Search results for "environmental factor"
showing 7 items of 47 documents
Population dynamics of oxiclinal species in lake Arcas-2 (Spain)
1995
‘Oxiclinal’ rotifer species show high concentrations just above the oxic-anoxic interface in the hypolimnion of some lakes. The stratification of their populations is best shown by sampling at close depth intervals and quantifying their densities by the Utermohl technique. With this technique we were able to count males which otherwise pass through filters and more accurately count egg production. We evaluated female, male and egg numbers of the two main oxiclinal species of lake Arcas-2: Filinia hofmanni and Anuraeopsis fissa, during two annual cycles (1990–91). F. hofmanni was an exclusive oxiclinal species. It had an exponential growth phase at the onset of stratification giving a distin…
Effects of salinity, temperature and food level on the demographic characteristics of the seawater rotifer Synchaeta littoralis Rousselet.
2001
A strain of the seawater species Synchaeta littoralis, isolated from a Spanish Mediterranean coastal salt marsh, was cultured in the laboratory and fed with the alga Tetraselmis sp. The effect of three salinities (25 per thousand, 30 per thousand and 35 per thousand), two temperatures (20 degrees C and 25 degrees C) and two food levels (75,000 and 150,000 cells ml(-1)) on demographic parameters was studied using a life table approach. Average lifespan (LS) ranged between 4.0 and 7.3 days, net reproductive rate (R(0)) between 4.2 and 9.1 offspring per female, and intrinsic growth rate (r) between 0.50 and 0.95 day(-1). Salinity and temperature had a significant negative effect (***p<0.001) o…
Temperature effects explain continental scale distribution of cyanobacterial toxins
2018
Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect…
Aspects of excessive antibiotic consumption and environmental influences correlated with the occurrence of resistance to antimicrobial agents
2021
International audience; This article explores the correlation between specific aspects of antibiotic usage, their resistance development, and environmental factors. The indiscriminate use of antibiotics led to environment contamination, selection and spreading of antibiotic-resistant organisms, and alteration of the microbial ecosystems balance. Sociobehavioural environmental factors and changes in the natural environment are major contributors to resistance development. Resistant bacteria strains' isolation in food, water, soil etc. demonstrates the environmental influence on the strains through antibiotics accumulation in the environment. It is difficult to assess the impact of antibiotic…
Influence of abiotic environmental factors on Pelargonium graveolens growth
2018
Ekstrakty pozyskiwane z roślin były używane, zwłaszcza w medycynie naturalnej, już od czasów antycznych. Przeprowadzono wiele badań, które dowodzą różnokierunkowych właściwości olejków eterycznych. Ten pozyskiwany z Pelargonium graveolens jest jedną z najbardziej cenionych substancji dla różnych gałęzi przemysłu, takich jak: kosmetyczna, mydlarska, perfumeryjna, aromaterapeutyczna, spożywcza czy medyczna. P. graveolens należy do rodziny Geraniaceae i zawiera około 280 gatunków różniących się morfologią i wyglądem zewnętrznym. Bylina ta jest krzewem sięgającym 1,3 m wysokości i ok. 1 m szerokości. Jest rodzima dla regionu Cape w południowej Afryce, natomiast została rozpowszechniona na więks…
The Influence of Contextual Aspects in Talent Development: Interaction Between Relative Age and Birthplace Effects in NBA-Drafted Players
2021
The aims of this study were two-fold: (1) to inspect separately for the relative age and birthplace effects for players selected in the National Basketball Association (NBA) draft; (2) to explore the interaction among these factors and analyse this interaction in players' career performance. The database was obtained from the official records of the players (n = 1,738), who were selected during the annual editions of the NBA Draft from 1990 to 2019. The participants' date of birth was analyzed according to the month of birth and divided into four quartiles. The place of birth was compared to the distribution of the general population' places of birth based on different communities' sizes. C…
Design of a Cleaning Program for a PV Plant Based on Analysis of Energy Losses
2015
Solar photovoltaic (PV) energy has grown significantly over the past few years. However, despite the increase in installed capacity, this energy source still raises important concerns related to the variability of power production. The short-term effects such as cloud shadowing and supply interruptions, as well as long-term effects such as dust accumulation, seasonal variation, and ageing of PV modules, can cause variability of power production. Therefore, the analysis of all the variability sources in order to provide statistically consistent power production data is an important challenge. This study presents a methodology to analyze data from a PV plant in order to have an independent ev…