Does seawater acidification affect survival, growth and shell integrity in bivalve juveniles?

Anthropogenic emissions of carbon dioxide are leading to decreases in pH and changes in the carbonate chemistry of seawater. Ocean acidification may negatively affect the ability of marine organisms to produce calcareous structures while also influencing their physiological responses and growth. The aim of this study was to evaluate the effects of reduced pH on the survival, growth and shell integrity of juveniles of two marine bivalves from the Northern Adriatic sea: the Mediterranean mussel Mytilus galloprovincialis and the striped venus clam Chamelea gallina. An outdoor flow-through plant was set up and two pH levels (natural seawater pH as a control, pH 7.4 as the treatment) were tested in long-term experiments. Mortality was low throughout the first experiment for both mussels and clams, but a significant increase, which was sensibly higher in clams, was observed at the end of the experiment (6 months). Significant decreases in the live weight (-26%) and, surprisingly, in the shell length (-5%) were observed in treated clams, but not in mussels. In the controls of both species, no shell damage was ever recorded; in the treated mussels and clams, damage proceeded via different modes and to different extents. The severity of shell injuries was maximal in the mussels after just 3 months of exposure to a reduced pH, whereas it progressively increased in clams until the end of the experiment. In shells of both species, the damaged area increased throughout the experiment, peaking at 35% in mussels and 11% in clams. The shell thickness of the treated and control animals significantly decreased after 3 months in clams and after 6 months in mussels. In the second experiment (3 months), only juvenile mussels were exposed to a reduced pH. After 3 months, the mussels at a natural pH level or pH 7.4 did not differ in their survival, shell length or live weight. Conversely, shell damage was clearly visible in the treated mussels from the 1st month onward. Monitoring the chemistry of seawater carbonates always showed aragonite undersaturation at 7.4 pH, whereas calcite undersaturation occurred in only 37% of the measurements. The present study highlighted the contrasting effects of acidification in two bivalve species living in the same region, although not exactly in the same habitat.

Functional consequences of prey acclimation to ocean acidification for the prey and its predator

Ocean acidification is the suite of chemical changes to the carbonate system of seawater as a consequence of anthropogenic carbon dioxide (CO2) emissions. Despite a growing body of evidences demonstrating the negative effects of ocean acidification on marine species, the consequences at the ecosystem level are still unclear. One factor limiting our ability to upscale from species to ecosystem is the poor mechanistic understanding of the functional consequences of the observed effects on organisms. This is particularly true in the context of species interactions. The aim of this work was to investigate the functional consequence of the exposure of a prey (the mussel Brachidontes pharaonis) to ocean acidification for both the prey and its predator (the crab Eriphia verrucosa). Mussels exposed to pH 7.5 for >4 weeks showed significant decreases in condition index and in mechanical properties (65% decrease in maximum breaking load) as compared with mussels acclimated to pH 8.0. This translated into negative consequences for the mussel in presence of the predator crab. The crab feeding efficiency increased through a significant 27% decrease in prey handling time when offered mussels acclimated to the lowest pH. The predator was also negatively impacted by the acclimation of the prey, probably as a consequence of a decreased food quality. When fed with prey acclimated under decreased pH for 3 months, crab assimilation efficiency significantly decreased by 30% and its growth rate was 5 times slower as compared with crab fed with mussels acclimated under high pH. Our results highlight the important to consider physiological endpoints in the context of species interactions.

Benthic and substrate cover data derived from a time series of photo-transect surveys for the Eastern Banks, Moreton Bay Australia, 2004-2015

This paper describes seagrass species and percentage cover point-based field data sets derived from georeferenced photo transects. Annually or biannually over a ten year period (2004-2015) data sets were collected using 30-50 transects, 500-800 m in length distributed across a 142 km**2 shallow, clear water seagrass habitat, the Eastern Banks, Moreton Bay, Australia. Each of the eight data sets include seagrass property information derived from approximately 3000 georeferenced, downward looking photographs captured at 2-4 m intervals along the transects. Photographs were manually interpreted to estimate seagrass species composition and percentage cover (Coral Point Count excel; CPCe). Understanding seagrass biology, ecology and dynamics for scientific and management purposes requires point-based data on species composition and cover. This data set, and the methods used to derive it are a globally unique example for seagrass ecological applications. It provides the basis for multiple further studies at this site, regional to global comparative studies, and, for the design of similar monitoring programs elsewhere.

Population genetic and dispersal modeling data for Bathymodiolus mussels from the Mid-Atlantic Ridge

The zip folder comprises a text file and a gzipped tar archive. 1) The text file contains individual genotype data for 90 SNPs, 9 microsatellites and the mitochondrial ND4 gene that were determined in deep-sea hydrothermal vent mussels from the Mid-Atlantic Ridge (genus Bathymodiolus). Mussel specimens are grouped according to the population (pop)/location from which they have been sampled (first column). The remaining columns contain the respective allele/haplotype codes for the different genetic loci (names in the header line). The data file is in CONVERT format and can be directly transformed into different input files for population genetic statistics. 2) The tar archive contains NetCDF files with larval dispersal probabilities for simulated annual larval releases between 1998 and 2007. For each simulated vent location (Menez Gwen, Lucky Strike, Rainbow, Vent 1-10) two NetCDF files are given, one for an assumed pelagic larval duration of 1 year and the other one for an assumed pelagic larval duration of 6 months (6m).

Ocean acidification alters the material properties of Mytilus edulis shells

Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature.

In situ measurements of hydrogen sulfide, oxygen, and temperature in diffuse fluids of the ultramafic-hosted Logatchev hydrothermal vent field (Mid-Atlantic Ridge)

The Logatchev hydrothermal vent field (14°45'N, Mid-Atlantic Ridge) is located in a ridge segment characterized by mantle-derived ultramafic outcrops. Compared to basalt-hosted vents, Logatchev high temperature fluids are relatively low in sulfide indicating that the diffuse, low temperature fluids of this vent field may not contain sufficient sulfide concentrations to support a chemosymbiotic invertebrate community. However, the high abundances of bathymodiolin mussels with bacterial symbionts related to free-living sulfur oxidizing bacteria suggested that bioavailable sulfide is present at Logatchev. To clarify if diffuse fluids above mussel beds of Bathymodiolus puteoserpentis provide the reductants and oxidants needed by their symbionts for aerobic sulfide oxidation, in situ microsensor measurements of dissolved hydrogen sulfide and oxygen were combined with simultaneous temperature measurements. High temporal fluctuations of all three parameters were measured above the mussel beds. H2S and O2 co-existed with mean concentrations between 9-31 µM (H2S) and 216-228 µM (O2). Temperature maxima (<= 7.4°C) were generally concurrent with H2S maxima (<= 156 µM) and O2 minima (>= 142 µM). Long-term measurements for 250 days using temperature as a proxy for oxygen and sulfide concentrations indicated that the mussels were neither oxygen- nor sulfide-limited. Our in situ measurements at Logatchev indicate that sulfide may also be bioavailable in diffuse fluids from other ultramafic-hosted vents along slow- and ultraslow-spreading ridges.

Absolute abundances of benthic foraminifers and stable isotopes from the Alvin dives 3709-3712

The presence of gas hydrates on the Blake Ridge diapir, northeastern Atlantic Ocean, offers an opportunity to study the impact of methane seepage on the ecology and geochemistry of benthic foraminifera in the late Holocene. Three push cores, covering a time span of ~ 1000 yrs, were retrieved from three distinct microhabitats at the top of the diapir at a water depth of ~ 2150 m: (i) sediments away from seepage (control core), (ii) sediments overlain by clusters of methanotrophic and thiotrophic bivalves, and (iii) chemoautotrophic microbial mats. The foraminiferal assemblages at the two seep sites are marked by a reduction in benthic foraminiferal species diversity, coupled with a near-absence of agglutinated species. However, an opportunistic population rise in CH4- or H2S-tolerant calcareous species (e.g., Globocassidulina subglobosa and Cassidulina laevigata) that utilize the abundant trophic resources at the seeps has led to an increase in the overall assemblage density there. The delta18O and delta13C values of three species of benthic foraminifera - Gyroidinoides laevigatus, Globocassidulina subglobosa, and Uvigerina peregrina - and the planktonic species Globorotalia menardii were acquired from all three cores. The benthic species from methane seeps yield delta13C values of 0.1 to - 4.2 (per mil VPDB), that are distinctly more 13C-depleted relative to the delta13C of 0.4 to - 1.0 (per mil VPDB) at the control (off seep) site. The species from a mussel-bed site exhibit more negative delta13C values than those from microbial mats, possibly reflecting different food sources and higher rate of anaerobic oxidation of methane. The positive delta13C values in the paired planktonic species suggest that authigenic carbonate precipitation did not overprint the observed 13C depletions. Hence the probable cause of negative delta13C of benthic foraminifera is primary calcification from Dissolved Inorganic Carbon (DIC) containing mixed carbon fractions from (a) highly 13C-depleted, microbially-oxidized methane and (b) a seawater source.

Immunomodulating effects of environmentally realistic copper concentrations in Mytilus edulis adapted to naturally low salinities, link to supplementary material

The monitoring of organisms' health conditions by the assessment of their immunocompetence may serve as an important criterion for the achievement of the Good Environmental Status (GES) as defined in the Marine Strategy Framework Directive (EU). In this context, the complex role of natural environmental stressors, e.g. salinity, and interfering or superimposing effects of anthropogenic chemicals, should be carefully considered, especially in scenarios of low to moderate contamination. Organisms from the Baltic Sea have adapted to the ambient salinity regime, however energetically costly osmoregulating processes may have an impact on the capability to respond to additional stress such as contamination. The assessment of multiple stressors, encompassing natural and anthropogenic factors, influencing an organisms' health was the main aim of the present study. Immune responses of Mytilus edulis, collected and kept at natural salinities of 12 per mil (LS) and 20 per mil (MS), respectively, were compared after short-term exposure (1, 7 and 13 days) to low copper concentrations (5, 9 and 16 µg/L Cu). A significant interaction of salinity and copper exposure was observed in copper accumulation. LS mussels accumulated markedly more copper than MS mussels. No combined effects were detected in cellular responses. Bacterial clearance was mostly achieved by phagocytosis, as revealed by a strong positive correlation between bacterial counts and phagocytic activity, which was particularly pronounced in LS mussels. MS mussels, on the other hand, seemingly accomplished bacterial clearance by employing additional humoral factors (16 µg/L Cu). The greatest separating factor in the PCA biplot between LS and MS mussels was the proportion of granulocytes and hyalinocytes while functional parameters (phagocytic activity and bacterial clearance) were hardly affected by salinity, but rather by copper exposure. In conclusion, immune responses of the blue mussel may be suitable and sensitive biomarkers for the assessment of ecosystem health in brackish waters (10-20 per mil S).

Epistolae secretae ad principem suum Augustum ...

At head of title: Arcana seculi decimi sexti Huberti Langueti ...

Water chemistry controls on minor elemental concentrations and strontium isotopic compositions of freshwater biogenic carbonate in northeastern Washington streams

Tracking the movement of migratory freshwater fish is essential to those invested in rebuilding declining fish populations. Using strontium isotopic signatures to match calcified fish tissues to streams where fish spawn is a useful method of tracking migratory fish where physical tracking methods such as radio, acoustic, or external tags, have proven unsuccessful. In this study, we develop tools to practice this method of tracking fish in Lake Roosevelt and its upstream tributaries in Washington State by analyzing the elemental concentrations and 87Sr/86Sr ratios of water samples, and mussel shell samples. This study evaluates whether mussel shells act as an appropriate proxy for water chemistry by comparing the 87Sr/86Sr isotope ratios of water samples to the 87Sr/86Sr isotope ratios of mussel shells sampled from the same, or nearby, locations. We compare concentrations of Ba, Ca, Cd, Cu, Fe, Mg, Pb, Sr, and U in the water and mussel shell samples to determine the feasibility of using mussel shells as a proxy for water chemistry. If it is determined that the concentrations of these elements in mussel shells reflect that of the surrounding water composition, the elemental composition of mussel shells can be compared to that of calcified tissues in fish, such as otoliths, to infer the location of the natal stream. We report analyses of water and mussel shell samples collected from Lake Roosevelt, Sanpoil River, Spokane River, Colville River, Kettle River, Pend Oreille River, Kootenay River, and Columbia River in Washington State. Each of these rivers is a tributary to Lake Roosevelt, and each flows through different geologic units. We hypothesize that the differences in the rock units of each stream’s watershed are reflected in the elemental concentrations and strontium isotopic ratios of water in each stream and in the lake. We also hypothesize that the composition of the mussel shells will match the composition of the water samples, therefore allowing us to use the mussel shells as a proxy for local water chemistry. Additionally, we hypothesize that the composition of the mussel shells will vary by location, and that we will be able to then infer where a fish is from by matching the composition of the fish in question to the mussels we have analyzed. We found that 87Sr/86Sr values for water and mussel hinge samples collected from tributaries east of Lake Roosevelt are significantly higher than the 87Sr/86Sr values for samples collected from tributaries west of Lake Roosevelt with averages of 0.7235 and 0.7089, respectively. The average 87Sr/86Sr ratios for water and mussel hinge samples collected within Lake Roosevelt is 0.7158, which is between the averages for samples collected east and west of the lake. Generally, older rocks are exposed on the east side of the lake, and younger rocks on the west side of the lake, so our 87Sr/86Sr values support the hypothesis that geologic units are a primary control on water chemistry, and that tributary compositions mix to form an average weighed by flow in Lake Roosevelt. The 87Sr/86Sr values for water and mussel shell samples collected from the same locations have a strong, positive linear correlation, suggesting that mussel shell 87Sr/86Sr ratios reflect the 87Sr/86Sr ratios of the ambient water. With these data, we can distinguish between different streams and the lake, but cannot distinguish between samples from within the same stream or within Lake Roosevelt. The Sr:Ca and Fe:Ca ratios of water samples show positive correlations with mussel shell compositions, with R2 values of 0.82 and 0.52, respectively. Ratios of Mg, Ba, Cu, Cd, Pb, and U to Ca showed little or no positive correlation between water and mussel shell samples. The elemental concentration data collected for this study do not demonstrate whether a correlation between elemental ratios in water samples and elemental ratios in mussel shell samples collected from the same location exists. Positive Sr:Ca and Fe:Ca correlations for water versus mussel shell samples indicate that perhaps for some elements, the composition of mussel shells are representative of the composition of ambient water. Using elemental concentration ratios to complement 87Sr/86Sr isotopic data may enhance our ability to identify correlations between water and mussel shell samples, and ultimately between mussel shell and otolith samples. The hinge part of a mussel shell may be used as a proxy for local water composition because the mussel shell composition reflects that of the local ambient water. The hinge of the mussel has the same composition as the whole mussel shell. We measured variation of 87Sr/86Sr ratios in the water among different streams and Lake Roosevelt. The 87Sr/86Sr values for samples collected in tributaries east of Lake Roosevelt, which erode older rocks, are higher for mussel shell and water samples than the average 87Sr/86Sr values for mussel shell and water samples collected in tributaries west of Lake Roosevelt, which flow through younger rocks.

The effects of density on the growth and survival of different families of juvenile Penaeus japonicus Bate

Variations in the growth and survival of six families of juvenile (initial mean weight = 4.16 g) Penaeus japonicus were examined at two densities (48 and 144 individuals m(-2)) in a controlled laboratory experiment. Survival was very high throughout the experiment (95.4%), but differed significantly between densities and rearing tanks. Family, sex and family x density interaction did not significantly affect survival. Mean specific growth rate (SGR) of the shrimp was 18% faster at the low density (1.93 +/- 0.05% day(-1)) than at high density (1.64 +/- 0.03% day(-1)). However, there was a small but significant interaction between family and density indicating that growth of the families was not consistent at both densities. The inconsistent growth of the families across the two densities resulted in a change in the relative performance (ranking) of families at each density. Sex, rearing tank and rearing cage also affected growth of the shrimp. Mean SGR of the females (1.79 +/- 0.03% day(-1)) was 5% faster than males (1.70 +/- 0.03% day(-1)) when averaged across both densities. Shrimp grew significantly faster in rearing tank 3 than rearing tank 1 or 2 at both densities. Results of the present study suggest that family x density interaction could affect the efficiency of selection for growth if shrimp stocks produced from shrimp breeding programs are to be grown across a wide range of densities. Crown Copyright (C) 2004 Published by Elsevier B.V. All rights reserved.

Prostanoids as friends, not foes: Further evidence from the interference by cycloxygenase-inhibitory drugs when inducing tolerance to experimental arthritigens in rats

Pharmacologists have generally been prejudiced against prostanoids, uncritically accepting their suppression as desirable therapy, especially for ‘quick-fix’ analgesia. This myopic perception for a long time ignored (a) the essentiality of prostanoid precursors in nutrition, (b) the physiological protective functions of natural prostaglandins (PGs) (vasculature, stomach, kidney), (c) resolution of inflammation after the expression of COX-2 and (d) increasing therapeutic use of either synthetic PGs (for erectile dysfunction, opthalmic disorders, inducing parturition, etc) or their natural precursors, e.g., ω3-rich polyunsaturated oils, to treat arthritis. Experimental studies in rats have indicated that prostaglandins (E series) are (i) useful, perhaps auto-regulators of established immunoreactivity and (ii) able to amplify (or even induce) anti-inflammatory activity with other agents. Furthermore, anti-prostanoid therapy (APT) can be arthritigenic!!, interfering with the acquisition of tolerance to some arthritigens. For patients with rheumatoid arthritis this additional side-effect of APT, barely recognised to date, may actually perpetuate their arthritis by impairing prostanoid-mediated remission processes. Hopefully, recent adverse publicity about COX-2 inhibitory drugs might stimulate serious re-assessment of some traditional anti-inflammatory therapies with low APT activity for the management of both acute pain (non-addictive cannabinoids, celery seed, etc.) and chronic inflammation, e.g., Lyprinol® (a mussel lipid extract).