Increasing Seawater Temperature Research Articles

Metagenomics reveals bacterioplankton community adaptation to long-term thermal pollution through the strategy of functional regulation in a subtropical bay

Thermal effluents from coastal nuclear power plants have led to undesirable pollution and subsequent ecological impacts on local marine ecosystems. However, despite the ecological importance, we know little about the impacts on functionality of bacterioplankton subjected in systems with long-term thermal pollution. We used metagenomic sequencing to study of the effect of thermal pollution on bacterioplankton community metagenomics in summer in a subtropical bay located on the northern coast of the South China Sea. Thermal pollution (>15 y), which resulted in an increase in the summer seawater temperature around 8°C and caused seawater temperature up to approximate 39°C, significantly decreased bacterioplankton metabolic potentials in photosynthesis, organic carbon synthesis, and energy production. The bacterioplankton community metagenomics underwent a significant change in its structure from Synechococcus-dominant autotrophy to Alteromonas, Vibrio, and Pseudoalteromonas-dominated heterotrophy, and significantly up-regulated genes involved in organic compound degradation and dissimilatory nitrate reduction for the matter and energy acquisition under thermal pollution. Moreover, the bacterioplankton community metagenomics showed an up-regulation with heating of genes involved in DNA repair systems, heat shock responsive chaperones and proteins, and proteins involved in other biological processes, such as biofilm formation and the biosynthesis of unsaturated fatty acids and glycan, to adapt to the thermal environment. Collectively, it indicates a functional regulation of bacterioplankton adaptation to high-temperature stress, which might advance the understanding of the molecular mechanisms of community adaptation to global extreme warming in aquatic ecosystems.

An Increase of Seawater Temperature Upregulates the Expression of Vibrio parahaemolyticus Virulence Factors Implicated in Adhesion and Biofilm Formation.

Climate change driven seawater temperature (SWT) increases results in greater abundance and geographical expansion of marine pathogens, among which Vibrio parahaemolyticus (Vp) causes serious economic and health issues. In addition, plastic pollution in the ocean constitutes a vector for harmful pathogens dissemination. We investigate the effect of elevated SWT on the expression of genes implicated in adhesion and biofilm formation on abiotic surfaces in the clinical Vp strain RIMD2210633, which expresses hemolysins. Among the genes studied, the multivalent adhesion molecule-7 and the GlcNAc-binding protein A were involved in the adhesion of Vp to abiotic and biotic surfaces, whereas the type IV pili, the mannose-sensitive hemagglutinin, and the chitin-regulated pilins facilitate attachment and biofilm formation. Data presented here show that at 21°C, Vp is still viable but does not either proliferate or express the virulence factors studied. Interestingly, at 27°C and as early as 1 h of incubation, all factors are transiently expressed in free-living bacteria only and even more upregulated at 31°C. These results clearly show that increased SWT has an important impact on the adhesion properties of free-living Vp to plastic support and thus emphasize the role of climate change in the spread of this pathogenic bacteria.

Transcriptional response of the azooxanthellate octocoral Scleronephthya gracillimum to seawater acidification and thermal stress

The stress responses to increased seawater temperature and marine acidification were investigated using a microarray to reveal transcriptional changes in S. gracillimum. For the study, corals were exposed to different stress experiments; high temperature only (26 °C, 28 °C and 30 °C), low-pH only (pH 7.5, pH 7.0 and pH 6.5) and dual stress experiments (28 °C + pH 7.8, 28 °C + pH 7.5 and 28 °C + pH 7.0), mortality and morphological changes in 24 h exposure experiments were investigated. The survival rates of each experimental group were observed. The gene expression changes in single and dual stress exposed coals were measured and the differentially expressed genes were classified with gene ontology analysis. The top three enriched gene ontology terms of DEGs in response to dual stress were metal ion binding (23.4%), extracellular region (17.2%), and calcium ion binding (12.8%). The gene showing the greatest increase in expression as a response to the dual stress was hemagglutinin/amebocyte aggregation factor, followed by interferon-inducible GTPase 5 and the gene showing the greatest decrease as a response to the dual stress was Fas-associating death domain-containing protein, followed by oxidase 2. These results represented the transcriptomic study focused on the stress responses of the temperate asymbiotic soft coral exposed to single and dual stresses. The combined effect of thermal and acidification stress on corals triggered the negative regulation of ion binding and extracellular matrix coding genes and these genes might serve as a basis for research into coral-specific adaptations to stress responses and global climate change.

Emergence of non-choleragenic Vibrio infections in Australia

Vibrio infection was rarely reported in Tasmania prior to 2016, when a multistate outbreak of Vibrio parahaemolyticus associated with Tasmanian oysters was identified and 11 people reported ill. Since then, sporadic foodborne cases have been identified following consumption of commercially- and recreationally-harvested oysters. The increases in both foodborne and non-foodborne Vibrio infections in Tasmania are likely associated with increased sea water temperatures. As oyster production increases and climate change raises the sea surface temperature of our coastline, Tasmania expects to see more vibriosis cases. Vibriosis due to oyster consumption has been reported in other Australian states, but the variability in notification requirements between jurisdictions makes case and outbreak detection difficult and potentially hampers any public health response to prevent further illness.

Changes in coral forest microbiomes predict the impact of marine heatwaves on habitat-forming species down to mesophotic depths

Global warming is causing the increase in intensity and frequency of heatwaves, which are often associated with mass mortality events of marine organisms from shallow and mesophotic rocky habitats, including gorgonians and other sessile organisms. We investigated the microbiome responses of the gorgonians Paramuricea clavata, Eunicella cavolini, and the red coral Corallium rubrum to the episodic temperature anomalies detected in the North Western Mediterranean, during August 2011. Although the investigated corals showed no signs of visible necrosis, the abundance of associated Bacteria and Archaea increased with increasing seawater temperature, suggesting their temperature-dependent proliferation. Coral microbiomes were highly sensitive to thermal anomaly amplitude and exhibited increased bacterial diversity to greater thermal shifts. This effect was explained by the decline of dominant bacterial members and the increase of new, rare and opportunistic taxa, including pathogens, revealing a direct effect of heatwave-induced alteration of the microbiomes and not a secondary consequence of coral necrosis.

Potassium incorporation and isotope fractionation in cultured scleractinian corals

Potassium (K) participates in coral biological activities and accumulates in their skeletons, driving the fractionation of stable K isotopes (41K/39K). Constraining the influences of biotic and abiotic controls on K isotope fractionation is important for interpreting coral records. However, the processes and mechanisms regulating K incorporation into coral skeletons and K isotope fractionation between seawater and coral skeletons remain unknown. Here, we combined isotopic and synchrotron-based spectroscopic analyses to evaluate the phase distribution and corresponding isotope variation of K in the skeleton of scleractinian (Porites australiensis) corals at a seawater temperature range from 20 to 29°C in aquaria culture experiments. Potassium in coral skeletons exists mainly as organic-K (K hosted in soluble and insoluble organic matrices) and carbonate-K (K incorporated into K2CO3 and aragonite) phases of various proportions. Coral δ41K values vary substantially in both direction and magnitude from the modern seawater δ41K composition (∼0.12‰), showing marked deviations (Δ41KCoral-Sea) from −2.00 to 0.67‰. As seawater temperature increases, the organic-K fraction increases, whereas δ41KCoral decreases. The variation in δ41KCoral reflects the relative proportions of organic-bound K to carbonate-associated K. In most cases, coral intracrystalline organic matrices preferentially sequester isotopically lighter K whereas carbonate phases prefer heavier K. Distinguishable inter-colony difference in skeletal δ41K of corals growing under the same culturing conditions reveals the influence of physiological controls on K partitioning and isotope fractionation. Although calcification rate correlates with temperature to different degrees in the studied corals, likely reflecting control of the difference in zooxanthellae density, we infer that calcification rate is not a major controlling factor on skeletal δ41K. Rather, skeletal δ41K correlates closely with K phase partitioning, which is ascribed to temperature-sensitive physiological modulation.

Assessing Effects of Sediment Delivery to Coral Reefs: A Caribbean Watershed Perspective

Coral reefs in the western Atlantic and Caribbean are deteriorating primarily from disease outbreaks, increasing seawater temperatures, and stress due to land-based sources of pollutants including sediments associated with land use and dredging. Sediments affect corals in numerous ways including smothering, abrasion, shading, and inhibition of coral recruitment. Sediment delivery resulting in deposition and water quality deterioration can cause degradation at the spatial scale of corals or entire reefs. We still lack rigorous long-term studies of coral cover and community composition before, during and after major sediment stress, and evidence of recovery after watershed management actions. Here we present an overview of the effects of terrestrial sediments on corals and coral reefs, with recent advances in approaches to watershed assessment relevant to the delivery of sediments to these ecosystems. We present case studies of northeastern Caribbean watersheds to illustrate challenges and possible solutions and to draw conclusions about the current state of knowledge of sediment effects on coral reefs. With a better understanding of erosion and the pathways of sediment discharge to nearshore reefs, there is the increased potential for management interventions.

Desert dust deposition supplies essential bioelements to Red Sea corals.

Climate change-related increase in seawater temperature has become a leading cause of coral bleaching and mortality. However, corals from the northern Red Sea show high thermal tolerance and no recorded massive bleaching event. This specific region is frequently subjected to intense dust storms, coming from the surrounding arid deserts, which are expected to increase in frequency and intensity in the future. The aerial dust deposition supplies essential bioelements to the water column. Here, we investigated the effect of dust deposition on the physiology of a Red Sea coral, Stylophora pistillata. We measured the modifications in coral and Symbiodiniaceae metallome (cellular metal content), as well as the changes in photosynthesis and oxidative stress status of colonies exposed during few weeks to dust deposition. Our results show that 1mgL-1 of dust supplied nanomolar amounts of nitrate and other essential bioelements, such as iron, manganese, zinc and copper, rapidly assimilated by the symbionts. At 25°C, metal bioaccumulation enhanced the chlorophyll concentration and photosynthesis of dust-exposed corals compared to control corals. These results suggest that primary production was limited by metal availability in seawater. A 5°C increase in seawater temperature enhanced iron assimilation in both control and dust-enriched corals. Temperature rise increased the photosynthesis of control corals only, dust-exposed ones having already reached maximal photosynthesis rates at 25°C. Finally, we observed a combined effect of temperature and bioelement concentration on the assimilation of molybdenum, cadmium, manganese and copper, which were in higher concentrations in symbionts of dust-exposed corals maintained at 30°C. All together these observations highlight the importance of dust deposition in the supply of essential bioelements, such as iron, to corals and its role in sustaining coral productivity in Red Sea reefs.

Marine aragonite evolution in the oxygen-decreasing interval before the Cenomanian-Turonian Ocean anoxic event (OAE2) in the southeastern Neo-Tethys

Environmental scenarios around the Cenomanian-Turonian ocean anoxic event (OAE2) interval are scarcely studied in the southeastern Neo-Tethys and not discussed in terms of variation of primary mineralogies of marine carbonates. Based on petrological and geochemical analyses, this study focuses on the increased aragonite abundance in the oxygen-decreasing interval before the OAE2 and its environmental implications in the southeastern Neo-Tethys. In central Iraq, the upper Cenomanian-lower Turonian Mishrif Formation represents marine carbonate records in the southeastern, tropical Neo-Tethys and includes five members from the lowermost Mi-5 to the uppermost Mi-1. From Mi-5 to Mi-1, dominant carbonate components and primary carbonate mineralogies vary. Mi-5 is dominated by primarily calcitic grains (mainly calcite shells of rudists and echinoids); Mi-4 and Mi-3 dominated by primarily aragonitic grains (mainly green algae and aragonitic bivalves) and planktonic calcitic foraminifera; and Mi-1 dominated by primarily calcitic ooids. Paleoenvironmental interpretations suggest: i) open marine, offshore settings for Mi-5 to Mi-3, and a shallow marine shoal setting for Mi-1; ii) a sea level rise from Mi-5 to Mi-3, followed by a sea level fall to Mi-1. The increasing aragonite abundance in Mi-4 and Mi-3 is exceptional and suggested to most likely reflect enhanced preservation of shallow-marine aragonite transported into open marine offshore settings. This enhanced aragonite preservation is likely related to an oxygen-decreasing level before the OAE2 in the offshore settings. Remarkably, these primarily aragonitic components are commonly preserved now as moldic pores in Mi-4 and Mi-3. The moldic pores are interpreted to be produced via deep burial dissolution of recrystallized aragonitic grains, based on petrological and geochemical analyses. Moreover, the primary carbonate compositional and mineralogical changes from Mi-5 to Mi-1 provide some potential clues for the environmental scenarios around the OAE2 interval in the southeastern, tropical Neo-Tethys: i) from Mi-5 to Mi-4 and Mi-3, the increasing abundance of primarily aragonitic components is accompanied by a sea level rise, increasing seawater temperature and decreasing oxygen level of bottom water; ii) from Mi-3 to Mi-1, the decreasing abundance of primarily aragonitic components is accompanied by a sea level fall, decreasing seawater temperature and enhanced microbial carbonate production.

Changes in functioning of the largest coastal North Sea flatfish nursery, the Wadden Sea, over the past half century

The international Wadden Sea is an important flatfish nursery. Information from the Dutch Wadden Sea indicates that the flatfish nursery function of the area has been affected during the last decades. Increased seawater temperature has affected settling, habitat suitability for and growth performance of the various flatfish species. Settling of plaice, flounder and to a lesser extent sole larvae occurs earlier nowadays. In the 1960s, 0-, I-, II- and III-group plaice were present, but since 2000, II-group has disappeared and densities of I-group have decreased. For juvenile flounder, II-group almost disappeared, and for dab, a decline in densities of all age groups was observed from the 1990s onwards. Summer temperatures exceed the optimum for the cold-water species (plaice, flounder and dab) with increasing frequency, level and duration. Only for 0-group sole, the period with optimal growth conditions has become longer and has resulted in increased growth. Mortality rates in 0-group plaice have increased, coinciding with an increase in water temperatures and an increase in the abundance of predators. The decrease in density of juvenile plaice and dab in the Wadden Sea has not affected recruitment to North Sea stocks, suggesting that other areas have taken over part of the nursery function. The predicted increase in seawater temperature in the next decades will continue to improve the conditions for sole. The temperature tolerance of plaice and dab and to a lesser extent flounder will further reduce their scope for growth and may ultimately result in their disappearance from the Wadden Sea.

Early Arrival of Spring-Spawner Atlantic Herring at Their Spawning Ground in the Kiel Fjord, Western Baltic, Relates to Increasing Sea Water Temperature

Early Arrival of Spring-Spawner Atlantic Herring at Their Spawning Ground in the Kiel Fjord, Western Baltic, Relates to Increasing Sea Water Temperature

Examination of Desalination Model Parameters on a Reverse Osmosis Desalination Simulation Model

The clean water and energy are both the most important needs of mankind. The increasing population and the necessity to meet the need for freshwater requirements make the desalination process a popular topic. The reverse osmosis is one of the most popular technique for desalination. The main advantages of the reverse osmosis over other desalination techniques are the lower energy consumption and the robustness to the salinity of feedwater. The ambient conditions are the key parameters affecting the efficiency of desalination process. On the other hand, the design parameters of a reverse osmosis desalination plant also play an important role in the process. In this paper, both ambient conditions and the design parameters are investigated. The contributions of the study are to determine variation the specific power consumption and related total power requirement of single stage reverse osmosis desalination plant model with the ambient conditions and design parameters. The effects of design parameters and ambient conditions for power requirements are given in the results section. The simulation studies are performed at constant production rate in order to see the effects of each parameter to product properties. The increase in seawater temperature for constant seawater salinity decreases the power consumption while increasing the salinity of final product. The results indicated that design parameters should be optimized according to the size of the designed system and salinity of feedwater. Also, a case study is performed for a point at Marmara Region, Turkey.

Theoretical and experimental study on the performance of a high-efficiency thermodynamic cycle for ocean thermal energy conversion

A new high-efficiency ocean thermal energy conversion (OTEC) system using non-azeotropic mixed working fluids with two regenerative cycles is proposed. Based on the first law of thermodynamics, a numerical calculation model for the proposed cycle was established to study the effects of the mass fraction of mixed working fluids, turbine inlet pressure and seawater temperature on the performance of the cycle system. An experimental plant of the proposed OTEC system was established to study the effects of seawater temperature and turbine inlet pressure on the cycle thermal efficiency. The results show that the cycle thermal efficiency and net output power of the system both increase with a decrease in cold seawater temperature or an increase in warm seawater temperature. The system cycle thermal efficiency and net output power both initially increase and then decrease with an increase of the working fluid mass fraction. The system cycle thermal efficiency and net output power both initially increase and then decrease with an increase of the turbine inlet pressure under a certain working fluid mass fraction. The experimental results of cycle thermal efficiency with various performance parameters were basically consistent with the theoretical analysis results; however, the experimental values were lower than the theoretical analysis results.

Explicit silicate cycling in the Kiel Marine Biogeochemistry Model version 3 (KMBM3) embedded in the UVic ESCM version 2.9

Abstract. We describe and test a new model of biological marine silicate cycling, implemented in the Kiel Marine Biogeochemical Model version 3 (KMBM3), embedded in the University of Victoria Earth System Climate Model (UVic ESCM) version 2.9. This new model adds diatoms, which are a key component of the biological carbon pump, to an existing ecosystem model. This new model combines previously published parameterizations of a diatom functional type, opal production and export with a novel, temperature-dependent dissolution scheme. Modelled steady-state biogeochemical rates, carbon and nutrient distributions are similar to those found in previous model versions. The new model performs well against independent ocean biogeochemical indicators and captures the large-scale features of the marine silica cycle to a degree comparable to similar Earth system models. Furthermore, it is computationally efficient, allowing both fully coupled, long-timescale transient simulations and “offline” transport matrix spinups. We assess the fully coupled model against modern ocean observations, the historical record starting from 1960 and a business-as-usual atmospheric CO2 forcing to the year 2300. The model simulates a global decline in net primary production (NPP) of 1.4 % having occurred since the 1960s, with the strongest declines in the tropics, northern midlatitudes and Southern Ocean. The simulated global decline in NPP reverses after the year 2100 (forced by the extended RCP8.5 CO2 concentration scenario), and NPP returns to 98 % of the pre-industrial rate by 2300. This recovery is dominated by increasing primary production in the Southern Ocean, mostly by calcifying phytoplankton. Large increases in calcifying phytoplankton in the Southern Ocean offset a decline in the low latitudes, producing a global net calcite export in 2300 that varies only slightly from pre-industrial rates. Diatom distribution moves southward in our simulations, following the receding Antarctic ice front, but diatoms are outcompeted by calcifiers across most of their pre-industrial Southern Ocean habitat. Global opal export production thus drops to 75 % of its pre-industrial value by 2300. Model nutrients such as phosphate, silicate and nitrate build up along the Southern Ocean particle export pathway, but dissolved iron (for which ocean sources are held constant) increases in the upper ocean. This different behaviour of iron is attributed to a reduction of low-latitude NPP (and consequently, a reduction in both uptake and export and particle, including calcite scavenging), an increase in seawater temperatures (raising the solubility of particulate iron) and stratification that “traps” the iron near the surface. These results are meant to serve as a baseline for sensitivity assessments to be undertaken with this model in the future.

Long-term series demonstrate small-scale differences in trends within fish assemblages explained by climate variability

Over 30 years (1985–2018) of environmental monitoring data in the Belgian part of the North Sea allowed us to study common and individual species trends within three spatially distinct demersal and benthopelagic fish assemblages in relation to climate-related variability. A combination of multivariate (dynamic factor analysis) and univariate modelling techniques (Trendspotter and Spearman rank correlations) showed that the observed trends in fish densities in two coastal (mud and fine sand) assemblages were best explained by sea surface temperature (SST)-related variables and the Atlantic multidecadal oscillation winter index (AMOwinter). Higher fish densities seem to be linked with extreme cold winters in the year before (e.g. 1985, 1996, 2010), while warmer years may be linked to lower fish densities (fine sand assemblage) a few years later. Trends for the more offshore coarse sand fish assemblage were rather related to the North-Atlantic Oscillation index (NAO) (next to AMOwinter), coupled to the circulation and inflow of warmer saline waters through the English Channel. The temporal decrease in densities in this assemblage may partially reflect climate and subsequent biological regime shifts, as described for the broader North Sea region.At the species level, both positive, negative and varying trends in densities were noted, dependent on the fish assemblage. Overall, densities of most Lusitanean (warm water) species increased over the last decade, positively correlated with most SST-related variables and AMOwinter-values, indicating a northward expansion of their habitat range, which corroborates the findings of other studies. On the contrary, several Boreal (cold water) species were negatively correlated with SST and AMOwinter, with more or less stable trends in density between 1985 and 2000 followed by a decrease in the last decade, potentially explained by a relocation to deeper waters to cope with increasing seawater temperatures. For plaice Pleuronectes platessa, a commercially important species, a linear and significant decrease in length was observed over the 34-year period, most probably related to a combination of climatic influences and fishing induced selection. The current study shows that environmental, climate related drivers are important to explain part of the biological variability and should be taken into account when investigating the direct impact of human activities on the marine, demersal and benthopelagic ecosystem.

Nutritional quality of giant kelp declines due to warming ocean temperatures

Giant kelp Macrocystis pyrifera forms extensive forests on temperate reefs, providing habitat and food for a diversity of marine life. Kelp biomass varies in response to changing ocean temperatures, but physiological responses as reflected in the nutritional quality of kelp tissue are poorly understood. Over a 19‐year period in southern California, we found that nutritional quality of giant kelp tissue declined; nitrogen content of giant kelp tissue declined by 18%, while carbon content proportionally increased. This decline in nutritional quality was associated with increasing seawater temperatures and with regional and local scale processes including upwelling as indicated by the biologically effective upwelling transport index, the El Niño‐Southern oscillation and the North Pacific Gyre oscillation. Changes in kelp stoichiometry with seawater temperature have important implications for nutrition and behavior of key consumers, such as sea urchins. Our results suggest that the consequences of projected declines in kelp abundance due to climate change may be compounded by reductions in its nutritional quality.

Elucidating gene expression adaptation of phylogenetically divergent coral holobionts under heat stress

As coral reefs struggle to survive under climate change, it is crucial to know whether they have the capacity to withstand changing conditions, particularly increasing seawater temperatures. Thermal tolerance requires the integrative response of the different components of the coral holobiont (coral host, algal photosymbiont, and associated microbiome). Here, using a controlled thermal stress experiment across three divergent Caribbean coral species, we attempt to dissect holobiont member metatranscriptome responses from coral taxa with different sensitivities to heat stress and use phylogenetic ANOVA to study the evolution of gene expression adaptation. We show that coral response to heat stress is a complex trait derived from multiple interactions among holobiont members. We identify host and photosymbiont genes that exhibit lineage-specific expression level adaptation and uncover potential roles for bacterial associates in supplementing the metabolic needs of the coral-photosymbiont duo during heat stress. Our results stress the importance of integrative and comparative approaches across a wide range of species to better understand coral survival under the predicted rise in sea surface temperatures.

Downregulation of PyHRG1, encoding a novel secretory protein in the red alga Pyropia yezoensis, enhances heat tolerance

An increase in seawater temperature owing to global warming is expected to substantially limit the growth of marine algae, including Pyropia yezoensis, a commercially valuable red alga. To improve our knowledge of the genes involved in the acquisition of heat tolerance in P. yezoensis, transcriptomes sequences were obtained from both the wild-type SG104 P. yezoensis and heat-tolerant mutant Gy500. We selected 1,251 differentially expressed genes that were up- or downregulated in response to the heat stress condition and in the heat-tolerant mutant Gy500, based on fragment per million reads expression values. Among them, PyHRG1 was downregulated under heat stress in SG104 and expressed at a low level in Gy500. PyHRG1 encodes a secretory protein of 26.5 kDa. PyHRG1 shows no significant sequence homology with any known genes deposited in public databases to date. However, PyHRG1 homologs were found in other red algae, including other Pyropia species. When PyHRG1 was introduced into the single-cell green alga Chlamydomonas reinhardtii, transformed cells overexpressing PyHRG1 showed severely retarded growth. These results demonstrate that PyHRG1 encodes a novel red algae-specific protein and plays a role in heat tolerance in algae. The transcriptome sequences obtained in this study, which include PyHRG1, will facilitate future studies to understand the molecular mechanisms involved in heat tolerance in red algae.

Heating performance and spatial analysis of seawater-source heat pump with staggered tube-bundle heat exchanger

Seawater-source heat pump (SWHP) system exhibits merits of building energy conservation and reducing carbon emissions, while enhancing the heat transfer of seawater heat exchangers is the key to improve the system performance. Here, a model of SWHP system with staggered tube-bundle heat exchanger is established and its performance in winter is numerically studied and verified by experiments. The wave theory is introduced into the mathematical model to describe the flow field of actual ocean and improve the accuracy. The heat transfer performance of staggered tube-bundle exchanger is investigated under icing conditions, and the results indicate that the ice layer thermal resistance outside the tube accounts for more than 28% of the total thermal resistance. The impacts of seawater temperature on the SWHP system performance are discussed and the average increment of heating capacity and COP is 0.12 kW and 0.046 respectively with the increase of seawater temperature by 1 °C. Furthermore, a spatial analysis of SWHP system in 29 coastal cities of China are analyzed and compared with air-source heat pump (ASHP) system. The results show that SWHP system has greater advantages than ASHP system, especially in the southern cities. This research comprehensively analyzes the technology, economy and geography of SWHP system from a more macro perspective, and it can promote the application of ocean thermal energy.

Contrasting Proteomic Responses of Adult and Larval Coral to High Temperatures

Climate change-induced increases in seawater temperature continue to impact coral reef ecosystems globally. There is a consequent need to characterize the responses of corals to thermal stress to understand the molecular processes underpinning these responses and identify hallmarks of resilience. Here we used an iTRAQ approach to compare the proteomes of adult corals (Pocillopora acuta) that had been thermally conditioned at a control (26°C) or elevated temperature (29.5°C) for three reproductive cycles, as well as the larvae released by these corals. We found that larvae responded more to high-temperature exposure at the protein level than their parents and that different proteins were affected between life stages; a single protein was up-regulated at high temperatures in both adults and their offspring, and its identity is currently unknown. Similarly, different cellular pathways were affected by high-temperature exposure between the coral hosts and their dinoflagellate endosymbionts; proteins involved in translation and protein trafficking were most likely to be affected by high-temperature exposure in the former, with photosynthesis being the most thermo-sensitive process in the latter. Collectively, these findings highlight the importance of considering both life stage and the composition of the coral holobiont when using molecular-scale data to model cellular processes associated with responses to future ocean warming.