Seawater Temperature Variations Research Articles

Retraction Note to: Change of offshore surface water temperature characteristics based on Bayesian regression and physical recovery of sports training

In this paper, a simple Bayesian distribution regression learning framework based on probability multi-scale kernel (RMK-BDR) is proposed to study the variation of offshore surface water temperature characteristics and the physical recovery of sports training based on Bayesian regression, which can solve the distribution regression problem of complex data. In the first stage of distributed regression learning, the average embedded estimator of the limited dimension of the same dimension is introduced. Through this method, the number of optimal center points can be adaptively selected according to the sample set, so as to avoid the influence on the sample size of inconsistent regression modeling. Climate change is the most important environmental problem in today’s society. The East China Sea and its adjacent Northwest Pacific have a very important impact on China’s climate. In recent years, it has gradually evolved into an area of international concern. The ocean can transport the heat storage to the atmosphere through the heat exchange between the ocean and the air, promote the movement of the atmosphere through the heat change, and affect the atmospheric cycle. Therefore, it is very important to study the annual and decades’ temporal and spatial variation of sea water temperature around China. At the same time, with the rapid development of basketball, the physical requirements of athletes are also higher and higher. There are many ways to improve the physical strength of basketball players. In addition to scientific training, nutritional support is also an important part. However, for a long time, the lack of understanding of nutritional support and the lack of relevant theoretical support have made nutritional support not fully applied in the basketball field.

Red Tide Events and Seasonal Variations in the Partial Pressure of CO2 and Related Parameters in Shellfish-Farming Bays, Southeastern Coast of Korea

Mixed results have been reported on the evaluation of the coastal carbon cycle and its contribution to the global carbon cycle, mainly due to the shortage of observational data and the considerable spatiotemporal variability arising from complex biogeochemical factors. In this study, the partial pressure of carbon dioxide (pCO2) and related environmental factors were measured in the Jinhae–Geoje–Tongyeong bay region of the southeastern Korean Peninsula in February 2014, August 2014, April 2015, and October 2015. The mean pCO2 of surface seawater ranged from 215 to 471 μatm and exhibited a high correlation with the surface seawater temperature when data for August were excluded (R2 = 0.69), indicating that the seasonal variation in CO2 could be largely attributed to the variation in seawater temperature. However, a severe red tide event occurred in August 2014, when the lowest pCO2 value was observed despite a relatively high seawater temperature. It is considered that the active biological production of phytoplankton related to red tides counteracted the summer increase in pCO2. Based on the correlation between pCO2 and temperature, the estimated decrease in pCO2 caused by non-thermal factors was approximately 200 μatm. During the entire study period, the air–sea CO2 flux ranged from −14.2 to 3.7 mmol m–2 d–1, indicating that the study area served as an overall sink for atmospheric CO2, and only functioned as a weak source during October. The mean annual CO2 flux estimated from the correlation with temperature was −5.1 mmol m–2 d–1. However, because this estimate did not include reductions caused by sporadic events of biological production, such as red tides and phytoplankton blooms, the actual uptake flux is considered to be higher. The mean saturation state (ΩAr) value of carbonate aragonite was 2.61 for surface water and 2.04 for bottom water. However, the mean ΩAr of bottom water was <2 in August and October, and the ΩAr values measured at some of the bottom water stations in August were <1. Considering that the period from August to October corresponds to the reproduction and growth stages of shellfish, such low ΩAr values could be very damaging to shellfish production and the aquaculture industry.

Assessing biofouling in Ocean Thermal Energy Conversion (OTEC) power plant – A review

Ocean Thermal Energy Conversion (OTEC) harnesses thermal energy stored at different seawater depths via power generation from a thermodynamic closed-loop cyclical system. Apart from its consistent energy generation, it could be diversified into other side industries, making OTEC an attractive and sustainable source of renewable energy. However, the process that utilises seawater as its main fluid is exposed to biofouling deposition due to unwanted growth and accumulation of biological elements on any contact surfaces, potentially affecting its efficiency and damaging equipment in the process. Considering that biofouling is an inevitable condition that may not be eliminated, a comprehensive study for assessing potential biofouling growth and deposition mechanism is a crucial step for strategizing effective biofouling management in a commercial and large-scale OTEC power plant facility. This review paper focuses on evaluating suitable biofouling assessment techniques specifically for a large-scale OTEC power plant facility. This is achieved by evaluating previous and proposed biofouling assessment techniques relevant to OTEC systems by focusing on their implementation under a realistic OTEC setup. The initial study indicated that the potential of biofouling deposition may be unavoidable in some sections in all OTEC models, despite biofouling-free design consideration. Previous OTEC biofouling studies were evaluated with reported physical and biological assessment approaches indicated the need to further improve these techniques especially in continuous and non-destructive methods. Therefore, several biofouling monitoring systems reported from other water treatment industries were considered for the OTEC systems, with findings indicated the importance of considering important OTEC operational parameters for feasible and robust biofouling monitoring systems. Two major parameters which are seawater intake flow rate and temperature variation at different seawater intake levels were evaluated under OTEC operational evaluation by considering examples of practices conducted in cooling water systems in the power plant industry. A realistic biofouling monitoring setup for mimicking continuous changes in biofouling deposition is required, in this case by side-connecting an operated OTEC power plant facility with a pilot plant setup or a side sampler. This step allows the application of proposed biofouling monitoring techniques under a realistic and uninterrupted biofouling deposition setup.

Cycle analysis and economic evaluation for seawater-LNG Organic Rankine Cycles

An Organic Rankine Cycle (ORC) has a variety of environmental and operating conditions, which result in different efficiency and net work of cycle. In this regard, it is important to determine the optimal operating conditions with the consideration of various operating variables since the outcomes of the low-grade waste heat recovery systems are low as well as highly dependent on the conditions. In this study, the ORC having seawater as a heat source and LNG cold energy as a heat sink is analyzed with cycle parameters as well as the environmental conditions such as seawater temperature. An ORC Economic evaluation Code (OEC) is developed to consider the effects of numerous parameters such as the pump outlet pressure, mass flow rate, pinch point, materials of the heat exchangers, the type of working fluid, cycle configuration, and seawater temperature simultaneously. Based on the analysis, an economic assessment is conducted, so we could find the optimal conditions for the designed ORC systems. Also, it is found that the seawater temperature variation could affect about 23.8% in terms of net work compared to fixed heat source temperature conditions.

Evidence of taxonomic non-equilibrium effects in the clumped isotope composition of modern cephalopod carbonate

The stable oxygen isotope composition (δ18O) of ammonites and belemnites is a common proxy for Jurassic and Cretaceous sea temperatures. The challenges and uncertainties associated with cephalopod δ18O and other proxy based paleotemperature reconstructions make cephalopods such as ammonites and belemnites a favourable target for carbonate clumped isotope paleothermometry. Our measurements of the clumped isotopic composition of modern cephalopods (Nautilus pompilius, Nautilus macromphalus, Nautilus belauensis and Sepia officianalis), however, confirm significant “vital effects” in clumped isotopic of cephalopod aragonite.We present the first intra-shell measurements of clumped isotopic composition of nautilus demonstrating that clumped isotope composition (∆47) is correlated with δ18O shell carbonate. We observe a decrease in ∆47 from juvenile to adult septa, which does not correspond with changes in surface seawater temperature or temperature variation on vertical migration of the nautilus within the water column. The clumped isotope composition of juvenile septa yield temperatures that are within error of growth temperature while most recently formed septa reflect growth temperatures 3–8 °C above the upper temperature limit of survival of the organism (27 °C). Non-equilibrium effects observed in the ∆47 of modern nautilus comprise up to a 29 °C overestimate in shell formation temperature.Combined δ18O and ∆47 measurements are used to differentiate between potential mechanisms that may generate non-equilibrium signatures observed. Non-equilibrium clumped isotope signatures may result from variations in the salinity of cameral fluid within nautilus chambers, dehydration of HCO3− and/or isotopic fractionation during CO2 diffusion across cell walls. The inter-skeletally variable non-equilibrium offsets in ∆47 of nautili aragonite observed in this study suggest that care must be taken when using the clumped isotope composition of cephalopod carbonate, in particular ammonite aragonite, as a paleotemperature proxy. Belemnite calcite and ontogenetically early septa of aragonitic ammonites may be feasible targets for paleotemperature reconstruction by carbonate clumped isotope thermometry.

Modeling and optimization of an ocean thermal energy conversion system for remote islands electrification

Electrification of remote zones is often characterized by high energy costs as a result of the fossil fuels supply and cost associated to its logistic. This study performs a theoretical model and optimization of an ocean thermal energy conversion (OTEC) system coupled to an organic Rankine cycle (ORC) generator for small scale applications in the San Blas archipelago (Panama). The gross electric power has been previously set at 125 kW for the eleven working fluids selected: ammonia, R152a, R1234yf, R1234ze, R125, R134a, R161, propane, isobutene, RE143a and decafluorobutane. Results show R1234yf gets the maximum thermodynamic and net electric efficiency (3.60% and 2.57%, respectively). Ammonia reaches the maximum net electric power (99.3 kW) and, thus, the lowest pumping losses (20.59% of the gross). Besides, despite decafluorobutane shows slightly lower electric power (98 kW) and efficiencies, this fluid does not present environmental hazardous features. Sensitivity analyses show that all performance parameters of the plant are strongly affected by deep and surface seawater temperature variation. Finally, for a surface seawater temperature of 30 °C and deep 5 °C, the net electric power reached is 94.6 kW for R1234yf, 99.3 kW for ammonia and 98.0 kW for decafluorobutane. The net electric efficiency is 2.57%, 2.53% and 2.42%, and the total area required by the heat exchangers is 890 m2, 940 m2 and 986 m2, respectively.

Calcification of planktonic foraminifer Pulleniatina obliquiloculata controlled by seawater temperature rather than ocean acidification

Abstract Planktonic foraminifera represent a major component of global marine carbonate production, and understanding environmental influences on their calcification is critical to predicting marine carbon cycle responses to modern climate change. The present study investigated the effects of different environmental influences on calcification of the planktonic foraminifer Pulleniatina obliquiloculata. By correcting the dissolution effect on the size-normalized weight (SNW) of P. obliquiloculata from deep-sea sediments, we provide a means of estimating initial size-normalized weight (ISNW) from which to assess secular changes in the degree of calcification of P. obliquiloculata. Core-top ISNW in P. obliquiloculata from the global tropical oceans is significantly positively correlated with calcification temperature, suggesting that temperature is the dominant control on calcification. Using Neogloboquadrina dutertrei SNW as an independent deep-water Δ[CO32−] proxy, we present an ISNW record for P. obliquiloculata from the western tropical Pacific since 250 ka. The response of ISNW to past seawater temperature variations further confirms the dominant influence of temperature on P. obliquiloculata calcification. A potential increase in calcification as a result of ocean warming may have reduced oceanic uptake of CO2 from the atmosphere and increased atmospheric pCO2, generating a positive feedback for global warming.

Temporal variation in daily temperature minima in coral reefs of Nanwan Bay, Southern Taiwan

Temporal variation in seawater temperature plays a crucial role in coral reef ecology. Nanwan Bay, Southern Taiwan is home to well-developed coral reefs, which frequently experience cold-water intrusions caused by internal wave-induced upwelling, that manifest in distinct daily temperature minima. These temperature minima and their associated sources were studied by recording in situ bottom temperatures and sea levels observed at depths of 5 and 30 m from May 2007 to September 2008. These data were then compared to the East Asian Seas Nowcast/Forecast System, and it was found that daily temperature minima presented large variations with magnitudes of 2–3 °C over periods from days to months. It was further demonstrated that the cold-water intrusions may have originated from depths of ~100 m and were strongly affected by westward propagating mesoscale eddies from the Pacific basin. An impinging warm anticyclonic eddy in July 2007 may have combined with the El Niño, resulting in temperatures surpassing 29 °C and degree heating days >4.0 °C-days at both depths, which were coincidental with a mass coral bleaching event. This eddy’s impact was additionally evident in high correlations between daily temperature minima and residual sea levels, suggesting that mesoscale eddies alter stratification, substantially influence temperature variation, and play important roles in understanding ecological processes on coral reefs.

Fine-scale delineation of Symbiodiniaceae genotypes on a previously bleached central Red Sea reef system demonstrates a prevalence of coral host-specific associations

Widespread coral bleaching occurred in the central Red Sea in 2010 and 2015. During both events, a cross-shelf and depth gradient of bleaching severity was identified within the Thuwal reef system, central Red Sea, Saudi Arabia. While bleaching and survival of coral taxa were monitored, neither in situ reef temperatures nor coral-associated algal communities (family Symbiodiniaceae) were characterized. Here, we determined coral host-associated Symbiodiniaceae communities and monitored temperatures along the same cross-shelf and depth gradient on six reefs in 2017 to better understand the role of these factors in the observed bleaching patterns and to generate a baseline for further studies. We characterized > 600 coral–algal associations across winter and summer in six genera of scleractinian coral (Pocillopora, Stylophora, Seriatopora, Galaxea, Gardineroseris, and Porites) and one fire coral (Family Milleporidae) using ITS2 next-generation sequencing in conjunction with the SymPortal analytical framework. We show that previous bleaching patterns correlate poorly with the largely coral host-specific structure of the 2017 Symbiodiniaceae community and are in better agreement with absolute and intraday sea water temperature variations monitored on the reefs. We demonstrate a greater distinctiveness of Symbiodiniaceae communities at the more severely bleached inshore reefs compared to those reefs further offshore. However, the potential Symbiodiniaceae community changes at these reefs prior to our sampling prevent us from evaluating this distinctiveness as determinative of the differences in bleaching severities. Based on our analyses, we discuss how fine-scale delineation of algal genotypes, including host-specific putative genotypes of Durusdinium trenchii that represent alluring targets for further taxonomic identification, corroborate a niche-adapted rather than generalist character of many coral–Symbiodiniaceae associations. In conclusion, as studies such as this one continue to build the global catalogue of coral–Symbiodiniaceae associations, we may be afforded a better oversight of how specialized coral–algal associations really are and how restricted their modification may be, both of which are critical considerations in predicting the adaptive potential of corals and the reef ecosystems they build.

Variation of seawater temperature and chlorophyll-a prior to and during upwelling event in Bali Strait, Indonesia: from observation and model

Coastal upwelling event can be observed clearly from drastic changes of seawater temperature and chlorophyll-a before and during the event. From observation and model output, time-series data of these variables provide important datasets to be used for further analysis, such as developing gaussian empirical model of net marine primary productivity (NPP). Here, the objectives of this study are to analysis variation of temperature and chlorophyll-a (chl-a) from both observation and model output datasets, and to evaluate model temperature and chl-a for estimating the NPP prior to and during the upwelling event in Bali Strait. The archive CTD collected in April, June and August 2013 and model output datasets were used in this study. It is shown that during peak of upwelling event in August 2013, observed temperature is minimum and chl-a is maximum in the upper 50 m depth. It is found surfacing isotherm of 25-26°C from sub-surface to sea surface. Furthermore, model output of temperature was in good agreement with observed data, complementing the evolution of upwelling for entire year. Estimated NPP from empirical model suggested that a high NPP distribution occurred in the eastern part of Bali Strait during peak of upwelling event.

Study on the local sea water temperature variation for the industrial water use of Al-Zour coastal area in Kuwait

Study on the local sea water temperature variation for the industrial water use of Al-Zour coastal area in Kuwait

High-resolution records of growth temperature and life history of two Nacella limpet species, Tierra del Fuego, Argentina

Stable isotope ratios in patelloid limpets of the genus Patella have been established as proxies for coastal environmental change at sub-monthly resolution along the eastern North Atlantic and Mediterranean Sea. Nacella deaurata (Gmelin 1791) and N. magellanica (Gmelin 1791) are common intertidal species of patelloid limpets inhabiting the coast of Tierra del Fuego, Argentina/Chile and are commonly found in Holocene archaeological deposits. Here, we examine oxygen and carbon isotope ratios (δ18Oshell and δ13Cshell, respectively) of modern specimens of N. deaurata and N. magellanica to test the hypotheses that: 1) they form their shells in isotopic equilibrium with ambient water; and 2) prominent growth lines form annually. Based on growth margin analysis of δ18Oshell values, we identified a positive offset of 1.3 ± 0.4‰ (N. deaurata) and 1.3 ± 0.3‰ (N. magellanica) from expected equilibrium, similar to other patelloid limpets. Because the offset is relatively consistent between observed and expected values, it can be taken into account to reliably reconstruct growth temperature. Seawater temperature estimated from oxygen isotope time series data falls within the observed range. Thus, N. deaurata and N. magellenica shells serve as reliable proxy archives of seasonal variation in coastal seawater temperature. Time series of δ13Cshell values do not vary seasonally in all shells; hence, the influence on its variation requires further study. The timing of prominent growth lines contextualized by the δ18Oshell time series form twice a year and therefore cannot be used to estimate lifespan. Future isotopic analysis of archaeological Nacella shells can potentially provide much needed information about Holocene climate change at sub-monthly resolution from high-latitude South American locations, and contribute to our understanding of human behavior and human-climate interactions.

Coral Reef Resilience in Taiwan: Lessons from Long-Term Ecological Research on the Coral Reefs of Kenting National Park (Taiwan)

Coral reefs in the Anthropocene are being subjected to unprecedented levels of stressors, including local disturbances—such as overfishing, habitat destruction, and pollution—and large-scale destruction related to the global impacts of climate change—such as typhoons and coral bleaching. Thus, the future of corals and coral reefs in any given community and coral-Symbiodiniaceae associations over time will depend on their level of resilience, from individual corals to entire ecosystems. Herein we review the environmental settings and long-term ecological research on coral reefs, based on both coral resilience and space, in Kenting National Park (KNP), Hengchun Peninsula, southern Taiwan, wherein fringing reefs have developed along the coast of both capes and a semi-closed bay, known as Nanwan, within the peninsula. These reefs are influenced by a branch of Kuroshio Current, the monsoon-induced South China Sea Surface Current, and a tide-induced upwelling that not only shapes coral communities, but also reduces the seawater temperature and creates fluctuating thermal environments which over time have favoured thermal-resistant corals, particularly those corals close to the thermal effluent of a nuclear power plant in the west Nanwan. Although living coral cover (LCC) has fluctuated through time in concordance with major typhoons and coral bleaching between 1986 and 2019, spatial heterogeneity in LCC recovery has been detected, suggesting that coral reef resilience is variable among subregions in KNP. In addition, corals exposed to progressively warmer and fluctuating thermal environments show not only a dominance of associated, thermally-tolerant Durusdinium spp. but also the ability to shuffle their symbiont communities in response to seasonal variations in seawater temperature without bleaching. We demonstrate that coral reefs in a small geographical range with unique environmental settings and ecological characteristics, such as the KNP reef, may be resilient to bleaching and deserve novel conservation efforts. Thus, this review calls for conservation efforts that use resilience-based management programs to reduce local stresses and meet the challenge of climate change.

Hydro-environmental Characteristics of Seawater around Boubyan Island, Kuwait Using Annual Variations of Seawater Temperature, Salinity and Tide Fluctuations

The temporal and spatial variations of seawater temperature, salinity, and tidal fluctuations are important parameters for understanding the hydrodynamic, water quality, and marine biological activity in the seawater. It is also important to study and understand the probability and statistical aspects of these parameters for the planning and implementation of different types of marine projects. These parameters were measured at five different locations around Boubyan Island, Kuwait, for a span of almost one year during 2015-16. Based on the analysis of the measured data, it is found that the seawater salinity has varied from 34.14 to 48.31 ppt. The seawater temperature is also found to vary from 10.83 oC to 35.67 oC. The seawater level has varied from -2.694 m to 2.378 m with respect to the mean sea level. It is found that the peak of the probability density of seawater level is flat valued, whereas the probability density of salinity and seawater temperature is multimodal. A comparison of present and past measured seawater temperatures revealed that in Khor Al-Sabiya, the seawater temperature is increasing at the rate of 0.034 oC/year, which clearly indicates the effect of global warming. A similar study reveals that the annual average increase in salinity at Khor Al-Sabiya is 0.38 ppt, which clearly indicates a significant reduction of freshwater flow from Shatt Al-Arab into the Arabian Gulf. Since Kuwait is investing in many projects around the Boubyan Island, the results of this study will be useful for the integrated and sustainable development of Boubyan and Failaka Islands in Kuwait.

Hydro-environmental Characteristics of Seawater around Boubyan Island, Kuwait Using Annual Variations of Seawater Temperature, Salinity and Tide Fluctuations

The temporal and spatial variations of seawater temperature, salinity, and tidal fluctuations are important parameters for understanding the hydrodynamic, water quality, and marine biological activity in the seawater. It is also important to study and understand the probability and statistical aspects of these parameters for the planning and implementation of different types of marine projects. These parameters were measured at five different locations around Boubyan Island, Kuwait, for a span of almost one year during 2015-16. Based on the analysis of the measured data, it is found that the seawater salinity has varied from 34.14 to 48.31 ppt. The seawater temperature is also found to vary from 10.83 oC to 35.67 oC. The seawater level has varied from -2.694 m to 2.378 m with respect to the mean sea level. It is found that the peak of the probability density of seawater level is flat valued, whereas the probability density of salinity and seawater temperature is multimodal. A comparison of present and past measured seawater temperatures revealed that in Khor Al-Sabiya, the seawater temperature is increasing at the rate of 0.034 oC/year, which clearly indicates the effect of global warming. A similar study reveals that the annual average increase in salinity at Khor Al-Sabiya is 0.38 ppt, which clearly indicates a significant reduction of freshwater flow from Shatt Al-Arab into the Arabian Gulf. Since Kuwait is investing in many projects around the Boubyan Island, the results of this study will be useful for the integrated and sustainable development of Boubyan and Failaka Islands in Kuwait.

Seasonal and interannual variation in the density of visible Apostichopus japonicus (Japanese sea cucumber) in relation to sea water temperature

Apostichopus japonicus (Japanese sea cucumber) is of ecological and economic importance in the coastal waters of Japan. To assess the apparent abundance of A. japonicus, density data of visible A. japonicus are required; however, the activity of this species on the sea floor changes with variations in sea water temperature. For example, at high sea water temperatures, A. japonicus takes shelter in the gaps of rocks or oyster shells. This change in its visibility on the sea floor makes it difficult to determine the apparent abundance of this species. In the present study, we aimed to clarify the optimal survey timing to assess the apparent abundance of A. japonicus based on the relationship between the density of visible A. japonicus and sea water temperature. Between 2010 and 2013, we evaluated how the density (ind. 100 m−2) of visible A. japonicus changes with sea water temperature in an area preferred by these organisms, Maizuru Bay, Kyoto, Japan, every 2 weeks. Seasonal changes in the density were consistent with seasonal variations in sea water temperature. Density increased when sea water temperature decreased and was at a maximum at minimum sea water temperatures. In addition, the density tended to change significantly over a short period. In some cases, the density after the lowest sea water temperature in March 2011 declined by half from 65 to 27 in just 2 weeks. Owing to considerable variations in the density of visible A. japonicus, we believe it is important to establish the appropriate survey timing to quantify the apparent abundance of this species, with our data suggesting that surveys should be performed during the season with the lowest sea water temperatures. Furthermore, at the lowest sea water temperatures in 2010, 2011, 2012, and 2013, the maximum densities were 99.0 (9.1 °C), 65.0 (9.7 °C), 41.3 (9.8 °C), and 8.7 (8.9 °C), respectively. Over 4 years, the density decreased to approximately 10% of that in the year with the peak density. Considering this decrease, it is suggested that A. japonicus in Maizuru Bay is overfished. Therefore, it is possible that the density of visible A. japonicus at the lowest sea water temperatures provides useful information for assessing the apparent abundance of this species.

Effects of temperature on the reproductive physiology of female elasmobranchs: The case of the narrownose smooth-hound shark (Mustelus schmitti)

The knowledge of how temperature influences elasmobranchs reproductive physiology allows a better understanding of their reproductive patterns. This study describes the relationship between temperature fluctuations and the plasmatic changes of the sex steroids related to reproduction: testosterone (T), estradiol (E2) and progesterone (P4), throughout the female reproductive cycle of the shark Mustelus schmitti. A total of 123 adult females were bi-monthly sampled in Buenos Aires, Argentina, coastal waters. Bottom temperatures were recorded at each sampling point and blood samples were taken from each female for plasma sex steroids measurement. Sex steroid plasma levels were analyzed in relation with maximum follicular diameter (MFD), uterosomatic index (USI, as indicator of pregnancy) and temperature using Generalized Additive Models. Plasmatic E2 and T increased during follicular growth until MFD reached 1.34 and 1.46 cm, respectively. Peak of T occurred at the follicular stage associated with parturition (MFD, 1.4–1.6 cm), just prior to final maturation and ovulation (MFD, 1.6–2.0 cm). Progesterone significantly increased at this last ovarian phase, while T and E2 decreased. The increase of USI with pregnancy was associated to a decrease in T and mainly E2 levels, while P4 remained unaffected. Prior to ovulation, T plasma levels decreased with temperature below to 13 °C and then increased progressively with a pronounced elevation above 17 °C, while E2 presented an opposite pattern. Progesterone plasma levels changed with temperature showing a similar pattern to that observed for T. Using M. schmitti shark as model species, this study shows a clear picture of how seawater temperature variations can affect the reproductive physiology in elasmobranch females. A hypothetical mechanism (based on T elevation driven by temperature increase and its connection by feedback with a P4 rise and parturition/ovulation induction) is proposed as evidence to support that the increase in temperature can trigger reproductive events in elasmobranchs. In addition to its ecological scope, this work contributes to reinforce the relatively scarce general knowledge of elasmobranchs reproductive physiology.

Macrobenthic diversity and sediment-water exchanges of oxygen and ammonium: Example of two subtidal communities of the eastern English Channel

In organic-rich shallow habitats, benthic macrofauna is known to play a major role in the geochemical functioning of surficial sediments through its metabolism, as well as its bioirrigation and/or bioturbation activity. In this paper, the effects of benthic macrofauna on metabolic fluxes at the sediment-water interface were studied at four dates, from winter to late summer, on two major macrobenthic communities of the eastern English Channel (macrotidal system): the fine sand Abra alba community (2 stations) and the sandy gravel Ophiothrix fragilis community (1 station). Oxygen and ammonium fluxes showed temporal changes that could be attributed to the variation of sea water temperature. Once the effect of temperature removed (using Q10 = 2.5), the average fauna mediated fluxes (FFauna) represented respectively 77% and 76% of average total fluxes. Considering the whole dataset, species number and biomass showed a significant correlation with fauna mediated fluxes of O2 and NH4+, while the relationships with abundance were not significant. The species composition of the community might influence ecosystem functioning, but in the present study, functional groups have a very poor relationship with FFauna (O2) and FFauna (NH4+). Despite the presence of engineer species, establishing general and simple rules to link macrofaunal parameters to functional attributes remains very difficult, suggesting that communities rather followed the idiosyncrasy and rivet hypothesis.

Stochastic Optimization of a Natural Gas Liquefaction Process Considering Seawater Temperature Variation Based on Particle Swarm Optimization

This paper presents a systematic stochastic optimization method for a dual mixed-refrigerant (DMR) process modeled with the simulator Aspen HYSYS. First, a base case design and an objective function are developed based on the simulator and an equation. Next, decision variables among many process variables are determined by a sensitivity analysis. Among the process variables, seawater temperature variation, which has a large impact on operation cost, is considered as a random variable. Since it is not possible to use a deterministic optimization solver for the simulator, a particle swarm optimization (PSO) technique, which employs a gradient-free optimization tool, is employed to solve a stochastic optimization problem. A case study shows the efficacy of the proposed algorithm. This method is general and can be applied to various processes modeled with commercial simulators.

The importance of local settings: within-year variability in seawater temperature at South Bay, Western Antarctic Peninsula

The Western Antarctic Peninsula (WAP) has undergone significant changes in air and seawater temperatures during the last 50 years. Although highly stenotherm Antarctic organisms are expected to be severely affected by the increase of seawater temperature, high-resolution datasets of seawater temperature within coastal areas of the WAP (where diverse marine communities have been reported) are not commonly available. Here we report on within-year (2016–2017) variation in seawater temperature at three sites on Doumer Island, Palmer Archipelago, WAP. Within a year, Antarctic organisms in South Bay were exposed to water temperatures in excess of 2 °C for more than 25 days and 2.5 °C for more than 10 days. We recorded a temperature range between −1.7° to 3.0 °C. Warming of seawater temperature was 3.75 times faster after October 2016 than it was before October. Results from this study indicate that organisms at South Bay are already exposed to temperatures that are being used in experimental studies to evaluate physiological responses to thermal stress in WAP organisms. Continuous measurements of short to long-term variability in seawater temperature provides important information for parametrizing meaningful experimental treatments that aim to assess the local effects of environmental variation on Antarctic organisms under future climate scenarios.