甘肃西峰晚第三纪红粘土地层中的蜗牛化石记录及其古环境意义

In this study, 260 mollusk fossil samples from a Red Clay sequence at Xifeng, Gansu province, in the northern China were analyzed quantitatively. 12 fossil species and four fossil zones have been identified. Three main ecological groups were determined based on ecological requirement of each mollusk taxon. According to fossil composition and succession of three ecological groups, the author discussed the origin and sedimentary environment of the red clay deposits, and the process of ecological environmental changes as well as the variations of the East Asia monsoons during 6.2-2.4 Ma in the Loess Plateau. A preliminary study on periodicity of paleoclimatic changes was also conducted by using spectral analysis method. The main results and conclusions are presented as follows:A continuous land mollusk fossil sequence of 6.2-2.4 Ma from Xifeng Red Clay Formation has been established, which provided a basic data for studying the environmental changes during late Miocene to Pliocene.The study of composition and preservation condition of mollusk fossils reveals a terrestrial in situ ecological population in the Red Clay Formation. All of identifiable mollusk species are composed of terrestrial taxa, which support the view that the Red Clay is an eolian origin, similar to the overlying Quaternary loess deposits.The mollusk record reveals the processes of ecological and environmental changes during 6.2-2.4 Ma in the Loess Plateau. Climatic changes experienced cold and dry from 6.2-5.4 Ma, warm and wet during 5.4-4.5 Ma, mild and moderate from 4.5-3-4 Ma, to rapid cooling and drying after 3.4 Ma. From '5.4- 2.4 Ma, climate was stepwise cooling. The cooling trend is in good agreement with a general1 0global cooling trend during this period, as documented by marine 5 0 records.4. Three remarked ecological shifts took place in mollusk assemblages from 6.2-2.4 Ma, focused on about 5.4, 4.5 and 3.4 Ma. The warming shift around 5.4 Ma was probably related to the rising of the global temperature. The cooling shifts around 4,5 and 3.4 Ma however might be closely linked to the uplift of Tibet Plateau and the development of Northern Hemisphere ice sheet.The succession in mollusk ecological groups also recorded the variability of the East Asian winter and summer monsoon. The winter monsoon dominated two periods from 6.2-5.4 Ma and from 3.4-2.4 Ma, while the summer monsoon was strong during 5.4-4.5 Ma. The variations in winter and summer monsoons were in phase during 4.5-3.4 Ma. Monsoon regimes changed with the duration about 1 Ma, which roughly corresponds to the cycle driven by tectonic activity on the time scales of ICP-IO7 years. In addition, mollusk fossils recorded the large amplitude and high frequency fluctuations overlapped on 105-107 years climate cycle.The maximum entropy spectral analysis and filter-band analysis of total mollusk individuals and three typical ecological groups suggest that the climate changes controlled mainly by solar insolation had periods about 70 ka and 40 ka on the time scales of 105 during late Miocene-Pliocene. Climatic periodicity intensified from 4.0 Ma, which reflected strengthened forcing by high latitude ice volume.

Long-Term Oceanographic and Ecological Research in the Western English Channel

Long-term research in the western English Channel, undertaken by the marine laboratories in Plymouth, is described and details of survey methods, sites, and time series given in this chapter. Major findings are summarized and their limitations outlined. Current research, with recent reestablishment and expansion of many sampling programmes, is presented, and possible future approaches are indicated. These unique long-term data sets provide an environmental baseline for predicting complex ecological responses to local, regional, and global environmental change. Between 1888 and the present, investigations have been carried out into the physical, chemical, and biological components (ranging from plankton and fish to benthic and intertidal assemblages) of the western English Channel ecosystem. The Marine Biological Association of the United Kingdom has performed the main body of these observations. More recent contributions come from the Continuous Plankton Recorder Survey, now the Sir Alister Hardy Foundation for Ocean Science, dating from 1957; the Institute for Marine Environmental Research, from 1974 to 1987; and the Plymouth Marine Laboratory, which was formed by amalgamation of the Institute for Marine Environmental Research and part of the Marine Biological Association, from 1988. Together, these contributions constitute a unique data series; one of the longest and most comprehensive samplings of environmental and marine biological variables in the world. Since the termination of many of these time series in 1987-1988 during a reorganisation of UK marine research, there has been a resurgence of interest in long-term environmental change. Many programmes have been restarted and expanded with support from several agencies. The observations span significant periods of warming (1921-1961; 1985-present) and cooling (1962-1980). During these periods of change, the abundance of key species underwent dramatic shifts. The first period of warming saw changes in zooplankton, pelagic fish, and larval fish, including the collapse of an important herring fishery. During later periods of change, shifts in species abundances have been reflected in other assemblages, such as the intertidal zone and the benthic fauna. Many of these changes appear to be related to climate, manifested as temperature changes, acting directly or indirectly. The hypothesis that climate is a forcing factor is widely supported today and has been reinforced by recent studies that show responses of marine organisms to climatic attributes such as the strength of the North Atlantic Oscillation. The long-term data also yield important insights into the effects of anthropogenic disturbances such as fisheries exploitation and pollution. Comparison of demersal fish hauls over time highlights fisheries effects not only on commercially important species but also on the entire demersal community. The effects of acute ("Torrey Canyon" oil spill) and chronic (tributyltin [TBT] antifoulants) pollution are clearly seen in the intertidal records. Significant advances in diverse scientific disciplines have been generated from research undertaken alongside the long-term data series.

Rapid biogeographical plankton shifts in the North Atlantic Ocean

Large-scale biogeographical changes in the biodiversity of a key zooplankton group (calanoid copepods) were detected in the north-eastern part of the North Atlantic Ocean and its adjacent seas over the period 1960–1999. These findings provided key empirical evidence for climate change impacts on marine ecosystems at the regional to oceanic scale. Since 1999, global temperatures have continued to rise in the region. Here, we extend the analysis to the period 1958–2005 using all calanoid copepod species assemblages (nine species assemblages based on an analysis including a total of 108 calanoid species or taxa) and show that this phenomenon has been reinforced in all regions. Our study reveals that the biodiversity of calanoid copepods are responding quickly to sea surface temperature (SST) rise by moving geographically northward at a rapid rate up to about 23.16 km yr−1. Our analysis suggests that nearly half of the increase in sea temperature in the northeast Atlantic and adjacent seas is related to global temperature rises (46.35% of the total variance of temperature) while changes in both natural modes of atmospheric and oceanic circulation explain 26.45% of the total variance of temperature. Although some SST isotherms have moved northwards by an average rate of up to 21.75 km yr−1 (e.g. the North Sea), their movement cannot fully quantify all species assemblage shifts. Furthermore, the observed rates of biogeographical movements are far greater than those observed in the terrestrial realm. Here, we discuss the processes that may explain such a discrepancy and suggest that the differences are mainly explained by the fluid nature of the pelagic domain, the life cycle of the zooplankton and the lesser anthropogenic influence (e.g. exploitation, habitat fragmentation) on these organisms. We also hypothesize that despite changes in the path and intensity of the oceanic currents that may modify quickly and greatly pelagic zooplankton species, these organisms may reflect better the current impact of climate warming on ecosystems as terrestrial organisms are likely to significantly lag the current impact of climate change.

Decadal changes in climate and ecosystems in the North Atlantic Ocean and adjacent seas

Climate change is unambiguous and its effects are clearly detected in all functional units of the Earth system. This study presents new analyses of sea-surface temperature changes and show that climate change is affecting ecosystems of the North Atlantic. Changes are seen from phytoplankton to zooplankton to fish and are modifying the dominance of species and the structure, the diversity and the functioning of marine ecosystems. Changes also range from phenological to biogeographical shifts and have involved in some regions of the Atlantic abrupt ecosystem shifts. These alterations reflect a response of pelagic ecosystems to a warmer temperature regime. Mechanisms are complex because they are nonlinear exhibiting tipping points and varying in space and time. Sensitivity of organisms to temperature changes is high, implicating that a small temperature modification can have sustained ecosystem effects. Implications of these changes for biogeochemical cycles are discussed. Two observed changes detected in the North Sea that could have opposite effects on carbon cycle are discussed. Increase in phytoplankton, as inferred from the phytoplankton colour index derived from the Continuous Plankton Recorder (CPR) survey, has been detected in the North Sea. This pattern has been accompanied by a reduction in the abundance of the herbivorous species Calanus finmarchicus. This might have reduced the grazing pressure and increase diatomaceous ‘fluff’, therefore carbon export in the North Sea. Therefore, it could be argued that the biological carbon pump might increase in this region with sea warming. In the meantime, however, the mean size of organisms (calanoid copepods) has dropped. Such changes have implications for the turnover time of biogenic carbon in plankton organisms and the mean residence time of particulate carbon they produce. The system characterising the warmer period is more based on recycling and less on export. The increase in the minimum turnover time indicates an increase in the ecosystem metabolism, which can be considered as a response of the pelagic ecosystems to climate warming. This phenomenon could reduce carbon export. These two opposite patterns of change are examples of the diversity of mechanisms and pathways the ecosystems may exhibit with climate change. Oversimplification of current biogeochemical models, often due to lack of data and biological understanding, could lead to wrong projection on the direction ecosystems and therefore some biogeochemical cycles might take in a warmer world.

Macrophysiology of Calanus finmarchicus in the North Atlantic Ocean

Copepods represent the major part of the dry weight of the mesozooplankton in pelagic ecosystems and therefore have a central role in the secondary production of the North Atlantic Ocean. The calanoid copepod species Calanus finmarchicus is the main large copepod in subarctic waters of the North Atlantic, dominating the dry weight of the mesozooplankton in regions such as the northern North Sea and the Norwegian Sea. The objective of this work was to investigate the relationships between both the fundamental and realised niches of C. finmarchicus in order to better understand the future influence of global climate change on the abundance, the spatial distribution and the phenology of this key-structural species. Based on standardised Principal Component Analyses (PCAs), a macroecological approach was applied to determine factors affecting the spatial distribution of C. finmarchicus and to characterise its realised niche. Second, an ecophysiological model was used to calculate the Potential Egg Production Rate (PEPR) of C. finmarchicus and the centre of its fundamental niche. Relationships between the two niches were then investigated by correlation analysis. We found a close relationship between the fundamental and realised niches of C. finmarchicus at spatial, monthly and decadal scales. While the species is at the centre of its niche in the subarctic gyre, our joint macroecological and macrophysiological analyses show that it is at the edge of its niche in the North Sea, making the species in this region more vulnerable to temperature changes.

Effects of elevated CO2 and temperature on an intertidal meiobenthic community

In the near future, the marine environment is likely to be subjected to simultaneous increases in temperature and decreased pH. The potential effects of these changes on intertidal, meiofaunal assemblages were investigated using a mesocosm experiment. Artificial Substrate Units containing meiofauna from the extreme low intertidal zone were exposed for 60 days to eight experimental treatments (four replicates for each treatment) comprising four pH levels: 8.0 (ambient control), 7.7 & 7.3 (predicted changes associated with ocean acidification), and 6.7 (CO2 point-source leakage from geological storage), crossed with two temperatures: 12 °C (ambient control) and 16 °C (predicted). Community structure, measured using major meiofauna taxa was significantly affected by pH and temperature. Copepods and copepodites showed the greatest decline in abundance in response to low pH and elevated temperature. Nematodes increased in abundance in response to low pH and temperature rise, possibly caused by decreased predation and competition for food owing to the declining macrofauna density. Nematode species composition changed significantly between the different treatments, and was affected by both seawater acidification and warming. Estimated nematode species diversity, species evenness, and the maturity index, were substantially lower at 16 °C, whereas trophic diversity was slightly higher at 16 °C except at pH 6.7. This study has demonstrated that the combination of elevated levels of CO2 and ocean warming may have substantial effects on structural and functional characteristics of meiofaunal and nematode communities, and that single stressor experiments are unlikely to encompass the complexity of abiotic and biotic interactions. At the same time, ecological interactions may lead to complex community responses to pH and temperature changes in the interstitial environment

Intertwined ocean and climate: implications for international climate negotiations

The atmosphere and ocean are two components of the Earth system that are essential for life, yet humankind is altering both. Contemporary climate change is now a well-identified problem: anthropogenic causes, disturbance in extreme events patterns, gradual environmental changes, widespread impacts on life and natural resources, and multiple threats to human societies all around the world. But part of the problem remains largely unknown outside the scientific community: significant changes are also occurring in the ocean, threatening life and its sustainability on Earth. This Policy Brief explains the significance of these changes in the ocean. It is based on a scientific paper recently published in Science (Gattuso et al., 2015), which synthesizes recent and future changes to the ocean and its ecosystems, as well as to the goods and services they provide to humans. Two contrasting CO2 emission scenarios are considered: the high emissions scenario (also known as “business-as-usual” and as the Representative Concentration Pathway 8.5, RCP8.5) and a stringent emissions scenario (RCP2.6) consistent with the Copenhagen Accord1 of keeping mean global temperature increase below 2°C in 2100.

Variaciones termométricas en la planta del pie y piernas valorada en corredores antes y después de correr 30 km

La termometría es una técnica no invasiva que permite cuantificar los cambios en la temperatura cutánea y evaluarla de forma cuantitativa. El aumento significativo de la temperatura puede indicar la existencia de patología. Se ha demostrado que la actividad muscular induce procesos de transferencia de calor entre los músculos y las capas superficiales de tejido. En este estudio queremos cuantificar los cambios de temperatura que se producen en los músculos del pie y miembro inferior tras una carrera de 30 km, para ello hemos utilizado una cámara termográfica de alta resolución. Contamos con la colaboración voluntaria de 32 sujetos sanos a los que procedimos a tomar fotografías de la planta del pie, parte anterior de la pierna, parte posterior de la pierna, parte anterior del muslo y parte posterior del muslo en dos etapas, primero antes de la carrera y segunda toma después de la carrera de 30 km, de esta manera pudimos valorar si había o no variación de temperatura en las zonas seleccionadas. Tras el análisis de los datos obtenidos encontramos significativas variaciones térmicas en Talón, cabeza primer metatarsiano, cabeza segundo metatarsiano, cabeza tercer metatarsiano, cabeza cuarto metatarsiano, cabeza quinto metatarsiano, apófisis estiloides quinto metatarsiano, arco longitudinal interno, maléolo interno, maléolo externo, peroneo lateral largo, vasto interno, vasto externo, recto femoral, tensor de la fascia lata, inserción cuádriceps, gemelo interno, tendón de Aquiles y Biceps femoral.

Climate drivers for peatland palaeoclimate records

Reconstruction of hydroclimate variability is an important part of understanding natural climate change on decadal to millennial timescales. Peatland records reconstruct 'bog surface wetness' (BSW) changes, but it is unclear whether it is a relative dominance of precipitation or temperature that has driven these variations over Holocene timescales. Previously, correlations with instrumental climate data implied that precipitation is the dominant control. However, a recent chironomid inferred July temperature record suggested temperature changes were synchronous with BSW over the mid-late Holocene. This paper provides new analyses of these data to test competing hypotheses of climate controls on bog surface wetness and discusses some of the distal drivers of large-scale spatial patterns of BSW change. Using statistically based estimates of uncertainty in chronologies and proxy records, we show a correlation between Holocene summer temperature and BSW is plausible, but that chronologies are insufficiently precise to demonstrate this conclusively. Simulated summer moisture deficit changes for the last 6000 years forced by temperature alone are relatively small compared with observations over the 20th century. Instrumental records show that summer moisture deficit provides the best explanatory variable for measured water table changes and is more strongly correlated with precipitation than with temperature in both Estonia and the UK. We conclude that BSW is driven primarily by precipitation, reinforced by temperature, which is negatively correlated with precipitation and therefore usually forces summer moisture deficit in the same direction. In western Europe, BSW records are likely to be forced by changes in the strength and location of westerlies, linked to large-scale North Atlantic ocean and atmospheric circulation. (C) 2009 Elsevier Ltd. All rights reserved.

Local temperature in quantum thermal states

We consider blocks of quantum spins in a chain at thermal equilibrium, focusing on their properties from a thermodynamical perspective. In a classical system the temperature behaves as an intensive magnitude, above a certain block size, regardless of the actual value of the temperature itself. However, a deviation from this behavior is expected in quantum systems. In particular, we see that under some conditions the description of the blocks as thermal states with the same global temperature as the whole chain fails. We analyze this issue by employing the quantum fidelity as a figure of merit, singling out in detail the departure from the classical behavior. As it may be expected, we see that quantum features are more prominent at low temperatures and are affected by the presence of zero-temperature quantum phase transitions. Interestingly, we show that the blocks can be considered indeed as thermal states with a high fidelity, provided an effective local temperature is properly identified. Such a result may originate from typical properties of reduced subsystems of energy-constrained Hilbert spaces. Finally, the relation between local and global temperatures is analyzed as a function of the size of the blocks and the system parameters.

A Temperature-Monitoring Vaginal Ring for Measuring Adherence

Background

Product adherence is a pivotal issue in the development of effective vaginal microbicides to reduce sexual transmission of HIV. To date, the six Phase III studies of vaginal gel products have relied primarily on self-reporting of adherence. Accurate and reliable methods for monitoring user adherence to microbicide-releasing vaginal rings have yet to be established.

Methods

A silicone elastomer vaginal ring prototype containing an embedded, miniature temperature logger has been developed and tested in vitro and in cynomolgus macaques for its potential to continuously monitor environmental temperature and accurately determine episodes of ring insertion and removal.

Results

In vitro studies demonstrated that DST nano-T temperature loggers encapsulated in medical grade silicone elastomer were able to accurately and continuously measure environmental temperature. The devices responded quickly to temperature changes despite being embedded in different thickness of silicone elastomer. Prototype vaginal rings measured higher temperatures compared with a subcutaneously implanted device, showed high sensitivity to diurnal fluctuations in vaginal temperature, and accurately detected periods of ring removal when tested in macaques.

Conclusions

Vaginal rings containing embedded temperature loggers may be useful in the assessment of product adherence in late-stage clinical trials.

Dynamic modelling of die melt temperature profile in polymer extrusion: Effects of process settings, screw geometry and material

Extrusion is one of the major methods for processing polymeric materials and the thermal homogeneity of the process output is a major concern for manufacture of high quality extruded products. Therefore, accurate process thermal monitoring and control are important for product quality control. However, most industrial extruders use single point thermocouples for the temperature monitoring/control although their measurements are highly affected by the barrel metal wall temperature. Currently, no industrially established thermal profile measurement technique is available. Furthermore, it has been shown that the melt temperature changes considerably with the die radial position and hence point/bulk measurements are not sufficient for monitoring and control of the temperature across the melt flow. The majority of process thermal control methods are based on linear models which are not capable of dealing with process nonlinearities. In this work, the die melt temperature profile of a single screw extruder was monitored by a thermocouple mesh technique. The data obtained was used to develop a novel approach of modelling the extruder die melt temperature profile under dynamic conditions (i.e. for predicting the die melt temperature profile in real-time). These newly proposed models were in good agreement with the measured unseen data. They were then used to explore the effects of process settings, material and screw geometry on the die melt temperature profile. The results showed that the process thermal homogeneity was affected in a complex manner by changing the process settings, screw geometry and material.

Caracterização molecular de cianobactérias de sistemas aquáticos portugueses

As alterações climáticas favorecem a ocorrência global de episódios de precipitação e seca extremas, colocando em risco a qualidade da água em sistemas aquáticos usados consumo humano ou recreação. O fenómeno de seca, em particular, será mais frequente e severo, alterando toda a hidrodinâmica dos sistemas aquáticos e, consequentemente, a ecologia das comunidades aquáticas. A ocorrência de blooms de cianobactérias intensificarse- á sob este novo cenário climático. Em Portugal, estudos parcelares em rios e barragens têm sido realizados com enfoque em cianobactérias tóxicas e outras bactérias patogénicas, mas não há trabalhos publicados acerca da composição da comunidade bacteriana (CCB). O presente trabalho pretende colmatar esta falha, com particular atenção para a ocorrência de blooms cianobacterianos, em vários sistemas aquáticos portugueses lóticos e lênticos. Este objectivo foi alcançado utilizando metodologias moleculares, como a técnica rDNA 16S-DGGE (Denaturing Gradient Gel Electrophoresis), independente do cultivo, e a sequenciação. Dados ambientais foram também determinados para correlacionar com as variações sazonais ou espaciais da diversidade da CCB. O impacto da seca na distribuição espacial da CCB foi também investigado. A lagoa da Vela é um caso de estudo especial, devido à vasta documentação sobre a ocorrência de blooms de cianobactérias durante os últimos anos, e várias estirpes isoladas de blooms foram estudadas em mais detalhe. Os resultados mostraram, em geral, perfis de DGGE típicos de verão vs. inverno nos sistemas aquáticos estudados. Nos sistemas lênticos, os filótipos dominantes afiliaram com Cyanobacteria (formas unicelulares, coloniais e filamentosas), eucariotas fototróficos e Actinobacteria, enquanto nos rios, Bacteroidetes e Betaproteobacteria foram dominantes. Nos sistemas lênticos, os factores mais significativos para a sazonalidade da CCB incluíram a temperatura da água, a condutividade e a clorofila a, apesar da variação extrema dos níveis de precipitação, sugerindo que a BCC poderá resistir a mudanças severas causadas pela seca. Nos rios, a sazonalidade da CCB foi principalmente definida pela temperatura e os níveis de amónia. No verão seco de 2005, as barragens do Alentejo (Sul de Portugal) mostraram similaridade na CCB, com filótipos comuns de Cyanobacteria, Actinobacteria e Alphaproteobacteria. No entanto, os perfis de DGGE sugerem filótipos ubíquos em sistemas portugueses geograficamente distantes. Na Lagoa da Vela, a seca conduziu à redução drástica do nível da água e à variação na diversidade espacial da CCB (e cianobactérias dominantes) e potencial tóxico, o que pode ter impacto directo nos utilizadores da lagoa. Os resultados também mostraram a presença de estirpes tóxicas de Microcystis na lagoa e um bloom não clonal de estirpes de Aphanizomenon aphanizomenoides, com diferentes morfótipos, genótipos e ecótipos.

Reference clock design for low power and low phase noise with temperature compensation

Thesis (Ph.D.)--University of Washington, 2016-03

The effects of temperature on nickel tocicity in goldfish (carassius auratus L.)

Although it is widely assumed that temperature affects pollutant toxicity, few studies have actually investigated this relationship. Moreover, such research as has been done has involved constant temperatures; circumstances which are rarely, if ever, actually experienced by north temperate, littoral zone cyprinid species. To investigate the effects of temperature regime on nickel toxicity in goldfish (Carassius auratus L.), 96- and 240-h LCSO values for the heavy metal pollutant, nickel (NiCI2.6H20), were initially determined at 2DoC (22.8 mg/L and 14.7 mg/L in artificially softened water). Constant temperature bioassays at 10°C, 20°C and 30°C were conducted at each of 0, 240-h and 96-h LCSO nickel concentrations for 240 hours. In order to determine the effects of temperature variation during nickel exposure it was imperative that the effects of a single temperature change be investigated before addressing more complex regimes. Single temperature changes of + 10°C or -10°C were imposed at rates of 2°C/h following exposures of between 24 hand 216 h. The effects of a single temperature change on mortality, and duration of toxicant exposure at high and low temperatures were evaluated. The effects of fluctuating temperatures during exposure were investigated through two regimes. The first set of bioassays imposed a sinewave diurnal cycle temperature (20.±.1DOC) throughout the 10 day exposure to 240-h LeSO Ni. The second set of investigations approximated cyprinid movement through the littoral zone by imposing directionally random temperature changes (±2°C at 2-h intervals), between extremes of 10° and 30°C, at 240-h LC50 Ni. Body size (i.e., total length, fork length, and weight) and exposure time were recorded for all fish mortalities. Cumulative mortality curves under constant temperature regimes indicated significantly higher mortality as temperature and nickel concentration were increased. At 1DOC no significant differences in mortality curves were evident in relation to low and high nickel test concentrations (Le., 16 mg/L and 20 mg/L). However at 20°C and 30°C significantly higher mortality was experienced in animals exposed to 20 mg/L Ni. Mortality at constant 10°C was significantly lower than at 30°C with 16 mg/L and was significantly loWer than each of 2DoC and 39°C tanks at 20 mg/L Ni exposure. A single temperature shift from 20°C to 1DoC resulted in a significant decrease in mortality rate and conversely, a single temperature shift from 20°C to 30°C resulted in a significant increase in mortality rate. Rates of mortality recorded during these single temperature shift assays were significantly different from mortality rates obtained under constant temperature assay conditions. Increased Ni exposure duration at higher temperatures resulted in highest mortality. Diurnally cycling temperature bioassays produced cumulative mortality curves approximating constant 20°C curves, with increased mortality evident after peaks in the temperature cycle. Randomly fluctuating temperature regime mortality curves also resembled constant 20°C tanks with mortalities after high temperature exposures (25°C - 30°C). Some test animals survived in all assays with the exception of the 30°C assays, with highest survival associated with low temperature and low Ni concentration. Post-exposure mortality occurred most frequently in individuals which had experienced high Ni concentrations and high temperatures during assays. Additional temperature stress imposed 2 - 12 weeks post exposure resulted in a single death out of 116 individuals suggesting that survivors are capable of surviving subsequent temperature stresses. These investigations suggest that temperature significantly and markedly affects acute nickel toxicity under both constant and fluctuating temperature regimes and plays a role in post exposure mortality and subsequent stress response.