Impaired learning of predators and lower prey survival under elevated CO2: a consequence of neurotransmitter interference

Ocean acidification is one of the most pressing environmental concerns of our time, and not surprisingly, we have seen a recent explosion of research into the physiological impacts and ecological consequences of changes in ocean chemistry. We are gaining considerable insights from this work, but further advances require greater integration across disciplines. Here, we showed that projected near-future CO2 levels impaired the ability of damselfish to learn the identity of predators. These effects stem from impaired neurotransmitter function; impaired learning under elevated CO2 was reversed when fish were treated with gabazine, an antagonist of the GABA-A receptor - a major inhibitory neurotransmitter receptor in the brain of vertebrates. The effects of CO2 on learning and the link to neurotransmitter interference were manifested as major differences in survival for fish released into the wild. Lower survival under elevated CO2 , as a result of impaired learning, could have a major influence on population recruitment.

Sea surface temperature and stable isotopes from 9 cores of the Northeastern Atlantic

Temporal and spatial patterns in eastern North Atlantic sea-surface temperatures (SST) were reconstructed for marine isotope stage (MIS) 11c using a submeridional transect of five sediment cores. The SST reconstructions are based on planktic foraminiferal abundances and alkenone indices, and are supported by benthic and planktic stable isotope measurements, as well as by ice-rafted debris content in polar and middle latitudes. Additionally, the larger-scale dynamics of the precipitation regime over northern Africa and the western Mediterranean region was evaluated from iron concentrations in marine sediments off NW Africa and planktic d13C in combination with analysis of planktic foraminiferal abundances down to the species level in the Mediterranean Sea. Compared to the modern situation, it is revealed that during entire MIS 11c sensu stricto (ss), i.e., between 420 and 398 ka according to our age models, a cold SST anomaly in the Nordic seas co-existed with a warm SST anomaly in the middle latitudes and the subtropics, resulting in steeper meridional SST gradients than during the Holocene. Such a SST pattern correlates well with a prevalence of a negative mode of the modern North Atlantic Oscillation. We suggest that our scenario might partly explain the longer duration of wet conditions in the northern Africa during MIS 11c compared to the Holocene.

Compilation of downward flux observations from sediment trap deployments in the Atlantic Ocean - Contribution to EURO-BASIN's Data integration

We provide a compilation of downward fluxes (total mass, POC, PON, BSiO2, CaCO3, PIC and lithogenic/terrigenous fluxes) from over 6000 sediment trap measurements distributed in the Atlantic Ocean, from 30 degree North to 49 degree South, and covering the period 1982-2011. Data from the Mediterranean Sea are also included. Data were compiled from different sources: data repositories (BCO-DMO, PANGAEA), time series sites (BATS, CARIACO), published scientific papers and/or personal communications from PI's. All sources are specifed in the data set. Data from the World Ocean Atlas 2009 were extracted to provide each flux observation with contextual environmental data, such as temperature, salinity, oxygen (concentration, AOU and percentage saturation), nitrate, phosphate and silicate.

(Table 1) Age control and temporal resolution of paleoceanographic records of the North Atlantic

Short-term changes in sea surface conditions controlling the thermohaline circulation in the northern North Atlantic are expected to be especially efficient in perturbing global climate stability. Here we assess past variability of sea surface temperature (SST) in the northeast Atlantic and Norwegian Sea during Marine Isotope Stage (MIS) 2 and, in particular, during the Last Glacial Maximum (LGM). Five high-resolution SST records were established on a meridional transect (53°N-72°N) to trace centennial-scale oscillations in SST and sea-ice cover. We used three independent computational techniques (SIMMAX modern analogue technique, Artificial Neural Networks (ANN), and Revised Analog Method (RAM)) to reconstruct SST from planktonic foraminifer census counts. SIMMAX and ANN reproduced short-term SST oscillations of similar magnitude and absolute levels, while RAM, owing to a restrictive analog selection, appears less suitable for reconstructing "cold end" SST. The SIMMAX and ANN SST reconstructions support the existence of a weak paleo-Norwegian Current during Dansgaard-Oeschger (DO) interstadials number 4, 3, 2, and 1. During the LGM, two warm incursions of 7°C water to occurred in the northern North Atlantic but ended north of the Iceland Faroe Ridge. A rough numerical estimate shows that the near-surface poleward heat transfer from 53° across the Iceland-Faroe Ridge up to to 72° N dropped to less than 60% of the modern value during DO interstadials and to almost zero during DO stadials. Summer sea ice was generally confined to the area north of 70°N and only rarely expanded southward along the margins of continental ice sheets. Internal LGM variability of North Atlantic (>40°N) SST in the GLAMAP 2000 compilation (Sarnthein et al., 2003, doi:10.1029/2002PA000771; Pflaumann et al., 2003, doi:10.1029/2002PA000774) indicates maximum instability in the glacial subpolar gyre and at the Iberian Margin, while in the Nordic Seas, SST was continuously low.

Glacier mass balances of Stubacher Sonnblickkees, Hohe Tauern Range, Eastern Alps, Austria, 1958/1959 to 2012/2013

Stubacher Sonnblickkees (SSK) is located in the Hohe Tauern Range (Eastern Alps) in the south of Salzburg Province (Austria) in the region of Oberpinzgau in the upper Stubach Valley. The glacier is situated at the main Alpine crest and faces east, starting at elevations close to 3050 m and in the 1980s terminated at 2500 m a.s.l. It had an area of 1.7 km² at that time, compared with 1 km² in 2013. The glacier type can be classified as a slope glacier, i.e. the relief is covered by a relatively thin ice sheet and there is no regular glacier tongue. The rough subglacial topography makes for a complex shape in the surface topography, with various concave and convex patterns. The main reason for selecting this glacier for mass balance observations (as early as 1963) was to verify on a complex glacier how the mass balance methods and the conclusions - derived during the more or less pioneer phase of glaciological investigations in the 1950s and 1960s - could be applied to the SSK glacier. The decision was influenced by the fact that close to the SSK there was the Rudolfshütte, a hostel of the Austrian Alpine Club (OeAV), newly constructed in the 1950s to replace the old hut dating from 1874. The new Alpenhotel Rudolfshütte, which was run by the Slupetzky family from 1958 to 1970, was the base station for the long-term observation; the cable car to Rudolfshütte, operated by the Austrian Federal Railways (ÖBB), was a logistic advantage. Another factor for choosing SSK as a glaciological research site was the availability of discharge records of the catchment area from the Austrian Federal Railways who had turned the nearby lake Weißsee ('White Lake') - a former natural lake - into a reservoir for their hydroelectric power plants. In terms of regional climatic differences between the Central Alps in Tyrol and those of the Hohe Tauern, the latter experienced significantly higher precipitation , so one could expect new insights in the different response of the two glaciers SSK and Hintereisferner (Ötztal Alps) - where a mass balance series went back to 1952. In 1966 another mass balance series with an additional focus on runoff recordings was initiated at Vernagtfener, near Hintereisferner, by the Commission of the Bavarian Academy of Sciences in Munich. The usual and necessary link to climate and climate change was given by a newly founded weather station (by Heinz and Werner Slupetzky) at the Rudolfshütte in 1961, which ran until 1967. Along with an extension and enlargement to the so-called Alpine Center Rudolfshütte of the OeAV, a climate observatory (suggested by Heinz Slupetzky) has been operating without interruption since 1980 under the responsibility of ZAMG and the Hydrological Service of Salzburg, providing long-term met observations. The weather station is supported by the Berghotel Rudolfshütte (in 2004 the OeAV sold the hotel to a private owner) with accommodation and facilities. Direct yearly mass balance measurements were started in 1963, first for 3 years as part of a thesis project. In 1965 the project was incorporated into the Austrian glacier measurement sites within the International Hydrological Decade (IHD) 1965 - 1974 and was afterwards extended via the International Hydrological Program (IHP) 1975 - 1981. During both periods the main financial support came from the Hydrological Survey of Austria. After 1981 funds were provided by the Hydrological Service of the Federal Government of Salzburg. The research was conducted from 1965 onwards by Heinz Slupetzky from the (former) Department of Geography of the University of Salzburg. These activities received better recognition when the High Alpine Research Station of the University of Salzburg was founded in 1982 and brought in additional funding from the University. With recent changes concerning Rudolfshütte, however, it became unfeasible to keep the research station going. Fortunately, at least the weather station at Rudolfshütte is still operating. In the pioneer years of the mass balance recordings at SSK, the main goal was to understand the influence of the complicated topography on the ablation and accumulation processes. With frequent strong southerly winds (foehn) on the one hand, and precipitation coming in with storms from the north to northwest, the snow drift is an important factor on the undulating glacier surface. This results in less snow cover in convex zones and in more or a maximum accumulation in concave or flat areas. As a consequence of the accentuated topography, certain characteristic ablation and accumulation patterns can be observed during the summer season every year, which have been regularly observed for many decades . The process of snow depletion (Ausaperung) runs through a series of stages (described by the AAR) every year. The sequence of stages until the end of the ablation season depends on the weather conditions in a balance year. One needs a strong negative mass balance year at the beginning of glacier measurements to find out the regularities; 1965, the second year of observation resulted in a very positive mass balance with very little ablation but heavy accumulation. To date it is the year with the absolute maximum positive balance in the entire mass balance series since 1959, probably since 1950. The highly complex ablation patterns required a high number of ablation stakes at the beginning of the research and it took several years to develop a clearer idea of the necessary density of measurement points to ensure high accuracy. A great number of snow pits and probing profiles (and additional measurements at crevasses) were necessary to map the accumulation area/patterns. Mapping the snow depletion, especially at the end of the ablation season, which coincides with the equilibrium line, is one of the main basic data for drawing contour lines of mass balance and to calculate the total mass balance (on a regular-shaped valley glacier there might be an equilibrium line following a contour line of elevation separating the accumulation area and the ablation area, but not at SSK). - An example: in 1969/70, 54 ablation stakes and 22 snow pits were used on the 1.77 km² glacier surface. In the course of the study the consistency of the accumulation and ablation patterns could be used to reduce the number of measurement points. - At the SSK the stratigraphic system, i.e. the natural balance year, is used instead the usual hydrological year. From 1964 to 1981, the yearly mass balance was calculated by direct measurements. Based on these records of 17 years, a regression analysis between the specific net mass balance and the ratio of ablation area to total area (AAR) has been used since then. The basic requirement was mapping the maximum snow depletion at the end of each balance year. There was the advantage of Heinz Slupetzky's detailed local and long-term experience, which ensured homogeneity of the series on individual influences of the mass balance calculations. Verifications took place as often as possible by means of independent geodetic methods, i.e. monoplotting , aerial and terrestrial photogrammetry, more recently also the application of PHOTOMODELLER and laser scans. The semi-direct mass balance determinations used at SSK were tentatively compared with data from periods of mass/volume change, resulting in promising first results on the reliability of the method. In recent years re-analyses of the mass balance series have been conducted by the World Glacier Monitoring Service and will be done at SSK too. - The methods developed at SSK also add to another objective, much discussed in the 1960s within the community, namely to achieve time- and labour-saving methods to ensure continuation of long-term mass balance series. The regression relations were used to extrapolate the mass balance series back to 1959, the maximum depletion could be reconstructed by means of photographs for those years. R. Günther (1982) calculated the mass balance series of SSK back to 1950 by analysing the correlation between meteorological data and the mass balance; he found a high statistical relation between measured and determined mass balance figures for SSK. In spite of the complex glacier topography, interesting empirical experiences were gained from the mass balance data sets, giving a better understanding of the characteristics of the glacier type, mass balance and mass exchange. It turned out that there are distinct relations between the specific net balance, net accumulation (defined as Bc/S) and net ablation (Ba/S) to the AAR, resulting in characteristic so-called 'turnover curves'. The diagram of SSK represents the type of a glacier without a glacier tongue. Between 1964 and 1966, a basic method was developed, starting from the idea that instead of measuring years to cover the range between extreme positive and extreme negative yearly balances one could record the AAR/snow depletion/Ausaperung during one or two summers. The new method was applied on Cathedral Massif Glacier, a cirque glacier with the same area as the Stubacher Sonnblickkees, in British Columbia, Canada. during the summers of 1977 and 1978. It returned exactly the expected relations, e.g. mass turnover curves, as found on SSK. The SSK was mapped several times on a scale of 1:5000 to 1:10000. Length variations have been measured since 1960 within the OeAV glacier length measurement programme. Between 1965 and 1981, there was a mass gain of 10 million cubic metres. With a time lag of 10 years, this resulted in an advance until the mid-1980s. Since 1982 there has been a distinct mass loss of 35 million cubic metres by 2013. In recent years, the glacier has disintegrated faster, forced by the formation of a periglacial lake at the glacier terminus and also by the outcrops of rocks (typical for the slope glacier type), which have accelerated the meltdown. The formation of this lake is well documented. The glacier has retreated by some 600 m since 1981. - Since August 2002, a runoff gauge installed by the Hydrographical Service of Salzburg has recorded the discharge of the main part of SSK at the outlet of the new Unterer Eisboden See. The annual reports - submitted from 1982 on as a contractual obligation to the Hydrological Service of Salzburg - document the ongoing processes on the one hand, and emphasize the mass balance of SSK and outline the climatological reasons, mainly based on the met-data of the observatory Rudolfshütte, on the other. There is an additional focus on estimating the annual water balance in the catchment area of the lake. There are certain preconditions for the water balance equation in the area. Runoff is recorded by the ÖBB power stations, the mass balance of the now approx. 20% glaciated area (mainly the Sonnblickkees) is measured andthe change of the snow and firn patches/the water content is estimated as well as possible. (Nowadays laserscanning and ground radar are available to measure the snow pack). There is a net of three precipitation gauges plus the recordings at Rudolfshütte. The evaporation is of minor importance. The long-term annual mean runoff depth in the catchment area is around 3.000 mm/year. The precipitation gauges have measured deficits between 10% and 35%, on average probably 25% to 30%. That means that the real precipitation in the catchment area Weißsee (at elevations between 2,250 and 3,000 m) is in an order of 3,200 to 3,400 mm a year. The mass balance record of SSK was the first one established in the Hohe Tauern region (and now since the Hohe Tauern National Park was founded in 1983 in Salzburg) and is one of the longest measurement series worldwide. Great efforts are under way to continue the series, to safeguard against interruption and to guarantee a long-term monitoring of the mass balance and volume change of SSK (until the glacier is completely gone, which seems to be realistic in the near future as a result of the ongoing global warming). Heinz Slupetzky, March 2014

High-resolution paleomagnetic investigation in the Iceland Basin

Based on discrete samples, we report new high-resolution records of the ~185 kyr Iceland Basin (IB) geomagnetic excursion from Ocean Drilling Project (ODP) Site 1063 on the Bermuda Rise (sedimentation rate 32 cm/kyr) and from ODP Site 983 in the far North Atlantic (sedimentation rate 18 cm/kyr). Two records from Holes 1063A and 1063B are very consistent, and provide the highest resolution of the detailed field behaviour during the IB excursion obtained so far. Inclination records from Holes 983B and 983C in the far North Atlantic are also very consistent, whereas declination anomalies deviate more notably. The pseudo-Thellier (PT) technique was applied along with more conventional palaeointensity proxies (NRM/ARM and NRM/kappa) to recover relative palaeointensity (RPI) estimates from Hole 1063A and Hole 983B. As expected, these proxies indicate that the field intensity generally dropped at both sites during the IB excursion, but also that the history of RPI from the two sites is different. VGPs from Site 1063 indicate that the field at this location experienced some stop-and-go behaviour between patches of intense vertical flux over North America and the tip of South America, areas which coincide fairly well with patches of preferred transitional VGP clustering from reversals and zones of high seismic velocity in the lower mantle. Changes in RPI at this location were generally gradual, possibly due to the proximity of these flux patches, and the first period of VGP-clustering over North America was accompanied by a conspicuous increase in RPI. VGPs from Site 983 track along a different path, and the associated RPI changes are very abrupt and completely synchronous with the onset and termination of the excursion. The differing VGP paths from Sites 1063 and 983 indicate that the global field structure during the IB excursion was not dominated by a single dipole.

Stable isotope analysis of Porites coral core from the Andaman Islands

North Atlantic climate variations are reflected in sedimentary records from the northern Indian Ocean in which two basins, the Arabian Sea and the Bay of Bengal, are strongly affected by the monsoon. Contrary to the Bay of Bengal the Arabian Sea plays an important role in the global marine nitrogen cycle. In its mid-water oxygen minimum zone (OMZ) bioavailable fixed nitrogen is reduced to nitrogen gas (NO3- - > N2), whereas oxygen concentrations are slightly above the threshold of nitrate reduction in the OMZ of the Bay of Bengal. A coral colony (Porites lutea) growing south of Port Blair on the Andaman Islands in the Bay of Bengal was studied for its response to changes in the monsoon system and its link to temperature changes in the North Atlantic Ocean, between 1975 and 2006. Its linear extension rates, d13C and d18O values measured within the coral skeleton reveal a strong seasonality, which seems to be caused by the monsoon-driven reversal of the surface ocean circulation. The sampling site appears to be influenced by low salinity Bay of Bengal Water during the NE monsoon (boreal winter) and by the high salinity Arabian Sea Water during the SW monsoon in summer. The high salinity Arabian Sea Water circulates along with the Summer Monsoon Current (S-MC) from the Arabia Sea into the Bay of Bengal. Decreasing d18O and reconstructed salinity values correlate to the increasing SSTs in the North Atlantic Ocean indicating a reduced influence of the S-MC at the sampling site in the course of northern hemispheric warming. During such periods oxygen-depletion became stronger in the OMZ of the Arabian Sea as indicated by the sedimentary records. A reduced propagation of oxygen-depleted high salinity Arabian Sea Water into the Bay of Bengal could be a mechanism maintaining oxygen concentration above the threshold of nitrate reduction in the OMZ of the Bay of Bengal in times of global warming.