Increase In Water Temperature Research Articles

Critical temperatures and aerobic metabolism in post-larvae of Pacific white shrimp Litopenaeus vannamei (Boone, 1931).

Increasing water temperature because of climate change decreases the oxygen concentration while increasing the oxygen requirement of species in aquatic environments. Temperature is one of the most important environmental factors affecting the physiological functions of organisms, especially poikilothermic animals, such as shrimp at all levels. In intensive shrimp culture, it is of great importance to know the tolerable temperature range of cultured species and their metabolism since this affects the physiological condition. In this study, critical temperatures (CTM: CTmin and CTmax) of Pacific white shrimp, Litopenaeus vannamei, post-larvae (PL), were determined at different acclimation temperatures of 15, 20, 25, and 30°C. Lower and upper incipient lethal temperatures (ILT: LILT and UILT) were also calculated for the PL. The thermal windows of the PL were developed using the CTM and ILT values. The standard metabolic rate (SMR) of the PL was determined based on the oxygen consumption rate (OCR) at the different acclimation temperatures mentioned above. The acclimation temperature had a subsequent effect on the thermal tolerance and SMR of the PL (P < 0.01). The PLs of Pacific white shrimp have high thermal tolerance and can survive at extreme temperatures (CTmin and CTmax: 8.2-43.8°C) with their large dynamic and static thermal window areas of 1128 and 931°C2, respectively. The optimal temperature range for Pacific white shrimp PLs is the 25-30°C range, where a decrease in SMR is determined with increasing temperature. The result of this study reveals that a range of 25-30°C is optimal for effective PL culture of Pacific white shrimp.

A 1000-year record of paleoclimate and paleoenvironment change inferred from sedimentary organic matter in Lake Azuei, Haiti

We studied sediment organic matter (OM) to reconstruct the environment over the last millennium using a sediment core from Lake Azuei, Haiti, also known as “Etang Saumatre.” Chronology for the 84-cm-long core was established with 11 14C dates and 210Pb analysis. Total organic carbon (TOC) concentrations in the sediment were low (0.58 ‐ 4.89%), as were total nitrogen (TN) values (0.06 ‐ 0.40%). Carbon isotopic ratio (δ13C) values were relatively negative and C/N ratios were low, suggesting that algae and terrestrial C3 plants were the primary sources of OM in the lake sediment. The inverse relationship between the nitrogen isotopic ratio (δ15N) and TOC is related to denitrification in the sediment. We identified five stratigraphic zones using a δ13C vs. C/N cross diagram: 1) Medieval Climate Anomaly 1 (MCA1) (1000–1050 CE), 2) Medieval Climate Anomaly 2 (MCA2) (1050–1100 CE), 3) Transition period between Medieval Climate Anomaly and Little Ice Age (MCA-LIA) (1150–1400 CE) 4) Little Ice Age (LIA) (1400–1800 CE), 5) Current Warm Period (CWP) (1800–2000 CE). These stratigraphic zones correspond to three climate episodes. The first was applied MCA1 and LIA periods, when there was a decrease in TOC and TN as well as in plankton-derived OM. This was accompanied by an increase in δ15N, which suggests denitrification due to suboxic conditions, likely caused by an increase in lake water temperature and dry conditions. The second climate episode was the MCA-LIA transition period and was characterized by high variability of TOC, δ13C and δ15N. The organic matter deposited during this period appeared to be a mixture of material originating from both autochthonous phytoplankton and allochthonous C3 plants. There was climate instability during this period, with alternations between wet and dry conditions, and thus likely variations in lake level. The third climate episode, the MCA2 and CWP periods, was characterized by an increase in TOC and TN values, and decrease in δ13C and δ15N values. This was chiefly attributable to more organic material input which was derived from C3 terrestrial vegetation growing around the lake. A decrease in δ15N indicated a reduction in denitrification, further suggesting an increase in the input of organic matter. Sedimentation during these periods occurred when there was more transport related to wet conditions.

Experimental studies on the enhancement in discharging characteristics of phase change material with steatite nanoparticles

Phase change materials are latent heat energy storage systems that can store huge quantities of thermal energy in a small volume. Latent heat energy storage systems are complicated to design due to the low thermal conductivity of phase change materials for discharging to enhance the heat capacity and latent heat storage. The objective of the study is to examine the discharging of phase change material in a latent heat energy storage system for maintaining the temperature of the water. Paraffin wax utilized as the phase change material due to its higher latent heat capacity. The experiments were performed with the flow of the hot water through a phase change material container by using a copper tube to enhance the discharging of phase change material during solidification to maintain the temperature of the water. Furthermore, the steatite nanoparticle has been dispersed with phase change material to enhance the discharging of characteristics. The steatite nanoparticle has been selected due to its low thermal conductivity, and the weight percentages nanoparticles were varied viz. 10 %, 20 %, 30 %, and 40 %. The increase in water temperature from 0.1 °C to 1 °C has been taken 7 h by enhancing the discharging of phase change material with various concentrations of the steatite nanoparticle. The work shows the significant discharging characteristics of phase change material with steatite nanoparticles. The nano-phase change material has the potential to maintain the temperature of water without any external energy for a particular duration, which shows cost-effectiveness.

Biogeographic Analysis Suggests Two Types of Planktonic Prokaryote Communities in the Barents Sea.

The Barents Sea is one of the most rapidly changing Arctic regions, with an unprecedented sea ice decline and increase in water temperature and salinity. We have studied the diversity of prokaryotic communities using 16S metabarcoding in the western and northeastern parts of the Barents Sea along the Kola Section and the section from Novaya Zemlya to Franz Joseph Land. The hypothesis-independent clustering method revealed the existence of two distinct types of communities. The most common prokaryotic taxa were shared between two types of communities, but their relative abundance was different. It was found that the geographic location of the sampling sites explained more than 30% of the difference between communities, while no statistically significant correlation between environmental parameters and community composition was found. The representatives of the Psychrobacter, Sulfitobacter and Polaribacter genera were dominant in samples from both types of communities. The first type of community was also dominated by members of Halomonas, Pseudoalteromonas, Planococcaceae and an unclassified representative of the Alteromonadaceae family. The second type of community also had a significant proportion of Nitrincolaceae, SAR92, SAR11 Clade I, NS9, Cryomorphaceae and SUP05 representatives. The origin of these communities can be explained by the influence of environmental factors or by the different origins of water masses. This research highlights the importance of studying biogeographic patterns in the Barents Sea in comparison with those in the North Atlantic and Arctic Ocean prokaryote communities.

Assessment of Osteobrama belangeri (Pengba), a high-value medium carp endemic to North-east India for thermal tolerance limits

Critical thermal maxima (CTmax), lethal temperature maxima (LTmax), opercular respirationrate (ORR - movement of operculum per minute), temperature quotient (Q10) and stressmarkers of Osteobrama belangeri (Pengba), a high-value medium carp endemic tohilly ecosystems of North-east India, were examined with the aim of understanding itsaquaculture potential and management requirements in the event of a temperature rise.Fish (7.82±0.35 cm/4.64±0.36 g) were acclimatised at 20, 25 and 30°C in insulated tanks(10 fish per tank) for 30 days. They were then exposed to a water temperature increase(@ 1°C day-1) using a locally-fabricated thermostat and assessed for CTmax, LTmax and ORR.As the acclimation temperature increased from 20 to 30°C, CTmax, LTmax and ORR of thefish significantly increased. Regression analysis indicated a strong positive correlationbetween acclimation temperatures and CTmax (y = 0.22x + 33.55, R² = 0.97) and LTmax(y = 0.27x + 32.86, R² = 0.99). Fish blood samples were collected at the endpoints ofCTmax and LTmax and analysed for serum alkaline phosphatase (ALP) activity. The resultsindicated that the fish experienced maximum stress at an acclimation temperature of 30°C(ALP: 38.7 U l-1), followed by 25°C (35.6 U l-1) and 20°C (31.7 U l-1). The results suggestedthat a water temperature increase above 30°C can impair the physiology of O. belangeri andconsequently, their reproductive competence. Therefore, in such events, proper managementand additional care are necessary to protect them from extinction. Keywords:Critical thermal maxima, Lethal temperaturemaxima, Osteobrama belangeri, Thermal limit,Temperature quotient

Application of a soil temperature model for simulating the effect of dis-trict heating pipes on drinking water pipelines

According to Dutch legislation the drinking water temperature is required to be below 25°C at the tap to meet legionella prevention [1]. This requirement possibly limits the storage of heat in the subsoil and the transport of heat through pipelines. In order to asses the impact of heat transport pipelines on the drinking water temperature in adjacent drinking water pipelines, a soil temperature model was developed. This coupled micro-climate [2] and heat transport model relates atmospheric conditions to the temperature distribution in the sub-surface [3]. The subsurface part of the model is based on a finite element discretization of the transient heat conduction equation in a single phase material. The coupling of the subsurface part of the model with atmospherical part of the model requires that the sensible heat flux, the latent heat flux, net radiation and the subsurface heat flux are in equilibrium at the land surface. Simulation periods of a number of years are discritized in time steps of one hour. The model is validated by comparing the model results with a large number of field measurements in the Dutch city Rotterdam-Kralingen [3].&#x0D; The validated model is used to predict the drinking water temperature in transport, primary and secondary pipeline networks. The transport networks supply heat and water to the primary networks. Primary networks distribute their heat and water to secondary networks that transport it to buildings.&#x0D; with and without heating pipelines parallel to drinking water pipelines, with a limited flow of drinking water. The inner diameter of the heat supply and return pipelines, which are usually located close to each other, is 160.3 mm. The heat supply temperature is 90°C and the return temperature is 70°C. The inner diameter of the drinking water pipelines is 152 mm. The heat transport pipelines consist of an inner steel pipe with a wall thickness of 4 mm, a PUR isolation of 56 mm and a PE sleeve of 4 mm. The finite element discretization captures the geometry of the insulated pipeline and associated effective thermal properties. Drinking water pipelines have a PVC wall with a thickness of 4 mm. The drinking water pipeline cover depth is 1.00 m, the distance in between the drinking water pipeline and heat return pipeline is 0.75 m and the soil cover of the heat supply pipelines is 1.00 m. Tiles cover a dry sandy soil for which the specific heat capacity is 800 J/kgK, the thermal conductivity is 1.6 W/mK and the density of the soil is 1600 kg/m3. The figure shows a seasonal variation of the drinking water temperature of 13.8°C and an increase of the drinking water temperature due to the presence of the heat transport pipelines of 2.0°C, which is almost constant throughout the year. The maximum drinking water temperature is found in August and amounts to 23.8°C if the heat pipelines are absent and 25.8°C if they are present.&#x0D; Table 1 presents the results of a study with variation of the drinking water pipeline soil cover, the distance in between drinking water pipeline and heat return pipeline and the soil cover of the heat supply pipelines. Based on this table decisions can be made on the type of construction and the effect of the heat transport pipelines on adjacent drinking water pipelines.&#x0D; The table shows that the cover depth of the drinking water pipeline strongly influences the increase of the drinking water temperature due to atmospheric conditions. A decrease of the soil cover from 2.00 m to 0.75 m raises the maximal temperature by 4.2°C. The presence of the heat transport pipelines increases the temperature of the drinking water by 1.7°C for the case of a small cover depth and 2.1°C for a large cover depth. A decrease of the distance in between the drinking water pipeline and the heat return pipeline from 2.5 m to 0.25 m raises the maximal drinking water temperature by 2.6 °C. The calculation results show that the drinking water temperature is not sensitive to the proposed cover depth variation of the heat supply pipelines. The computational results for all networks considered, are collected in an expert tool that can be accessed via: https://www.tkiwatertechnologie.nl/projecten/opwarming-van-drinkwater/.

Intraregional variability of exotic and native zooplankton in Basque coast estuaries (inner Bay of Biscay): effect of secondary dispersion, estuary features and regional environmental gradients

The zooplankton of five estuaries of the Basque coast (southeast Bay of Biscay) was surveyed in summer 2019 to check the intraregional spread of exotic species and analyse the cross-estuary differences in brackish and neritic communities related to the arrival of exotic species and the summertime geographic gradient of water temperature. Results revealed that all the studied estuaries have been colonized by Oithona davisae but not by Acartia tonsa and Pseudodiaptomus marinus. Environmental constraints due to estuarine hydrological features partly explained such differences, and the role of secondary spread opportunities remained less clear. Cross-estuary differences in the brackish community mainly reflected changes in the dominance of the native species Acartia bifilosa relative to different exotic copepod species. The neritic holoplankton differed in the contribution of thermophilic species in agreement with the thermal west–east increase of surface water temperature in the inner Bay of Biscay in summer. The detection of large numbers of larvae of the exotic crab Rhithropanopeus harrisii only in one of the estuaries highlighted the role of exotic benthic species in enhancing intraregional differences in estuarine meroplankton. Differences in the dominance of neritic or brackish species as a function of salinity and distance from coastline were also explored.

Synergistic Effects of Climate Change and Alien Fish Invasions in Freshwater Ecosystems: A Review

The interaction between climate warming and alien fish invasions could have severe consequences in inland waters, which represent isolated environments with high biodiversity richness. Due to the current climatic trend, increasing water temperatures and salinization, shorter ice cover period, and altered flow regimes are predicted for these environments. The aim of this review is to offer a comprehensive analysis at a global scale of the recent studies available in the literature, focused on the responses of invasive freshwater fish to the effects of climate change in both lotic and lentic environments. To achieve this purpose, we selected 34 relevant papers, using the Scopus and Google Scholar database. New alien species establishment, distribution range expansion of species already introduced, and exacerbating impacts on freshwater ecosystems and the native fish communities they host were included in the topics covered by the analyzed papers. Despite the uncertainties related to the unpredictability with which the effects of global warming will occur, the findings of the selected studies served as a support to evaluate conservation and management implications, with particular reference to possible mitigation strategies.

Molecular Dynamics Simulation Study on Adsorption Characteristics of Illite for Hg2+

The Three Gorges Reservoir area of the Yangtze River has formed vast riverine fallout zones as a result of its periodic water storage and flood discharge operations, and the main constituents of this area are quaternary loose clays. It is important to study the microscopic characteristics of clay minerals in these fallout zones and their adsorption properties of Hg2+ to guide the environmental safety of the fallout zones in the Three Gorges Reservoir area. In this context, the authors of this paper used X-ray diffraction (XRD) experiments to reveal the main clay mineral compositions in the fallout zones and then constructed the molecular model structures of the clay minerals based on molecular dynamics theory and studied the adsorption characteristics of these clay minerals with Hg2+ in depth. The results show that the main clay minerals in the Three Gorges Reservoir area fallout zone include illite, illite-mixed layer and green-mixed layer, in which the content of illite ranges from 21% to 54%. Taking illite as the study object, the heat of adsorption of Hg2+ in illite ranged from 14.83 kJ·mol−1 to 31.92 kJ·mol−1, which is a physical adsorption. The heat of adsorption was mainly affected by the water content and had little relationship with temperature. With the gradual increase in water content, the heat of adsorption gradually decreases. The adsorption amount of Hg2+, on the other hand, is jointly affected by water content and temperature and decreases with the increase in water content and temperature; under natural environmental conditions (P = 0.1 Mpa), the adsorption characteristics of Hg2+ in illite change with the change in water content. When the water content was between 0% and 6.95%, the increase in water content led to an increase in the interlayer spacing of illite, and the adsorption of Hg2+ in illite was in a monolayer state, with the adsorption peaks located from 4.5~5.5 Å. When the water content increased to 6.95% to 13.90%, the layer spacing of illite reached the maximum, and the adsorption of Hg2+ in illite transitioned from a monolayer to a bilayer, with the adsorption peaks located between 5 Å and 9~10 Å, respectively. When the water content was further increased to 13.90% to 20.85%, the increase in water content instead led to a slight decrease in the layer spacing of illite, showing a tendency of transitioning from a bilayer to a monolayer adsorption layer, which at the same time changed the number of adsorption layers of Hg2+; the study also revealed that the interaction between illite and Hg2+ was regulated by van der Waals and Coulomb forces, whereas the increase in temperature promoted the Hg2+ +diffusion, and an increase in water content inhibits the diffusion of Hg2+. In summary, these findings provide valuable theoretical support for solving the problem of Hg2+ pollution in the Three Gorges Reservoir Decline Zone.

Prevalence and effects of a parasitic trematode on the blue mussel, Mytilus edulis, in the Boston Harbor

The blue mussel, Mytilus edulis, is a keystone species in the North Atlantic that plays critical roles in nutrient cycling, water filtration, and habitat creation. Blue mussel populations have declined significantly throughout the North Atlantic due to various factors, including habitat loss, pollution, increasing water temperature, and parasites. One parasite is Proctoeces maculatus, a digenetic trematode, which uses M. edulis as an intermediate host. This parasite causes reduced growth, castration, and death in mussels. The range of P. maculatus has expanded northward from Cape Cod, MA to Maine which may be associated with rising temperatures in the Gulf of Maine. To evaluate the negative impacts of P. maculatus on mussels, we analyzed its infections in M. edulis throughout the Boston Harbor, MA. P. maculatus was present in every population and time point analyzed, with approximately 50% of mussels in the harbor infected. The parasite reduced gonadal development in infected mussels, which could lead to decreased fecundity. Severe P. maculatus infections induced a stress response, indicated by increased HSP70 expression. We developed a non-destructive hemolymph-based assay to determine if mussels are infected with P. maculatus, thus speeding up the evaluation process and eliminating the need to sacrifice individuals. With P. maculatus’ continued expansion northward, more mussel populations will be under threat from this parasite.

Population and Transcriptomic Changes of the Tropical Fish Parasite Caligus confusus (Copepoda: Caligidae) with Seasonal Variations in Sea Temperature

Fish–parasite systems could be subject to two scenarios under climate change: (i) increased water temperature might enhance parasite metabolism, allowing the parasite to spread rapidly; (ii) parasitism could decrease if the optimal temperature for growth and transmission is exceeded. Sea lice are parasitic copepods commonly found on marine fish in tropical regions, yet their biology remains poorly investigated. In this study, we analyzed the changes in infection levels and the transcriptomic response of the tropical sea louse Caligus confusus to two seasonal seawater temperatures (30 °C, “warm”, and 21 °C, “cold”). The prevalence of C. confusus was significantly higher in the colder water. A de novo transcriptomic analysis of C. confusus, the first for a tropical sea louse, revealed 426 over-expressed and 1402 down-expressed transcripts at the lower temperature. In particular, we observed over-expression of transcripts encoding vitellogenins (vit-1, vit-2, vit-4, and vit-6) and matrix metalloproteinases (mmp-2 and mmp-9), which are involved in reproduction and development. These results suggest that the cold tropical season physiologically favors C. confusus and that low temperature favors embryo development, which might ultimately lead to a higher prevalence. It is possible, therefore, that climate change could reduce some tropical sea lice populations during extreme warming events.

Radiolaria and Phaeodaria (siliceous Rhizaria) in south-western and northern Norwegian fjords during late summer 2016: dominant species and biomass in shallow-water assemblages

To determine the present-day community composition of siliceous Rhizaria (Radiolaria and Phaeodaria) in Norwegian fjords, plankton tows were conducted in south-western and northern Norwegian fjords in September 2016. The mean total abundance of radiolarians was 306 m–3 in the Sognefjord complex, which was the southern research site, and, in the north, 945 m–3 in Malangen and 89 m–3 in Balsfjord, both above the Arctic Circle. Sticholonche zanclea was the most abundant radiolarian in the Sognefjord complex and Malangen, accounting for 78–100% (mean 89%) of radiolarian abundance. The mean total abundance of phaeodarians was 1554 m–3 in the Sognefjord complex, 51 m–3 in Malangen and 11 m–3 in Balsfjord. Medusetta arcifera was the most abundant phaeodaria in the Sognefjord complex, accounting for &gt;99% of phaeodarian abundance, but was absent in Malangen and Balsfjord, where Protocystis tridens accounted for &gt;96% of phaeodarian abundance. The carbon biomass of S. zanclea and M. arcifera was 188 and 438 µg C m–3, respectively, which is similar to and 8.6 times higher than, respectively, that of phaeodarians &gt;1 mm in the western North Pacific, suggesting that M. arcifera contributes to organic carbon transport in the Sognefjord complex. Amphimelissa setosa (Nassellaria, Radiolaria), which was a dominant species in the study area in 1982–83, was absent in the present study in all sampled fjords. This could have been caused by the approximately 2 °C increase in water temperature that has occurred since 1990 and can be taken as evidence of a climate-change-associated local temperature rise linked to the warming of advected Atlantic Water.

Effect of Climate Change on Water Temperature and Stratification of a Small, Temperate, Karstic Lake (Lake Kozjak, Croatia)

As closed systems, lakes are extremely vulnerable to climate change. Understanding the response to climate change is crucial for effective management and conservation of the lakes and their associated ecosystems. This study focuses on Lake Kozjak, Croatia, a small lake belonging to the Plitvice Lakes system. This system represents a unique hydrogeological karstic phenomenon, closely dependent on a delicate biochemical balance necessary for tufa formation. We apply a simple one-dimensional model, SIMO v.1.0, to predict future water temperature in Lake Kozjak under three scenarios (RCP2.6, RCP4.5 and RCP8.5) from 2006 to 2100. The model was calibrated using measured water temperature profiles and meteorological data from a nearby station. In addition to analyzing the average temperatures of the epilimnion, hypolimnion and the whole lake, we also studied the surface and bottom layer temperatures and their relation to specific forcing parameters. The Schmidt stability index was used as a quantitative indicator to assess lake stability. The simulation results indicate average lake water temperature increase of 0.51, 1.41 and 4.51 °C (100 y)−1 for RCP2.6, RCP4.5 and RCP8.5, respectively. This increase in the water temperature is not accompanied by a substantial strengthening of stratification under RCP2.6 and RCP4.5 scenarios due to the temperature raise being present both in the epilimnion and hypolimnion. However, significant lengthening of the stratification period is observed even for the most stringent scenario, 16, 28 and 47 d (100 y)−1 for RCP2.6, RCP4.5 and RCP8.5, respectively. The predicted water temperature increase and prolonged stratification period may carry serious ecological and environmental implications.Highlights• Mean lake water temperature is projected to increase by 0.51 to 4.51 °C (100 y)−1.• Baseline scenario surface temperature increase of 5.2 °C (100 y)−1 is predicted.• Stratification period is predicted to lengthen by 16 (RCP2.6) to 47 days (RCP8.5).• Substantial stratification strengthening is expected only under RCP8.5.

Potential water‐related risks to the electric power industry associated with changing surface water conditions

AbstractThis study identifies and summarizes potential risks to operations, regulatory compliance, supply chains, and infrastructure of the electric power industry from changing surface water conditions resulting from global climate change. The results help inform companies/utilities seeking to incorporate climate change risk in their planning and decision‐making processes by ranking risk severity and likelihood of occurrence on both a regional basis and by risk receptor. The assessment includes identification of potential risks to: (1) thermal generating, (2) hydroelectric, (3) land‐based renewable generating, and (4) transmission and distribution assets. These risks may result from such projected changes as reduced water availability (e.g., for hydroelectric or once‐through cooling), increased water temperatures (e.g., decrease in cooling efficiency, inability to meet discharge permit conditions), increased flood severity (e.g., increased streambank erosion and/or damage to river‐adjacent infrastructure), and decreased water quality (e.g., from increased transport of sediment and dissolved solids). The potential risks identified from this qualitative risk‐assessment are documented in a graphical format depicting both severity and likelihood. This approach allows for comparison of risks across a portfolio and for future prioritization of adaptation strategies. A total of 32 risks were identified in the study, including nine risks to infrastructure, six risks to operations, four risks to supply chain, and 13 environmental/regulatory risks.

Modeling the Distribution of Atlantic Croaker and Spot in a Dynamic Seascape Using Metabolic Scope

In estuarine and coastal systems, anthropogenic activities and directional changes in global air temperatures have led to increased water temperatures, as well as increased frequency and severity of episodic hypoxia. These alterations have had population-level effects on aquatic organisms, including changes in species-specific distributions. Because physiology is the transfer function connecting environmental conditions to individual behaviors and eventually to population-level effects, we used individual-based models (IBMs) that incorporate changes in metabolic scope as motivation for movement. Our objective was to investigate the effects of temperature and hypoxia on the distribution of Atlantic croaker and spot in Chesapeake Bay. We compared the predicted monthly fish distributions from the IBMs with apparent fish distributions recorded by the VIMS Juvenile Fish Trawl Survey during 1988–2014. IBMs failed to reproduce accurately the apparent spatial distributions of Atlantic croaker and spot. More specifically, compared with the trawl survey, IBMs predicted larger proportions of these two species would be captured in the lower regions of Chesapeake Bay and smaller proportions in the York and Rappahannock rivers. We postulate that, because similar thermal and oxygen conditions were occupied by fish in the IBMs and in the wild, temperature may not be the most important factor motivating the movement of Atlantic croaker and spot in Chesapeake Bay, and other spatial factors (e.g., prey availability) act in concert with temperature and hypoxia to determine the spatial distributions of Atlantic croaker and spot in Chesapeake Bay. Alternatively, surveys used to estimate species occurrences could be biased if gear vulnerability is affected by temperature or oxygen conditions (or both). Additional research is needed to clarify which condition is true or if a combination of these factors (and others) led to discrepancies between predicted and apparent fish distributions based on trawl survey data.

Triggers affecting crayfish burrowing behaviour

Surface water inhabiting crayfish are well-known for the impact on their surroundings. This impact has been related to loss of biodiversity and deteriorating water quality for invasive crayfish. Crayfish dig burrows for various reasons like lack of natural shelters, avoiding an upcoming drought, or high crayfish density and this may lead to increased sediment transport and accelerated bank instability. All crayfish are considered to have burrowing capability, but not all species have been observed burrowing. Studies comparing this behaviour among different species in standardized ways are scarce. Crayfish burrowing was investigated under standardized laboratory conditions to reveal differences among species and their sex. All studied species occur in the Netherlands and were the native Astacus astacus (Linnaeus, 1758), the Eurasian Pontastacus leptodactylus (Eschscholtz, 1823) and the invasive North American Faxonius virilis (Hagen, 1870), F. limosus (Rafinesque 1817), Pacifastacus leniusculus (Dana, 1852), Procambarus acutus (Girard 1852), and P. clarkii (Girard, 1852). As burrowing triggers were evaluated presence of shelter, increased light intensity, increased water temperature, and increased crayfish density. Results showed species-specific and sometimes sex-specific differences in burrowing behaviour among crayfish. The response to burrowing triggers was also species-specific and no two species reacted identical to all triggers. Absence of shelter was a strong driver to burrow for A. astacus, F. limosus and F. virilis, while increased light intensity triggered burrowing behaviour in P. leptodactylus, P. acutus and P. clarkii and lowered activity of F. limosus. Burrowing behaviour of P. clarkii was mostly influenced by increased water temperature. Significant differences between females and males were observed for P. leptodactylus, P. leniusculus and P. acutus in the shelter, increased density and increased water temperature treatment, respectively. Understanding the triggers that invoke burrowing may help managing populations of these invasive species.

Carbonate Chemistry and the Potential for Acidification in Georgia Coastal Marshes and the South Atlantic Bight, USA

In coastal regions and marginal bodies of water, the increase in partial pressure of carbon dioxide (pCO2) in many instances is greater than that of the open ocean due to terrestrial (river, estuarine, and wetland) influences, decreasing buffering capacity and/or increasing water temperatures. Coastal oceans receive freshwater from rivers and groundwater as well as terrestrial-derived organic matter, both of which have a direct influence on coastal carbonate chemistry. The objective of this research is to determine if coastal marshes in Georgia, USA, may be “hot-spots” for acidification due to enhanced inorganic carbon sources and if there is terrestrial influence on offshore acidification in the South Atlantic Bight (SAB). The results of this study show that dissolved inorganic carbon (DIC) and total alkalinity (TA) are elevated in the marshes compared to predictions from conservative mixing of the freshwater and oceanic end-members, with accompanying pH around 7.2 to 7.6 within the marshes and aragonite saturation states (ΩAr) <1. In the marshes, there is a strong relationship between the terrestrial/estuarine-derived organic and inorganic carbon and acidification. Comparisons of pH, TA, and DIC to terrestrial organic material markers, however, show that there is little influence of terrestrial-derived organic matter on shelf acidification during this period in 2014. In addition, ΩAr increases rapidly offshore, especially in drier months (July). River stream flow during 2014 was anomalously low compared to climatological means; therefore, offshore influences from terrestrial carbon could also be decreased. The SAB shelf may not be strongly influenced by terrestrial inputs to acidification during drier than normal periods; conversely, shelf waters that are well-buffered against acidification may not play a significant role in mitigating acidification within the Georgia marshes.

Artisanal Inland Water Fishing and Challenges of Livelihood Sustainability in Ibi Local Government Area, Taraba State Nigeria

This study examined challenges of livelihood sustainability from artisanal inland water fishing activities in Ibi LGA, Taraba State, Nigeria. Descriptive survey design was adopted. Purposive sampling was used in selecting 406 respondents from 12 communities in 6 political wards of the LGA. Descriptive statistics was used to analyse 401 questionnaires retrieved. Findings of the study reveal decline in daily fish catch from three baskets 10 years ago to only one basket presently. Also, income from fishing has declined from ₦150,000 ($192) monthly 10 years ago to less than ₦50,000 ($64) presently. Factors responsible for decline in fish catch include rising water level, temperature increase, pollution, climate change, seasonality and unsustainable fishing practices. The unsustainable fishing practices include use of chemicals, small size nets and mosquito nets in fishing. The results reveal that fishermen engaged in non-fishing activities, fish farming and construction of fishing ponds along the floodplain as a way of achieving livelihood sustainability. Challenges of livelihood sustainability include seasonality of fishing activities, decline in fish stocks, use of traditional fishing methods and unsustainable fishing practices among others. The study recommend the need to enforce extant laws on fishery protection, enlightenment campaign, and government support to fishing cooperatives.

Prediction on Filtration Period of Granular Bed Filter Used in Purifying Produced Water in Oil Field

Summary The granular bed filter can purify the water produced in the crude oil production process by adsorbing oil droplets and suspended solids. A regeneration operation is needed to clean the granular media and recover filtration capacity after a certain operation duration. Currently, filtration models are mainly used for one type of particle removal, with few applications in the filtration system of produced water containing oil droplets and suspended solids. However, the different deposition morphologies of oil droplets and suspended solids in the filter bed can affect the prediction of the filtration process. In this work, we develop a transient filtration model based on the multiphase system transport equations coupled with the filtration rate and momentum exchange equations to predict simultaneously the effluent concentration and the pressure drop buildup, which considers the effect of deposition morphologies of oil droplets and suspended solids on filtration behaviors. The model hypothesizes that particle removal occurs through deep bed filtration mechanisms, and initial filtration coefficients are predicted by trajectory analysis without relying on experimental data. After that, we propose a method for predicting the filtration period, and analyze the effect of particle size and water temperature on the filtration process. Results show that the filtration process can be divided into two major stages—the main filtration zone migration, followed by the saturation front migration. With an S-shape increase in the effluent concentration, the pressure drop of the filter bed increases in a parabolic shape. When the diameter median of suspended solids is 5 μm, and the water temperature is 20°C, the filtration period was determined to be 24 hours to meet both water quality and maximum usable pressure drop of 20 kPa. With the increase in non-Brownian suspended solid size, the interception and gravitational forces increase the removal efficiency of suspended solids, which results in a slight decrease in the removal efficiency of oil droplets and an increase in the pressure drop of the filter bed. As the water temperature increases, the viscosity of the produced water decreases, and the oil droplets and suspended solids are more easily removed, but the pressure drop of the filter bed increases. In this work, we provide new ideas and methods to properly design, operate, and manage filters in a sustainable and energy-efficient way.

Investigation of Proliferative Kidney Disease in Brown Trout and Habitat Characteristics Associated with a Swiss Wastewater Treatment Plant

Wastewater treatment plants (WWTP) play a critical role in mitigating adverse environmental impacts of urban and industrial wastewater by removing pollutants and reducing the risk of contamination. Discharges of treated effluents from WWTPs can still have significant effects on freshwater ecosystems, particularly on sensitive species like brown trout. We analyzed the effects of a modern WWTP on a freshwater ecosystem, studying fish biodiversity and biomass, the occurrence of the parasitic disease Proliferative Kidney Disease (PKD) on brown trout, river water temperatures throughout the year and fish habitat and diversity. No major differences between up- and downstream of the WWTP were observed in habitat structure and attractiveness, fish biomass and species diversity, nor in PKD prevalence or intermediate host presence. However, immediately at the WWTP’s effluent and continuing downstream, the water temperature rose by almost 1 °C. While WWTPs are crucial for reducing the environmental impact of urban and industrial wastewater, their effluents can still have important consequences for freshwater ecosystems. Brown trout are particularly susceptible to increases in water temperature, especially regarding PKD severity and consequent mortality. To ensure the long-term health and sustainability of freshwater ecosystems, it is imperative to improve measures to minimize water temperature rises and mitigate downstream cascade effects on sensitive organisms like brown trout.