Rise In Seawater Temperature Research Articles

Settlement, mortality and growth of the asari clam (Ruditapes philippinarum) for a collapsed population on a tidal flat in Nakatsu, Japan

Although fluctuation and decline in bivalve populations have been reported worldwide, the underlying processes are not yet fully understood. This lack of understanding is partly due to an absence of demographic information for the early post-settlement period. This is the case particularly for annual production of the asari clam (also commonly known as the Manila clam, Ruditapes philippinarum) in Japan, which has greatly decreased in recent years. A remarkable decrease has been observed in the Nakatsu tidal flat, where current yields are less than 0.02% of the maximum yield. Possible explanations for this decline are: 1. limitation on recruitment due to overfishing; and 2. the demographic processes of growth and mortality have been altered by environmental changes, such as rise in seawater temperature or decrease in phytoplankton abundance. However, because of a lack of demographic information (e.g., the initial densities of larval settlement and mortality and growth rates post-settlement), the reasons for the decline, and the relative importance of each period in the life cycle in determining population abundance, remain unclear. Despite the decline, we observed high levels of recruitment of 0-year-class clams on the Nakatsu tidal flat in spring 2005, where more than 10,000 individuals m−2 3–5mm in shell length, estimated to have settled during the previous autumn, were observed. To obtain demographic information on the Nakatsu clams, we investigated two factors. First, we investigated the distribution of the 0-year-class clams and their rate of change in density as a combination of mortality, emigration and immigration on the whole tidal flat after a year. Second, we investigated the rate of change in the density and growth of clams after settlement in the center of the flat for 3years. The rate of decrease in the density of the 0-year-class clams over the whole tidal flat after a year was greater at the stations where the initial density was higher. This suggests that density-dependent processes such as predation or competition may affect population levels. In the center of the flat, the initial density of settlement was more stable than the rate of decrease after settlement. These results suggest that the clam population on this tidal flat is probably suppressed by variable but high mortality rates after settlement, not by recruitment limitation.

Benthic assemblages and temperature effects on Paracentrotus lividus and Arbacia lixula larvae and settlement

Recruitment is a principal controlling factor in population dynamics of marine species. In marine invertebrates with a planktonic larval stage, such as echinoids, recruitment is assured by larval supply, settlement and juvenile survival. Larval supply and juvenile survival are affected by a wide range of factors, including temperature, presence of predators, quality and quantity of food. Echinoid larval settlement is mainly conditioned by the finding of a suitable substrate to metamorphose. The sea urchins Arbacia lixula and Paracentrotus lividus are considered key species of the Mediterranean infralittoral rocky shores. At high densities, the grazing activity of both species can produce and maintain barren grounds, a particular habitat condition characterized by extremely low cover values of erect algae with high presence of naked substrates and encrusting corallinales, poor in biodiversity and ecosystem functions. We tested the role of different settlement substrates on the metamorphosis competent larvae of the two species. Furthermore, from our larval rearing trails we were able to identify strong temperature effects on larval development of the two species. P. lividus and A. lixula larvae have been reared at 18°C but for the second species it was necessary to use higher temperatures (22°C) to perform settlement experiments, as in the 18°C set all larvae died in the first week. Both species larvae have been fed Cricosphaera elongata. Metamorphosis of competent larvae has been induced using different substrates: naked stones, Lithophyllum incrustans, Stypocaulon scoparium, Corallina elongata, turf forming algae and Posidonia oceanica. For each species, two larval batches were used for settlement experiments; for each larval batch two replicates/substrates were set up. No differences in the rate of metamorphosis on any of the tested substrates were observed for P. lividus, while A. lixula showed to prefer naked stones and encrusting coralline algae Considering that A. lixula population growth may trigger barren extension on rocky shores, this may lead to a positive feedback between barren extension and A. lixula population density. Furthermore, our results suggest that the predicted rise in seawater temperature may favor A. lixula larval survival and inhibit P. lividus. Combining information on temperature tolerance with other sources of information for these species in the Mediterranean, it is possible to develop a conceptual model of the interaction between the two species and the alternative state of their habitats.

Using the Acropora digitifera genome to understand coral responses to environmental change

Despite the enormous ecological and economic importance of coral reefs, the keystone organisms in their establishment, the scleractinian corals, increasingly face a range of anthropogenic challenges including ocean acidification and seawater temperature rise. To understand better the molecular mechanisms underlying coral biology, here we decoded the approximately 420-megabase genome of Acropora digitifera using next-generation sequencing technology. This genome contains approximately 23,700 gene models. Molecular phylogenetics indicate that the coral and the sea anemone Nematostella vectensis diverged approximately 500 million years ago, considerably earlier than the time over which modern corals are represented in the fossil record (∼240 million years ago). Despite the long evolutionary history of the endosymbiosis, no evidence was found for horizontal transfer of genes from symbiont to host. However, unlike several other corals, Acropora seems to lack an enzyme essential for cysteine biosynthesis, implying dependency of this coral on its symbionts for this amino acid. Corals inhabit environments where they are frequently exposed to high levels of solar radiation, and analysis of the Acropora genome data indicates that the coral host can independently carry out de novo synthesis of mycosporine-like amino acids, which are potent ultraviolet-protective compounds. In addition, the coral innate immunity repertoire is notably more complex than that of the sea anemone, indicating that some of these genes may have roles in symbiosis or coloniality. A number of genes with putative roles in calcification were identified, and several of these are restricted to corals. The coral genome provides a platform for understanding the molecular basis of symbiosis and responses to environmental changes.

The Widely-Distributed Indo-Pacific Zoanthid Palythoa Tuberculosa: A Sexually Conservative Strategist

Here we characterize the reproductive strategy of Palythoa tuberculosa (Esper, 1791) in the northern Gulf of Aqaba. Polyp sampling revealed that P. tuberculosa is a protandrous hermaphrodite over its life cycle, but has an annual protogynous hermaphroditic cycle. Fecundity was highest in the center of the colonies, with a mean (± SD) of 1196 ± 629 oocytes polyp-1. Spawning coincided with a rise in seawater temperature, and occurred on the first week after full moon each month (June-August). Gamete release and fertilization success peaked 2 d after full moon. Larvae developed into zoanthellae 13 d post-fertilization. High fecundity and long larval developmental periods suggest high investment in sexual reproduction. Nonetheless, a low recruitment was noted on the reef. Palythoa tuberculosa appears to maintain its complex reproductive strategy throughout its wide geographic distribution.

Antarctic Benthic Fauna in the Global Climate Change

In the last 50 years a significant climatic shift has been observed along the Antarctic Peninsula (air and seawater temperature rise, glacial retreat, localized instances of lowered shallow waters salinities). Many Antarctic marine benthic invertebrates are adapted to specific environmental conditions (e.g. low stable temperatures, high salinity and oxygen content). Changes caused by global climate changes and subsequent glacial melting can be expected to have significant impacts on species physiology and distribution. The rise of sea water temperature coupled with such additional stress factors as melt water run-off, increased ice disturbance, disruption of food webs or invasion of alien species can be a serious problem for their long-term survival.

The base of the Toarcian (Early Jurassic) in the Almonacid de la Cuba section (Spain). Ammonite biostratigraphy, magnetostratigraphy and isotope stratigraphy

The Almonacid de la Cuba section, located in the Iberian Range, in central-eastern Spain, contains an outstanding record of the Pliensbachian-Toarcian boundary (Early Jurassic). Four ammonite assemblages, characterized respectively by the presence of Pleuroceras, Canavaria, Dactylioceras (Eodactylites) and Dactylioceras (Orthodactylites) have been distinguished. The base of the Toarcian is located at level CU35.2, based on the first occurrence of Dactylioceras. The presence of Boreal and Mediterranean taxa allows correlation between both bioprovinces. Magnetostratigraphy shows the most complete record of reversals of the Earth magnetic field for the base of Toarcian. The onset of the positive δ13C excursion which has been found in the Toarcian of several sections in Europe has been recorded. Average paleotemperatures for the latest Pliensbachian Spinatum Zone was about 12.5°. Seawater temperature rise during the lowermost Toarcian, reaching average temperatures of 16.7°C at the Tenuicostatum Zone. The 87 Sr/ 86 Sr curve fits with the LOWESS calibration curve.

Environmental determinants correlated to Vibrio harveyi‐mediated death of marine gastropods

Vibrio harveyi is an emerging pathogen that causes mass mortality in a wide variety of marine animal species; however, it is still unclear which environmental determinants correlate V. harveyi dynamics and the bacterium-mediated death of marine animal life. We conducted a correlation analysis over a 5-year period (2003-2007) analysing the following data: V. harveyi abundance, marine animal mortality and environmental variables (seawater temperature, salinity, pH, chlorophyll a, rainfall and total viable bacterial counts). The samples were collected from a coastal area in northern Japan, where deaths of a marine gastropod species (Haliotis discus hannai) have been reported. Our analysis revealed significant positive correlations between average seawater temperature and average V. harveyi abundance (R = 0.955; P < 0.05), and between average seawater temperature and V. harveyi-mediated abalone death (R = 0.931; P < 0.05). Based on the regression model, n degrees C rise in seawater temperature gave rise to a 21(n)-fold increase in the risk of mortality caused by V. harveyi infection. This is the first report providing evidence of the strong positive correlation between seawater temperature and V. harveyi-mediated death of marine species.

DISINTEGRATION OF THE CELLS OF SIPHONOUS GREEN ALGA CODIUM EDULE (BRYOPSIDALES, CHLOROPHYTA) UNDER MILD HEAT STRESS(1).

The siphonous green alga Codium edule P. C. Silva (Bryopsidales, Chlorophyta) has the highest covering ratio among the macroalgae on the coral reef of Nanwan Bay in southern Taiwan, but its population in the subtidal region drastically decreases from July to September each year. The objective of this study was to determine whether the high temperature of summer could be the basis for this population decrease. Chlorophyll fluorescence measurements revealed that when the algae were incubated at 35°C (a temperature that can be reached in southern Taiwan during the summer), their photosynthetic activities were almost completely inhibited after about 8 h. The circadian rhythm of photosynthesis was disrupted at a temperature as low as 32°C. TEM studies showed that 4 h incubation at 35°C induced a decrease in turgidity accompanied by vacuole shrinkage and plasmolysis. The marked disintegrative changes, including damage to organelles, such as chloroplasts and nuclei, occurred after about 8 h, at which time central vacuoles collapsed and the cell interior was then filled with numerous small vesicles. Our results suggested that the rise in seawater temperature during the summer could be one of the major causes of the massive death of C.edule in the field.

Seawater temperature and carbon isotope variations in belemnites linked to mass extinction during the Toarcian (Early Jurassic) in Central and Northern Spain. Comparison with other European sections

The Early Toarcian mass extinction marks one of the critical events in the history of the Earth. Many of these events have been linked to important climate changes. Two sections of the Toarcian showing high-resolution ammonite-based biostratigraphy are studied in Central and Northern Spain. Stable isotope datasets, based on the analysis of 192 diagenetically screened belemnite calcite and 41 bulk carbonates, allowed the construction of δ 13C curves and a δ 18O-based palaeotemperature. Comparison of the extinction pattern with other sections in Europe and northern Africa shows that the Early Toarcian mass extinction boundary occurred at the Tenuicostatum–Serpentinum transition, and that the organic-rich facies linked to the Oceanic Anoxic Event and the associated negative δ 13C excursion are diachronous. From a latest Pliensbachian cooling interval, a first increment of seawater temperature averaging about 4.5 °C, started around the Pliensbachian–Toarcian boundary and developed during the earliest Toarcian Tenuicostatum Biochron, marking the beginning of the main extinction interval. From the Tenuicostatum–Serpentinum transition up to the Bifrons Biochron, a rise in seawater temperature averaging 5.7 °C to 7.8 °C was recorded. This warming interval, which started rapidly and which seems to be synchronous at least in Western Europe, is considered one of the main factors responsible for mass extinction. For some authors this rapid warming was probably due to a massive injection of greenhouse gases into the atmosphere, but it does not seem to be recorded in belemnite calcite, and the origin of these possible gases is largely debated in the literature. Additional isotope excursions were found in the studied sections in Spain during the Middle and Late Toarcian. A negative δ 13C bel excursion has been recorded at the latest Bifrons Biochron. Above this shift, the Illustris–Vitiosa subzones thermal peak, which represents a 2–3 °C Δ T, could be linked to one of the tectonomagmatic activity peaks recorded in the Karoo Basin. A renewal in the ammonite and brachipod faunas coincident with this climatic change has been recognized in NW Europe and Western Tethys. An interesting thermal peak has also been detected in belemnites of the Insigne Subzone. Δ T is in the order of 3 °C, and in both sections the thermal peak is included into a δ 13C bel negative excursion of about − 1.5‰. Relative synchrony with the new age for the Karoo main magmatic activity (178–180 Ma) indicates that the δ 13C negative anomaly and the warming interval could be caused by the release of volcanogenic greenhouse gases. At this short interval, noteworthy changes in the abundance and diversity of the recorded assemblages in several faunal groups of NW Europe and Tethys are observed. The uppermost Levesquei Subzone thermal peak has only been recognized in the deposits of the section located in Central Spain and coincides with a positive δ 13C excursion.

わが国における&lt;I&gt;Vibrio vulniificus&lt;/I&gt;感染症患者誌上調査

Vibrio vulnificus is found globally in marine coastal waters. Infection with this organism, via ingestion of raw shellfish or exposure to marine water, can cause necrotizing fasciitis and sepsis, which have high mortality and short latency. In Japan, many cases have been reported since 1980, mainly from hospitals in western prefectures. However, because of the sporadic nature of infection outbreaks, a thorough epidemiologic survey has not been done. We studied the epidemiological and clinical characteristics of Vibrio vulnificus infections reported in Japan from 1975 to 2005. We identified 185 cases using the medical article search engines Ichushi (Japan Medical Abstracts Society), CiNii (Citation Information by National Institute of Informatics), and PubMed over 30 years. The median age of patients was 59. The number of male patients was eight times the number of female patients; however, no significant difference in mortality was found between genders. In yearly distributions of patients, 20 cases were reported in 2001, a year in which we experienced more rainfall and a longer rainy season in Northern Kyushu. In monthly distribution, about 80% of cases were reported from July to September when sea water temperatures rise. About 40% of cases were reported in four prefectures around the Ariake Sea. The underlying disease indicated liver dysfunction in 90% of patients, but mortality was the same regardless of the infection pathway (oral ingestion or wound). Because of its rapid aggravation and high mortality rate, public education is important to prevent new cases. It is also highly recommended that patients with preexisting liver dysfunction avoid raw fish and limit exposure to marine water during the summer.

Fluctuating algal symbiont communities in Acropora palifera (Scleractinia: Acroporidae) from Taiwan

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 295:113-121 (2005) - doi:10.3354/meps295113 Fluctuating algal symbiont communities in Acropora palifera (Scleractinia: Acroporidae) from Taiwan Chaolun Allen Chen1,2,*, Jih-Terng Wang3, Lee-Shing Fang4, Ya-Wen Yang1 1Research Center for Biodiversity, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC2Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan, ROC3Department of Food Science and Technology, Tajen Institute of Technology, Yanpu, Pingtung 907, Taiwan, ROC4National Museum of Marine Biology and Aquarium, Hengchun, Pingtung 946, Taiwan, ROC *Email: cac@gate.sinica.edu.tw ABSTRACT: Seasonal dynamics of algal symbiont communities from the reef flat-dwelling coral Acropora palifera was monitored from January 2000 to July 2001 at Tantzei Bay, Kenting National Park, southern Taiwan. Zooxanthellae density and pigment contents monitored throughout the 18 mo sampling period indicated that no significant bleaching occurred in A. palifera. Molecular phylotyping showed that 2 distinct symbionts, Phylotypes C and D, were associated with A. palifera, either individually or simultaneously. Population surveys throughout the bimonthly sampling period demonstrated that the symbiont community within A. palifera was highly dynamic with significant fluctuations; a drop in the Phylotype D percentage occurred in May, which was correlated with a rise in seawater temperature in the late spring/early summer at the sampled reef. Direct tracking of tagged corals provided evidence that seasonal fluctuations in the algal symbiont communities not only involve changes in zooxanthellae densities and pigment contents, but also a reshuffling of different Symbiodinium phylotypes. Our study highlights that stress tolerance among phylotypes urgently needs to be re-evaluated through a better understanding of the physiological traits of symbionts. KEY WORDS: Symbiont community · Phylotype · Stress tolerance · nlsrDNA RFLPs · Symbiont reshuffling Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 295. Online publication date: June 23, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

The Vibrio shiloi/Oculina patagonica model system of coral bleaching.

The scleractinian coral Oculina patagonica undergoes bleaching (loss of its endosymbiotic zooxanthellae) every summer in the eastern Mediterranean Sea when seawater temperatures rise. The causative agent of the disease is Vibrio shiloi. The pathogen adheres to a beta-galactoside-containing receptor in the coral mucus, penetrates into epithelial cells, differentiates into a viable-but-not-culturable form, multiplies, and produces a proline-rich peptide toxin that inhibits photosynthesis of the zooxanthellae in the presence of ammonia. Several of the virulence factors, such as adhesin, toxin, and superoxide dismutase, are produced only at the elevated summer seawater temperatures. The fireworm Hermodice carunculata is a winter reservoir and spring/summer vector for V. shiloi. The generality of the bacterial hypothesis of coral bleaching is discussed.

The role of ecological divergence in speciation between intertidal and subtidal Scoloplos armiger (Polychaeta, Orbiniidae)

The concept of ecological speciation implies that habitat differences may split a species by strong selection and rapid adaptation even under sympatric conditions. Studies on the polychaete Scoloplos armiger in the Wadden Sea (North Sea) indicate sibling species existing in sympatry: the intertidal ‘Type I’ with holobenthic development out of egg cocoons and the subtidal ‘Type S’ producing pelagic larvae. In the current study, Types I and S are compared in habitat-related traits of reproductive timing and physiological response to hypoxia and sulphide. Spawnings of Type I and Type S recorded over six years overlap in spring and both appear to be triggered by a rise in seawater temperature above 5 °C. Type S exhibits an additional autumn spawning (at seawater temperatures around 10 °C) which was previously unknown and is absent in Type I. The overall abundance of pelagic larvae in the Wadden Sea is higher in spring than in autumn. Tolerance of both sulphide and hypoxia was lower in Type S than in Type I. This correlates with a 5 to 10-fold lower sulphide concentration in the subtidal compared to the intertidal habitat. Physiological tolerance and divergence in developmental mode appear as traits which may have led to reproductive isolation between Type I and Type S. Their role in allopatric and sympatric speciation scenarios in S. armiger is discussed. Since the pelagic dispersal mode has been neglected so far, a reassessment of population dynamics models for S. armiger is suggested.

50 Can the effects of ocean warming on temperate reef communities be accurately predicted? lessons from a large scale, long term field experiment in central California

One of the most commonly predicted effects of global ocean warming on marine communities is a poleward shift in the distribution of species with an associated replacement of cold‐water species by warm‐water species. Such predictions are imprecise and based largely on broad correlations in uncontrolled studies that examine changes in species composition and abundance relative to seawater temperature. Before‐After‐Control‐Impact (BACI) analyses of the effects of a large thermal discharge shows that an induced 3.4 deg. C rise in seawater temperature over 10 years along 2 km of rocky coastline resulted in significant community‐wide changes in 150 species of algae and invertebrates relative to controls. Contrary to predictions from biogeographic models, there was no trend towards warm‐water species with southern geographic affinities replacing cold‐species with northern affinities. Instead, communities were greatly altered in apparently cascading responses to changes in abundance of several habitat‐forming taxa, particularly subtidal kelps (e.g. Pterygophora californica) and intertidal foliose red algae (e.g. Mazzaella flaccida). Many temperature sensitive algae decreased greatly in abundance, whereas many invertebrate grazers increased. The results indicate that the responses of temperate reef communities to ocean warming can be strongly coupled to direct effects on habitat‐forming taxa and indirect effects operating through ecological interactions. Given our understanding of temperate reef ecology and its local variability, the results also suggest that accurate predictions of the effects of global ocean warming will be difficult to make.

RECOVERY AND GENETIC DIVERSITY OF THE INTERTIDAL KELP LESSONIA NIGRESCENS (PHAEOPHYCEAE) 20 YEARS AFTER EL NIÑO 1982/831

Massive mortality in kelp beds of the Pacific coasts of North and South America was caused by the rise in surface seawater temperature during the El Niño Southern Oscillation (ENSO) event of 1982/83, the strongest in the four and half previous centuries. In northern Chile a stretch of 600 km of coastline showed massive mortality of the intertidal kelp species Lessonia nigrescens Bory, of which only a few individuals managed to survive. Kelps and their associated biodiversity recovered but kelp beds re‐colonization in general was variable in time and space seemingly very slow along northern Chilean coasts. Here we show, effectively, that northward re‐colonization advanced less than 60 km in 20 years. Conversely, kelp beds of the Northern Hemisphere recovered 300 km in only six months after the same ENSO event. Genetic diversity in the two most affected populations of L. nigrescens shows half of the heterozygosity and polymorphism with respect to that observed in six non affected populations. In addition, geographically separated populations seem highly isolated as evidenced by high and significant fixation indices (all FST values over 0.4).

Reproductive cycle and spawning induction in the gregarious brittle star Ophiothrix fragilis (Echinodermata) in the Oosterschelde (Netherlands)

Summary The reproductive biology of the gregarious brittle star Ophiothrix fragilis is described using the gonad index (GI) and the maturity index (MI) in conjunction with the photoperiod and water temperature. The ophiuroid has a typical annual reproductive cycle going through five distinct reproductive stages. After a resting period during the winter season, the growth and maturation period begins in parallel with a rise in seawater temperature. Spawning takes place during summer after which the gonads regress and the next cycle begins. The rise in temperature seems to influence gonadal growth and more specifically the maturation period of the gametogenic cycle, the indices each attaining higher values earlier in 1999 than in 2000, temperature having reached a maximum a month earlier that year. Representation of the MI in polar coordinates shows a relatively homogenous population during the winter and spring season (resting and maturation periods respectively) while the summer season is more heterogeneous due to the presence of individuals in various reproductive stages. Elevated water temperatures (above 16°C,) mechanical stress believed to be due to strong hydrodynamics and the release of gametes by conspecifics seem to induce spawning in males and females with the former being more sensitive to these cues.

Coral mortality and recovery in response to increasing temperature in the southern Arabian Gulf

Analysis of a new data set for sea surface temperature shows that the seawater temperature rise in 1998 in the southern Arabian Gulf was the largest since 1870; it also showed that there is an underlying rising trend of sea surface temperature across the whole of the measured area spanning 5 degrees longitude and 3 degrees latitude. Over the last 50 years, sea surface temperature rise was about 0.2°C per decade, though this has accelerated to about 0.45°C per decade in the last 20 years. The pattern in temperature values in each 1 degree ‘cell’ are used to show that, at any one time, temperature rises towards the east of this area, which supports the concept of a general anti-clockwise circulation in the southeastern half of the Arabian Gulf. Spatial and temporal patterns in sea surface temperature rises also show that the mean temperature field at any location is similar to that which existed in the one degree cell immediately to its east approximately 30 years earlier.Coral cover in shallow water (&amp;lt;3 m depth) was &amp;lt;1 percent immediately following the 1998 event, due to near total mortality of vast areas of shallow Acropora (stagshorn) corals. Deeper than 3 m there was increasing survival of the large Porites (boulder) corals, survival increasing with depth. Coral survival improved towards the east, though overall, less than twenty coral species were found altogether. Juvenile recruitment also increased towards the east, and at any one site, recruitment increased with increasing depth. The identity of new juveniles was mainly faviid corals, not the Acropora or Porites which dominated these reefs before the 1998 event. This suggests that there may be a phase shift to a different stable state in terms of coral communities. We also speculate that, because the Arabian Gulf contains an extreme warm-tolerant subset of the Indian Ocean coral fauna, the changes seen in the Gulf may reflect future patterns across a greater part of the Indian Ocean.

A novel Vibrio sp. pathogen of the coral Pocillopora damicornis

A coral pathogen was isolated from the diseased tissue of Pocillopora damicornis in Zanzibar. The pathogenic bacterium, referred to as Vibrio coralyticus YB, was classified as a member of the genus Vibrio. Based on its 16S rDNA sequence, V. coralyticus is probably a new species. In controlled aquaria experiments at 26–29°C, inoculation of pure cultures of V. coralyticus YB either into the seawater or by direct contact onto the coral caused tissue lysis of P. damicornis fragments. At 29°C, lysis began as small white spots after 3–5 days, rapidly spreading so that by 2 weeks the entire tissue was destroyed, leaving only the intact bare skeleton. When an infected diseased coral was placed in direct contact with a healthy one, the healthy coral lysed in 2–4 days, further indicating that the disease was contagious. Inoculation with as few as 30 bacteria ml–1 was sufficient to infect and lyse corals. Seawater temperature was a critical variable for the infectious process: infection and lysis occurred rapidly at 27–29°C, slowly at 26°C and was not observed at 25°C. The data suggest that the presence of V. coralyticus YB, even in low numbers, in seawater surrounding a coral reef will lead to tissue destruction of P. damicornis, when seawater temperatures rise.

The efficacy of a single intraperitoneal injection of either flumequine or oxytetracycline hydrochloride in prevention of outbreaks of atypical Aeromonas salmonicida infection in goldsinny wrasse, Ctenolabrus rupestris L., following stress.

In this investigation, the efficacy of a single intraperitonealinjection of either flumequine or oxytetracycline hydrochloride to preventoutbreak of atypical Aeromonas salmonicida infection ingoldsinny wrasse, Ctenolabrus rupestris, following stresswas studied. Six groups of goldsinny wrasse, each of 50 individuals, weretreated with an intraperitoneal injection of either propylene glycol : saline(50 : 50), 200 mg kg−1 of oxytetracycline or 50mg kg−1 of flumequine dissolved in propyleneglycol : saline (50 : 50). Three days following medication the fish in allgroups were stressed by an intraperitoneal injection of prednisolone acetate(0.05 ml) and a rise in seawater temperature from 9 to 11°C. Mortality was observed daily for 21 days. Flumequine wasthe more effective with a mean cumulative mortality of 5% compared tooxytetracycline with 54%. The mean cumulative mortality in the unmedicatedcontrol groups was 84%. Bacterial examination of kidneys from dead fishconfirmed the presence of atypical A. salmonicida as theprobable cause of death. Minimum inhibitory concentration (MIC) values forflumequine and oxytetracycline against the isolated A.salmonicida were determined to 0.13 μgml−1, and 2.0 μg ml−1,respectively.

MRI measurements of partial pressure of CO2 in surface waters of the Pacific during 1968–70: re-evaluation and comparison of data with those of the 1980s and 1990s

During 1968 to 72, scientists of the Meteorological Research Institute/Japan Meteorological Agency measured CO2 in the surface seawater and overlying air in the Pacific Ocean quasicontinuously to examine CO2 exchange between the sea and the atmosphere. From the data remaining in our laboratory from that time, we re-evaluated the partial pressure of CO2 in surface seawater (pCOs2) by taking into account pressure broadening effects due to the use of CO2-in-N2 standards, the use of chemical desiccant (Mg(ClO4)2), calibration using background air data, seawater temperature rise between the equilibrator and sea surface, the WMO CO2 mole fraction scale, and differences in pressure during the oceanic CO2 measurements from those of standards and background air in the nondispersive infra-red gas analyser cell. The overall uncertainty of pCOs2 measurements for the cruises from 1968 to 1970 was estimated to be less than 3.6 ¼atm, which allowed us to evaluate temporal variations in the carbonate system over a few decades, but uncertainty was higher (¾ 10 ¼atm) for the cruise from 1971 to 1972 because of serious malfunctions of the system. The re-evaluated pCOs2 data from 1968 to 1970 exhibit patterns similar to those observed at the same place and time of year (within 30 days) in 1982/83, 1988, 1995 and 1996, but compared with levels in the 1980s and 1990s the pCOs2 level was clearly lower in the wide area of the Pacific except south of the Subtropical Front (STF; 47°S) in the Australian sector. The observed pCOs2 increased by 34 ±5 ¼atm (n = 133) for the area 7°N to 35°N, 138°E to 147°E from February 1969 to February 1995, 29 ±5 ¼atm (n = 247) for the area 9°N to 35°N, 138°E to 165°E from February 1970 to February/March 1996, 26 ±7 ¼atm (n = 224) for the area 29°N to 51°N, 170°W from April 1970 to April 1988, and 41 ±9 ¼atm (n = 165) for the area 10°S to 45°S, 148°E to 166°E from January/February 1969 to January/February 1995. In the northern subtropics (7°N to 35°N, 138°E to 147°E), we estimated the long-term increase (35 ±6 ¼atm, n= 133) after removing seasonal variations that were obtained from the pCOs2-sea surface temperature (SST) relationship. Observed and seasonally adjusted increases were nearly equal to those of the partial pressure of CO2 in the air (1.4 ¼atm yr-1) over the same time intervals. South of the STF, pCOs2 increase as found in the subtropics was not detected, mostly due to the large variability of pCOs2 (250 to 380 ¼atm in 1968/69) on small spatial scales. The average pCOs2 south of the STF showed large variations on time scales of months and years that affect the estimation of the growth rate of atmospheric CO2.