Acid-base regulation in the Dungeness crab (Metacarcinus magister)

Homeostatic regulation allows organisms to secure basic physiological processes in a varying environment. To counteract fluctuations in ambient carbonate system speciation due to elevated seawater pCO2 (hypercapnia), many aquatic crustaceans excrete/accumulate acid-base equivalents through their gills; however, not much is known about the role of ammonia in this response. The present study investigated the effects of hypercapnia on acid-base and ammonia regulation in the Dungeness crab, Metacarcinus magister on the whole animal and isolated gill levels. Hemolymph pCO2 and [HCO3]- increased in M. magister acclimated to elevated pCO2 (330 Pa), while pH remained stable. Additionally, hemolymph [Na+], [Ca2+], and [SO4]2- were significantly increased. When challenged with varying pH during gill perfusion, the pH of the artificial hemolymph remained relatively unchanged. Overall, ammonia production and excretion, as well as oxygen consumption, were reduced in crabs acclimated to elevated pCO2, demonstrating that either (amino acid) oxidation is reduced in response to this particular stress, or nitrogenous wastes are excreted in an alternative form.

Proteomic and metabolomic responses of Pacific oyster Crassostrea gigas to elevated pCO2 exposure

The gradually increased atmospheric CO2 partial pressure (pCO2) has thrown the carbonate chemistry off balance and resulted in decreased seawater pH in marine ecosystem, termed ocean acidification (OA). Anthropogenic OA is postulated to affect the physiology of many marine calcifying organisms. However, the susceptibility and metabolic pathways of change in most calcifying animals are still far from being well understood. In this work, the effects of exposure to elevated pCO2 were characterized in gills and hepatopancreas of Crassostrea gigas using integrated proteomic and metabolomic approaches. Metabolic responses indicated that high CO2 exposure mainly caused disturbances in energy metabolism and osmotic regulation marked by differentially altered ATP, glucose, glycogen, amino acids and organic osmolytes in oysters, and the depletions of ATP in gills and the accumulations of ATP, glucose and glycogen in hepatopancreas accounted for the difference in energy distribution between these two tissues. Proteomic responses suggested that OA could not only affect energy and primary metabolisms, stress responses and calcium homeostasis in both tissues, but also influence the nucleotide metabolism in gills and cytoskeleton structure in hepatopancreas. This study demonstrated that the combination of proteomics and metabolomics could provide an insightful view into the effects of OA on oyster C. gigas. BIOLOGICAL SIGNIFICANCE: The gradually increased atmospheric CO2 partial pressure (pCO2) has thrown the carbonate chemistry off balance and resulted in decreased seawater pH in marine ecosystem, termed ocean acidification (OA). Anthropogenic OA is postulated to affect the physiology of many marine calcifying organisms. However, the susceptibility and metabolic pathways of change in most calcifying animals are still far from being understood. To our knowledge, few studies have focused on the responses induced by pCO2 at both protein and metabolite levels. The pacific oyster C. gigas, widely distributed throughout most of the world's oceans, is a model organism for marine environmental science. In the present study, an integrated metabolomic and proteomic approach was used to elucidate the effects of ocean acidification on Pacific oyster C. gigas, hopefully shedding light on the physiological responses of marine mollusk to the OA stress.

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).

Effects of elevated CO2 on early life history development of the yellowtail kingfish, Seriola lalandi, a large pelagic fish

An increasing number of studies have examined the effects of elevated carbon dioxide (CO2) and ocean acidification on marine fish, yet little is known about the effects on large pelagic fish. We tested the effects of elevated CO2 on the early life history development and behaviour of yellowtail kingfish, Seriola lalandi. Eggs and larvae were reared in current day control (450 µatm) and two elevated CO2 treatments for a total of 6 d, from 12 h post-fertilization until 3 d post-hatching (dph). Elevated CO2 treatments matched projections for the open ocean by the year 2100 under RCP 8.5 (880 µatm CO2) and a higher level (1700 µatm CO2) relevant to upwelling zones where pelagic fish often spawn. There was no effect of elevated CO2 on survival to hatching or 3 dph. Oil globule diameter decreased with an increasing CO2 level, indicating potential effects of elevated CO2 on energy utilization of newly hatched larvae, but other morphometric traits did not differ among treatments. Contrary to expectations, there were no effects of elevated CO2 on larval behaviour. Activity level, startle response, and phototaxis did not differ among treatments. Our results contrast with findings for reef fish, where a wide range of sensory and behavioural effects have been reported. We hypothesize that the absence of behavioural effects in 3 dph yellowtail kingfish is due to the early developmental state of newly hatched pelagic fish. Behavioural effects of high CO2 may not occur until larvae commence branchial acid-base regulation when the gills develop; however, further studies are required to test this hypothesis. Our results suggest that the early stages of kingfish development are tolerant to rising CO2 levels in the ocean.

Comparison of the stable carbon and nitrogen isotopic values of gill and white muscle tissue of fish

The potential use of stable carbon and nitrogen isotope ratios (d13C, d15N) of fish gills for studies on fish feeding ecology was evaluated by comparing the d13C and d15N of gill tissue with the more commonly used white muscle tissue. To account for the effect of lipid content on the d13C signatures, a study-specific lipid correction model based on C:N ratios was developed and applied to the bulk d13C data. For the majority of species in the study, we found no significant difference in d13C values between gill and muscle tissue after correction, but several species showed a small (0.3-1.4 per mil) depletion in 13C in white muscle compared to gill tissue. The average species difference in d15N between muscle and gill tissue ranged from -0.2 to 1.6 per mil for the different fish species with muscle tissue generally more enriched in 15N. The d13C values of muscle and gill were strongly linearly correlated (R**2 = 0.85) over a large isotopic range (13 per mil), suggesting that both tissues can be used to determine long-term feeding or migratory habits of fish. Muscle and gill tissue bulk d15N values were also strongly positively correlated (R**2= 0.76) but with a small difference between muscle and gill tissue. This difference indicates that the bulk d15N of the two tissue types may be influenced by different isotopic turnover rates or a different composition of amino acids.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Characterication of metals in hemolymph and tissues of the Antarctic bivalve Laternula elliptica

A high input of lithogenic sediment from glaciers was assumed to be responsible for high Fe and Mn contents in the Antarctic soft shell clam Laternula elliptica at King George Island. Indeed, withdrawal experiments indicated a strong influence of environmental Fe concentrations on Fe contents in bivalve hemolymph, but no significant differences in hemolymph and tissue concentrations were found among two sites of high and lower input of lithogenic debris. Comparing Fe and Mn concentrations of porewater, bottom water, and hemolymph from sampling sites, Mn appears to be assimilated as dissolved species, whereas Fe apparently precipitates as ferrihydrite within the oxic sediment or bottom water layer prior to assimilation by the bivalve. Hence, we attribute the high variability of Fe and Mn accumulation in tissues of L. elliptica around Antarctica to differences in the geochemical environment of the sediment and the resulting Fe and Mn flux across the benthic boundary.