Rise In Seawater Temperature Research Articles

Octocoral Sexual Reproduction: Temporal Disparity Between Mesophotic and Shallow-Reef Populations

Mesophotic coral-reef ecosystems (MCEs) are light-dependent communities occurring at 30 to ~150 m depth in the clear waters of tropical and sub-tropical regions. The extent to which MCEs and shallow benthic populations are connected, and whether coral sexual reproduction is maintained under the mesophotic environmental conditions, are still unclear. Despite the trend of increasing studies concerning the MCEs, the reproductive traits of MCE Indo-Pacific octocorals have remained uninvestigated to date. The current study engages with two common zooxanthellate octocorals in the northern Red Sea: the internal-brooder Ovabunda spp. and the surface-brooder Rhytisma fulvum fulvum. It addresses the hypothesis that, similar to their shallow-zone conspecifics, the upper mesophotic populations also reproduce sexually. We analyze the reproductive traits of tropical, upper mesophotic octocoral populations and compare them for the first time to the traits of their conspecifics on shallow reefs. In addition, we discuss the timing of surface-brooding events in relation to lunar phase and daily seawater temperature. The populations of Ovabunda spp. in the upper MCE and shallow-water display several similar reproductive traits (e.g., maximal gonad diameter and fecundity). Consequently, this species seems to be a successful depth-generalist. In contrast, the reproductive features of R. f. fulvum differ between the reefs in the upper MCE and in those shallow-water, with a decreased abundance of female colonies, lower fecundity, and a lower percentage of colonies exhibiting surface-brooding in the former. It thus seems that the R. f. fulvum population encounters certain constraints in the MCE that may, in turn, lead to its reduced reproductive performance there. In addition, surface-brooding events for R. f. fulvum in the upper-mesophotic zone and in shallow-water were separated by two weeks. Since a distinctive seawater temperature rise preceded each surface-brooding event, temperature regimes at different depths may present extrinsic cues that influence the timing of reproduction. The findings from this study contribute to our understanding of the life-history of mesophotic benthic inhabitants in general and of octocorals in particular. Overall, the current findings reinforce the viewpoint that the refuge potential of MCEs may be reflective of species-specific reproductive traits.

A sudden end-Permian mass extinction in South China

Previous studies of the end-Permian mass extinction have established that it was geologically rapid, but condensed sections have made it difficult to establish the exact timing of the extinction relative to fluctuations in the ocean carbon cycle, oxygen levels, and temperature. Integrated high-precision U-Pb geochronology, biostratigraphy, and chemostratigraphy from a highly expanded section at Penglaitan, Guangxi, South China reveal a sudden end-Permian mass extinction that occurred at 251.939 +/- 0.031 Ma, which is temporally coincident with the extinction recorded in Bed 25 of the Meishan section. Despite the significantly expanded nature of the section and extensive collecting of more than ten major marine fossil groups, there is no evidence of a decline of biotic diversity prior to the extinction interval and no Permian-type species survive the extinction at this location. Fossil range data suggest a nearly instantaneous extinction at the top of a narrow stratigraphic interval limited to 31 +/- 31 k.y. The extinction was preceded by and/or accompanied by fluctuations in delta C-13(carb) and delta C-13(org) of 2-3 parts per thousand and 3-5 degrees C in seawater temperature. A larger, more rapid seawater temperature rise of 6-8 degrees C immediately followed the extinction level at Penglaitan. The extinction is spatially associated with a thick unit of tuff and tuffaceous sandstones (Bed 141) indicating massive pyroclastic input. It is correlative with an ash layer (Bed 25) in the deeper water setting at Meishan, where some Permian-type organisms survived the extinction. Our study reveals that the survivability of Permian taxa after the major extinction pulse is variable and dependent upon the severity of environmental perturbation in different sedimentary settings. The sudden extinction may fit a scenario in which the onset of Siberian Traps and South China intensive volcanism similar to 420 k.y. before the extinction may have diminished the ecological resilience of communities and reduced ecological functions with little change in diversity. In such an environmentally stressed condition, a single environmental disturbance could trigger the sudden collapse of global ecosystems.

Trematode infection modulates cockles biochemical response to climate change

Resulting mainly from atmospheric carbon dioxide (CO2) build-up, seawater temperature rise is among the most important climate change related factors affecting costal marine ecosystems. Global warming will have implications on the water cycle, increasing the risk of heavy rainfalls and consequent freshwater input into the oceans but also increasing the frequency of extreme drought periods with consequent salinity increase. For Europe, by the end of the century, projections describe an increase of CO2 concentration up to 1120 ppm (corresponding to 0.5 pH unit decrease), an increase in the water temperature up to 4 °C and a higher frequency of heavy precipitation. These changes are likely to impact many biotic interactions, including host–parasite relationships which are particularly dependent on abiotic conditions. In the present study, we tested the hypothesis that the edible cockle, Cerastoderma edule, exposed to different salinity, temperature and pH levels as proxy for climate change, modify the infection success of the trematode parasite Himasthla elongata, with consequences to cockles biochemical performance. The results showed that the cercariae infection success increased with acidification but higher biochemical alterations were observed in infected cockles exposed to all abiotic experimental stressful conditions tested. The present study suggested that changes forecasted by many models may promote the proliferation of the parasites infective stages in many ecosystems leading to enhanced transmission, especially on temperate regions, that will influence the geographical distribution of some diseases and, probably, the survival capacity of infected bivalves.

Going down together: invasive host, Charybdis longicollis (Decapoda: Brachyura: Portunidae) and invasive parasite, Heterosaccus dollfusi (Cirripedia: Rhizocephala: Sacculinidae) on the upper slope off the Mediterranean coast of Israel

ABSTRACTThe swimming crab Charybdis longicollis, native to the western Indian Ocean, was first recorded in the Mediterranean in 1954. It is now established from Egypt to Greece, and dominates the sandy-mud bottoms at 25–80 m in the southeastern Mediterranean. The success of C. longicollis is attributed to its high fecundity, agonistic behaviour and omnivorous diet, as well as the rise in seawater temperature. Since the early 1990s its populations in Israel and Turkey have been heavily parasitized by the alien rhizocephalan Heterosaccus dollfusi, which impacts its host’s behaviour, growth and fecundity, and causes mortality. Yet, 60 years after its first record in the Mediterranean, the population of C. longicollis seems durable, and has recently spread to the lower shelf and upper slope off Israel, where it is common at 80 m and is found down to 250 m, greatly increasing its spatial spread. The maximal percentage of parasitization was 87.2%, 88.8%, 75.5% and 81.8% at depths of 40, 60, 80, 100 m, respectively, and 50% at 120 and 250 m. Here, we hypothesize on the possible contribution of the depletion of its putative fish predators, mainly rays, to the prevalence of C. longicollis on the lower shelf.

Effects of the 2015 heat wave on benthic invertebrates in the Tabarca Marine Protected Area (southeast Spain)

In the late summer of 2015, extensive mortality of scleratinian corals, gorgonians, and sponges was observed in the Marine Protected Area of Tabarca (southeast Spain). Quantitative data indicated that at 25 m depth the sea fan Eunicella singularis was the most affected species (50% of colonies affected by partial mortality); while in shallow waters more than 40% of the endemic scleractinian coral Cladocora caespitosa population showed tissue lesions that affected more than 10% of their surfaces. Other affected species were the scleractinian corals Oculina patagonica and Phyllangia mouchezii, the sea fan Leptogorgia sarmentosa and the sponge Sarcotragus fasciculatus. This mortality event coincided with an abnormal rise in seawater temperature in this region. Microbiological analysis showed a higher abundance of culturable Vibrio species in invertebrates exhibiting tissue lesions, which indicated that these opportunistic pathogens could be a key factor in the process.

Probabilistic remaining life estimation for deteriorating steel marine infrastructure under global warming and nutrient pollution

The longer-term serviceability and structural safety of steel infrastructure exposed to seawater conditions may be affected by global warming and by seawater nutrient pollution. These may affect abiotic and biotic (microbial) corrosion. A model for long-term corrosion is developed from data obtained from steel piling exposed for 33 years in a seawater harbour. The effects on corrosion losses on the structural reliability of steel sheet piling as used in harbours world-wide were investigated as a function of seawater temperature rise from global warming and of seawater nutrient pollution. The results show that structural reliability is more sensitive to likely nutrient pollution than to predicted increases in seawater temperature, noting also that global warming also could increase nutrient pollution from anthropological sources.

From Tropical to Sub-Tropical: Prolonged Reproductive Activity of the Invasive Ascidian Microcosmus exasperatus in the Eastern Mediterranean

The solitary ascidian Microcosmus exasperatus is globally distributed in tropical and sub-tropical waters. In the Mediterranean it is considered an invasive species introduced through the Suez Canal, with a restricted distribution in the eastern basin. In order to understand the potential of this species to establish sustainable communities at additional sites in the Mediterranean, we studied its reproduction cycle over a 2-year period in relation to seawater temperature and chlorophyll-a data. Although M. exasperatus reproduces seasonally, with significantly greater activity in summer and early fall, mature oocytes occur throughout the year, suggesting multiple spawning periods. We found that reproductive effort significantly correlated with seawater temperature, while chlorophyll-a showed a low and insignificant explanatory power. A combined regression model of both parameters yielded the highest explained variance, suggesting a synergic effect of these two factors. Such a prolonged reproductive activity period enables repeated recruitment events. In view of the anticipated rise in seawater temperature, we predict that this species will gradually expand its distribution further across the Mediterranean.

Reproduction, abundance and survivorship of two Alveopora spp. in the mesophotic reefs of Eilat, Red Sea.

Although the study of coral reproduction has advanced tremendously over the last few decades, a particular gap exists in our knowledge of the reproductive modes of corals from ‘mesophotic coral ecosystems’ (MCEs) found at 30–150 m depth. Here, we report for the first time on the reproductive patterns, living cover, and survivorship under different light treatments of two scleractinian species from the MCEs of Eilat, Red-Sea: Alveopora allingi and A. ocellata. Both species are found exclusively within MCEs and are high in both abundance and relative cover. These species display a synchronous gametogenic cycles with consecutive oocyte growth and development. Peak of reproductive activity occurs in late summer (September-October), typified by accelerated oocyte growth, coinciding with the rise in seawater temperature. Estimates of fecundity show mean monthly maxima of 48.5 ± 26.3 and 23.5 ± 11.8 (Mean ± SE) oocytes per cm2 for A. allingi and A. ocellata respectively, prior to spawning. A comparison of light and temperature regimes in the shallow vs. MCE environments is presented, and the response of these species to changes in these parameters is discussed. A call encouraging the much-needed studies on the sexuality and reproductive modes of MCE coral species is expressed.

Global change and climate‐driven invasion of the Pacific oyster (Crassostrea gigas) along European coasts: a bioenergetics modelling approach

AbstractAimThe spread of non‐indigenous species in marine ecosystems world‐wide is one of today's most serious environmental concerns. Using mechanistic modelling, we investigated how global change relates to the invasion of European coasts by a non‐native marine invertebrate, the Pacific oyster Crassostrea gigas.LocationBourgneuf Bay on the French Atlantic coast was considered as the northern boundary of C. gigas expansion at the time of its introduction to Europe in the 1970s. From this latitudinal reference, variations in the spatial distribution of the C. gigas reproductive niche were analysed along the north‐western European coast from Gibraltar to Norway.MethodsThe effects of environmental variations on C. gigas physiology and phenology were studied using a bioenergetics model based on Dynamic Energy Budget theory. The model was forced with environmental time series including in situ phytoplankton data, and satellite data of sea surface temperature and suspended particulate matter concentration.ResultsSimulation outputs were successfully validated against in situ oyster growth data. In Bourgneuf Bay, the rise in seawater temperature and phytoplankton concentration has increased C. gigas reproductive effort and led to precocious spawning periods since the 1960s. At the European scale, seawater temperature increase caused a drastic northward shift (1400 km within 30 years) in the C. gigas reproductive niche and optimal thermal conditions for early life stage development.Main conclusionsWe demonstrated that the poleward expansion of the invasive species C. gigas is related to global warming and increase in phytoplankton abundance. The combination of mechanistic bioenergetics modelling with in situ and satellite environmental data is a valuable framework for ecosystem studies. It offers a generic approach to analyse historical geographical shifts and to predict the biogeographical changes expected to occur in a climate‐changing world.

Viral and Bacterial Epibionts in Thermally-Stressed Corals

The periodic rise in seawater temperature is one of the main environmental determinants of coral bleaching. However, the direct incidence of these episodic thermal anomalies on coral-associated microbiota and their subsequent effects on coral health are still not completely understood. In this study, we investigated the dynamics of three main microbial communities of the coral holobiont (e.g., Symbiodinium, bacteria and viruses), during an experimental thermal stress (+4 °C) conducted on the scleractinian Fungia repanda. The heat-treatment induced coral bleaching after 11 days and resulted in a final elevation of ca. 9, 130 and 250-fold in the abundance of mucosal viruses, bacteria, and Symbiodinium, respectively. On the contrary, the proportion of actively respiring bacterial cells declined by 95% in heat-stressed corals. The community composition of epibiotic bacteria in healthy corals also greatly differed from bleached ones, which also exhibited much higher production rates of viral epibionts. Overall, our results suggest that the shift in temperature induced a series of microbial changes, including the expulsion and transfer of Symbiodinium cells from the coral polyps to the mucus, the collapse of the physiological state of the native bacterial associates, a substantial alteration in their community structure, and accompanied by the development of a cortege of highly active virulent phages. Finally, this study provides new insights into the environmentally-driven microbial and viral processes responsible for the dislocation of the coral holobiont.

Ocean warming ameliorates the negative effects of ocean acidification on Paracentrotus lividus larval development and settlement

Ocean warming and acidification both impact marine ecosystems. All organisms have a limited body temperature range, outside of which they become functionally constrained. Beyond the absolute extremes of this range, they cannot survive. It is hypothesized that some stressors can present effects that interact with other environmental variables, such as ocean acidification (OA) that have the potential to narrow the thermal range where marine species are functional. An organism's response to ocean acidification can therefore be highly dependent on thermal conditions. This study evaluated the combined effects of predicted ocean warming conditions and acidification, on survival, development, and settlement, of the sea urchin Paracentrotus lividus. Nine combined treatments of temperature (19.0, 20.5 and 22.5 °C) and pH (8.1, 7.7 and 7.4 units) were carried out. All of the conditions tested were either within the current natural ranges of seawater pH and temperature or are within the ranges that have been predicted for the end of the century, in the sampling region (Canary Islands). Our results indicated that the negative effects of low pH on P. lividus larval development and settlement will be mitigated by a rise in seawater temperature, up to a thermotolerance threshold. Larval development and settlement performance of the sea urchin P. lividus was enhanced by a slight increase in temperature, even under lowered pH conditions. However, the species did show negative responses to the levels of ocean warming and acidification that have been predicted for the turn of the century.

The Indo-Pacific oyster Spondylus spinosus Schreibers, 1793 in the Eastern Mediterranean Sea: reproductive features

Populations of the Indo-Pacific invasive bivalve Spondylus spinosus in the Eastern Mediterranean occur at high densities and occupy vast areas of the rocky habitats along the Israeli coast where they are cemented to hard substratum in an oyster-like fashion. We studied the reproductive features of this bivalve in part of the area where it has invaded and found it to be gonochoric, featuring a reproducing population with a sex ratio of 1:1, annual gonad development and an inferred spawning period coinciding with the seasonal rise in seawater temperature. It is suggested that these reproductive features support high fertilisation rates and fecundity, thus contributing to the maintenance of its populations in the new environment.

海洋酸化和全球变暖对贝类生理生态的影响研究进展

研究表明海洋酸化和全球变暖已严重威胁到海洋生态系统稳的定性及生物多样性。由于人类活动，大气中不断增加的CO₂不仅造成全球气候异常，而且大量的CO₂被海洋吸收，造成了海水中H⁺浓度增加，即海洋酸化（Ocean Acidification）。海洋酸化严重影响海洋生物的生存和繁衍，尤其是有壳类生物，如贝类，甲壳类，棘皮类等。主要影响方面包括生物的产卵受精，孵化，早期发育，钙化，酸碱调节，免疫功能，蛋白质合成，基因表达，摄食及能量代谢等一系列和生理相关的机能，进而对个体行为学，种群结构和海洋生态系统造成严重危害。目前，已有大量海洋酸化对海洋贝类的生理生态影响的报道，与此同时，全球变暖导致海洋温度升高伴随着海洋酸化同步发生。因此，为了更加准确地预测海洋生物应对全球气候变化的生理生态应答，越来越多的学者开始致力于研究温度和海洋酸化的复合胁迫对海洋生物交互影响作用。综述了近年来海洋酸化对贝类生理生态的影响，主要从个体早期发育、钙化、免疫、繁殖等方面做了系统的阐述，还对酸化和温度对贝类的复合环境胁迫效应也做了综合分析，以期为今后的海洋酸化研究提供基础理论。;Global climate change due to industrialization and anthropogenic activities has been a critical problem worldwide since the last century. Because of anthropogenic activity, the increasing atmospheric concentration of CO₂ not only caused temperature rise, but also increased the H⁺ concentration in the seawater with the large CO₂ absorption, namely ocean acidification. Global average sea surface temperature is significantly higher than before, and the ocean surface pH is also evidently reduced because of the sequestration of a large number of CO₂ by the ocean. Elevated atmospheric CO₂ is set to increase mean global temperatures by 2-4℃, and reduce the surface ocean pH by as much as 0.5 unit in the next century. It is crucial to forecast the impacts of global climate change on eco-physiology of marine organisms, especially in a multiple stressor situation expected by the end of this century. Some studies have showed that ocean acidification and global warming heavily threaten the marine ecosystem and biodiversity. Ocean acidification affects survival and reproduction of marine organisms negatively, especially those organisms with shells, such as shellfish, crustacean and echinodermata. The most influenced aspects include fertilization, hatching, early development, calcification, acid-base balance, immune function, protein synthesis, gene expression, feeding and energy metabolism, all of which are relevant to physiological functions, and ocean acidification further impacts the individual behavior, population structure and marine ecosystem. To date, a large number of studies have revealed eco-physiological responses of shellfish to ocean acidification, focusing on the mechanisms that underlie physiological plasticity at molecular level with some reference to whole organism fitness. At the same time, seawater temperature rise resulting from global warming occurs with ocean acidification simultaneously. However, the combined effects of elevated temperature and pH variation on coastal and estuarine shellfish are less explored. Many sessile organisms, such as mussels, are unable to move fleetly to avoid warming and acidified areas, so their physiological activities and behavioural responses may be influenced. There is a growing demand to understand the responses of the marine biota to these environmental stressors. Thus, to predict the eco-physiological responses of marine organisms to global climate change more realistic and accurate, more and more researchers try to study the combined effects of warming and ocean acidification. This paper reviewed eco-physiological effects of ocean acidification on shellfish in recent years, mainly from individual early development, calcification, immune responses and reproduction etc. Moreover, the combined effects of ocean acidification and warming on shellfish were summarized and analyzed, expecting to provide some basic information for studying biological responses to ocean acidification in the future. The future worthy research points include the latitudinal variation in the eco-physiological responses of species populations, the latent effects or carry-over effects, referring to effects resulting from conditions experienced in adult or larval stage, that are expressed in subsequent stages, and the interactions between shellfish and their predators. Such information is needed if we are to determine if future climate change will drive a reorganization of benthic communities and also adversely impact commercially important fisheries. Scientific progress generated by such eco-physiological studies will be central to meeting current and future conservation and management goals.

실험실에서 사육된 고랑가리비 Chlamys swiftii 수정란 발생과 유생 성장

고랑가리비의 산란을 유도하고 수정난의 발생과 유생의 성장과정을 조사하였다. 산란자극 방법으로 광 자극, 간출 자극, 온도 자극, 그리고 간출 후 온도자극을 수온 <TEX>$16{\pm}0.5^{\circ}C$</TEX>에서 각각 실시하였다. 광 자극은 암컷 1마리당 700-900천개, 온도 자극은 700-800천개로 적은 산란량을 보인 반면 간출 자극은 700-1,200천개로 높았으며 간출 자극 후 온도자극이 1,000-1,500천개로 가장 높은 산란량을 보였다. 수정율에 있어 광 자극은 암컷 1마리당 71.7%, 온도자극은 73.4%, 간출 자극이 73.6%이었으며 간출 자극 후 온도자극은 76.3%로 가장 높았으나 자극방법에 따른 수정율의 유의적인 차이는 없었다. 수정란부터 D상 유생으로의 수온별 발생과정을 조사하기 위하여 비이커에 ml당 1,000개의 수정란을 수용하고 각각 <TEX>$8^{\circ}C$</TEX>, <TEX>$12^{\circ}C$</TEX>, <TEX>$16^{\circ}C$</TEX>, <TEX>$20^{\circ}C$</TEX> 및 <TEX>$24^{\circ}C$</TEX>에서 D상 유생으로 발생하는 생존율을 광학현미경을 사용하여 30분 간격으로 관찰한 결과, <TEX>$8^{\circ}C$</TEX>와 <TEX>$24^{\circ}C$</TEX>의 실험군이 4.1%와 3.2%로 생존율이 낮은 편이었으며 <TEX>$16^{\circ}C$</TEX>에서 32.7%로 가장 높은 생존율을 보여주었다. 수정란의 크기는 <TEX>$72{\pm}2.1{\mu}m$</TEX>, 담륜자 유생은 <TEX>$103{\pm}3.8{\mu}m$</TEX>, D상 유생은 <TEX>$129{\pm}10.4{\mu}m$</TEX>, 각정기 유생은 <TEX>$145{\pm}16.8{\mu}m$</TEX>, 후기 유생은 <TEX>$197{\pm}13.6{\mu}m$</TEX>이었으며 528시간 후에 각장 <TEX>$245{\pm}15.8{\mu}m$</TEX>의 초기 부착종묘로 성장하였다. The development of swift's scallop Chlamys swiftii, reared in the laboratory, has been examined through the investigation of morphological characteristics in fertilized egg, larvae and juvenile. Eggs were fertilized with a dilute sperm solution to improve the survival of fertilized eggs. Developing larvae were maintained at a temperature of <TEX>$16{\pm}0.5^{\circ}C$</TEX> and salinity concentration of 33 ppt. We have investigated the fertilization rates and egg number spawned at several stimulating conditions such as sunlight exposure, air dry, seawater temperature rise (<TEX>$5^{\circ}C$</TEX>) and seawater temperature rise (<TEX>$5^{\circ}C$</TEX>) after exposure of air dry for spawning induction of swift's scallop Chamys swiftii. Stimulation treated with sunlight exposure and seawater temperature rise (<TEX>$5^{\circ}C$</TEX>) have shown the spawning number of 700,000-900,000 and 700,000-800,000 per individual, respectively while stimulation treated with seawater temperature rise (<TEX>$5^{\circ}C$</TEX>) after exposure of air dry have shown the high spawning number of 1,000,000-1,500,000 per individual. Survival rate of D-shaped larvae of swift's scallop put into the different seawater temperatures of <TEX>$8^{\circ}C$</TEX>, <TEX>$12^{\circ}C$</TEX>, <TEX>$16^{\circ}C$</TEX>, <TEX>$20^{\circ}C$</TEX> and <TEX>$24^{\circ}C$</TEX> has been 4.1%, 11.6%, 32.7%, 18.6% and 3.2%, respectively. Fertilized eggs with the diameter of <TEX>$72{\mu}m$</TEX> developed into trochophore larvae of <TEX>$103{\pm}3.8{\mu}m$</TEX> shortly after 35 hours and to D larvae of <TEX>$129{\pm}10.4{\mu}m$</TEX> shell length within 72 hours. It took 336 hours to become initial Umbo-stage larva of <TEX>$145{\pm}16.8{\mu}m$</TEX> shell length. Post larvae, which have been <TEX>$197{\pm}13.6{\mu}m$</TEX> shell length, spontaneously have settled in the attachment substances. It have required 528 hours from fertilized eggs to early attached juvenile to become initial juvenile size of <TEX>$245{\pm}15.8{\mu}m$</TEX> shell length.

Temperature Dependent Effects of Elevated CO2 on Shell Composition and Mechanical Properties of Hydroides elegans: Insights from a Multiple Stressor Experiment

The majority of marine benthic invertebrates protect themselves from predators by producing calcareous tubes or shells that have remarkable mechanical strength. An elevation of CO2 or a decrease in pH in the environment can reduce intracellular pH at the site of calcification and thus interfere with animal’s ability to accrete CaCO3. In nature, decreased pH in combination with stressors associated with climate change may result in the animal producing severely damaged and mechanically weak tubes. This study investigated how the interaction of environmental drivers affects production of calcareous tubes by the serpulid tubeworm, Hydroides elegans. In a factorial manipulative experiment, we analyzed the effects of pH (8.1 and 7.8), salinity (34 and 27‰), and temperature (23°C and 29°C) on the biomineral composition, ultrastructure and mechanical properties of the tubes. At an elevated temperature of 29°C, the tube calcite/aragonite ratio and Mg/Ca ratio were both increased, the Sr/Ca ratio was decreased, and the amorphous CaCO3 content was reduced. Notably, at elevated temperature with decreased pH and reduced salinity, the constructed tubes had a more compact ultrastructure with enhanced hardness and elasticity compared to decreased pH at ambient temperature. Thus, elevated temperature rescued the decreased pH-induced tube impairments. This indicates that tubeworms are likely to thrive in early subtropical summer climate. In the context of climate change, tubeworms could be resilient to the projected near-future decreased pH or salinity as long as surface seawater temperature rise at least by 4°C.

Palaeotethys seawater temperature rise and an intensified hydrological cycle following the end-Permian mass extinction

The end-Permian mass extinction has been associated with severe global warming. Main stage volcanism of the Siberian Traps occurred at or near the extinction interval and has been proposed as a likely greenhouse catalyst. In this study, a high-resolution δ18O record is established using diagenetically resistant apatite of conodonts and low-Mg calcite of brachiopods from stratigraphically well-constrained Permian–Triassic (P–Tr) boundary successions in northwestern Iran. A new evaluation is made for previously published conodont δ18O values from South China and revised palaeotemperatures are presented together with new data from Wuchiapingian to Griesbachian sections in Iran. δ18O data from P–Tr sections in Iran document tropical sea surface temperatures (SST) of 27–33°C during the Changhsingian with a negative shift in δ18O starting at the extinction horizon, translating into a warming of SSTs to over 35°C. The results are consistent with re-calculated SSTs of the South Chinese sections. Warming was associated with an enhanced hydrological cycle involving increased tropical precipitation and monsoonal activity in the Tethys Sea. Global warming, intensification of the hydrological cycle and associated processes, vertical water column stratification, eutrophication and subsequent local anoxia may all have facilitated an extinction event.

Regional warming and decline in abundance of Euchaeta plana (Copepoda, Calanoida) in the nearshore waters of the East China Sea

We analyzed data collected in 1959, 1981, and 1999-2009 in the nearshore waters of the East China Sea (30°00′-32°00′N, 122°00′-123°30′E) to reveal the potential impact of recent regional warming on the abundance of Euchaeta plana Mori, 1937. In a relatively cold period, such as in 1959, E. plana was a dominant species in the study area, and the species was most abundant in spring. However, the abundance of E. plana dropped from 14.1 ind./m3 in spring of 1959 to 0.6 ind./m3 in 2002 with seawater temperature rise. Accordingly, its frequency decreased from 96.3% to 51.9%. A significant decrease in abundance of E. plana was also observed in spring of 1999-2009 compared to 1959 and 1981. This change was negatively related to surface water temperature in May ( r = − 0 . 68 , p < 0 . 01 ), and the decline in abundance was accompanied by decreasing in its maximum abundance ( r = 0 . 90 , p < 0 . 01 ) and occurrence frequency ( r = 0 . 86 , p < 0 . 01 ). Regional warming is thought to be mainly responsible for the decrease in abundance of E. plana in the nearshore waters of the East China Sea. The abundance of E. plana peaked in spring at temperature of 17.8°C, and it is sensitive to temperature fluctuation, suggesting that E. plana is a warm-temperate species and could act as an indicator of marine ecosystem changes in the nearshore waters of the East China Sea.

Rise and fall of pandemic Vibrio parahaemolyticus serotype O3:K6 in southern Chile

Seafood consumption-related diarrhoea increased drastically in Chile when the pandemic strain of Vibrio parahaemolyticus serotype O3:K6 reached Region de Los Lagos, where most of Chile's seafood is produced. Outbreaks peaked in 2005 with 3725 clinical cases in this region and gradually decreased to fewer than 10 cases in 2010 and 2011. We show here that the pandemic strain concurrently vanished from mussels; we also report further environmental data. Integration of the 2010/2011 data with those obtained since 2004 suggests that after its arrival in southern Chile, the pandemic strain grew in mussels, likely facilitated by a minor rise in surface seawater temperature and by warming of the mussels in the intertidal region due to frequent sunny days. However, since these environmental parameters probably equally affected the pandemic strain and more than 30 V. parahaemolyticus DNA restriction clusters that inhabit local shellfish, a selective effect of bacteriophages is proposed. Lytic bacteriophage VP93 may have favoured the growth of the pandemic strain versus similar phage-sensitive strains, as shown here in a particular case. However, the pandemic strain's decline may have been promoted by temperate phage VP58.5, which kills the pandemic strain and increases the UV sensitivity of lysogenized phage-resistant cells.

The shifting biogeography of reef corals during the Oxfordian (Late Jurassic). A climatic control?

Until recently, the Jurassic was thought to have been a period characterised by a predominantly warm and equable climate. During the Oxfordian (a time span of six million years in the Late Jurassic) the distribution of tropical coral reefs was limited to about 35°N and near to 25°S. However, in Middle Oxfordian time, coral reefs were abundant only at higher latitudes and almost entirely missing near the equator. During that time the area of maximum reef development had shifted poleward to a belt lying between 20°N and 35°N, leaving hardly any coral formations at the lower inner-tropical latitudes. After demise towards the end of Middle Oxfordian time, the low-latitude reefs recovered during the Late Oxfordian, accompanied by a southward migration of reef corals in the northern hemisphere. As suggested by stable isotope and palynological data, the faunal migration can be correlated with a significant rise in seawater temperature during the Middle Oxfordian.

Setting new thermal standards for transitional and coastal (TraC) waters

The construction of a new generation of coastal power stations in the UK and other western European countries has highlighted the absence of robust standards for thermal discharges to transitional and coastal waters. The proposed discharge volumes are greater than hitherto, yet there has been little independent critical examination of their potential impact, whilst much of the existing guidance has been adapted from freshwater practice. This review considers the available knowledge on the tolerance and behaviour of fish and other marine biota to heated effluents. Appropriate ways are suggested of grouping fish species to reflect their sensitivity to thermal effects. The plethora of existing standards are considered and their validity assessed in a framework of predicted seawater temperature rise. Those species or groups of organisms most likely to be affected are identified and finally specific recommendations for thermal standards consistent with long term sustainability are proposed.