Increase In Water Temperature Research Articles

Refining the Occurrence of Viral Encephalopathy and Retinopathy, Photobacteriosis, and Vibriosis in Connection with Seawater Physicochemical Parameters: A Five-Year Case Study

The marine environment and its physicochemical parameters play a pivotal role in the context of fish farming. Fundamental physicochemical factors of water, including temperature (T°C), salinity (S psu), dissolved oxygen (D.O. mg/l), and pH, exert a profound influence on the physiology of farmed aquatic animals and the composition of microbial communities. This study aimed to establish correlations between documented disease occurrences in sea bass intensive rearing and the prevailing physicochemical parameters of water. The objective was to analyse the significance of these parameters in disease outbreaks and develop a predictive model for the outbreak risk of key diseases. To this end, real-time physicochemical data were collected daily over five years (2011-2015) from two fish farms (A and B) located in the Gulf of Argostoli, island of Cephalonia, Western Greece. The focus was on incidences of Viral Encephalopathy and Retinopathy (VER), Photobacteriosis caused by Photobacterium damselae subsp. piscicida (PHDP) and Vibriosis caused by Vibrio anguillarum serotype O1 (VAO1). Statistically significant correlations were found between increasing water temperature and salinity and the occurrence of VER, PHDP, and VAO1 diseases. The reduction of dissolved oxygen, when combined with other parameters, synergistically triggered the manifestation of these three diseases. The study’s findings were discussed within the context of their potential to predict disease outbreaks based on fluctuations in the physicochemical parameters of water and anticipated climate change scenarios.

Land use in catchments of small streams and a hydrological urban heat island – a case study in Kielce city (Poland)

ABSTRACT This article presents the spatial and temporal value and dynamics of water temperature in small streams flowing through a city of 200,000 inhabitants. The analysis is based on stationary measurements of a water temperature in eight (8) catchment outlets of various uses (including forest, suburban, urbanised). The water temperature was measured daily for 4 years (06 UTC; electronic thermometers; accuracy: 0.1°C). The study has shown that the water temperature in streams is clearly modi fied by the nature of land use prevailing in the catchment, represented by the imperviousness index. Urbanised areas caused a significant increase in minimum, mean and maximum temperature values on a daily, monthly and annual cycle. The determined relationship indicates that every 1% increase in impervious catchment area causes a water temperature increase of 0.1°C. The presented and documented facts justify the use of the term ‘hydrological urban heat island’, which began to appear in the literature.

Local environments, not invasive hybridization, influence cardiac performance of native trout under acute thermal stress.

Climate-induced expansion of invasive hybridization (breeding between invasive and native species) poses a significant threat to the persistence of many native species worldwide. In the northern U.S. Rocky Mountains, hybridization between native cutthroat trout and non-native rainbow trout has increased in recent decades due, in part, to climate-driven increases in water temperature. It has been postulated that invasive hybridization may enhance physiological tolerance to climate-induced thermal stress because laboratory studies indicate that rainbow trout have a higher thermal tolerance than cutthroat trout. Here, we assessed whether invasive hybridization improves cardiac performance response to acute water temperature stress of native wild trout populations. We collected trout from four streams with a wide range of non-native admixture among individuals and with different temperature and streamflow regimes in the upper Flathead River drainage, USA. We measured individual cardiac performance (maximum heart rate, "MaxHR", and temperature at arrhythmia, "ArrTemp") during laboratory trials with increasing water temperatures (10-28°C). Across the study populations, we observed substantial variation in cardiac performance of individual trout when exposed to thermal stress. Notably, we found significant differences in the cardiac response to thermal regimes among native cutthroat trout populations, suggesting the importance of genotype-by-environment interactions in shaping the physiological performance of native cutthroat trout. However, rainbow trout admixture had no significant effect on cardiac performance (MaxHR and ArrTemp) within any of the three populations. Our results indicate that invasive hybridization with a warmer-adapted species does not enhance the cardiac performance of native trout under warming conditions. Maintaining numerous populations across thermally and hydrologically diverse stream environments will be crucial for native trout to adapt and persist in a warming climate.

Climate change and the biodiversity of alpine ponds: Challenges and perspectives.

Inland waters are among the most threatened biodiversity hotspots. Ponds located in alpine areas are experiencing more rapid and dramatic water temperature increases than any other biome. Despite their prevalence, alpine ponds and their biodiversity responses to climate change have been poorly explored, reflecting their small size and difficult access. To understand the effects of climate change on alpine pond biodiversity, we performed a comprehensive literature review for papers published since 1955. Through analysis of their geographic distribution, environmental features, and biodiversity values, we identified which environmental factors related to climate change would have direct or indirect effects on alpine pond biodiversity. We then synthesized this information to produce a conceptual model of the effects of climate change on alpine pond biodiversity. Increased water temperature, reduced hydroperiod, and loss of connectivity between alpine ponds were the main drivers of biodiversity geographic distribution, leading to predictable changes in spatial patterns of biodiversity. We identified three major research gaps that, if addressed, can guide conservation and restoration strategies for alpine ponds biodiversity in an uncertain future.

The effect of water temperature changes on biological water quality assessment

Increasing temperatures caused by anthropogenic climate change are leading to changes in the composition of local communities across biomes. This has implications for ecological assessment methods that rely on macroinvertebrates as bioindicators of water quality. To investigate the influence of changing water temperature on these assessment methods, we analysed macroinvertebrate data from Swiss national monitoring programs. We used a species distribution model to simulate temperature change effects on macroinvertebrate communities and estimated the resulting changes on three biological indices commonly used in Switzerland, namely the species richness of Ephemeroptera, Plecoptera and Trichoptera (EPT), the Swiss biological (IBCH) index along with its components, as well as the species at risk pesticides (SPEARpesticides) index. While results vary by temperature scenario and index, our model results for the most realistic water temperature increase scenario of + 2 °C across most sites in Switzerland suggest no, or only a minor, influence of temperature (not accounting for other hydrological changes). Our model projection predicted only a small increase in the probability of occurrence for 70 % of the studied families. The sensitivity to temperature as captured in our model is generally not very high and varies among the biological indices: on average across all sites, a + 2 °C increase in temperature resulted in a 7 % increase in EPT species richness, a 4 % increase in the IBCH index, and a less than 1 % increase in the SPEARpesticides index. Our study suggests the robustness of these biological indices to moderate warming and points towards the usefulness of these biological indices for the next few decades as tools for water quality assessment. Despite some limitations of statistical species distribution models (e.g., not accounting for dispersal limitation or biotic interactions, predictive performance varying by taxon), the study provides valuable insights into the complex relationships between environmental factors and macroinvertebrate communities, and the potential impacts of future temperature change. These findings can inform conservation and management efforts for these important ecological systems.

Joint effects of warming and salinization on instream leaf litter decomposition assessed through a microcosm experiment

Stream ecosystem functioning is often impaired by warming and salinization, but the joint effect of both environmental stressors on key processes such as leaf litter decomposition is virtually unknown, particularly in the tropics. We experimentally explored how increased water temperature (26, 29 and 32°C) and salinity (no salt addition, 0.1, 1.0 and 10 g l−1 NaCl added) affected the rates of total, microbial and detritivore-mediated decomposition, in stream microcosms containing leaf litter of Ficus insipida and larvae of Chironomus sp. collected from tropical streams. Effects of temperature were strong and consistent with previous findings: it promoted microbial decomposition and reduced decomposition mediated by detritivores, which showed greater feeding activity at 26°C. Salinity was negatively correlated with microbial decomposition at 32°C; it also had a negative influence on detritivore-mediated decomposition, which was nevertheless non-significant due to the high detritivore mortality at higher salinities. Notably, total decomposition was reduced with the joint presence of both factors (32°C and salt addition treatments, compared to 26°C and no salt addition), indicating the existence of additive effects and highlighting the relevance of multiple-stressor contexts when assessing the consequences of global change on stream ecosystems.

Laser tissue welding by using collagen excitation at a 1,720 nm near-infrared optical window III.

Laser tissue welding (LTW) is a method of fusing incised tissues together. LTW has the potential to revolutionize plastic surgery and wound healing techniques by its ability to produce watertight, scarless seals with minimal foreign body reaction. While using thermal mechanisms to achieve LTW, energy from the incident laser is absorbed by water in the tissue. As the water temperature increases, partial denaturing of the collagen triple helix briefly occurs, which is quickly followed by renaturation of collagen as the tissue cools, thus providing a watertight seal. This research study investigates the efficacy of direct collagen excitation at 1,720nm to accomplish LTW. This wavelength falls within the near-infrared (NIR) optical window III. The tensile strengths of pig skin that have been welded with NIR continuous-wave (CW) diode lasers at 1,455nm, which promote thermal mechanisms of tissue welding, and 1,720nm wavelengths, are compared. Near-infrared lasers tuned to 1,455 and 1,720nm were used to weld incised pieces of porcine skin together without extrinsic solders or dyes. The tensile force of the welded tissues was measured using a digital force gauge. The average tensile force of the welded pig skin using the 1,720nm laser was approximately four times greater than that using the CW 1,455nm laser, suggesting that LTW accomplished through direct collagen excitation in the NIR optical window III provides greater tensile strengths.

Juvenile hormone and temperature effects in the postzygotic parental investment of male waterbug Abedus ovatus (Belostomatidae)

AbstractParental investment is any expenditure of time or energy by parents that increases their offspring survival at the cost of future reproduction. The costs associated with parental investment can be reflected in a deterioration of their physiological condition. In insects, juvenile hormone has been identified as having a role in the control of parental care. However, its effects on parental investment remain unclear for many taxa, especially in species with exclusive paternal care. We evaluated whether juvenile hormone influences postzygotic parental investment in Abedus ovatus, a waterbug with exclusive paternal care. Males provide parental care by carrying eggs on their backs and ventilating them by generating water currents through push‐ups called brood pumping. In an experiment, we applied methoprene (an analog of juvenile hormone) to males at early and late parental care stages and quantified the frequency of brood pumping and the contents of energy reserves (lipids, carbohydrates, and glycogen) at the end of parental care as a measure of physiological condition. We found that methoprene increases the frequency of brood pumping only when the water temperature increases. However, there was no correlation between the parent's energy reserves and methoprene treatments. We found that males who cared for large egg pads had lower amounts of lipids and carbohydrates at the end of parental care, and both effects are greater as the water temperature increases. These results suggest that energy expenditure during parental care is high due to intense muscular activity during brood pumping, which depletes male energy reserves and could affect future reproduction.

Variability of marine epifauna assemblages in response to the microhabitat type and thermal stress

Anthropogenic activities like overfishing, urban and industrial developments, and coastal pollution are some of the stressors affecting the marine environment. Thermal pollution from coastal industries like power plants represents the main cause of increased temperatures in water bodies, which can affect the marine community structure and function. The aim of this study was: 1) to compare the epifaunal communities associated with three different types of microhabitats: articulated coralline algae around coral colonies (CWC), articulated coralline algae in the absence of coral colonies and other benthic organisms (CNB), and the seaweed Ecklonia cava (ECK); and 2) to determine the potential changes in epifaunal communities in acute response to the increased water temperature resulting from coastal power plant activities in Jeju Island, South Korea. Our findings revealed a strong association between epifaunal abundance and microhabitat type, with CNB exhibiting the highest abundance while ECK showed the lowest. Additionally, an increase in temperature of 0.5–1.5 °C was observed to not alter the overall abundance of epifauna at the impact site, however, it did lead to a shift in the community composition. There was a notable decline in the abundance of amphipods-caprellids, polychaetes, gastropods, and bivalves with their densities nearly halving in response to thermal stress. Furthermore, there was a shift in dominant taxa, transitioning from amphipods-caprellids to amphipods-non-caprellids. Conversely, other taxonomic groups such as isopods and copepods showed a remarkable surge in abundance following the temperature rise. These findings highlight the relationship between rising temperatures and epifaunal community composition while emphasizing taxa’s different responses to thermal stress.

Probabilistic monitoring of meteorological drought impacts on water quality of major rivers in South Korea using copula models

The impacts of drought range from water supply for humans to ecosystems. Drought affects river water quality by disturbing the hydrological regime in a variety of ways, and can degrade water quality by reducing surface and groundwater availability. In particular, drought-induced low flows, reduced nutrient dilution, and extreme increases in water temperature affect various water quality parameters in streams. Furthermore, the effects of drought on stream water quality may vary from season to season and from stream segment to stream segment, which requires careful investigation. In this study, Environmental Drought Condition Index - water quality (EDCI-wq) is proposed using a bivariate copula joint probability model between meteorological drought index and river water quality. Using this, environmental drought with respect to water quality is defined, and it is confirmed that environmental drought with respect to water quality can be routinely monitored through time series analysis and mapping of the proposed EDCI-wq. In addition, in order to express the environmental drought condition more explicitly to the general public, the environmental drought condition is graded into four classes based on the EDCI-wq. Furthermore, the sensitivity of river water quality to meteorological drought was estimated using the copula joint probability model, which allowed us to identify river segments that are relatively more sensitive to meteorological drought events.

A circle that closes. First report of Echinolittorina punctata (Gmelin, 1791) (Gastropoda; Littorinidae) for the coasts of Sardinia

Echinolittorina punctata (Gmelin, 1791), a thermophilic supralittoral species, was historically distributed along the Atlantic coasts from southern Spain to Senegal, and in the southern and eastern sectors of the Mediterranean. In the latter sea it has spread its range northwards only in recent years, moving up the Tyrrhenian coasts of Italy up to Tuscany, the Adriatic ones up to Croatia, and the southern coasts of Western Europe up to France. Sardinia, in an intermediate position between the Italian Tyrrhenian coasts and the southern Spanish and French ones, both recently colonized by E. punctata, presented itself as a foreseeable new settlement area. The discovery of some populations of this species in north-western Sardinia, along the coasts of the municipality of Porto Torres, represents the first report for Sardinia. It fills the last missing range gap for this species to be defined as widely distributed in the Mediterranean. The expansion of this species further northward in the Mediterranean seems linked to the general increase in sea water temperatures resulting from climate change.

Climatic sensitivity of seasonal ice-cover, water temperature and biogeochemical cycling in Lake 239 of the Experimental Lakes Area (ELA), Ontario, Canada

Regional climate plays an important role on in-lake physical and biogeochemical processes and determines the state of water quality and ecology of the lakes. This paper presents the result of a one-dimensional numerical modelling of lake ice cover, water temperature, as well as nutrient and phytoplankton dynamics in Lake 239 (Rawson Lake) located in the Experimental Lakes Area (ELA), Ontario, Canada. Using observed meteorological and inflow/outflow data, the Multi-year Lake simulation model (MyLake) was setup to replicate measured lake water temperature, ice-cover, dissolved organic carbon, particulate and dissolved phosphorus, and chlorophyll-a concentrations over the entire depth of the lake. The sensitivity of the lake to changes in climatic drivers, specifically to changes in surface air temperature and wind speed, was examined by incrementally changing the model input forcing for temperature and wind speed and mapping the resulting changes in the simulated outputs. The results show that lake processes are generally as sensitive to changes in wind speed as they are to changes in air temperature. Simulated changes in lake variables corresponding to projected changes in Global Climate Models (GCMs) under RCP4.5 and RCP8.5 emission scenarios reveal a general increase in lake water temperature and the corresponding decrease in lake ice thickness and ice cover duration under the changing climate. While lake water temperature increases at all depths, the shallow epilimnion layer is more sensitive to the changing climate than the deeper hypolimnion layer, reaching mean annual change value of +3.7 °C for RCP 8.5 and the 2090s as compared to the 1990s baseline period. While the simulated change in lake ice thickness reaches −20 cm by 2090s for the RCP 8.5 scenario, the corresponding change in ice-cover duration reaches -47 days. These changes are shown to result in seasonal changes in the biogeochemical cycling over the depth of the lake with projected increases in chlorophyll-a concentration during ice covered season of December to May reaching up to +0.15 mg/m3 for RCP 8.5 and the 2090s followed by a decrease during open water season of June to November reaching −0.15 mg/m3 compared to the 1990s baseline period.

Drivers of rising monthly water temperature in river estuaries

AbstractRiver estuaries are habitats for a variety of organisms, including many temperature‐sensitive species; water temperatures in estuaries are affected by several factors as they are influenced by both terrestrial and marine environments. Therefore, understanding the factors that influence river estuaries are essential for environmental management. However, no information exists on temperature change at high temporal resolution and over a wide area; moreover, the relationship with environmental factors has not yet been clarified. Here, we have described the actual status of water temperature change in riverine estuaries and its relationship with environmental factors for a wide area of the Japanese archipelago. Our results indicated that 217 of 294 rivers showed a significant monthly increase in water temperature. The average annual change in rates of water temperature increase was the highest in October at 0.090°C yr−1 and lowest in February at 0.068°C yr−1. Furthermore, snowfall, air temperature increase, sea water temperature, and land use were identified as factors increasing the rate of water temperature increase. Factors influencing the increase in river estuarine water temperature varied from month to month—with meteorological factors being the strongest influencers from spring to fall, and anthropogenic factors in winter. Our findings emphasize the importance of considering not only meteorological and oceanographic phenomena, but also anthropogenic influences and topographic features to understand the pattern of water temperature changes in river estuaries.

Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves

Abstract. The impacts of climate change on marine organisms have been increasingly documented in laboratory and experimental studies. However, the use of different taxonomic groupings and the assessment of a range of processes make identifying overall trends challenging. Meta-analysis has been used to determine general trends, but coarse taxonomic granularity may mask phylogenetically specific responses. Bivalve molluscs are a data-rich clade of ecologically and economically important calcifying marine taxa that allow for the assessment of species-specific vulnerability across developmental stages. Drawing on the large body of available literature, we conduct a meta-analysis of 203 unique experimental set-ups in order to examine how bivalve growth responds to increased water temperature, acidity, deoxygenation, and changes in salinity in 10 climate change stressor combinations. This is the most complete examination of bivalve responses to date and shows that anthropogenic climate change will disproportionally affect particular families, suggesting taxonomic differentiation in climate change response. Specifically, Mytilidae, Ostreidae, and Pectinidae (67 % of experiments) respond with negative effect sizes for all individual stressors, whereas responses in Pinnidae, Tellinidae, and Veneridae are more complex. Our analysis shows that earlier studies reporting negative impacts on bivalves are driven by only three or four well-studied, commercially important families. Despite the taxonomic differentiation, almost all drivers and their combinations have significant negative effects on growth. The synergistic impacts of deoxygenation, acidification, and temperature result in the largest negative effect size. Infaunal taxa, including Tellinidae and Veneridae, appear more resistant to warming and oxygen reduction than epifaunal or motile taxa, but this difference between the two taxa is also based on a small number of data points. The current focus of experimental set-ups on commercially important taxa and families within a small geographic range creates gaps in the understanding of global impacts on these economically important foundation organisms.

Inshore juvenile lobsters threatened by warming waters and migratory fish predators in southern New England

The southern New England stock of the American lobster Homarus americanus has declined since its peak in the 1990s. While the decline of lobsters has been directly attributed to warming sea temperatures, indirect effects such as migratory fish species shifting north may also be important. Two sets of experiments and a survey of gut contents collected from wild-caught scup Stenotomus chrysops and black sea bass Centropristis striata during the summer were performed to assess thermal and predatory stressors on juvenile lobsters. A temperature experiment compared the growth and survival of young-of-year (YOY) and 1 yr old lobsters in ambient seawater and seawater warmed or cooled by 3°C. Two predation experiments compared the survival of juvenile lobsters in treatments with scup, black sea bass, and Asian shore crabs Hemigrapsus sanguineus. Increased water temperature did not increase mortality in juvenile lobsters, but it did tend to have a negative impact on growth and weight gain of YOY lobsters and weight gain of 1 yr old lobsters. In the predation experiments, fewer lobsters survived in mesocosms with black sea bass and scup than in the control treatment. Fish gut contents contained few lobsters, but black sea bass stomachs contained many juvenile cancer crabs, signifying that the fish prey in cobble habitat that is preferred by both juvenile cancer crabs and lobsters. While juvenile lobsters can survive current temperatures, they may face compounding challenges as warmer water slows their growth and leaves them more susceptible to predation by increasing numbers of migratory scup and black sea bass.

High densities of large tuaki, the New Zealand cockle Austrovenus stutchburyi, provide a post-settlement predation refuge for conspecific juveniles

Bivalves are ecosystem engineers, and their effective management relies on a full understanding of the mechanisms that influence population dynamics. Juvenile tuaki (New Zealand cockle) Austrovenus stutchburyi, a numerically dominant and ecologically important bivalve in New Zealand estuaries, were found at higher densities when surrounded by high densities of large adults within Waitati Inlet, in southern New Zealand. Consequently, we hypothesised that adults provided a refuge from predation for juveniles, resulting in higher juvenile survival and retention in dense beds. The observed pattern was consistent with post-settlement Allee effects, where declines in density and truncated size distributions may have resulted in unsuccessful recruitment if a density threshold was reached. Field experiments were undertaken in 2020 and 2021 to test the potential sheltering effect of adults on retention and survival of juveniles, with and without the addition of organic loading of sediments. Presence of adults had significant effects on juvenile retention and interaction with organic loading in 2020, but not in 2021. To isolate the effects of adult presence on predation of juveniles, a series of laboratory experiments were carried out using the predatory crab Ovalipes catharus. Juvenile survivorship from crab predation was enhanced in the presence of large adults, consistent with the hypothesised sheltering effect. Further, predation rates increased significantly from winter to summer, which correlated with increasing water temperatures and the breeding and moult cycle of crabs. These findings across surveys, field and laboratory manipulations have significant implications for effective fisheries management and restoration of bed-forming bivalves.

Establishing a Marine Protected Area in the Waters Surrounding Dokdo: Necessity and Legality

Dokdo is an area with considerable marine biodiversity, which plays an important role in historical, geographical, and marine tourism. Recently, climate change has increased water temperatures in its surrounding waters, significantly threatening the balance of the marine ecosystem in Dokdo. This study analyzes South Korean and international laws as grounds for the necessity of establishing marine protected areas and the legal validity of such establishment to protect Dokdo’s marine ecosystem and increase the island’s social, cultural, and educational perspectives and marine tourism value within literature reviews and doctrinal study. Moreover, South Korea needs coordination and cooperation with Japan to prevent potential conflicts and implement measures for conflict management by designating Dokdo and its surrounding waters as marine protected areas.

Continuous warming shifts the community pattern of periphytic protozoan fauna in marine environments

Protozoan fauna is playing an important role in the functioning of microbial food webs by transferring the flux of material and energy from low to high tropic levels in marine ecosystems. To assess effects of elevated temperature on the marine ecosystem, periphytic protozoan communities were used as the test microbial fauna, and were incubated in a temperature-controlled circulation system in a successive temperature gradient of 22 (control), 25, 28, 31 and 34 °C. The results showed that: (1) the test microbial fauna was shifted in both species composition and community structure; (2) the average taxonomic distinctness represented a clear decreasing trend, (3) while the variation in taxonomic distinctness significantly increased with increase of water temperature; and (4) the community pattern was significantly departed from an expectation when temperature increased by 12 °C. These results suggested that Protozoa may be used as a useful bioindicator of global warming in marine ecosystems.

Numerical study on thermal hydraulics characteristics during steam submerged jet condensation from rectangular CD nozzle

The phenomenon of steam-water direct contact condensation (DCC) has significant importance in nuclear industry due to its rapid and efficient heat and mass transfer rates. In this numerical study, three dimensional simulations of steam submerged jet condensation from rectangular converging-diverging (CD) nozzle into subcooled water has been investigated. The steam condensation phenomenon has been captured from thermal phase change model as user defined function (UDF) in ANSYS Fluent software. The computational results were validated using experimental results as well as previously published numerical study. The effects of steam pressure and water temperature on distributions of various thermal hydraulics parameters including velocity, pressure, temperature, heat and mass transfer characteristics have been studied. The steam pressure and water temperature have been kept in the range of 200–500 kPa and 20–60 °C, respectively. The maximum value of jet velocity and heat transfer coefficient have been found as 803 m/s and 2.73 MW/m2K respectively. The peak velocity value increases with steam pressure. After maximum expansion point, the velocity profile curve is shifted downstream with steam pressure. The axial pressure distribution first decreases and then increases from expansion-compression waves. The axial temperature profile followed the similar trend as observed for axial steam pressure distribution. At constant steam pressure, the maximum rate of heat transfer coefficient decreases with the increase in water temperature. The maximum mass transfer rate under prescribed flow conditions has been found as 2789.8 kg/m3s. The peak mass transfer rate decreases with steam pressure and water temperature. The peak rates for heat and mass transfer have been observed in the nearby vicinity of nozzle exit location.

Cytogenetic Analysis of the Crustacean Pontogammarus robustoides (Amphipoda, Gammaridae) at Increased Water Temperature under Conditions of Microcosm

Adaptive reactions of <i>Pontogammarus robustoides</i>, a representative of the family Gammaridae, were studied at the cellular level at the increase in water temperature to its critical values under conditions of a model ecosystem - a microcosm. A cytogenetic analysis of its embryo cells was carried out and the activity of nucleoli of somatic cells was investigated. It has been shown that normal development of <i>P. robustoides</i> embryo cells was observed within the temperature range from 25.0°C to 27.5°C. The increase in water temperature up to 30.0-30.5°C resulted in such structural and functional changes in its cells as the increase in chromosome aberrations and the increase in the number of micronuclei. At the prolonged exposure to the increased water temperature, these indices approached critical levels. The number of embryo cells with nuclear fragmentation increased, which is evidence of the development of the processes directed to apoptosis. The destruction of embryo cell structures was registered at 32.0°C. The total volume of nucleoli in the somatic cells increased, which can be indicative of the increased synthesis of proteins probably involved in the processes of adaptation. A decrease in water temperature to the initial level of 25.0°C favored recovery of the structural and functional indices of Gammaridae genome. However, a high contribution of cell division disorders was still observed, which was accompanied by a significant decrease in the number of micronuclei.