(Table 1) Results of measurements of production characteristics of phytoplankton and some physical parameters of the environment in the northeastern Norwegian Sea in July 1995

From July 4 to 18,1995 surface chlorophyll a concentrations (C_cs) and integral primary production (C_ps) were studied in the northeastern part of the Norwegian Sea (73°42'N; 13°16'E), over a test area where an accident of the nuclear submarine Komsomolets had taken place. It was found that during this interval C_cs decreased by factor of about 3.3 (from 0.78 to 0.24 mg/m**3); average chlorophyll concentration within the photo-synthetic layer (C_cl) decreased by factor of about 3.5 (from 0.97 to 0.28 mg/m**3). The value of C_ps in the water column varied slightly (from 445 to 539 mg C/m**2 per day), since decrease in C_cl was compensated both by 1.5-fold growth of the photosynthetic layer thickness (from 40 to 60 m) and by 2.1-fold increase in its average assimilation number (from 0.58 to 1.20 mg C/mg chl a per hour). Monthly averages of C_ps were obtained from published data on seasonal C_cs changes and on the level of incident solar irradiation. They were found to be less than 100 mg C/m**2 per day in March and October and 100-500 mg C/m**2 per day in April-June. Annual primary production calculated from above values was equal to 105 g C/m**2.

Effects of ocean acidification on growth and physiology of Ulva lactuca (Chlorophyta) in a rockpool-scenario, link to supplementary data

Rising atmospheric CO2-concentrations will have severe consequences for a variety of biological processes. We investigated the responses of the green alga Ulva lactuca (Linnaeus) to rising CO2-concentrations in a rockpool scenario. U. lactuca was cultured under aeraton with air containing either preindustrial pCO2 (280µatm) or for the end of the 21st century predicted (700µatm) pCO2 for 31 days. We addressed the following question: Will elevated CO2-concentrations affect photosynthesis (net photosynthesis, rETR(max), Fv/Fm, pigment composition) and growth of U. lactuca in rockpools with limited water exchange? Two phases of the experiment were distinguished: In the initial phase (day 1-4) the Seawater Carbonate System (SWCS) of the culture medium could be adjusted to the selected atmospheric pCO2 condition by continuous aeration with target pCO2 values. In the second phase (day 4-31) the SWCS was largely determined by the metabolism of the growing U. lactuca biomass. In the initial phase, Fv/Fm and rETR(max) were only slightly elevated at high CO2-concentrations whereas growth was significantly enhanced. After 31 days the Chl a content of the thalli was significantly lower under future conditions and the photosynthesis of thalli grown under preindustrial conditions was not dependent on external carbonic anhydrase. Biomass increased significantly at high CO2-concentrations. At low CO2-concentrations most adult thalli disintegrated between day 14 and 21, whereas at high CO2-concentrations most thalli remained integer until day 31. Thallus disintegration at low CO2-concentrations was mirrored in a drastic decline in seawater DIC and HCO3-. Accordingly, the SWCS differed significantly between the treatments. Our results indicated a slight enhancement of photosynthetic performance and significantly elevated growth of U. lactuca at future CO2-concentrations. The accelerated thallus disintegration at high CO2-concentrations under conditions of limited water exchange indicates additional CO2 effects on the life cycle of U. lactuca when living in rockpools.

Direct effects of increased CO2 concentrations in seawater on the net primary production of charophytes in a shallow, coastal, brackish-water ecosystem

Charophytes are found in fresh and brackish waters across the globe and play key roles in coastal ecosystems. However, their response to increasing CO2 is not well understood. The aim of the study was to detect the effects of elevated CO2 on the physiology of charophyte species growing in the brackish Baltic Sea by measuring net primary production. Mesocosm experiments were conducted in the Kõiguste Bay (N Gulf of Riga) during the field season of 2012. Separate mesocosms were maintained at different pCO2 levels: 2000, 1000 and 200 µatm. The experiments were carried out with three species of charophytes: Chara aspera, C. tomentosa and C. horrida. The short-term photosynthetic responses of charophytes to different treatments were measured by the oxygen method. The results show that elevated CO2 levels in brackish water may enhance the photosynthetic activity of charophyte species and suggest that increasing CO2 in the Baltic Sea could have implications for interspecific competition and community structure in a future high CO2 world.

Seasonal production patterns of planktonic foraminifera in the NE Atlantic Ocean

Sediment trap samples from OMEX 2 (49°N, 13°W) provide a continuous record of the seasonal succession of planktonic foraminifera in the midlatitude North Atlantic and reveal a complex relationship between periods of production and specific hydrographic conditions. Neogloboquadrina pachyderma dextral coiling (d.), Globigerina bulloides, and Globorotalia inflata are found in great numbers during both the spring and summer seasons, whereas Globigerina quinqueloba, Globorotalia hirsuta, Globorotalia scitula, and Globigerinita glutinata are associated predominantly with the increase in productivity during the spring bloom. Globigerinella aequilateralis, Orbulina universa, and Globigerinoides sacculifer are restricted to late summer conditions following the establishment of a warm, well-stratified surface ocean. An annually integrated fauna from the sediment trap, comprising ~13,000 individuals, is used to evaluate the accuracy of five faunal-based statistical methods of paleotemperature estimation. All of the temperature reconstruction techniques produce estimates of ~16°C and ~11°C for summer and winter surface temperature, respectively, which are in excellent agreement with regional hydrographic data and suggest that the sediment trap assemblage is well represented in the core top faunas. Analysis of the key species that dominate the OMEX 2 sediment trap fauna, G. bulloides, G. inflata, and N. pachyderma d., based on d18O derived temperatures from North Atlantic core top samples, suggests that seasonal variations in planktonic foraminiferal production are nonuniform across the midlatitudes and that this is likely to complicate reconstructing past seasonal hydrographic dynamics using these taxa.

(Table 2) Production parameters of phytoplankton and some associated parameters in the area of the Titanic Polygon

Studies were carried out mostly in the area of RMS Titanic wreck site (41°44'N, 49°57'W) located above the continental slope and the south of the Grand Banks of Newfoundland. In a period from 18.06 to 24.09.2001 five surveys of production characteristics of surface phytoplankton were conducted over 5-9 days. Mean values of these characteristics obtained during the surveys were 9.2-11.7 mg C/m**3 per day for primary production (C_phs), 0.102-0.188 mg/m**3 for chlorophyll a (C_chls), and 4.44-7.42 mg C/mg chl. a per hour for assimilation number (AN). The main reason for low C_phs variability was a significant inverse relationship (R=-0.66) between AN and C_chls found over the research area. When cold shelf waters dominated in the area (27.07 to 19.08.2001), C_chls values for the slope region (0.125+/-0.031 µg/l) and for the outer shelf (0.130+/-0.040 µg/l) were similar. During strengthening of influence of warmer slope waters within area (from 29.08 to 13.09.2001), C_chls concentration within surface waters of the outer shelf was 0.152+/-0.039 µg/l and exceeded one for the slope region (0.094+/-0.004 µg/l) by factor 1.6. Against the background of low Cchls values, the High values of integral primary production in the water column (510-1010 mg C/m**2 per day) at low C_chls values measured within the area were determined both by high assimilation activity of phytoplankton and by the deep (30-40 m) maximum of primary production. Main reasons for formation of such a maximum were high chlorophyll concentration within the layer of the deep chlorophyll maximum (up to 0.5-2.5 µg/l) and in the relatively high solar irradiance within this layer varying from 1.4 to 8.6% of subsurface PAR.

Combined effects of coral reef foraminifera Marginopora vertebralis and Heterostegina depressa in a multi-fractorial experiment

Warming and changes in ocean carbonate chemistry alter marine coastal ecosystems at an accelerating pace. The interaction between these stressors has been the subject of recent studies on reef organisms such as corals, bryozoa, molluscs, and crustose coralline algae. Here we investigated the combined effects of elevated sea surface temperatures and pCO2 on two species of photosymbiont-bearing coral reef Foraminifera: Heterostegina depressa (hosting diatoms) and Marginopora vertebralis (hosting dinoflagellates). The effects of single and combined stressors were studied by monitoring survivorship, growth, and physiological parameters, such as respiration, photochemistry (pulse amplitude modulation fluorometry and oxygen production), and chl a content. Specimens were exposed in flow-through aquaria for up to seven weeks to combinations of two pCO2 (~790 and ~490 µatm) and two temperature (28 and 31 °C) regimes. Elevated temperature had negative effects on the physiology of both species. Elevated pCO2 had negative effects on growth and apparent photosynthetic rate in H.depressa but a positive effect on effective quantum yield. With increasing pCO2, chl a content decreased in H. depressa and increased in M. vertebralis. The strongest stress responses were observed when the two stressors acted in combination. An interaction term was statistically significant in half of the measured parameters. Further exploration revealed that 75 % of these cases showed a synergistic (= larger than additive) interaction between the two stressors. These results indicate that negative physiological effects on photosymbiont-bearing coral reef Foraminifera are likely to be stronger under simultaneous acidification and temperature rise than what would be expected from the effect of each of the stressors individually.

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.

Responses of the Emiliania huxleyi Proteome to Ocean Acidification

Ocean acidification due to rising atmospheric CO2 is expected to affect the physiology of important calcifying marine organisms, but the nature and magnitude of change is yet to be established. In coccolithophores, different species and strains display varying calcification responses to ocean acidification, but the underlying biochemical properties remain unknown. We employed an approach combining tandem mass-spectrometry with isobaric tagging (iTRAQ) and multiple database searching to identify proteins that were differentially expressed in cells of the marine coccolithophore species Emiliania huxleyi (strain NZEH) between two CO2 conditions: 395 (~current day) and ~1340 p.p.m.v. CO2. Cells exposed to the higher CO2 condition contained more cellular particulate inorganic carbon (CaCO3) and particulate organic nitrogen and carbon than those maintained in present-day conditions. These results are linked with the observation that cells grew slower under elevated CO2, indicating cell cycle disruption. Under high CO2 conditions, coccospheres were larger and cells possessed bigger coccoliths that did not show any signs of malformation compared to those from cells grown under present-day CO2 levels. No differences in calcification rate, particulate organic carbon production or cellular organic carbon: nitrogen ratios were observed. Results were not related to nutrient limitation or acclimation status of cells. At least 46 homologous protein groups from a variety of functional processes were quantified in these experiments, of which four (histones H2A, H3, H4 and a chloroplastic 30S ribosomal protein S7) showed down-regulation in all replicates exposed to high CO2, perhaps reflecting the decrease in growth rate. We present evidence of cellular stress responses but proteins associated with many key metabolic processes remained unaltered. Our results therefore suggest that this E. huxleyi strain possesses some acclimation mechanisms to tolerate future CO2 scenarios, although the observed decline in growth rate may be an overriding factor affecting the success of this ecotype in future oceans.

Seawater carbonate chemistry and growth rate during experiments with phylotypes of Symbiodinium (Dinophyceae), 2011

We investigated the effect of elevated partial pressure of CO2 (pCO2) on the photosynthesis and growth of four phylotypes (ITS2 types A1, A13, A2, and B1) from the genus Symbiodinium, a diverse dinoflagellate group that is important, both free-living and in symbiosis, for the viability of cnidarians and is thus a potentially important model dinoflagellate group. The response of Symbiodinium to an elevated pCO2 was phylotype-specific. Phylotypes A1 and B1 were largely unaffected by a doubling in pCO2 in contrast, the growth rate of A13 and the photosynthetic capacity of A2 both increased by ~ 60%. In no case was there an effect of ocean acidification (OA) upon respiration (dark- or light-dependent) for any of the phylotypes examined. Our observations suggest that OA might preferentially select among free-living populations of Symbiodinium, with implications for future symbioses that rely on algal acquisition from the environment (i.e., horizontal transmission). Furthermore, the carbon environment within the host could differentially affect the physiology of different Symbiodinium phylotypes. The range of responses we observed also highlights that the choice of species is an important consideration in OA research and that further investigation across phylogenetic diversity, for both the direction of effect and the underlying mechanism(s) involved, is warranted.

Trematomus bernacchii experimental data files

As a response to ocean warming, shifts in fish species distribution and changes in production have been reported that have been partly attributed to temperature effects on the physiology of animals. The Southern Ocean hosts some of the most rapidly warming regions on earth and Antarctic organisms are reported to be especially temperature sensitive. While cellular and molecular organismic levels appear, at least partially, to compensate for elevated temperatures, the consequences of acclimation to elevated temperature for the whole organism are often less clear. Growth and reproduction are the driving factors for population structure and abundance. The aim of this study was to assess the effect of long-term acclimation to elevated temperature on energy budget parameters in the high-Antarctic fish Trematomus bernacchii. Our results show a complete temperature compensation for routine metabolic costs after 9 weeks of acclimation to 4°C. However, an up to 84% reduction in mass growth was measured at 2 and 4°C compared with the control group at 0°C, which is best explained by reduced food assimilation rates at warmer temperatures. With regard to a predicted temperature increase of up to 1.4°C in the Ross Sea by 2200, such a significant reduction in growth is likely to affect population structures in nature, for example by delaying sexual maturity and reducing production, with severe impacts on Antarctic fish communities and ecosystems.

Pore-water chemistry of abyssal Arabian Sea surface sediments

Benthic fluxes and pore-water compositions of silicic acid, nitrate and phosphate were investigated for surface sediments of the abyssal Arabian Sea during four cruises (1995-1998). Five sites located in the northern (NAST), western (WAST), central (CAST), eastern (EAST), and southern (SAST) Arabian Sea were revisited during intermonsoonal periods after the NE- and SW-Monsoon. At these sites, benthic fluxes of remineralized nutrients from the sediment to the bottom water of 36-106, 102-350 and 4-16 mmol/m**2/yr were measured for nitrate, silicic acid and phosphate, respectively. The benthic fluxes and pore-water compositions showed a distinct regional pattern. Highest fluxes were observed in the western and northern region of the Arabian Sea, whereas decreasing fluxes were derived towards the southeast. At WAST, the general temporal pattern of primary production, related to the NE- and SW-Monsoon, is reflected by benthic fluxes. In contrast, at sites NAST, SAST, CAST, and EAST a temporal pattern of fluxes in response to the monsoon is not obvious. Our results reveal a clear coupling between the general regional pattern of production in surface waters and the response of the benthic environment, as indicated by the flux of remineralized nutrients, though a spatially differing degree of decoupling during transport and remineralization of particulate organic matter and biogenic opal was observed. This has to be taken into account regarding budget calculations and paleoceanographic topics.

qPCR counts of mRNA for hepatic reference gene selection in juvenile female Atlantic salmon from perturbation experiments under artificial temperature conditions

The dataset contains raw data (quantification cycle) for a study which determined the most suitable hepatic reference genes for normalisation of qPCR data orginating from juvenile Atlantic salmon (14 days) exposed to 14 and 22 degrees C. These results will be useful for anyone wanting to study the effects of climate change/elevated temperature on reproductive physiology of fish (and perhaphs other vertebrates).

Plankton abundances in water samples of cruise EBENE

The Etude du Broutage en Zone Equatoriale (EBENE) transect (8°S-8°N) explored the equatorial high-nutrient, low-chlorophyll (HNLC) zone and adjacent oligotrophic areas during a La Niña period (October-November 1996). During this time the passage of a tropical instability wave also influenced the region north of the equator. We present a brief summary of EBENE findings, with an emphasis on phytoplankton utilization by the assemblage of protistan and animal consumers. Despite significant variability over the diel cycle, phytoplankton biomass at the equator was relatively constant on a 24-hour timescale, denoting a dynamic balance between growth and losses. The magnitude of the daily cycle in phytoplankton biomass was well constrained by in situ observations of the diel variability in pigments and suspended particulates, by 14C uptake rates from in situ incubations, and from experimental determinations of specific growth and grazing rates. The general equilibrium of production and grazing processes is illustrated by applying biomass-specific grazing rates from the equatorial station to measured planktonic biomass along the EBENE transect and comparing them to measured 14C uptake. Most of the grazing turnover is supported by the production of Prochloroccus (31%) and picoeukaryotic algae (34%). Among the consumers, microzooplankton (<200 µm) account for 59-98% of the grazing losses. The coherence of the results obtained by independent methods suggests that the essential features of the system have been adequately represented by rate and standing stock assessments from the EBENE study.

Radioisotopes and He accumulation in deep sea sediments of the Ontong Java Plateau

The accumulation of extraterrestrial 3He, a tracer for interplanetary dust particles (IDPs), in sediments from the Ontong Java Plateau (OJP; western equatorial Pacific Ocean) has been shown previously to exhibit a regular cyclicity during the late Pleistocene, with a period of ~100 ka. Those results have been interpreted to reflect periodic variability in the global accretion of IDPs that, in turn, has been linked to changes in the inclination of Earth's orbit with respect to the invariable plane of the solar system. Here we show that the accumulation in OJP sediments of authigenic 230Th, produced by radioactive decay of 234U in seawater, exhibits a 100-ka cyclicity similar in phase and amplitude to that evident in the 3He record. We interpret the similar patterns of 230Th and 3He accumulation to reflect a common origin within the ocean-climate system. Comparing spatial and temporal patterns of sediment accumulation against regional patterns of biological productivity and against the well-established pattern of CaCO3 dissolution in the deep Pacific Ocean leads to the further conclusion that a common 100-ka cycle in accumulation of biogenic, authigenic and extraterrestrial constituents in OJP sediments reflects the influence of climate-related changes in sediment focusing, rather than changes in the rate of production or supply of sedimentary constituents.