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Stable carbon isotope ratios (δ13C) of mussel soft tissues have been widely used to characterize baseline δ13C isoscapes and identify carbon sources at the base of coastal food webs. Extending soft tissue δ13C records back in time, however, is extremely challenging due to very limited sample availability. Here, we test if the stable carbon isotopic composition of periostracum (the outermost organic layer of the shell) in the Mediterranean mussel (Mytilus galloprovincialis) can be used as an environmental archive, similar to soft tissue records. In general, spatial and seasonal variations of periostracum δ13C values are comparable to those of soft tissues, but apparently the latter are more time-averaged and smoothed. Irrespective of such offset, there is a significant linear correlation between mussel periostracum and soft tissue δ13C values (R2 = 0.608, p

Sea surface salinity (SSS) is a key parameter to understand and predict many physical, chemical and biological processes in dynamic coastal environments. Yet, in many regions, instrumental measurements are spatially sparse and insufficiently long, hindering our ability to document changes, causes, and consequences of SSS across different time scales. Therefore, there is an need to develop a robust proxy to extend SSS records back in time. Here, we test whether SSS can be reconstructed reliably and quantitatively from shell oxygen isotopic ratios (δ18Oshell) of the mussel Mytilus galloprovincialis (Lamarck, 1819) in Otsuchi Bay, Northern Japan. δ18Oshell ratios vary spatially and temporally and exhibit strong linear correlations with both sea surface temperature (SST) and SSS measurements, indicating that the composite signal recorded by δ18Oshell measurably responds to variations in both parameters. By combining contemporaneous variations of SST and δ18Oshell, SSS records encoded into mussel shells are deconvolved that significantly correlate with in situ SSS values. To further validate the robustness of δ18Oshell as a quantitative SSS proxy, high-resolution and temporally aligned time-series of δ18Oshell-derived SSS are reconstructed that are highly synchronous with the instrumental records. In particular, two lowered SSS scenarios occur concomitantly with periods of the summer monsoon and typhoon events. δ18Oshell-derived SSS time-series are also comparable to those from numerical modeling. In conclusion, our findings demonstrate that mussel δ18Oshell signatures can be used as a useful tool to construct high-resolution records of SSS in the coastal regions.

Massive populations of sardines inhabit both the western and eastern boundaries of the world’s subtropical ocean basins, supporting both commercial fisheries and populations of marine predators. Sardine populations in western and eastern boundary current systems have responded oppositely to decadal scale anomalies in ocean temperature, but the mechanism for differing variability has remained unclear. Here, based on otolith microstructure and high-resolution stable isotope analyses, we show that habitat temperature, early life growth rates, energy expenditure, metabolically optimal temperature, and, most importantly, the relationship between growth rate and temperature are remarkably different between the two subpopulations in the western and eastern North Pacific. Varying metabolic responses to environmental changes partly explain the contrasting growth responses. Consistent differences in the life-history traits are observed between subpopulations in the western and eastern boundary current systems around South Africa. These growth and survival characteristics can facilitate the contrasting responses of sardine populations to climate change., 大洋の東西で異なるマイワシの環境応答 --耳石が示すグローバル生存戦略の鍵--. 京都大学プレスリリース. 2022-10-17.

To investigate the population dynamics of naturally recruited wild Japanese eels, fisheries data of wild individuals in Okayama Prefecture were investigated as a case study. Wild and stocked eels were discriminated using a recently developed method based on otolith stable isotopes. Of the 161 eels captured in freshwater areas where eels had been stocked, 98.1% were discriminated as stocked. In contrast, 82.8% of 128 eels captured in coastal areas where eels are not stocked were discriminated as wild. There was a significant decrease in longline and set-net catch per unit effort between 2003 and 2016 in the coastal areas where most eels were discriminated as wild, indicating ongoing depletion of wild Japanese eels in these waters.

Temperature-dependent aragonite and calcite formation by scleractinian corals were examined in low molar (m) Mg/Ca seawater, the experimental conditions replicating the fluctuating mMg/Ca levels prevailing throughout the Phanerozoic Eon. Incubation and skeletal growth monitoring of juveniles of the scleractinian coral Acropora solitaryensis for 4 months from the planula stage, in seawater with mMg/Ca ratios of 5.2, 1.0, and 0.5, and temperatures of 19–28 °C, indicated that polymorphism of present-day scleractinian corals in low mMg/Ca seawater is also influenced by seawater temperature. However, corals produced more aragonite than formed in inorganic CaCO3 precipitation experiments under the same conditions, except at 19 °C. Although the aragonite content reflected the results of the latter (abiotic) experiments at 19 °C, it is suggested that aragonitic scleractinian corals controlled skeletal formation biologically under low mMg/Ca conditions at higher temperature, growth rates being faster at 25 °C and slower at 19 °C for all mMg/Ca ratios. Compared with growth rates under the present-day-equivalent seawater Mg/Ca level of 5.2, juvenile growth decreased by 62.8% ± 14.7% and 56.7% ± 6.7% under mMg/Ca levels of 1.0 and 0.5, respectively; the results suggest that growth of aragonitic scleractinian corals is suppressed throughout varying seasonal temperatures under low mMg/Ca conditions. This supports previous findings from variable temperature perspectives that scleractinian corals grow more slowly in low mMg/Ca (Cretaceous) seawater, interpreted as a possible explanation for the hiatus in scleractinian reef building in the Cretaceous Period.

We evaluated the use of the stable oxygen isotope (δ 18 O) in the otolith as a proxy for the temperature history of Japanese sardine Sardinops melanostictus individuals. Japanese sardine juveniles were reared in three different water temperatures over the course of a month. Otolith δ 18 O ( δ otolith ) was analyzed by extracting the portions formed during the rearing period using a micromill. δ 18 O of the rearing water ( δ water ) was also analyzed. A linear relationship between otolith δ 18 O and ambient water temperature was identified as follows: δ otolith − δ water = −0.18 * T + 2.69 (r 2 = 0.91, p Sardinops spp., with resulting application to wild Japanese sardine captured in the Pacific Ocean showing that it estimates a more realistic in situ temperature. Our findings suggest that the Japanese sardine-specific isotopic fractionation equation should be used when interpreting otolith δ 18 O of the Japanese sardine, and the methods presented here could also be useful to understand the temperature history of other fish species.

The Yesso scallop, Patinopecten yessoensis (Jay), is one of the most important bivalve species in the Japanese and Chinese mariculture industry. In recent years, however, high incidences of scallop shell deformity and mortality have occurred with increasing frequency, but timing of onset and underlying causes are often unclear. Here, we proposed a promising δ18Oshell-based method for constraining the onset of shell deformity and mortality of P. yessoensis. Following six months of intermediate suspension culture in Funka Bay, Northern Japan, shells from healthy, deformed and dead scallops were randomly sampled. High-resolution seawater temperature time-series computed from healthy scallop shell δ18O profiles were precisely and temporally aligned to the instrumental temperature curve, thus allowing δ18Oshell-derived temperature time-series from deformed and dead scallops to be contextualized and allowing timing of scallop deformity and death to be retrieved. Irrespective of scallop shell length, onsets of deformity were anchored in February, and since then deformed scallops grew slowly in comparison to healthy individuals. Without exception, however, dead scallops had already ceased their shell building and died before February, indicating different underlying causes of scallop deformity and mortality. Perhaps most promisingly, considering that shells do not have any isotopic turn-over and once formed, temperature information is locked in. Thus, this approach holds great promise for identifying time anchor points (onsets of deformity and death) in archived scallops collected over different time scales, especially during massive mortality events.

With high-temperature stress due to climate change threatening corals in the tropics, cooler high latitudes may become a potential refuge. Already established high latitudes coral communities experience severe cold stress during winter, stress that would be fatal to most of the tropical coral species. Here we studied the physiological response of two high latitude coral species in Japan: Alveopora japonica and Porites heronensis, through field transplantation and in situ incubations. The specimens experienced 243 days at a temperature under 18 °C, which is the limit for the development of reefs and, and 110 days under 15 °C. While bleaching was observed for both species, none of the specimens died, highlighting the high resilience of temperate coral species to cold stress. The survival strategies to the cold temperature seem to differ among the species. P. heronensis exhibited decreased Fv/Fm and highly decreased metabolism (photosynthesis, calcification, respiration, ETSA) suggesting that this species could survive the winter by decreasing its basal metabolism. It also shows a mitotic index of more than 30% during the warmer period that could a prompt recovery from the stress experienced during winter. A. japonica, which showed several bleaching for around three months, also showed decreased metabolism but to a lesser extent suggesting that it was able to use an alternative source of energy. These kinds of adaptations to cold stress may not be widespread among tropical coral species, highlighting the need for better conservation of this future reservoir of biodiversity that represents marginal high latitude coral communities.

Although coral skeletons generally comprise aragonite crystals, changes in the molar Mg/Ca ratio (mMg/Ca) in seawater result in the incorporation of calcite crystals. The formation mechanism of aragonite and calcite crystals in the scleractinian coral Acropora tenuis was therefore investigated by RNA-seq analysis, using early growth stage calcite (mMg/Ca = 0.5) and aragonite (mMg/Ca = 5.2)-based corals. As a result, 1,287 genes were up-regulated and 748 down-regulated in calcite-based corals. In particular, sixty-eight skeletogenesis-related genes, such as ectin, galaxin, and skeletal aspartic acid-rich protein, were detected as up-regulated, and six genes, such as uncharacterized skeletal organic matrix protein 5, down-regulated, in low-Mg/Ca conditions. Since the number of down-regulated genes associated with the skeletal organic matrix of aragonite skeletons was much lower than that of up-regulated genes, it is thought that corals actively initiate construction of an aragonite skeleton by the skeletal organic matrix in low-Mg/Ca conditions. In addition, different types of skeletal organic matrix proteins, extracellular matrix proteins and calcium ion binding proteins appeared to change their expression in both calcite-formed and normal corals, suggesting that the composition of these proteins could be a key factor in the selective formation of aragonite or calcite CaCO3.

Sulfur-containing compounds are important components of all organisms, but few studies have explored sulfate utilization in corals. Our previous study found that the expression of a sulfur transporter (SLC26A11) was upregulated in the presence of Symbiodinium cells in juveniles of the reef-building coral Acropora tenuis. In this study, we performed autoradiography using 35S-labeled sulfate ions (35SO4 2−) to examine the localization and amount of incorporated radioactive sulfate in the coral tissues and symbiotic algae. Incorporated 35SO4 2− was detected in symbiotic algal cells, nematocysts, ectodermal cells and calicoblast cells. The combined results of 35S autoradiography and Alcian Blue staining showed that incorporated 35S accumulated as sulfated glycosaminoglycans (GAGs) in the ectodermal cell layer. We also compared the relative incorporation of 35SO4 2− into coral tissues and endosymbiotic algae, and their chemical fractions in dark versus light (photosynthetic) conditions. The amount of sulfur compounds, such as GAGs and lipids, generated from 35SO4 2− was higher under photosynthetic conditions. Together with the upregulation of sulfate transporters by symbiosis, our results suggest that photosynthesis of algal endosymbionts contributes to the synthesis and utilization of sulfur compounds in corals., Summary: 35S-labeled sulfate incorporated into various cells of coral demonstrates that photosynthesis of endosymbiotic algae contributes to the synthesis and utilization of sulfur compounds.

Ocean acidification can negatively impact marine bivalves, especially their shell mineralization processes. Consequently, whether marine bivalves can rapidly acclimate and eventually adapt in an acidifying ocean is now increasingly receiving considerable attention. Projecting the fate of this vulnerable taxonomic group is also pivotal for the science of sclerochronology – the study which seeks to deduce records of past environmental changes and organismal life-history traits from various geochemical properties of periodically layered hard tissues (bivalve shells, corals, fish otoliths, etc.). In this review, we provide a concise overview of the long-term and transgenerational responses of marine bivalves to elevated pCO2 manifested at different levels of biological organization, with a specific focus on responses of geochemical properties (stable carbon and oxygen isotopes, minor and trace elements and microstructures) of their shells. Without exception, positive transgenerational responses to an elevated pCO2 scenario projected for the year 2100 have been found in all five bivalve species hitherto studied, under the umbrella of two non-genetic mechanisms (increased maternal provisioning and epigenetic inheritance), suggesting that marine bivalves have remarkable transgenerational phenotypic plasticity which allows them to respond plastically and acclimate rapidly in an acidifying ocean. Rapid transgenerational acclimation, especially in terms of physiological processes, however, hinders a reliable interpretation of proxy records. Transgenerationally acclimated bivalves can actively modify the calcification physiology in response to elevated pCO2, which in turn affects the processes of almost all geochemical proxies preserved in their shells. In particular, stable carbon isotopes, metabolically regulated elements (Na, K, Cu, Zn, Fe, etc.), and shell microstructures can be highly biased. In this context, we propose a number of challenges and opportunities the field of sclerochronology may face.

The frequency and severity of coral bleaching events have increased in recent decades. Regionally, human-attributed nutrient pollution, particularly nitrate, has increased in coastal areas due to inflow from rivers and groundwater. The combined effects of increased nitrate concentrations with high temperature or high light on bleaching events and reactive oxygen species levels (ROS) were tested. Coral fragments of Montipora digitata were incubated for 3 and 6 days at different light intensities (200 and 600 μmol m −2 s −1 ), temperatures (27 and 32 °C), and nitrate concentrations (

Coral reefs in Japan are threatened by multiple environmental stresses at both the global and the local scales. Declining water quality in coastal reefs has been reported in the Okinawa region due to red soil runoff, agricultural fertilizers, and antifouling chemicals. Many studies on the stress responses of corals have been conducted by Japanese researchers. For example, metabolic changes due to stresses such as high temperature and chemical discharge have been reported in quantitative terms. Antioxidant enzyme activities and mycosporine-like amino acids have been studied as possible defense mechanisms against environmental stress. Moreover, coral bleaching has been frequently reported and actively studied since the 1980s in Japan. The synergistic effects of multiple stressors have also been studied, with several studies reporting accelerated bleaching under conditions of high seawater temperature and low water quality (high nitrate concentration and high bacterial abundance). The importance of water flow has been extensively studied, and it has been suggested to allow more rapid recovery from bleaching and a higher survival rate. To mitigate environmental stresses on coral reefs, it is important to evaluate risks due not only to global warming but also to local stresses.

To determine the temperature history of early life stages of chub mackerel (Scomber japonicus), otolith stable oxygen isotope ratios (δ18Ootolith) of larval and juvenile fish collected in the Kuroshio–Oyashio transition area during 2004–2015 were analyzed, and experienced temperatures were estimated accordingly. The δ18Ootolith values decreased with otolith growth during the larval stage, whereas those for juveniles were positively correlated with otolith radius and increased with increasing otolith size. Combinations of δ18Ootolith values, average otolith daily increment width, and daily age were representative of the differences between better and poorer recruitment years, the former being characterized by earlier spawning and faster growth (resulting from cooler experienced temperatures), and the latter by slower growth. Analyzed fish were sorted into larval and early juvenile growth stages by cluster analysis; the high-growth cluster exhibited higher δ18Ootolith values than the low-growth cluster. The conversion of δ18Ootolith values to water temperature indicated that the higher growth cluster experienced a water temperature ca. 2.0 °C cooler during the later juvenile stage. Therefore, our results suggest the presence of a growth positive spiral, wherein individuals with high initial growth proactively enter cooler water temperature areas, accessing a highly nutritious diet resulting in further rapid growth.

A new polyacetylene carboxylic acid named montiporic acid D (1) was isolated along with a known polyacetylene alcohol, (Z)-13,15-hexadecadien-2,4-diyn-1-ol (2) from scleractinian coral Montipora digitata. The structures of compounds were determined by analyses of NMR and MS spectra.

All corals have a common structure: two tissue layers enclose a lumen, which forms the gastric cavity. Few studies have described the processes occurring inside the gastric cavity and its chemical and biological characteristics. Here, we show that the coral gastric cavity has distinct chemical characteristics with respect to dissolved O2, pH, alkalinity, and nutrients (vitamin B12, nitrate, nitrite, ammonium, and phosphate) and also harbors a distinct bacterial community. From these results, the gastric cavity can be described as a semi-closed sub-environment within the coral. Dissolved O2 shows very low constant concentrations in the deepest parts of the cavity, creating a compartmentalized, anoxic environment. The pH is lower in the cavity than in the surrounding water and, like alkalinity, shows day/night variations different from those of the surrounding water. Nutrient concentrations in the cavity are greater than the concentrations found in reef waters, especially for phosphate and vitamin B12. The source of these nutrients may be internal production by symbiotic bacteria and/or the remineralization of organic matter ingested or produced by the corals. The importance of the bacteria inhabiting the gastric cavity is supported by the finding of a high bacterial abundance and a specific bacterial community with affiliation to bacteria found in other corals and in the guts of other organisms. The findings presented here open a new area of research that may help us to understand the processes that maintain coral health.

In order to investigate the incorporation of Sr, Mg, and U into coral skeletons and its temperature dependency, we performed a culture experiment in which specimens of the branching coral (Porites cylindrica) were grown for 1 month at three seawater temperatures (22, 26, and 30 C). The results of this study showed that the linear extension rate of P. cylindrica has little effect on the skeletal Sr/Ca, Mg/Ca, and U/Ca ratios. The following temperature equations were derived: Sr/Ca (mmol/ mol) = 10.214(±0.229) � 0.0642(±0.00897) � T (C) (r 2 = 0.59, p < 0.05); Mg/Ca (mmol/mol) = 1.973(±0.302) + 0.1002 (±0.0118) � T (C) (r 2 = 0.67, p < 0.05); and U/Ca (lmol/mol) = 1.488(±0.0484) � 0.0212(±0.00189) � T (C) (r 2 = 0.78, p < 0.05). We calculated the distribution coefficient (D) of Sr, Mg, and U relative to seawater temperature and compared the results with previous data from massive Porites corals. The seawater temperature proxies based on D calibrations of P. cylindrica established in this study are generally similar to those for massive Porites corals, despite a difference in the slope of DU calibration. The calibration sensitivity of DSr, DMg, and DU to seawater temperature change during the experiment was 0.64%/C, 1.93%/C, and 1.97%/C, respectively. These results suggest that the skeletal Sr/Ca ratio (and possibly the Mg/Ca and/or U/Ca ratio) of the branching coral P. cylindrica can be used as a potential paleothermometer. 2011 Elsevier Ltd. All rights reserved.

Various stresses induce the formation of reactive oxygen species (ROS) in biological cells. In addition to stress-induced ROS, we studied the photochemical formation of hydroxyl radicals (˙OH), the most potent ROS, in coral tissues using phosphate buffer-extracted solutions and a simulated sunlight irradiation system. ˙OH formation was seen in extracts of both coral host and endosymbiont zooxanthellae. This study is the first to report quantitative measurements of ˙OH photoformation in coral tissue extracts. Our results indicated that whether or not coral bleaching occurred, coral tissues and symbiotic zooxanthellae have the potential to photochemically produce ˙OH under sunlight. However, no significant difference was found in the protein content-normalized formation rates of ˙OH between corals incubated under different temperatures and irradiance conditions. ˙OH formation rates were reduced by 40% by reducing the UV radiation in the illumination. It was indicated that UV radiation strongly affected ˙OH formation in coral tissue and zooxanthellae, in addition to its formation through photoinhibition processes.

Coral reefs are deteriorating worldwide due to various stresses, including pollution of hazardous chemicals such as antifouling chemicals. Occurrence and impacts of a new antifouling biocide Irgarol-1051 (2-methylthio- 4-tert- butylamino -6-cyclopropylamino -s-triazine) have been studied in coral reef waters around Okinawa Islands, Japan. The average concentration of Irgarol detected at commercial and fisheries Ports was 24.70 ± 9.88 ng/L. In Naha Bay, the average concentration of Irgarol was 10.00±12.98 ng/L. The average level detected around the Ports has already approaches the environmental risk limit for the marine organisms. Irgarol was detected in waters at the frequency of 92.3 % (24/26) of the total samples collected during two sampling campaigns (September and December, 2007) at the Ports. In Naha Bay, Irgarol was detected by 40.5 % (17/42) of the total water samples collected monthly from Sep., 2007 to Feb., 2008, indicating that Irgarol is widely detected along the coastal shorelines of Okinawa Island. The eco- toxicological study revealed that the rate of photosynthesis in the coral Galaxea fascicularis was significantly reduced by 18 % and 121 % relative to control when the corals were exposed to 1000 and 10,000 ng/L of Irgarol, respectively. The calcification rate dropped by 98.3 % relative to control when the corals were exposed to 10,000 ng/L of Irgarol. The results of the present study report the wide occurrence of new antifouling biocide Irgarol around coastal areas of Okinawa Island. However, the contamination does not pose serious threat on the photosynthesis and calcification of corals under short term exposure (96 h).

Coral metabolism reflects the physiological condition of a coral colony. We studied coral metabolism using a continuous-flow, complete mixing (CFCM) experimental system. Small-size Goniastrea aspera coral colonies were incubated in the CFCM system with and without hydrogen peroxide (H2O2) added to the supplied seawater (0 µM H2O2 for 12 days; 0, 0.3, 3.0, and 30 µM H2O2 for 3 days, for each treatment) Without addition of H2O2, coral metabolism, including photosynthesis (gross primary productivity) and calcification, was relatively stable and there were no significant metabolic changes, suggesting that, without H2O2 added to the CFCM system, the corals did not suffer significant stress from the experimental system over a 12-day incubation period. When H2O2 was added, large decreases in photosynthesis and calcification were observed. The non-parametric Mann–Whitney U-test showed that there were statistically significant differences in photosynthesis after addition of 3.0 µM and 30 µM H2O2, compared with the control. We also found statistically significant differences in net calcification after addition of 30 µM H2O2. Thus, the incubation experiments suggest that higher H2O2 concentrations in seawater clearly influence coral metabolism. However, the results also suggest that the current seawater H2O2 level in Okinawa is not likely to pose significant acute effects on the metabolic activities of corals.

We examined quantitative changes in the metabolism of the coral Galaxea fascicularis caused by increases in both hydrogen peroxide (H2O2) concentration and seawater temperature. Seawater temperatures were maintained at 27 or 31°C in a well-controlled incubation chamber, and three levels of H2O2 concentration (0, 0.3, 3.0 μM) were used in experimental treatments. Gross primary production, calcification rates and respiration rates were all affected by increased H2O2 concentrations and high seawater temperatures. Individual treatments of high H2O2 or elevated seawater temperature alone caused significant declines in coral photosynthesis and calcification rates within the 3-day incubation period. The synergistic effect of high H2O2 combined with high seawater temperature resulted in a 134% increase in respiration rates, which surpassed the effect of either H2O2 or high seawater temperature alone. Our results suggest that both high H2O2 concentrations and elevated temperatures in seawater can strongly affect coral metabolism; however, these effects cannot be estimated by simply summing the effects of individual stress parameters.

The distribution of corals in Japan covers a wide range of latitudes, encompassing tropical to temperate zones. However, coral communities in temperate zones contain only a small subset of species. Among the parameters that determine the distribution of corals, temperature plays an important role. We tested the resilience to cold stress of three coral species belonging to the genus Acropora in incubation experiments. Acropora pruinosa, which is the northernmost of the three species, bleached at 13 °C, but recovered once temperatures were increased. The two other species, A. hyacinthus and A. solitaryensis, which has a more southerly range than A. pruinosa, died rapidly after bleaching at 13 °C. The physiological effects of cold bleaching on the corals included decreased rates of photosynthesis, respiration and calcification, similar to the physiological effects observed with bleaching due to high temperature stress. Contrasting hot bleaching, no increases in antioxidant enzyme activities were observed, suggesting that reactive oxygen species play a less important role in bleaching under cold stress. These results confirmed the importance of resilience to cold stress in determining the distribution and northern limits of coral species, as cold events causing coral bleaching and high mortality occur regularly in temperate zones.

We investigated the chemical composition and photochemical formation of hydroxyl (OH) radicals in the water-soluble fractions (WSF) of aerosol particles collected in Okinawa, Japan. Bulk aerosol samples were collected for 2–7 days at a time by a high-volume air sampler over a 3-month period. Major ions present in the WSF solutions were SO42−, Na+, and Cl−. Sulfate ion concentrations were much higher when Yellow Sand events occurred. The mass-based Cl−/Na+ ratio found in the WSF solutions averaged 49.7%, much lower than the ratio in seawater, indicating that chlorine was lost from the aerosol particles. A negative correlation (R=−0.67) was found between the Cl−/Na+ ratio and the concentration of non-sea-salt–SO42−. We confirmed the photochemical formation of OH radicals in the study samples using illumination experiments at 313 nm. The apparent quantum yields of OH radical photoformation, based on the total absorbance at 313 nm, ranged from ND to 0.0017, with a mean±1 SD of 0.0010±0.0005. Hydroxyl radical photoformation rates from nitrate and nitrite photolyses, estimated based on nitrate and nitrite ion concentrations and our illumination conditions, averaged 32±24% and

The coral species, Montipora digitata and seagrass, Thalassia hemprichii , co-inhabit the southern portion of the reef moat in Bise, Okinawa, Japan. To elucidate the biogeochemical relationship between coral and seagrass in mixed communities of the coral reef ecosystem, the carbon metabolisms and the inorganic nitrogen flux rates were estimated in various reef habitats. We used benthic chambers to investigate sandy, seagrass, coral-seagrass mixed communities, coral, and acorn worm habitats. Relatively high concentrations of nitrate and nitrite ions (NO x ) were observed in all habitats due to coastal groundwater inflow. The uptake rate constant of NO x was the highest in the coral-seagrass habitat and was significantly different from the rate constant in the seagrass habitat, indicating that seagrass benefits from co-inhabitation with coral. Dissolution of CaCO 3 was observed in the seagrass and coral-seagrass communities. This decline in basal coral carbonate substrate may contribute to increased fragmentation and dispersal of the coral habitat. On a biogeochemical scale, the coral-seagrass relationship benefits the seagrass in terms of NO x availability and benefits the coral in terms of carbonate dissolution, increasing fragmentation, and furthering habitat development.

The effects of elevated temperature and high pCO2 on the metabolism of Galaxea fascicularis were studied with oxygen and pH microsensors. Photosynthesis and respiration rates were evaluated from the oxygen fluxes from and to the coral polyps. High-temperature alone lowered both photosynthetic and respiration rates. High pCO2 alone did not significantly affect either photosynthesis or respiration rates. Under a combination of high-temperature and high-CO2, the photosynthetic rate increased to values close to those of the controls. The same pH in the diffusion boundary layer was observed under light in both (400 and 750 ppm) CO2 treatments, but decreased significantly in the dark as a result of increased CO2. The ATP contents decreased with increasing temperature. The effects of temperature on the metabolism of corals were stronger than the effects of increased CO2. The effects of acidification were minimal without combined temperature stress. However, acidification combined with higher temperature may affect coral metabolism due to the amplification of diel variations in the microenvironment surrounding the coral and the decrease in ATP contents.

M.A. Sheikh1,5, T. Oomori1, H. Fujimura1, T. Higuchi1, T. Imo1,6, A. Akamatsu1, T. Miyagi2, T. Yokota3 and S. Yasumura4 1Department of Chemistry, University of the Ryukyus, Okinawa, 2Okinawa Prefectural Institute of Health and Environment, Okinawa 3Water Quality Control Office, Okinawa Prefectural Bureau, Okinawa 4WWF Japan, Minato-ku, Tokyo 5Research Unit, The State University of Zanzibar, 6Faculty of Science, Samoa National University, 1,2,3,4Japan 5Tanzania 6Samoa

Various stresses induce the formation of reactive oxygen species (ROS) in biological cells. In addition to stress-induced ROS, we studied the photochemical formation of hydroxyl radicals (˙OH), the most potent ROS, in coral tissues using phosphate buffer-extracted solutions and a simulated sunlight irradiation system. ˙OH formation was seen in extracts of both coral host and endosymbiont zooxanthellae. This study is the first to report quantitative measurements of ˙OH photoformation in coral tissue extracts. Our results indicated that whether or not coral bleaching occurred, coral tissues and symbiotic zooxanthellae have the potential to photochemically produce ˙OH under sunlight. However, no significant difference was found in the protein content-normalized formation rates of ˙OH between corals incubated under different temperatures and irradiance conditions. ˙OH formation rates were reduced by 40% by reducing the UV radiation in the illumination. It was indicated that UV radiation strongly affected ˙OH formation in coral tissue and zooxanthellae, in addition to its formation through photoinhibition processes.

From Cladonia rangiferina were isolated two novel abietane diterpenoids, hanagokenols A (1) and B (2). Also in this investigation, four known abitetane diterpenoids (3-6), four known labdane diterpenoids (7-10), one known isopimarane diterpenoid (11), and six known aromatic compounds were isolated. These structures were elucidated primarily through extensive NMR experiments. Hanagokenol A (1) was a unique abietane diterpene having an ether linkage between C-6 and C-18 of sugiol. Hanagokenol B (2) is also a unique secoabietane diterpene, having gamma-lactone which occurred by cleavage and subsequently oxidation between C-6/C-7 of 12-hydroxydehydroabietinol. Furthermore, all the isolated compounds (1-17) were tested for the antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).

From Cladonia rangiferina were isolated two novel abietane diterpenoids, hanagokenols A (1) and B (2). Also in this investigation, four known abitetane diterpenoids (3-6), four known labdane diterpenoids (7-10), one known isopimarane diterpenoid (11), and six known aromatic compounds were isolated. These structures were elucidated primarily through extensive NMR experiments. Hanagokenol A (1) was a unique abietane diterpene having an ether linkage between C-6 and C-18 of sugiol. Hanagokenol B (2) is also a unique secoabietane diterpene, having gamma-lactone which occurred by cleavage and subsequently oxidation between C-6/C-7 of 12-hydroxydehydroabietinol. Furthermore, all the isolated compounds (1-17) were tested for the antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).

Chromone glucosides, takanechromones A-C (1, 2 and 5) and chromanone glucosides, named takanechromanones A and B (3 and 4), were isolated from the methanolic extracts of Hypericumsikokumontanum together with 27 known compounds. Their structures were established based on spectroscopic evidence. The isolated compounds and some chromone derivatives were assayed for antimicrobial activity against Helicobacter pylori and cytotoxicity against human cancer cell lines.

A small-scale chamber experimental system was designed to study the effects of temperature on colony-level coral metabolism. The system continuously supplies fresh seawater to the chamber, where it is mixed immediately and completely with the seawater already present. This continuous-flow complete-mixing system (CFCM system), in conjunction with theoretical equations, allows quantitative determination of chemical uptake and release rates by coral under controlled environmental conditions. We used the massive hermatypic coral Goniastrea aspera to examine variations in pH, total alkalinity, and total inorganic carbon for 16 days at 27 degrees C under controlled light intensities (300 and 0 micromol m(-2) s(-1)). We confirmed the stability of the CFCM system with respect to coral photosynthetic and calcification fluxes. In addition, we obtained daily photosynthetic and calcification rates at different temperatures (27 degrees C, 29 degrees C, 31 degrees C, and 33 degrees C). When seawater temperature was raised from 31 degrees C to 33 degrees C, the gross primary production rate (Pgross) decreased 29.5%, and the calcification rate (G) decreased 85.7% within 2 days. The CFCM system allows quantitative evaluation of coral colony chemical release and uptake rates, and metabolism.