ALBERT

Description: Many shallow coastal systems experience diel fluctuations in dissolved oxygen (DO) and pH that can intensify throughout the summer season and expose estuarine organisms to repeated episodes of coastal hypoxia and acidification. In temperate regions, larval release of the economically important blue crab Callinectes sapidus occurs in the summer, and while the earliest stage (zoea I) larvae are susceptible to persistent low DO and low pH conditions, their sensitivity to diel fluctuations is unknown. Here, a series of short-term (〈=96 h) experiments were conducted to investigate the survival of C. sapidus zoea I larvae exposed to a range of diel cycling hypoxic and acidified conditions and durations. Two experiments comparing a diel cycling DO/pH treatment (fluctuating from 30% air saturation to 103% averaging 66%/and from pH 7.26 to 7.80 averaging 7.53) to a static low DO/pH treatment (43%/7.35), a static moderate DO/pH treatment (68%/7.59), and a static control treatment (106%/7.94) indicated that survival in the diel cycling treatment was significantly lower than the moderate treatment (p 〈 0.05) by 75 and 48% over 96 and 48 h, respectively, despite comparable mean experimental DO/pH values. Three other experiments aimed at identifying the effective minimum duration of low DO/low pH to significantly depress larval survival under diel cycling conditions revealed that 8 h of low DO/low pH (28%/7.43) over a 24-h diel cycle consistently decreased survival (p 〈 0.05) relative to control conditions by at least 55% regardless of experimental duration (72-, 48-, and 24-h experiments). An increase in DO beyond saturation to supersaturation (160%) and pH beyond normocapnic to highly basified (8.34) conditions during the day phase of the diel cycle did not improve survival of larvae exposed to nocturnal hypoxia and acidification. Collectively, these experiments demonstrate that diel cycling does not provide newly hatched C. sapidus larvae a temporal refuge capable of ameliorating low DO/pH stress, but rather is more lethal than chronic exposure to comparable average DO/pH conditions. Given that larvae exposed to a single nocturnal episode of moderate hypoxia and acidification experience significantly reduced survival, such occurrences may depress larval recruitment.

Description: Coastal zones can be focal points of acidification where the influx of atmospheric CO2 can be compounded by additional sources of acidity that may collectively impair calcifying organisms. While the photosynthetic action of macrophytes may buffer against coastal ocean acidification, such activity has not been well-studied, particularly among aquacultured seaweeds. Here, we report on field and laboratory experiments performed with North Atlantic populations of juvenile hard clams (Mercenaria mercenaria), eastern oysters (Crassostrea virginica), and blue mussels (Mytilus edulis) grown with and without increased CO2 and with and without North Atlantic kelp (Saccharina latissima) over a range of aquaculture densities (0.3 – 2 g/L). In all laboratory experiments, exposure to elevated pCO2 (〉1,800 µatm) resulted in significantly reduced shell- and/or tissue-based growth rates of bivalves relative to control conditions. This impairment was fully mitigated when bivalves were exposed to the same acidification source but also co-cultured with kelp. Saturation states of aragonite were transformed from undersaturated to saturated in the acidification treatments with kelp present, while the acidification treatments remained undersaturated. In a field experiment, oysters grown near aquacultured kelp were exposed to higher pH waters and experienced significantly faster shell and tissue based growth rates compared to individuals grown at sites away from kelp. Collectively, these results suggest that photosynthesis by S. latissima grown at densities associated with aquaculture increased pH and decreased pCO2, fostering a carbonate chemistry regime that maximized the growth of juvenile bivalves. As S. latissima has been shown to benefit from increased CO2, growing bivalves and kelp together under current or future acidification scenarios may be a synergistically beneficial integrated, multi-trophic aquaculture approach.

Description: Neutral, volatile polyfluorinated alkyl substances (PFAS) were determined in high-volume air samples collected onboard the German research vessel Polarstern during cruise ANT-XXIII/1 between Bremerhaven, Germany (53° N) and Capetown, Republic of South Africa (33° S) in fall 2005. An optimized and validated analytical protocol was used for the determination of several fluorotelomer alcohols (FTOHs) as well as N-alkylated fluorooctane sulfonamides and sulfonamidoethanols (FOSAs/FOSEs). Quantitative analyses were done by gas chromatography-mass spectrometry. This study provides the first concentration data of airborne PFAS from the Southern Hemisphere. Results indicate a strongly decreasing concentration gradient from the European continent toward less industrialized regions. The study confirms that airborne PFAS are mainly restricted to the Northern Hemisphere with a maximum concentration of 190 pg/m**3 (8:2 FTOH) in the first sample collected in the channel between the European mainland and the UK. However, south of the equator, trace amounts of several FTOHs and FOSAs with a maximum of 14 pg/m**3 (8:2 FTOH) could still be detected. Furthermore, a selection of ionic PFAS including perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) were determined in the particulate phase of high-volume air samples by liquid chromatography-mass spectrometry. Levels of ionic PFAS were almost 2 orders of magnitude lower than those of neutral PFAS, with maximum concentrations in the first sample of 2.5 pg/m**3 (PFOS) and 2.0 pg/m**3 (PFOA).

Description: High-resolution stable oxygen and carbon isotope analyses and detailed sedimentological and geochemical investigations were performed in order to (i) reconstruct the paleoclimate and paleoceanography of the Greenland Sea associated with late Quaternary glacial-interglacial cycles, and (ii) to link the terrestrial and deep-sea climatic records. The reconstruction of the paleoenvironmental history of the East Greenland margin and the correlation between the terrestrial and deep sea records are major objectives of the ESF-PONAM-Programme (European Science Foundation - Polar North Atlantic Margins). For this study 16 gravity and 2 box cores were recovered along the East Greenland continental margin between 69° N and 72° N on three W-E transects running from the shelf to the deep sea.

Description: Stable isotope records, and sedimentological and organic-geochemical investigations of marine sediments from the east Greenland Sea at 70°N provide important information about glacial-interglacial variations of paleoenvironments through the last 225 kyr. The oxygen isotope records established on the planktonic foraminifer N. pachyderma sin. show some excursions from the global climate pattern, probably due to local/regional overprint by meltwater supply. The cold, low-saline East Greenland Current and fluctuations in sea-ice covering were a crucial element controlling the carbonate production in the subsurface/surface water column in the east Greenland Sea over the last 225 kyr. The beginning of Termination Ia is AMS 14C dated at about 15.8 kyr B.P. and interpreted as a Greenland Ice Sheet meltwater signal. The stage 2/3 boundary is dated at about 25 kyr B.P. The timing of the onset of the last deglacial meltwater event is about 800 years earlier than that of the Barents Shelf Ice Sheet meltwater signal recorded in the Fram Strait. Several major pulses of increased supply of coarse-grained terrigenous material by glacio-marine processes occurred during the last 225 kyr. The supply of coarse-grained ice-rafted debris at the East Greenland continental slope reached maximum values during the last glacial maximum (stage 2/Weichselian, 15-19 kyr B.P.). The drastic climatic change and the gradual retreat of continental ice masses/glaciers during the last deglaciation (Termination I) are clearly documented in the marine sedimentary sequences from shelf and upper slope environments. This process resulted in distinctly decreased supply and deposition of ice-rafted debris in the open shelf-upper slope environments. During Termination I, the sea-ice cover also decreased, causing an increase in surface-water productivity, indicated by increased organic carbon and biogenic opal deposition.

Description: High-resolution stable oxygen and carbon isotope analyses and detailed sedimentological and geochemical investigations were performed in order to i) reconstruct the paleoclimate and paleoceanography of the Greenland Sea associated with late Quaternary glacial-interglacial cycles, and ii) to link the terrestrial and deep-sea climatic records. The reconstruction of the paleoenvironmental history of the East Greenland margin and the correlation between the terrestrial and deep sea records are major objectives of the ESF-PONAM-Programme (European Science Foundation - Polar North Atlantic Margins). For this study 16 gravity and 2 box cores were recovered along the East Greenland continental margin between 69°N and 72°N on three W-E transects running from the shelf to the deep sea. The glaciomarine sediments recovered from the heavily ice-covered East Greenland continental margin reflect changes associated with the glacial/interglacial climatic cycles of the last 240 ka. The glaciomarine sediments are characterised by a dominance of terrestrially derived components and a lower content of biogenic components. Glaciomarine sedimentation processes, terrigenous sediment input, and biogenic productivity in the study area are strongly influenced by fluctuations in the extent of the Greenland Ice Sheet, extent of the sea-ice cover, rate of iceberg drifting, meltwater input, and changes in the East Greenland Current (EGC). The relatively low carbonate content (〈10 %) and the dominant occurrence of N. pachyderma sin. (〉95 %) throughout the sediment sequences indicate a low biological productivity in the surface water resulting from the extensive sea-ice cover and the strong influence of cold and low-saline polar waters of the EGC. An increase in the surface-water productivity, on the other hand, occurred during certain periods within interglacial and glacial stages. This indicates that the sea ice along the Western margin of the Greenland Sea was at least seasonally reduced during these time intetvals. Based on the accumulation rates of the coarse terrigenous matter (〉63 µm) and amounts of IRD, the advance and retreat of East Greenland glaciers over the past 200 ka can be correlated with those postulated from the terrestrial records. At least five repeated advances and retreats of glaciers beyond the coastline are proposed between the late Early to Middle Weichselian (65-61, 59-51, 48-42, 35-31, and 28-25 ka). Maximum fluxes of IRD recorded along the continental margin between 21 and 16 ka, reflect the maximum extent of East Greenland glaciers probably reaching the shelf break at that time. The stable oxygen isotope records measured on the planktonic foraminifer N. pachyderma sin. reveal some excursions from the global climate record due to a local andlor regional overprint through meltwater supply andlor cold water masses of the EGC. Distinct meltwater events are documented during Terminations II and l and at the beginning of Stage 3 resulting from the collapse of the Greenland Ice Sheet. The early period of all glacial stages (i.e. 716, 514, and 312) was subjected to an abrupt and rapid build-up of a sea-ice cover. Hence, a distinct decrease in the carbonate content, the low number of planktonic foraminifers, and light d13C values reflect the strong reduction in the C02 exchange between the atmosphere and ocean, and the surface-water productivity, resulting from a meltwater cap andlor an extensive sea-ice cover. The onset of Termination l is characterised by a distinct shift towards light d180 values, a dramatic decrease in the IRD-flux, and a marked increase in organic matter, indicating the rapid retreat of East Greenland glaciers and a reduced sea-ice cover. According to distinct shifts toward light d180 and heavy d13C values of N. pachyderma sin. and O. umbonatus, the present-day circulation Patterns of surface- and deep-water masses were probably established between 7.4 and 6.1 ka. This is very similar to the timing estimated from studies On microfossil assemblages of the Greenland Sea. In particular, the distinct IRD peaks correlate with the fluctuations of the Greenland Ice Sheet during the last two glacial-interglacial cycles. Most of the major IRD peaks correspond to periods of cooling of air temperatures over Greenland. During the interval between 225 and 60 ka, the IRD peaks are in phase (at the 23-kyr orbital processional cycle) with maximum Summer Insolation at 70°N This suggests that the Greenland Ice Sheet may have experienced a predominantly 23-kyr cycle of growth and decay, and therefore, collapsed and discharged large volumes of icebergs to the Greenland Sea when Summer insolation reached its maxima. During the last glacial period, there is a strong correlation between major pulses in the supply of IRD, and the Bond Cycles and the Heinrich Events recorded in the GRIP ice core and North Atlantic deep-sea sediments. Furthermore, the higher frequency of IRD events on millennial scales matches the cooling phase of the abrupt Dansgaard-Oeschger Cycles recorded in the GRIP ice core. Consequently, the apparent evidence of millennial scale IRD events in the North Atlantic and the GIN Sea suggests coherent fluctuations of the large northern hemisphere ice sheets (i.e. the Fennoscandian/Barents Sea and Laurentide/Greenland ice sheets) during the last glacial period.

Description: Coastal zones of the Humboldt Current Upwelling System (HCUS) are composed both of rocky and sandy beaches inhabited by macrozoobenthic communities. These show oscillating changes in the dominance of species; the abundance of the sand crab Emerita analoga is linked to phases of the El Niño Southern Oscillation (ENSO). The biogenic surfaces of these crabs serve as substrate for opportunistic colonizers. This study is the first record of an epibiosis between E. analoga and the rock mussel Semimytilus algosus, detected at a southern Peruvian sandy beach. Mussels fouled a wide size-range of adult E. analoga (7.3%) but they themselves belonged to small-size classes. The largest S. algosus was 17.4 mm in length. Highest permanence of epibionts was found on larger sand crabs (maximum between 24 and 27 mm). Significantly more mussels were found on the ventral surface (39.4%) compared to 10 other surface areas of the sand crab. Possible benefits and disadvantages of the observed epibiosis for both the basibiont and the epibiont are discussed.

Description: Holocene climate variability is investigated in the North Pacific and North Atlantic realms, using alkenone-derived sea-surface temperature (SST) records as well as a millennial scale simulation with a coupled atmosphere-ocean general circulation model (AOGCM). The alkenone SST data indicate a temperature increase over almost the entire North Pacific from 7 cal kyr BP to the present. A dipole pattern with a continuous cooling in the northeastern Atlantic and a warming in the eastern Mediterranean Sea and the northern Red Sea is detected in the North Atlantic realm. Similarly, SST variations are opposite in sign between the northeastern Pacific and the northeastern Atlantic. A 2300 year long AOGCM climate simulation reveals a similar SST seesaw between the northeastern Pacific and the northeastern Atlantic on centennial time scales. Our analysis of the alkenone SST data and the model results suggests fundamental inter-oceanic teleconnections during the Holocene.

Description: High-resolution stable oxygen and carbon isotope and sedimentological investigations were carried out on four west-east profils at the East Greenland continental margin between 68° and 75°. The sediment cores represent distinct flacial/interglacial palaeoclimatic episodes over the past 190 ka. Based on oxygen isotope stratigraphy and AMS 14C dating, our data can be well correlated with the global climate record. However, there are some excursions from the global climate curve suggesting a local/regional overprint by meltwater events of the Greenland Ice Sheet, especially at the beginning of isotope stage 3 and during Termination I. Distinct high-amplitude variations in supply of ice-rafted debris (IRD) indicate repeated advances and retreats of the Greenland Ice Sheet, causing fluctiations in the massive production and transport of icebergs into the Greenland Sea. During the last 190 ka, a number of IRD peaks appear to be correlated with cooling cycles observed in the GRIP Greenland Ice Core. Drastic events in iceberg discharge along the East Greenland continental margin recurred at very short intervals of 100-300 years (i.e. much more frequently than the about 10 000 years associated with Heinrich events), suggesting short-term collapses of the Greenland Ice Sheet on these time-scales. These late Weichselian Greenland Ice Sheet oscillations appear to be in phase with those in the Barents Sea area. Maximum flux rates of terrigenous (ice-rafted) material were recorded at the continental slope between about 21 and 16 ka, which may correspond to the maximum (stage 2) extension of glaciers on Greenland. The beginning ot Termination I is documented by a distinct shift in the oxygen isotopes and a most prominent decrease in flux of IRD at the continental slope caused by the retreat of continental ice masses.