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Netherlands North Sea ocean acidification monitoring programme dataset v2023.10
No full textMonitoring programme of the Dutch Ministry of Infrastructure and Water Management to improve the understanding of dynamics and trends in ocean acidification parameters in the Dutch sector of the North Sea. This dataset (version 2023.10) contains all measurements from all batches of analysis up to and including October 2023 for which auxiliary variables (temperature, salinity and nutrients) were available from Rijkswaterstaat at the time of publication, specifically, 982 measurements of dissolved inorganic carbon, 981 of total alkalinity and 983 of pH, from 22 January 2018 to 22 March 2023. This dataset is a replacement for the previous version (v10; doi:10.25850/nioz/7b.b.tc). All data that appear in both this and the previous version are identical except for 49 DIC measurements which have been adjusted by up to 3 ?mol/kg due to an improved calibration and 3 measurements of nutrients which have changed almost negligibly due to updated auxiliary data from Rijkswaterstaat
Hydrography and velocity data from the Long-term Ocean Circulation Observations (LOCO) mooring in the central Irminger Sea: Deployment ten (LOCO2_10) August 2012 to July 2014
No full textThe data set under this specific DOI contains data from the tenth LOCO2 deployment (LOCO2_10), from 2 August 2012 to 26 July 2014.
Data from other deployments can be found through the related identifyers.
The LOCO2 mooring was started as part of the Dutch Long-term Ocean Circulation Observations project. LOCO2 was moored in the central Irminger Sea at approximately 59.2N, 39.5W from summer 2003 until summer 2018. It was equipped with Acoustic Doppler Current Profilers for the upper ocean (2500m) circulation, a near bottom SBE37 to record the temperature and salinity of the Denmark Strait Overflow Water and (from the 10th deployment onwards) another SBE37 at around 150m. A McLane Moored Profiler (MMP) equipped with a CTD was programmed to make profiles along the mooring cable between ~150m depth and ~2400m depth.
LOCO2 was positioned in the center of the Irminger Gyre, underneath the strong atmospheric forcing of the Greenland Tip Jet, in order to study deep winter convection in the Irminger Sea. Data and results are described in the following publications:
- de Jong, M. F., van Aken, H. M., V?ge, K., and R. S. Pickart (2012). Convective mixing in the central Irminger Sea: 2002-2010. Deep-Sea Research I, 63, 36-51. https://doi.org/10.1016/j.dsr.2012.01.003
- van Aken, H. M., and M. F. de Jong (2012). Hydrographic variability of Denmark Strait Overflow Water near Cape Farewell with multi-decadal to weakly time scales. Deep-Sea Research I, 66, 41-50. https://doi.org/10.1016/j.dsr.2012.04.004
- de Jong, M. F. and L. de Steur (2016). Strong winter cooling over the Irminger Sea in winter 2014-2015, exceptional deep convection, and the emergence of anomalously low SST. Geophysical Research Letters, 43, 13, 7106-7113. https://doi.org/10.1002/2016GL069596
- de Jong, M.F., M. Oltmanns, J. Karstensen, and L. de Steur (2018). Deep convection in the Irminger Sea observed with a dense mooring array. Oceanography 31(1):50?59. https://doi.org/10.5670/oceanog.2018.109
- de Jong, M.F., Fogaren, K.E., Le Bras, I., Trafford, L. and H. Palevsky (submitted 2023). Convection in the central Irminger Sea; insights into variability and the roles of surface forcing and stratification from 19 years of high resolution mooring data
Hydrography and velocity data from the Long-term Ocean Circulation Observations (LOCO) mooring in the central Irminger Sea: Deployment eleven (LOCO2_11) September 2014 to July 2015
No full textThe data set under this specific DOI contains data from the eleventh LOCO2 deployment (LOCO2_11), from 16 September 2014 to 18 July 2015.
Data from other deployments can be found through the related identifyers.
The LOCO2 mooring was started as part of the Dutch Long-term Ocean Circulation Observations project. LOCO2 was moored in the central Irminger Sea at approximately 59.2N, 39.5W from summer 2003 until summer 2018. It was equipped with Acoustic Doppler Current Profilers for the upper ocean (2500m) circulation, a near bottom SBE37 to record the temperature and salinity of the Denmark Strait Overflow Water and (from the 10th deployment onwards) another SBE37 at around 150m. A McLane Moored Profiler (MMP) equipped with a CTD was programmed to make profiles along the mooring cable between ~150m depth and ~2400m depth.
LOCO2 was positioned in the center of the Irminger Gyre, underneath the strong atmospheric forcing of the Greenland Tip Jet, in order to study deep winter convection in the Irminger Sea. Data and results are described in the following publications:
- de Jong, M. F., van Aken, H. M., V?ge, K., and R. S. Pickart (2012). Convective mixing in the central Irminger Sea: 2002-2010. Deep-Sea Research I, 63, 36-51. https://doi.org/10.1016/j.dsr.2012.01.003
- van Aken, H. M., and M. F. de Jong (2012). Hydrographic variability of Denmark Strait Overflow Water near Cape Farewell with multi-decadal to weakly time scales. Deep-Sea Research I, 66, 41-50. https://doi.org/10.1016/j.dsr.2012.04.004
- de Jong, M. F. and L. de Steur (2016). Strong winter cooling over the Irminger Sea in winter 2014-2015, exceptional deep convection, and the emergence of anomalously low SST. Geophysical Research Letters, 43, 13, 7106-7113. https://doi.org/10.1002/2016GL069596
- de Jong, M.F., M. Oltmanns, J. Karstensen, and L. de Steur (2018). Deep convection in the Irminger Sea observed with a dense mooring array. Oceanography 31(1):50?59. https://doi.org/10.5670/oceanog.2018.109
- de Jong, M.F., Fogaren, K.E., Le Bras, I., Trafford, L. and H. Palevsky (submitted 2023). Convection in the central Irminger Sea; insights into variability and the roles of surface forcing and stratification from 19 years of high resolution mooring data
CTD seawater dissolved inorganic carbon and total alkalinity for R/V Sonne cruise SO289.
No full textThis dataset contains 395 measurements (all from the CTD rosette) of seawater dissolved inorganic carbon (DIC) and total alkalinity (TA) from the South Pacific Ocean. The samples were collected during R/V Sonne cruise SO289 in February-April 2022, as part of the GEOTRACES GP21 research programme to build an understanding of the distribution, origins, and depletions of trace elements and their isotopes (TEIs) in a lesser-explored ocean region. Measurements for TA and DIC were carried out using a VINDTA 3C instrument (#014, Marianda, Germany). All analysis was conducted at the NIOZ Royal Netherlands Institute for Sea Research. Bad results from technical issues during analysis have been removed from these results, so there are no recognised issues. The NIOZ created the metadata entry and is responsible for holding master copies of the data
Data from: The effects of gas extraction under intertidal mudflats on sediment and macrozoobenthic communities
No full text1- Land subsidence in intertidal environments may change the flooding regime and sediment composition, two drivers of the macrozoobenthic community. In the Dutch Wadden Sea, a UNESCO world heritage site, gas extraction has resulted in an average subsidence of intertidal mudflats of 2 mm y-1. These mudflats support an abundant macrozoobenthic community that offers important resources for birds and fish. The area is managed through the “hand on the tap” principle, meaning that human activities should be halted if they affect the natural values. To what extent land subsidence affects sediment and macrozoobenthos remains unknown and is increasingly important given sea level rise.
2- Taking advantage of a large-scale monitoring program, we evaluated the effect of anthropogenically caused subsidence on sediment composition and macrozoobenthos. Nearly 4600 points were sampled yearly (2008-2020) across the Dutch Wadden Sea, allowing us to compare sediment composition and macrozoobenthos biomass within and outside the subsidence area while controlling for the main drivers of these variables. We also compared population trends within and outside the subsidence area for 31 species with different habitat use.
3- Mud fraction was 3% higher within the subsided area and median grain size decreased at 1 µm y-1 while remaining constant in other mudflats. This had no effect on the total biomass of macrozoobenthos. Within the subsidence area, however, the biomass of species that use deeper areas increased compared to outside, and the opposite was true for species using shallower habitat.
4- Policy implications: Land subsidence is related to changes in median grain size and macrozoobenthic community composition. However, because thresholds have not been defined, it is not clear if this requires management actions. For a successful implementation of the “hand on the tap” principle in the Wadden Sea, it is necessary to define beforehand the relevant variables that represent the natural values, implement proper monitoring, and define thresholds above which effects are not acceptable. We propose median grain size, mud fraction and macrozoobenthic composition as good measures of the natural values of the Wadden Sea, and the methods used here as a way for identifying anthropogenic effects on them
Marine nitrogen cycling dynamics under altering redox conditions: insights from deposition of sapropels S1 and the ambiguous S2 in the Eastern Mediterranean Sea
No full textThe eastern Mediterranean Sea (EMS) sedimentary record is periodically interspersed with organic- rich ?sapropel? layers. Sapropels are characteristic of basin-wide anoxic events, triggered by precession-forced insolation maxima. Relatively subdued insolation maxima, however, are not always expressed as distinct sapropel events. The EMS sedimentary record hereby allows anoxia and nitrogen (N) cycling tipping points to be investigated, which may act as analogues for modern deoxygenation. To this end, we investigated a ~68 kyr EMS sedimentary record, containing the well-established sapropel S1 (deposited in two phases: S1a [~10.5?8.5 ka BP] and S1b [~7.8?6.1 ka BP]) and sediments timed to the ambiguous S2 sapropel (~53 ka BP). We focus on lipid biomarkers of microorganisms to reconstruct key components of the N cycle: (1) anaerobic ammonium oxidation (anammox) using ladderanes and a stereoisomer of bacteriohopanetetrol (BHT-x), (2) dinitrogen gas (N2) fixation using heterocyte glycolipids (HGs), and (3) nitrification by Thaumarchaeota using crenarchaeol. During S1, export-productivity (indicated by the barium to aluminum ratio) and anoxia (indicated by redox-sensitive trace elements and benthic foraminifer assemblages) are enhanced. Thaumarchaeota are most abundant in S1a, while anammox is enhanced throughout S1. N2-fixation (indicated by bulk sedimentary ?15N) occurs throughout S1, while the highest heterocyte cyanobacteria abundance is at the S1a termination and S1 interval. Ladderane presence suggests additional episodes of bioavailable N removal between ~69 to 39 cal ka BP. These episodes correspond to brief periods of water column deoxygenation, with anoxia occurring at the sediment-water interface in sediments timed to S2 (53?51 cal ka BP). During these episodes, ladderanes co-occur with the BHT-34R stereoisomer, but not BHT-x. Compound-specific ?13CBHT-34R indicates an anammox source. Our results highlight various modes of operation of the N cycle during the different deoxygenation events. During S1a, a combination of N-loss and P-supply may have reinforced anoxia, by favoring diatom-diazotroph symbiotic consortia. Conversely, a coupling between N2-fixation and anammox was not observed during S1b and the S2-timed interval, either because loss of bioavailable N was insufficient or diazotrophs were nutrient limited. During these periods, anammox may have provided negative feedback on anoxia by quenching primary production
Chapter 4 - Algal-induced biogeomorphic feedbacks lay the groundwork for coastal wetland development
No full textCoastal wetlands provide valuable ecosystem services, including biodiverse habitats, carbon sequestration potential and nature-based flood defense. The establishment of saltmarsh vegetation and other key wetland species on bare tidal flats relies on windows of opportunity, which are traditionally linked to physical factors such as hydrodynamic conditions, substrate stability and drainage. However, observations on tidal flats suggest that plant seedlings settle in high densities on raised sedimentary ridges colonized by mats of primitive filamentous algae (Vaucheria sp.). Such algal-covered ridges were previously shown to have higher sediment strength than substrate without algae. Here, we investigated whether these measurements can be explained by physical processes only, or that biological (Vaucheria-induced) processes influence early saltmarsh establishment through the formation of stabilized bedforms. We performed two experiments under controlled mesocosm conditions, to test the hypotheses that i) Vaucheria grows better on elevated topographic relief, ii) the binding force of their algal filaments increases sediment strength, which consequently iii) maintains and creates elevated topographic relief on which algal growth is further facilitated. The existence of this algal-induced biogeomorphic feedback cycle was confirmed in our experiments. Our findings reveal that halophytic plants are not the only important ecosystem engineer in coastal wetlands, but that fast-growing, mat- forming species like Vaucheria also play a major role by creating stable and elevated sedimentary relief. Our study indicates that biota can widen the windows of opportunity for ecosystem establishment, which can be utilized to optimally design managed coastal realignment projects that aim at the restoration of coastal ecosystems
Loss of nitrogen via anaerobic ammonium oxidation (anammox) in the California current system during the late Quaternary
No full textThe California current system (CCS) hosts one of the largest oxygen minimum zones (OMZs) in the world: the Eastern North Pacific (ENP) OMZ, which is dissociated into a subtropical and tropical region (i.e., the ESTNP and ETNP). In the modern ENP OMZ, bioavailable nitrogen (N) is lost via denitrification and anaerobic ammonium oxidation (anammox). Even so, paleo-reconstructions of N-loss have focused solely on denitrification. Fluctuations in bulk sedimentary ?15N over glacial-interglacial cycles have been interpreted to reflect variations in denitrification rates in response to ETNP OMZ intensity changes. This ?15N signal is thought to be transported northwards to the ESTNP OMZ. Here, we present the first CCS sedimentary record of ladderane lipids, biomarkers for anammox, located within the ESTNP OMZ (32?N; 118?W). Over the last two glacial terminations (~160 cal ka BP), ladderane concentrations were analysed in combination with the index of ladderanes with five cyclobutane moieties (NL5), short-chain (SC) ladderane degradation products, and productivity proxies. This shows that: 1) ladderanes derived from anammox bacteria living within the ESTNP OMZ water column; 2) ladderanes were continuously present, with relatively high concentrations during both glacial- and interglacial-periods, showcasing the ESTNP OMZ must have retained an anoxic core in which N-loss occurred; and 3) anammox abundance appears to have been driven both by OM-remineralization and advection changes, which regulated nutrient and oxygen levels. Our study shows that anammox was an important feature in the CCS and provides a more holistic picture of N-loss dynamics and the development of the ESTNP OMZ over glacial-interglacial cycles. Lastly, ladderanes and their SC-products were also detected in 160?500 cal ka BP sediments (15.7?37.5 mbsf; analysed at a low temporal resolution), highlighting their potential as anammox biomarkers in relatively deeper buried sediments for future studies
Discrete underway surface seawater dissolved inorganic carbon and total alkalinity for R/V Sonne cruise SO289.
No full textThis dataset contains 32 measurements (all from the underway water system) of seawater dissolved inorganic carbon (DIC) and total alkalinity (TA) from the South Pacific Ocean. The samples were collected during R/V Sonne cruise SO289 in February-April 2022, as part of the GEOTRACES GP21 research programme to build an understanding of the distribution, origins, and depletions of trace elements and their isotopes (TEIs) in a lesser-explored ocean region. Measurements for TA and DIC were carried out using a VINDTA 3C instrument (#014, Marianda, Germany) and a Seal QuAAtro, gas-segmented continuous flow analyser. All analysis was conducted at the NIOZ Royal Netherlands Institute for Sea Research. Bad results from technical issues during analysis have been removed from these results, so there are no recognised issues. The NIOZ created the metadata entry and is responsible for holding master copies of the data
Social Distancing Seals
No full textMany species aggregate in dense colonies. Species-specific spatial patterns provide clues about how colonies are shaped by various (a-)biotic factors, including predation, temperature regulation, or disease transmission. Using aerial imagery, we examined these patterns in colonies on land of two sympatric seal species: the harbour seal and grey seal. Results show that the density of grey seals on land is twice as high as that of harbour seals. Furthermore, the nearest neighbour distance (NND) of harbour seals (median = 1.06 m) is significantly larger than that of grey seals (median = 0.53 m). When the observed seal locations were shuffled slightly through spatial simulation, the frequency of the smallest NNDs (0-25 cm) increased, while the most frequently observed NNDs decreased, implying that both species actively display social distancing. As harbour seals are more prone to infectious diseases, we hypothesize that the larger NNDs might be a behavioural response to reduce pathogen transmission. The observed differences in spatial patterns can be used as a practical tool to differentiate between harbour and grey seals in remote sensing applications, particularly in low to medium resolution imagery (e.g., satellite imagery), where morphological characteristics alone are insufficient to differentiate between species