽  
Point Pattern ◽  
Hybrid Design ◽  
Population Densities ◽  
Population Groups

OBJECTIVE: to analyze the spatial distribution of tuberculosis in Crato, Ceará, Brazil, from 2002 to 2011, aiming to check for a point pattern. METHODS: This is an ecological, temporal trend and hybrid design study, with a quantitative approach. A total of 261 cases of tuberculosis were geo-referenced and 20 (7.1%) were considered as losses due to the lack of address. The profile of patients in 10 years of study was in accordance with the following pattern: men aged between 20 and 59 years, with low schooling, affected by the pulmonary form of tuberculosis and who were cured from the disease. RESULTS: The analysis of the spatial distribution of tuberculosis points out that in the period of study, new cases of the disease were not distributed on a regular basis, indicating a clustered spatial pattern, confirmed by the L-function. The map with the density of new cases estimated by the Kernel method showed that the "hot" areas are more concentrated in the vicinity of the central urban area. CONCLUSION: The study allowed pointing out areas of higher and lower concentration of tuberculosis, identifying the spatial pattern, but it also recognized that the disease has not reached all of the population groups with the same intensity. Those who were most vulnerable were the ones who lived in regions with higher population densities, precarious living conditions, and with intense flow of people.

scholarly journals A Quantitative Evaluation of the Multiple Narratives of the Recent Sahelian Regreening*

2016 ◽  
Vol 8 (1) ◽  
pp. 67-83 ◽  
Author(s):  
Mimi Stith ◽  
Alessandra Giannini ◽  
John del Corral ◽  
Susana Adamo ◽  
Alex de Sherbinin
Keyword(s):  
Spatial Distribution ◽  
Population Density ◽  
Environmental Change ◽  
Burkina Faso ◽  
Social Dimensions ◽  
Adaptation To Climate Change ◽  
Southern Central ◽  
Second Category ◽  
The Impact

Abstract A spatial analysis is presented that aims to synthesize the evidence for climate and social dimensions of the “regreening” of the Sahel. Using an independently constructed archival database of donor-funded interventions in Burkina Faso, Mali, Niger, and Senegal in response to the persistence of drought in the 1970s and 1980s, the spatial distribution of these interventions is examined in relation to population density and to trends in precipitation and in greenness. Three categories of environmental change are classified: 1) regions at the northern grassland/shrubland edge of the Sahel where NDVI varies interannually with precipitation, 2) densely populated cropland regions of the Sahel where significant trends in precipitation and NDVI decouple at interannual time scales, and 3) regions at the southern savanna edge of the Sahel where NDVI variation is independent of precipitation. Examination of the spatial distribution of environmental change, number of development projects, and population density brings to the fore the second category, covering the cropland areas where population density and regreening are higher than average. While few, regions in this category coincide with emerging hotspots of regreening in northern Burkina Faso and southern central Niger known from case study literature. In examining the impact of efforts to rejuvenate the Sahelian environment and livelihoods in the aftermath of the droughts of the 1970s and 1980s against the backdrop of a varying and uncertain climate, the transition from desertification to regreening discourses is framed in the context of adaptation to climate change.

scholarly journals Effects of population density on cauliflower crop (Brassica oleracea L. var. botrytis)

1981 ◽  
Vol 38 (1) ◽  
pp. 1-10
Author(s):  
Keigo Minami ◽  
Ricardo Victoria Fº
Keyword(s):  
Population Density ◽  
Brassica Oleracea ◽  
Plant Population ◽  
Population Densities ◽  
Plant Population Density ◽  
Brassica Oleracea L ◽  
Quality Weight

An experiment was carried out to study the effects of the following population densities cauliflowers (plants per ha): 20,833 (0.60 m x 0.80 m), 25,641 (0.60 m x 0.65 m), ....37.037 (0.60 m x 0.45 m) , 55.555 (.0.60 m x 0.30 m), and 111,111 (0,60 m x 0,15 m) ; variety Snow ball. It was concluded that the effects of plant population density are greater on curd quality (weight and size) than on production per ha. The best plant population density to produce cauliflowers curd for Brazil market is from 20,000 to 25,000 plants/ha while for mini-curd is above 55,000 plants/ha.

scholarly journals Geospatial characterizing of Under-Five Mortality in Alexandria, Egypt

2021 ◽  
Author(s):  
Mahmoud Adel Hassan ◽  
Ahmed Mohamed Ramadan ◽  
Mohamed Mostafa Tahoun ◽  
Abdelrahman Omran ◽  
Shimaa Gad El-karim Ali ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Spatial Distribution ◽  
Cardiovascular Diseases ◽  
Population Density ◽  
Spatial Pattern ◽  
Under Five ◽  
Size Population ◽  
Access To Water ◽  
Alexandria City ◽  
Low Incidence

This study aimed to identify geo-spatial pattern of under-five mortality (U5M) in Alexandria and its key determinants. We analyzed the geospatial distribution of 3064 deaths registered at 24 health offices reported from January 2018 to June 2019. The localities of Alexandria city were clustered into high and low incidence areas. Neonates represented 58.7% of U5M, while post-neonates and children were 31.1%, 10.2% respectively. Male deaths were significantly higher (P=0.036). The main leading causes of U5M were prematurity (28.32%), pneumonia (11.01%), cardiac arrest (10.57%), congenital malformation (9.95%), and childhood cardiovascular diseases (9.20%). Spatial distribution of U5M (including the most common three causes) tend to be clustered in western parts of Alexandria (El Hawaria, Bahig, Hamlis and Ketaa Maryiut). Another 9 clusters are at risk of being hotspots. Illiteracy, divorce, and poor locality characteristics (household size, population density, and access to water supply and sanitation), were statistically significant predictors of U5M.

Population dynamics and production of a brine shrimp, Parartemia zietziana Sayce (Crustacea : Anostraca), in two salt lakes in westren Victoria, Australia

1977 ◽  
Vol 28 (4) ◽  
pp. 417 ◽  
Author(s):  
R Marchant ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Temperature Stress ◽  
Brine Shrimp ◽  
Dry Weight ◽  
Salt Lakes ◽  
Confidence Limits ◽  
Length Frequency ◽  
Population Densities ◽  
The Mean

Quantitative samples of P. zietziana were taken monthly for two years from Pink Lake and Lake Cundare. Shrimps were usually contagiously distributed. To reduce error, samples were stratified resulting in confidence limits of 40-50% for the mean population density. Despite this variability, stable trends emerged, and variation was not so great as to mask significant differences. Length-frequency analyses distinguished cohorts; a regression was established between length and dry weight, enabling growth to be estimated from samples. By combining growth with population densities in Allen curves, production was computed. In Pink Lake and Lake Cundare mean pro- duction was 11.3 and 1.0 g dry weight m-2 year-1 respectively. Generally there were two or three generations per year, but time and extent of recruitment were not predictable. Each generation suffered continuous mortality, the death of young shrimps accounting for most of the production. This mortality remains unexplained; there are no significant predators and salinity and temperature stress would occur only during summer.

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