Relative Influence Of Temperature Research Articles

Analysis of spatiotemporal distribution of air quality index (AQI) in the state of West Bengal, India from 2016 to 2021

The ambient air quality is progressively declining, especially in emerging countries, due to increased urbanization, high demands of energy, and industrialization. High risks to human health and environmental degradation are associated with air pollution. The analysis of the Air Quality Index (AQI) serves as a valuable tool for simplifying the communication of air quality in a specific region, making it easily comprehensible to the general public. The United States Environmental Protection Agency (USEPA) and Indian air quality regulations recommend mathematical functions to compute sub-indices for calculating the AQI. The main objectives of this study were to evaluate the AQI status from a different point of view (monthly, seasonal, and annual variations and association of AQI with meteorological factors) and estimate the future AQI. The monthly AQI values in West Bengal vary from “Satisfactory to Moderate” level from 2016 to 2021. In district-wise, the highest AQI was observed in Kolkata (189), Bardhaman (178), and Murshidabad (167) in the year 2016; Kolkata (180), Bardhaman (155), and Howrah (155) in 2017; Howrah (180), Kolkata (179) and Hoogly (166) in 2018; Howrah (170), Kolkata (156) and Bardhaman (156) in 2019; Howrah (150), South 24 Parganas (137), and Kolkata (136) in 2020 and Howrah (161), Kolkata (139), and South 24 Parganas (139) in 2021 respectively in Winter season. The association between meteorological parameters, such as temperature (r = − 0.605, p < 0.001), relative humidity (r = − 0.647, p < 0.001), and precipitation (r = − 0.821, p < 0.001) and AQI shows a significant strong negative correlation (p < 0.05). In addition, the relative influence of temperature, precipitation, and relative humidity was 53.13%, 36.69%, and 10.18%, respectively, on AQI variation. Temperature plays a significant role in association with AQI distribution in the atmosphere than RH and precipitation. The distribution of AQI in the whole state of West Bengal showed a higher AQI observed in the Southern part compared to the northern part of the state. The study's conclusions and recommendations can help stakeholders and policymakers’ to control and improve the deterioration of air quality caused by concerns about AQI and human health.

The relative influence of temperature and ontogeny on groundfish distribution varies across life stages

AbstractDistributional changes for fish populations may be difficult to interpret since temperature responses are often confounded with ontogenetic shifts. However, the relative importance of these two types of fish movement (temperature responses and ontogenetic shifts) to population distribution remains largely unstudied. This study presents the first attempt to compare the two types of movement in depth, latitude and longitude for 10 abundant groundfish species across size class and subregion. We utilized large, quality‐controlled datasets from random depth‐stratified, bottom trawl surveys consistently conducted during the summer along NE Pacific shelf from 1996 to 2015. We show that the size structure of each species varied across years and subregions with dramatically strong or poor recruitments for some species in 2015 during a marine heatwave. Principal component analysis (PCA) demonstrated that ontogenetic shifts in depth represented the primary movement pattern while temperature responses in latitude and longitude constituted a major, but a secondary pattern. Re‐run by size class, PCA results further showed that the influence of temperature and ontogeny on population distribution varied by size classes with greater ontogenetic shifts in smaller fish and elevated temperature responses in larger fish. We further show substantial ontogeny‐induced movements by depth, latitude and longitude with high variability among species and subregions. Our analyses suggest that failing to account for size structure can lead to serious misinterpretation of population distributional changes in all three dimensions: depth, latitude and longitude for populations with or without episodic recruitments.

Central European Agroclimate over the Past 2000 Years

Abstract Central Europe has experienced a sequence of unprecedented summer droughts since 2015, which had considerable effects on the functioning and productivity of natural and agricultural systems. Placing these recent extremes in a long-term context of natural climate variability is, however, constrained by the limited length of observational records. Here, we use tree-ring stable oxygen and carbon isotopes to develop annually resolved reconstructions of growing season temperature and summer moisture variability for central Europe during the past 2000 years. Both records are independently interpolated across the southern Czech Republic and northeastern Austria to produce explicit estimates of the optimum agroclimatic zones, based on modern references of climatic forcing. Historical documentation of agricultural productivity and climate variability since 1090 CE provides strong quantitative verification of our new reconstructions. Our isotope records not only contain clear expressions of the medieval (920–1000 CE) and Renaissance (early sixteenth century) droughts, but also the relative influence of temperature and moisture on hydroclimatic conditions during the first millennium (including previously reported pluvials during the early third, fifth, and seventh centuries of the Common Era). We conclude that Czech agricultural production has experienced significant extremes over the past 2000 years, which includes periods for which there are no modern analogs. Significance Statement As temperatures increase, droughts are becoming a growing concern for European agriculture. Our study allows recent extremes to be contextualized and helps to better the understanding of potential drivers. Stable carbon and oxygen isotopes in oak tree rings were analyzed to reconstruct year-to-year and longer-term changes in both temperature and moisture over central Europe and the past 2000 years. We combine these proxy-based climate reconstructions to model how well crops were growing in the past. The early fifth and the early sixteenth centuries of the Common Era were most likely characterized by extreme conditions beyond what has been experienced in recent decades. Our reconstructions of natural variability might be used as a baseline in projections of future conditions.

Predicting Parasite Dynamics in Mixed-Use Trans-Himalayan Pastures to Underpin Management of Cross-Transmission Between Livestock and Bharal.

The complexities of multi-use landscapes require sophisticated approaches to addressing disease transmission risks. We explored gastro-intestinal nematode (GINs) infections in the North India Trans-Himalayas through a socio-ecological lens, integrating parasite transmission modelling with field surveys and local knowledge, and evaluated the likely effectiveness of potential interventions. Bharal (blue sheep; Pseudois nayaur), a native wild herbivore, and livestock share pasture year-round and livestock commonly show signs of GINs infection. While both wild and domestic ungulates had GINs infections, egg counts indicated significantly higher parasite burdens in bharal than livestock. However, due to higher livestock densities, they contributed more to the total count of eggs and infective larvae on pasture. Herders also reported health issues in their sheep and goats consistent with parasite infections. Model simulations suggested that pasture infectivity in this system is governed by historical pasture use and gradually accumulated larval development during the summer, with no distinct short-term flashpoints for transmission. The most effective intervention was consequently predicted to be early-season parasite suppression in livestock using temperature in spring as a cue. A 1-month pause in egg output from livestock could lead to a reduction in total annual availability of infective larvae on pasture of 76%, potentially benefitting the health of both livestock and bharal. Modelling suggested that climate change over the past 33 years has led to no overall change in GINs transmission potential, but an increase in the relative influence of temperature over precipitation in driving pasture infectivity. Our study provides a transferable multi-pronged approach to investigating disease transmission, in order to support herders' livelihoods and conserve wild ungulates.

Climatic Drivers of Plant Species Distributions Across Spatial Grains in Southern Africa Tropical Forests

Understanding the importance of climate in determining species distribution and how it might change as a function of spatial grain size is a vital issue for species distribution modelling (SDM), yet it is often not accounted for in models and has not been extensively addressed in under sampled areas in tropical forests. Using extensive field sampled vegetation plots data on species occurrences and current climate conditions we modelled 150 plant species in the Okavango River Basin, to map their current projected suitable climate space at 2km2, 5km2, 10km2, 20km2 and 50km2 pixel resolution. Relationships between the variable importance scores and variable identity and their interaction with predictor spatial grain were investigated using Generalised Linear Models and post-hoc analysis. We found variation in the relative influence of temperature and precipitation variables across the spatial grains. The importance of the determinants of species distribution may change between species but such changes are less determined by the predictor’s spatial grain. Potential evapotranspiration consistently exhibited the greatest influence in determining species and richness distribution across spatial grains. We found that the spatial grain of predictors had no effect on the model predictive power and that varying predictor spatial grains had only negligible effects on the model performance measured by AUC and Kappa statistics. The spatial grains of climatic predictors used showed no effect on species richness pattern either. Our results indicate that in areas with relatively low topographic variation, modelling at coarse spatial grain for conservation purposes can be acceptable. Moreover, we show that in tropical areas that have comparatively homogeneous climatic conditions along large spatial extents the variable importance is not influenced by predictor spatial grain. For projections of contemporary species suitable climate space in relatively flat and topographically homogeneous areas which often have a climatically homogenous landscape, more attention must be given to the identity of the selected predictor variables for modelling species distributions than to their spatial grain size. We suggest that in species distribution modelling for conservation planning, assessment of the input datasets spatial grain should be informed and guided by knowledge of the landscape level topographic conditions, as protocol.

The relative influence of temperature and size‐structure on fish distribution shifts: A case‐study on Walleye pollock in the Bering Sea

AbstractResearch has estimated associations between water temperature and the spatial distribution of marine fishes based upon correlations between temperature and the centroid of fish distribution (centre of gravity, COG). Analysts have then projected future water temperatures to forecast shifts in COG, but often neglected to demonstrate that temperature explains a substantial portion of historical distribution shifts. We argue that estimating the proportion of observed distributional shifts that can be attributed to temperature vs. other factors is a critical first step in forecasting future changes. We illustrate this approach using Gadus chalcogrammus (Walleye pollock) in the Eastern Bering Sea, and use a vector‐autoregressive spatiotemporal model to attribute variation in COG from 1982 to 2015 to three factors: local or regional changes in surface and bottom temperature (“temperature effects”), fluctuations in size‐structure that cause COG to be skewed towards juvenile or adult habitats (“size‐structured effects”) or otherwise unexplained spatiotemporal variation in distribution (“unexplained effects”). We find that the majority of variation in COG (including the north‐west trend since 1982) is largely unexplained by temperature or size‐structured effects. Temperature alone generates a small portion of primarily north–south variation in COG, while size‐structured effects generate a small portion of east–west variation. We therefore conclude that projections of future distribution based on temperature alone are likely to miss a substantial portion of both the interannual variation and interdecadal trends in COG for this species. More generally, we suggest that decomposing variation in COG into multiple causal factors is a vital first step for projecting likely impacts of temperature change.

Factors Controlling Soil Organic Carbon Stocks with Depth in Eastern Australia

Understanding the potential of soil to store soil organic carbon (SOC) is important for potential climate change mitigation strategies and assessing soil health issues. We examined the factors controlling SOC storage in eastern Australian soils and how these vary with depth. Models were developed using a set of readily interpreted covariates to represent key soil forming factors together with multiple linear regression (MLR) and Cubist piecewise decision tree techniques. Independent validation demonstrated concordance correlation coefficients up to 0.68 for SOC density in near surface layers but progressively decreasing with depth. The results demonstrate the key role of climate (rainfall and maximum temperatures) in controlling SOC stocks, with parent material (lithology) and vegetation cover also being key drivers, while topography and aspect are of lesser influence, at least at this sub-continental scale. The relative influence of temperature and land use/vegetation cover decreases with depth, while that of parent material increases. The necessity of considering a combination of factors when deriving meaningful estimates of current or projected SOC storage is demonstrated with quantitative estimates of SOC stocks in 45 different climate-parent material-vegetation cover regimes. Average SOC stocks in the 0- to 30-cm depth interval range from 16.3 Mg ha-1 in dry, highly siliceous parent material environments with low vegetation cover, up to over 145.0 Mg ha-1 in wet, mafic parent material environments with high vegetation cover. Results suggest that the proportion of SOC stock in the 30- to 100-cm interval as a proportion of the top 100 cm varies from a low of 41% in wet climates up to a high of 59% in dry climates. Climate appears to be the dominant controller of subsoil SOC storage proportion, with parent material and vegetation cover also having restricted influence.

Calcareous nannoplankton ecology and community change across the Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM; ca. 55.8 Ma) is thought to coincide with a profound but entirely transient change among nannoplankton communities throughout the ocean. Here we explore the ecology of nannoplankton during the PETM by using multivariate analyses of a global data set that is based upon the distribution of taxa in time and space. We use these results, coupled with stable isotope data and geochemical modeling, to reinterpret the ecology of key genera. The results of the multivariate analyses suggest that the community was perturbed significantly in coastal and high-latitudes sites compared to the open ocean, and the relative influence of temperature and nutrient availability on the assemblage varies regionally. The open ocean became more stratified and less productive during the PETM and the oligotrophic assemblage responded primarily to changes in nutrient availability. Alternatively, assemblages at the equator and in the Southern Ocean responded to temperature more than to nutrient reduction. In addition, the assemblage change at the PETM was not merely transient—there is evidence of adaptation and a long-term change in the nannoplankton community that persists after the PETM and results in the disappearance of a high-latitude assemblage. The long-term effect on communities caused by transient warming during the PETM has implications for modern-day climate change, suggesting similar permanent changes to nannoplankton community structure as the oceans warm.

The relative influence of temperature, moisture and their interaction on range limits of mammals over the past century

AbstractAimsI determine the relative importance of temperature and moisture acting alone and in tandem for range contractions and expansions of mammalian species over c. 70 years.LocationThe contiguous United States west of the eastern border of the Rocky Mountains (103.77° W).MethodsMuseum records of 67 mammalian species from two time periods (1900–39 and 1970–2009), mean annual temperature and mean annual precipitation are used to model historic and modern distributions. For each era the region outside each species’ range in the opposing era is assigned to zones of range limitation: temperature alone is prohibitive, moisture alone is prohibitive, both preclude the species, or both have values that alone are within the species’ tolerance range but in combination are outside its climatic niche (‘interaction’ limitation). The relative importance of each type of limitation is estimated by their intersection with regions of range contraction and expansion.ResultsAveraged across species, 82 ± 3% (± SE) of the areas of contraction are now occupied by interaction limitation, and 74 ± 5% of areas expanded into were historically occupied by similar zones. In comparison, areas of range shift in which just temperature or moisture acting alone would have excluded the species comprise between only 9 and 17%, and areas in which both factors are limiting are negligible. Expansions into and contractions from regions of interaction limitation occurred more often than expected by chance given the distribution of this type of limitation in the wider study region.Main conclusionsParticular combinations of temperature and moisture can interact directly or indirectly to limit species ranges even when these factors alone do not exceed species tolerances. Change in the correlation between of range‐limiting factors can have as much effect on species ranges as absolute change in those factors by themselves.

Recruitment success in a roach Rutilus rutilus population of a hydrologically stable chalk river: relative influences of temperature and flow

Ecology of Freshwater FishVolume 21, Issue 2 p. 168-171 Letter Recruitment success in a roach Rutilus rutilus population of a hydrologically stable chalk river: relative influences of temperature and flow Helen Beardsley, Helen Beardsley Environment Agency Eastern Area, Anglian Region, Norwich, UK Centre for Conservation Ecology and Environmental Change, School of Applied Sciences, Bournemouth University, Poole, Dorset, UKSearch for more papers by this authorJ. Robert Britton, J. Robert Britton Centre for Conservation Ecology and Environmental Change, School of Applied Sciences, Bournemouth University, Poole, Dorset, UKSearch for more papers by this author Helen Beardsley, Helen Beardsley Environment Agency Eastern Area, Anglian Region, Norwich, UK Centre for Conservation Ecology and Environmental Change, School of Applied Sciences, Bournemouth University, Poole, Dorset, UKSearch for more papers by this authorJ. Robert Britton, J. Robert Britton Centre for Conservation Ecology and Environmental Change, School of Applied Sciences, Bournemouth University, Poole, Dorset, UKSearch for more papers by this author First published: 17 January 2012 https://doi.org/10.1111/j.1600-0633.2011.00549.xCitations: 6 Dr.J. R. Britton, Centre for Conservation Ecology, School of Conservation Sciences, Bournemouth University, Poole, Dorset BH12 5BB, UK. E-mail: [email protected] Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume21, Issue2April 2012Pages 168-171 RelatedInformation

Seasonal change in body length of important small copepods and relationship with environmental factors in Jiaozhou Bay, China

Differences among species in prosome length and in species’ response to environmental factors do exist. Therefore, it is useful to examine prosome length for different copepod species in variable environments. Seasonal variations in prosome length of four small copepods and their copepodite stages in the Jiaozhou Bay were compared and the relative influence of temperature, salinity, and chlorophyll concentration were examined. Two peaks were found in the mean prosome length of Paracalanus parvus (in early winter and May). For Acartia bifilosa, the maximum values of all copepodites occurred mainly from February to April, and decreased to the bottom in July. Prosome length of Acartia pacifica peaked when it first appeared in June, then reached to the minimum in July. Parvocalanus crassirostris only appeared from late summer to autumn and the mean prosome length showed no clear changes. Correlations of adult prosome length with environmental factors were evaluated. For the four species, temperature was negatively correlated to prosome length except for P. crassirostris. But the different species varied markedly in their responds to temperature. A. bifilosa showed a more definite trend of size variation with temperature than P. parvus and A. pacifica. Correlations of prosome length with salinity were significantly positive for almost all the small copepods. The relationship between chlorophyll concentration and prosome length was complicated for these copepods, but for P. parvus, chlorophyll concentration was also an important affecting factor. Furthermore, investigation needs to be done on food quality for some copepod. These results are essential to estimate the biomass and the production, and to understand these small copepods’ population dynamics in this human-affected bay.

Effects of temperature and elemental concentration on the chemical composition of juvenile yellow perch (Perca flavescens) otoliths

Otolith microchemistry studies assume that a relationship exists between the concentration of trace elements in the environment and otolith chemical composition. Although this assumption has been tested using marine and estuarine fish in controlled laboratory experiments, the relationships among temperature, ambient elemental concentration, and otolith chemical composition for freshwater species is not well documented. Here, juvenile yellow perch ( Perca flavescens ) were reared under different concentrations of four elements (Ba, Mg, Mn, and Sr) crossed with three temperatures (10 °C, 15 °C, and 20 °C) to determine the interactive influence of ambient elemental concentrations and temperature on otolith chemical composition. Sr:Ca and Ba:Ca were significantly related to ambient elemental concentrations, but Mg:Ca and Mn:Ca were not. Although the relative influence of temperature was less than that of ambient elemental concentrations, Sr:Ca, Ba:Ca, and Mn:Ca were all influenced by either water temperature or the interaction between temperature and elemental concentration, but the direction of the temperature effect differed for each element. Patterns in our partition coefficients are consistent with the idea that uptake of strontium facilitates uptake of barium. Overall, yellow perch otolith element composition was influenced primarily by ambient Sr and Ba concentrations, but temperature could potentially confound the results of otolith microchemistry studies.

Survival of phytopathogenic bacteria during waste composting

The survival of phytopathogenic bacteria, Erwinia carotovora subsp. carotovora, Xanthomonas campestris pv. vesicatoria, and Pseudomonas syringae pv. syringae was investigated during a horticultural waste composting process to determine to what extent they were eliminated during the process. The relative influence of temperature, antagonistic compost microorganisms, and phenolic compounds was assessed and compared. Results showed that all phytopathogenic bacteria disappeared in less than 60 h of composting, these bacteria showing low resistance to high temperatures (50, 60 and 70 °C). The highest survival was 1 h at 60 °C for P. s. syringae and 15 min at 70 °C for E. c. carotovora. None survived >15 h at 50 °C. Some culture filtrates of other compost microorganisms and some phenolic compounds also had an inhibitory effect which differed according to the phytopathogenic bacterial species. Composting is therefore considered a useful method for recycling horticulture wastes and eliminating phytopathogenic bacteria.

Spatial dynamics of habitat suitability for the growth of newly settled winter flounder Pseudopleuronectes americanus in an estuarine nursery

The relationship between the growth of early juvenile winter flounder (Psuedopleu- ronectes americanus, Walbaum; 17 to 27 mm standard length (SL)) and the spatial dynamics of estu- arine gradients immediately following larval settlement was examined using field enclosure tech- niques in a temperate nursery. Enclosures (n = 60; 3 fish per enclosure) were deployed throughout the Navesink River/Sandy Hook Bay estuarine system, New Jersey, in a nested spatial design that allowed measurement of growth variation in time at 3 spatial scales (between regions: × distance (D) = 12.3 km, SD = 3.6, n = 2; between sectors: × D = 4.3 km, SD = 1.3, n = 6; between stations: × D = 1.8 km, SD = 0.8, n = 12). Three 12 d enclosure experiments were performed over 40 consecutive days from mid-May through June 1999. Flounder growth (range = 0 to 0.9 mm SL d -1 enclosure -1 ) was dynamic at a regional spatial scale. Generalized additive modeling indicated that growth was most rapid at relatively cool temperatures (<21°C) and low salinities (<24‰). However, spatial analysis of partial growth indicated that the relative influences of temperature and salinity changed over time. Salinity effects were strongest during the earliest experiment (May 20 to June 1) when temperatures were cool (<20°C) throughout the estuary. During this period, salinities were conducive for rapid growth throughout the river. From June 4 to 16, salinities remained optimal in the river, but as the system warmed, temperatures conducive for rapid growth contracted into the bay and temperature effects became stronger than salinity effects. Growth was more rapid in the bay, but not as high as that measured during the first experiment in the river where optimal salinities and temperatures overlapped within the estuary. With continued warming and curtailed freshwater runoff, tempera- tures were sub-optimal throughout the estuary, salinities were conducive for rapid growth only in the upper river, and from June 18 to 30 growth rates were relatively low. Our analysis suggests that habitat suitability for the growth of juvenile fish can be spatially dynamic because multiple regula- tory factors vary simultaneously in space and time. Rapid growth occurs at sites and times when optimal conditions for regulatory factors intersect in space, but the spatial coincidence of optimal conditions can be ephemeral.

The relative influence of temperature and food on the metabolism of a marine invertebrate.

Many benthic marine invertebrates exhibit a seasonal cycle in activities such as feeding, growth and reproduction. In temperate regions, this seasonality is typically correlated with coincident cycles in photoperiod, temperature and food availability and it can be difficult to determine which of these environmental factors is the key driver. Polar regions are characterised by greatly reduced seasonal variation in temperature, and an enhanced seasonality of food availability; they therefore form a natural laboratory for distinguishing the ecological effects of food from those of temperature. Here, we report a study of the common shallow water urchin Sterechinus neumayeri from Rothera Point, Antarctica. This species exhibits a marked seasonal variation in metabolic rate and feeding activity (which ceases completely in winter). In this study the metabolic rate of urchins collected in late winter and held in the laboratory without food was compared with that of wild urchins undertaking the transition to summer feeding and growth. Starved urchins showed a small rise in metabolic rate in summer which could be explained entirely by the small increase in temperature (Q(10)=2.5). At the same time, the wild population showed a much larger increase in metabolic rate related largely to the costs of feeding and growth. Rates of nitrogen excretion were also much larger in wild urchins, and the O:N atomic ratio indicated that starved urchins were depending to a greater extent on lipid and carbohydrate. Gut mass and test organic content showed no change in starved urchins, indicating that metabolic substrate was being provided by the gonad. The data suggest that in wild S. neumayeri only 15-20% of the summer increase in metabolism is caused directly by the temperature rise whereas 80-85% is caused by increased physiological activity associated with feeding, growth and spawning.

Maintenance of ladybeetle diversity across a heterogeneous African agricultural/savanna land mosaic

The importance of agricultural land for maintaining indigenous biodiversity is an important contemporary issue. A large agricultural estate in Swaziland, which is a mosaic of citrus orchards, exotic tree windbreaks, indigenous riparian vegetation and savanna was investigated. The distribution of larval and adult coccinellids within the habitat types, and the relative influences of temperature, relative humidity, ground insolation and prey presence was assessed over a 2-year period. The highest coccinellid densities and species richness occurred within the orchards. Riparian habitats on the boundaries of the estate were closer to the orchard habitat in species composition than was the natural savanna. Not surprisingly, the presence/absence of prey was the most important variable which determined coccinellid distribution and density in the agricultural landscape. Relative humidity, temperature and ground insolation had no significant effect on coccinellid densities. Some species, such as the exotic Cheilomenes lunata, and the indigenous Scynmus sp. and Nephus sp. were widely dispersed and occurred in all habitats, while the economically important but exotic species, Rodolia cardinalis was only within the citrus orchards. Overall, the coccinellid assemblage was not a good indicator of habitat type. Nevertheless, a variety of habitat types (i.e. a heterogenous landscape) appear to be essential for the survival of most coccinellids. Indeed, the heterogeneous agricultural and natural land mosaic provides maximum plant diversity and hence coccinellid diversity, thus increasing the potential for natural control of pest prey species in the orchards, while at the same time maximizing survival of indigenous coccinellids.

Seasonal variations in copepod body length: a comparison between different species in the Lagoon of Venice

The seasonal variation in length of the most abundant copepod species in the lagoon of Venice were compared and the relative influence of temperature, chlorophyll concentration and salinity examined. Temperature seems to be the primary factor influencing copepod body length in the lagoon of Venice, but the different species vary markedly in their response. Calanoid copepods (Acartia clausi, A. tonsa, Paracalanus parvus and Centropages ponticus) showed a more definite trend of size variation with temperature than the cyclopoids (Oithona nana and O. similis) and the harpacticoid Euterpina acutifrons. The size of the poecilostomatoids Oncaea media and O. subtilis was not affected by temperature, and was almost constant over time. Differences in the metabolic rates, longevity and specialization of calanoid, cyclopoid and harpacticoid copepods could explain their different responses to temperature.

On the relationship between food, reproduction and survival of two carabid beetles: Calathus melanocephalus and Pterostichus versicolor

Abstract. The relative influences of temperature and availability of food on reproduction, survival and growth of all developmental stages of two carabid beetle species are discussed with special reference to the suggested relationship between availability of food, size of egg production and survival of adults from one breeding season to the next. Temperature as well as food supply influence the length of larval growth and adult body size. Beetles grown at low temperatures and low amounts of food are smaller than those grown at higher temperature and with more food. The number of eggs laid per female was correlated with the amount of food gathered. There was no inverse relationship (trade‐off) between reproductive output and survival in the field until the next breeding season. In 1980 no significant relationship was found between winter mortality and the amounts of food gathered by beetles in the period after reproduction and before winter diapause. However, in 1981 in C. melanocephalus a lower number of starved beetles survived the winter than the fed ones and‘field’beetles. Only in the first part of the feeding activity period in autumn can enough food be gathered by C.melunocephalus for successful hibernation. In the second part of this period there is not enough food to build up the fat reserves needed to survive the winter. Difference in population fluctuations of both species are discussed in relation to their life histories.

Influence of sulfur dioxide on soot formation in diffusion flames

An overventilated coflowing axisymmetric laminar ethylene diffusion flame was used to study the influence of sulfur dioxide addition to both the fuel and oxidizer on soot formation. The experiments were designed such that the relative influences of temperature, fuel concentration, and direct chemical interaction can be isolated when sulfur dioxide is added to the fuel side in varying quantities. A quantitative assessment of these three effects was made using an Arrhenius type expression that makes allowance for changes in flame profiles and flame residence times. It was shown that the reduced soot resulting from adding sulfur dioxide to the fuel side is due to a reduction in flame temperature and a reduction in the fuel concentration. No indication of a chemical effect was observed up to 35%–40% sulfur dioxide in ethylene. However, when sulfur dioxide mole fraction exceeds 40%, the effect of the direct chemical interaction becomes important in addition to thermal and dilution effects. The influence of sulfur dioxide on the air side was found to be a purely thermal effect when allowance was made for the altered oxidant concentration.

TEMPERATURE DETERMINATION OF MALE OUTCROSSING ABILITY IN A SIMULTANEOUS HERMAPHRODITE.

Phally, a genital dimorphism found in some species of self-compatible simultaneous hermaphrodites, presents an opportunity to examine factors maintaining outcrossing within an animal species in the presence of recombination. Both aphallics and euphallics can self-fertilize but only euphallics develop a functional penis and prostate allowing them to donate sperm. Previous studies of phally in the gastropod Bulinus truncatus (Mollusca: Pulmonata) suggest that phally may be under direct genetic control in some populations and strongly influenced by environmental factors in others. Experiments reported here identify temperature as a cue affecting phally determination in two populations of B. truncatus. In both populations, a higher proportion of euphallics was produced at low temperature (22 ± 1°C) than at high temperature (30 ± 1°C). Temperatures experienced by parents did not affect the proportion of euphallics they produced. Instead, phally was sensitive to temperature during the egg stage postoviposition and during the hatchling stage; the relative influence of temperature before and after hatching varied between populations. The total number of hatchlings reaching maturity at high and low temperature did not differ, but at low temperature, snails took longer to hatch and mature, and had lower survivorship. Just as studies of environmental sex determination have shed light on selective pressures influencing sex ratio evolution, we suggest that temperature-sensitive phally determination may shed light on the selective pressures maintaining outcrossing in B. truncatus.