ALBERT

Description: Warming air and sea temperatures, longer open-water seasons and sea-level rise promote the erosion of permafrost coasts in the Arctic, which profoundly impacts organic matter pathways. Although estimates on organic carbon (OC) fluxes from erosion exist for some parts of the Arctic, little is known about how much OC is transformed into greenhouse gases (GHGs). In this study we investigated two different coastal erosion scenarios on Qikiqtaruk – Herschel Island (Canada) and estimate the potential for GHG formation. We distinguished between a delayed release represented by mud debris draining a coastal thermoerosional feature and a direct release represented by cliff debris at a low collapsing bluff. Carbon dioxide (CO2) production was measured during incubations at 4 °C under aerobic conditions for two months and were modelled for four months and a full year. Our incubation results show that mud debris and cliff debris lost a considerable amount of OC as CO2 (2.5 ± 0.2 and 1.6 ± 0.3% of OC, respectively). Although relative OC losses were highest in mineral mud debris, higher initial OC content and fresh organic matter in cliff debris resulted in a ~three times higher cumulative CO2 release (4.0 ± 0.9 compared to 1.4 ± 0.1 mg CO2 gdw-1), which was further increased by the addition of seawater. After four months, modelled OC losses were 4.9 ± 0.1 and 3.2 ± 0.3% in set-ups without seawater and 14.3 ± 0.1 and 7.3 ± 0.8% in set-ups with seawater. The results indicate that a delayed release may support substantial cycling of OC at relatively low CO2 production rates during long transit times onshore during the Arctic warm season. By contrast, direct erosion may result in a single CO2 pulse and less substantial OC cycling onshore as transfer times are short. Once eroded sediments are deposited in the nearshore, highest OC losses can be expected. We conclude that the release of CO2 from eroding permafrost coasts varies considerably between erosion types and residence time onshore. We emphasize the importance of a more comprehensive understanding of OC degradation during the coastal erosion process to improve thawed carbon trajectories and models.

Description: Drilling of a 21.8-m-deep borehole on top of the 10.5-m-high Nori pingo that stands at 32 m asl in Grøndalen Valley (Spitsbergen) revealed a 16.1-m-thick massive ice enclosed by frozen sediments. The hydrochemical compositions of both the massive ice and the sediment extract show a prevalence of Na+ and Cl� ions throughout the core. The upper part of the massive ice (stage A) has low mineralization and shows an isotopically closed-system trend in δ18O and δD isotopes decreasing down-core. Stage B exhibits high mineralization and an isotopically semi-open system. The crystallographic structure of Nori pingo’s massive ice provides evidence of several large groundwater intrusions that support the defined formation stages. Analysis of local aquifers leads to suggest that the pingo was hydraulically sourced through a local fault zone by low mineralized sodium–bicarbonate groundwater of a Paleogene strata aquifer. This groundwater was enriched by sodium and chloride ions while filtering through marine valley sediments with residual salinity. The comparison between the sodium–chloride-dominated massive ice of the Nori pingo and the sodium–bicarbonate-dominated ice of the adjacent Fili pingo that stands higher up the valley may serve as an indicator for groundwater source patterns of other Nordenskiöld Land pingos.

Description: Boreal forests cover over half of the global permafrost area and protect underlying permafrost. Boreal forest development, therefore, has an impact on permafrost evolution, especially under a warming climate. Forest disturbances and changing climate conditions cause vegetation shifts and potentially destabilize the carbon stored within the vegetation and permafrost. Disturbed permafrost-forest ecosystems can develop into a dry or swampy bush- or grasslands, shift toward broadleaf- or evergreen needleleaf-dominated forests, or recover to the pre-disturbance state. An increase in the number and intensity of fires, as well as intensified logging activities, could lead to a partial or complete ecosystem and permafrost degradation. We study the impact of forest disturbances (logging, surface, and canopy fires) on the thermal and hydrological permafrost conditions and ecosystem resilience. We use a dynamic multilayer canopy-permafrost model to simulate different scenarios at a study site in eastern Siberia. We implement expected mortality, defoliation, and ground surface changes and analyze the interplay between forest recovery and permafrost. We find that forest loss induces soil drying of up to 44%, leading to lower active layer thicknesses and abrupt or steady decline of a larch forest, depending on disturbance intensity. Only after surface fires, the most common disturbances, inducing low mortality rates, forests can recover and overpass pre-disturbance leaf area index values. We find that the trajectory of larch forests after surface fires is dependent on the precipitation conditions in the years after the disturbance. Dryer years can drastically change the direction of the larch forest development within the studied period.

Description: Upscaling plant biomass distribution and dynamics is essential for estimating carbon stocks and carbon balance. In this respect, the Russian Far East is among the least investigated sub-Arctic regions despite its known vegetation sensitivity to ongoing warming. We representatively harvested above-ground biomass (AGB; separated by dominant taxa) at 40 sampling plots in central Chukotka. We used ordination to relate field-based taxa projective cover and Landsat-derived vegetation indices. A general additive model was used to link the ordination scores to AGB. We then mapped AGB for paired Landsat-derived time slices (i.e. 2000/2001/2002 and 2016/2017), in four study regions covering a wide vegetation gradient from closed-canopy larch forests to barren alpine tundra. We provide AGB estimates and changes in AGB that were previously lacking for central Chukotka at a high spatial resolution and a detailed description of taxonomical contributions. Generally, AGB in the study region ranges from 0 to 16 kg m−2, with Cajander larch providing the highest contribution. Comparison of changes in AGB within the investigated period shows that the greatest changes (up to 1.25 kg m−2 yr−1) occurred in the northern taiga and in areas where land cover changed to larch closed-canopy forest. As well as the notable changes, increases in AGB also occur within the land-cover classes. Our estimations indicate a general increase in total AGB throughout the investigated tundra–taiga and northern taiga, whereas the tundra showed no evidence of change in AGB.

Description: The aim of the expedition CACOON Sea was to investigate the transition from fresh water to salt water and its impact on fate and quality on dissolved and particulate organic and inorganic carbon and nitrogen. This is in accordance with the main Changing Arctic Carbon cycle in the cOastal Ocean Near-shore (CACOON, https://www.changing-arctic-ocean.ac.uk/project/cacoon/) project goal to investigate the changing freshwater export and impact of terrestrial permafrost thaw into the near-shore zone of the Laptev Sea.

Description: With the CACOON project, we aim to quantify the effect of changing freshwater export and terrestrial permafrost thaw on the type and fate of river-borne organic matter (OM) delivered to Arctic coastal waters, and resultant changes on ecosystem functioning in the coastal Arctic Ocean. The CACOON ice expedition was the first step to set the observational basis for the projects combined observational, experimental and modelling approach. With the gained sample material, we will conduct laboratory experiments to parameterise the susceptibility of terrigenous carbon to abiotic and biotic transformation and losses, and then use the results from these to deliver a marine ecosystem model capable of representing the major biogeochemical cycles of carbon, nutrients and OM cycling in these regions. We will apply this model to assess how future changes to freshwater runoff and terrigenous carbon fluxes alter the biogeochemical structure and function of shelf ecosystems. Our aims for the project are the following: • generate novel seasonally-explicit datasets of OM source and transformation across the Lena River nearshore environments • identify and parameterise key abiotic and biotic processes affecting terrestrial organic matter fluxes from land-to-ocean • deliver projections of how future changes to freshwater runoff and terrestrial organic matter fluxes will alter the biogeochemical structure and function of shelf ecosystems.

Description: Background: Extreme terrestrial, analogue environments are widely used models to study the limits of life and to infer habitability of extraterrestrial settings. In contrast to Earth’s ecosystems, potential extraterrestrial biotopes are usually characterized by a lack of oxygen. Methods: In the MASE project (Mars Analogues for Space Exploration), we selected representative anoxic analogue environments (permafrost, salt-mine, acidic lake and river, sulfur springs) for the comprehensive analysis of their microbial communities. We assessed the microbiome profile of intact cells by propidium monoazide-based amplicon and shotgun metagenome sequencing, supplemented with an extensive cultivation effort. Results: The information retrieved from microbiome analyses on the intact microbial community thriving in the MASE sites, together with the isolation of 31 model microorganisms and successful binning of 15 high-quality genomes allowed us to observe principle pathways, which pinpoint specific microbial functions in the MASE sites compared to moderate environments. The microorganisms were characterized by an impressive machinery to withstand physical and chemical pressures. All levels of our analyses revealed the strong and omnipresent dependency of the microbial communities on complex organic matter. Moreover, we identified an extremotolerant cosmopolitan group of 34 poly-extremophiles thriving in all sites. Conclusions: Our results reveal the presence of a core microbiome and microbial taxonomic similarities between saline and acidic anoxic environments. Our work further emphasizes the importance of the environmental, terrestrial parameters for the functionality of a microbial community, but also reveals a high proportion of living microorganisms in extreme environments with a high adaptation potential within habitability borders.

Description: With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore cross- cutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge.The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system scientific research and provide an important foundation for advancing multiscale modeling capabilities in the Arctic.

Description: Climate change is destabilizing permafrost landscapes, affecting infrastructure, ecosystems, and human livelihoods. The rate of permafrost thaw is controlled by surface and subsurface properties and processes, all of which are potentially linked with each other. However, no standardized protocol exists for measuring permafrost thaw and related processes and properties in a linked manner. The permafrost thaw action group of the Terrestrial Multidisciplinary distributed Observatories for the Study of the Arctic Connections (T-MOSAiC) project has developed a protocol, for use by non-specialist scientists and technicians, citizen scientists, and indigenous groups, to collect standardized metadata and data on permafrost thaw. The protocol introduced here addresses the need to jointly measure permafrost thaw and the associated surface and subsurface environmental conditions. The parameters measured along transects include: snow depth, thaw depth, vegetation height, soil texture, and water level. The metadata collection includes data on timing of data collection, geographical coordinates, land surface characteristics (vegetation, ground surface, water conditions), as well as photographs. Our hope is that this openly available dataset will also be highly valuable for validation and parameterization of numerical and conceptual models, and thus to the broad community represented by the T-MOSAiC project.

Description: To explore the potential of urban settings as habitats for testate amoebae, five historical parks in Potsdam (Germany) were sampled at different sites. A total of 32 sampling sites was chosen in proximity to deciduous (Acer, Castanea, Fagus, Tilia, Platanus, Quercus) and coniferous (Fraxinus, Picea, Pinus, Tsuga) trees. Meadows and creeks were also sampled. The overall taxonomic record comprises 76 species and sub-species. High species numbers of 〉20 per sample were found in meadows and below Fagus, Tilia, and Quercus trees. The species richness per park ranges from 33 to 46 taxa. Most species belong to the eurybiontic ecological group, although litter-inhabiting and hygrophilic and hydrophilic species were also present. Common species found in more than 50% of all samples (superdominants) belong to the genera Centropyxis, Cyclopyxis, Euglypha, and Trinema. Interestingly, the rare Frenopyxis stierlitzi which inhabits tree hollows was found as a recently described species in a new genus Frenopyxis BOBROV & MAZEI 2020 in the Babelsberg Park. The studied testate amoebae are characterized by a high degree of morphological and morphometric plasticity. Therefore, the study of testate amoebae in urban settings will reveal new insights into their ecology and enhance the definition of morphometric variability for single species.

Description: Net catches of cephalopods were obtained during the cruises POS320/2 (March 2005), MSM49 (November/December 2015) and WH383 (March/April 2015) off Cabo Verde at a total of 18 stations at depths between 0 and 1000 m. Cephalopods were caught during POS320/2 with either a Isaacs-Kidd midwater trawl (IKMT) with a 6 m2 net opening, 4 mm mesh size equipped with a flowmeter, a Hydro-Bios Multinet Maxi with a 0.5 m2 net opening and 500 µm mesh size between the surface and 250 m water depth, or an 80 feet bottom trawl. Net sampling during MSM49 was conducted with two types of multiple opening/closing nets (MOCNESS) and an IKMT. The smaller MOCNESS had a net opening of 1 m2 opening (three nets with a mesh size of 2 mm and six nets with a mesh size of 335 μm) and the larger MOCNESS a net opening of 10 m2 opening (five nets, mesh size: 1.5 mm) and were deployed between the surface to 1000 m. The IKMT had a net opening of 7 m2 and ended in a cod end of 500 µm mesh size. It was deployed to a maximum depth of 500 m. During WH383 a pelagic trawl ('Aalnetz', Engel Netze, Bremerhaven, Germany) with a mouth opening of 16 x 30 m, length of 150 m including multiple opening-closing device, 260 meshes by 180 cm stretched mesh size at the front, a cod end 20 mm stretched mesh-opening and a 1.8 mm inlet sewn into last 1 m of cod end was used with a multisampler (Construction Services AS, Bergen, Norway) allowing depth-stratified sampling. During WH383 three strata (mean vertical extension of ca. 40 m) were trawled mostly during night and one time during daytime at depths between 30 and 700 m in horizontal tows for 30 minutes per stratum with a mean speed of three knots (2.8-3.3 kn). During this cruise, night trawls took place at 22:00 local time, and the day-time trawl at 12:00 local time. Onboard, cephalopods were identified morphologically to the lowest taxonomic level possible (species, genus or family), and whole specimens were preserved in formalin as voucher.

Description: Time-series data of physical oceanography and carbon/particle export were obtained from mooring HG-N-FEVI-37 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS114, and recovered during PS121. The attached archive contains raw data files of two Seabird SBE37 microcats (nominal depths: 48m, 2626m; sampling interval 1h), two AADI RCM11 current meters (nominal depths: 2448m, 2624m; sampling interval 1h) and one AADI Seaguard current meter (nominal depth: 210m; sampling interval 1h). The mooring also included two sediment traps (nominal depths: 203m, 2441m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical & biological oceanography, nutrient biogeochemistry and molecular biology were obtained from mooring HG-IV-S-3 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS114, and recovered during PS121. The attached archive contains raw data files of two Seabird SBE37 microcats (nominal depths: 26m, 52m; sampling interval 1h) and one Wetlabs ECO Triplet fluorometer (nominal depth: 24m; sampling interval 2h). The Wetlabs ECO PAR sensor (nominal depth: 24m; sampling interval 1h) was flooded and all data was lost. The mooring also included a McLane RAS water sampler (nominal depth: 24m) and a McLane PPS phytoplankton sampler (nominal depth: 26m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable. The processed data of all sensors will be made available in separate entries.

Description: Time-series data of physical & biological oceanography, nutrient biogeochemistry, molecular biology and carbon/particle export were obtained from mooring HG-EGC-5 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS114, and recovered during PS121. The attached archive contains raw data files of three Seabird SBE37 microcats (nominal depths: 72m, 241m, 508m; sampling interval 1h), three AADI RCM11 current meters (nominal depths: 79m, 248m, 511m; sampling interval 1h), one AADI Seaguard current meter (nominal depth: 987m, sampling interval 1h), one Wetlabs ECO PAR sensor (nominal depth: 72m; sampling interval 1h), one Wetlabs ECO Triplet fluorometer (nominal depth: 72m; sampling interval 2h), two Satlantics SUNA nitrate sensors (nominal depths: 72m, 241m; sampling interval 4h), one Sunburst SAMI-pCO2 sensor (nominal depth: 241m; sampling interval 1h) and two Sunburst SAMI-pH sensors (nominal depths: 72m, 241m; sampling interval 3h). One Sunburst SAMI-pCO2 sensor (72m) was flooded and all data was lost. The mooring also included two McLane RAS water samplers (nominal depths: 72m, 241m) and one sediment trap (nominal depth: 504m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical & biological oceanography, nutrient biogeochemistry and molecular biology were obtained from mooring F4-W-2 in the Fram Strait in August 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of one Seabird SBE37 microcat (nominal depths: 249m; sampling interval 1h), one Satlantics SUNA nitrate sensor (nominal depth: 249m; sampling interval 6h), one Sunburst SAMI-pCO2 sensor (nominal depth: 249m; sampling interval 2h) and one Sunburst SAMI-pH sensor (nominal depth: 249m; sampling interval 3h). The mooring also included a McLane RAS water sampler (nominal depth: 249m). The profiling SBE19plus system that was operated on the NGK winch (nominal depth: 153m) was lost. Additionally, the available data could not be downloaded from the main controller due to a corrupt SD card. Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical & biological oceanography, nutrient biogeochemistry and molecular biology were obtained from mooring HG-IV-S-4 in the Fram Strait in August 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of three Seabird SBE37 microcats (nominal depths: 18m, 23m, 47m; sampling interval 1h), two Seabird SBE56 temperature loggers (nominal depths: 28m, 38m; sampling interval 30s), one Wetlabs ECO Triplet fluorometer (nominal depth: 23m; sampling interval 2h) and one Wetlabs ECO PAR sensor (nominal depth: 23m; sampling interval 2h). One ISUS nitrate sensor (nominal depth: 23m) was flooded and no data is available. The mooring also included a McLane RAS water sampler (nominal depth: 23m) and a McLane PPS phytoplankton sampler (nominal depth: 25m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical oceanography and ocean current velocities were obtained from mooring HG-N-S-1 in the Fram Strait in September 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of five Seabird SBE37 microcats (nominal depths: 29m, 45m, 72m, 244m, 394m; sampling interval 1h), five Seabird SBE56 temperature loggers (nominal depths: 39m, 94m, 144m, 315m; sampling interval 30s), one upward-looking RDI Workhorse 300kHz ADCP (nominal depth: 44m; sampling interval 1h) and one upward-looking RDI Workhorse Longranger ADCP (nominal depth: 394m; sampling interval 1h). The top float and attached SBE37 were lost a few months after deployment. Consequently, the upper 50 m of line, including one SBE37, two SBE56s and the 300kHz ADCP fell below the second set of floats at 50 m, which makes the ADCP data basically unusable. One SBE56 (nominal depth: 194m) was also lost due to a failure of the plastic attachment. Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical oceanography, nutrient biogeochemistry, molecular biology and carbon/particle export were obtained from mooring F4-S-3 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of two Seabird SBE37 microcats (nominal depths: 16m, 21m, 47m; sampling interval 1h), one Seabird SBE56 temperature logger (nominal depth: 38m; sampling interval: 30s), one Wetlabs ECO PAR sensor (nominal depth: 21m; sampling interval 2h), one Wetlabs ECO Triplet fluorometer (nominal depth: 21m; sampling interval 2h), one Satlantics SUNA nitrate sensor (nominal depth: 21m; sampling interval 6h), one Sunburst SAMI-pCO2 sensor (nominal depth: 21m; sampling interval 2h) and one Sunburst SAMI-pH sensor (nominal depth: 21m; sampling interval 3h). The mooring also included a McLane RAS water sampler (nominal depth: 21m), a McLane PPS phytoplankton sampler (nominal depth: 23m) and two sediment traps (nominal depths: 204m, 613m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical oceanography, ocean current velocities and bio-optical seawater properties were obtained from mooring HG-IV-SWIPS-2019 (alternative name: HG-IV-W-4) in the Fram Strait in August 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of an integrated profiling SBE52plus system (nominal depth: 125m) and a single AADI Seaguard current meter (nominal depth: 154m; sampling interval: 1h). Due to technical issues with the SWIPS winch, the associated sensors only delivered useful profiling data during the first 2 months, albeit at a higher frequency than originally planned. Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical oceanography, ocean current velocities and hydroacoustics were obtained from mooring F4-19 in the Fram Strait in August 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of 7 Seabird SBE37 microcats (nominal depths: 76m, 153m, 253m, 402m, 502m,731m, 1204m; sampling interval 1h), four Seabird SBE56 temperature loggers (nominal depths: 53m, 102m, 203m, 323m; sampling interval 30s), one upward-looking RDI Workhorse 300kHz ADCP (nominal depth: 53m; sampling interval 1h), one upward-looking RDI Workhorse Longranger ADCP (depth: 382m; sampling interval 1h) and two Nortek Aquadopp current meters (nominal depths: 730m, 1205m; sampling interval 20min). The 300 kHz ADCP stopped recording after 3 months due to a battery failure. The mooring also included an ASL Acoustic Zooplankton Fish Profiler (nominal depth: 103m; data archived elsewhere) and a Develogic Sonovault (nominal depth: 800m; data archived elsewhere). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical oceanography, ocean current velocities and carbon/particle export were obtained from mooring HG-N-FEVI-39 in the Fram Strait in September 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of two Seabird SBE37 microcats (nominal depths: 57m, 2646m; sampling interval 1h), two AADI RCM11 current meters (nominal depths: 2468m, 2644m; sampling interval 1h/2h) and one AADI Seaguard current meter (nominal depth: 230m; sampling interval 1h). The mooring also included two sediment traps (nominal depths: 223m, 2461m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical oceanography, ocean current velocities and carbon/particle export were obtained from mooring HG-IV-FEVI-40 in the Fram Strait in August 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of five Seabird SBE37 microcats (nominal depths: 79m, 257m, 404m, 1204m, 2530m; sampling interval 1h), four Seabird SBE56 temperature loggers (nominal depths: 104m, 154m, 204m, 329m; sampling interval 30s), one Nortek Aquadopp current meter (nominal depth: 754m; sampling interval 20 min), one RDI Longranger ADCP (nominal depth: 413m; sampling interval 1h) and four AADI Seaguard current meters (nominal depths: 207m, 1234m, 2352m, 2528m; sampling interval 1h). The mooring also included three sediment traps (nominal depths: 200m, 1227m, 2345m) and one BioOptical Platform (nominal depth: 569m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical & biological oceanography, ocean current velocities, nutrient biogeochemistry, molecular biology and carbon/particle export were obtained from mooring HG-EGC-6 in the Fram Strait in August 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of three Seabird SBE37 microcats (nominal depths: 67m, 236m, 453m; sampling interval 1h), three AADI RCM11 current meters (nominal depths: 74m, 243m, 456m; sampling interval 1h), one AADI Seaguard current meter (nominal depth: 981m, sampling interval 1h), one Wetlabs ECO PAR sensor (nominal depth: 67m; sampling interval 2h), one Wetlabs ECO Triplet fluorometer (nominal depth: 67m; sampling interval 2h), two Satlantic SUNA nitrate sensors (nominal depths: 67m, 236m; sampling interval 6h), two Sunburst SAMI-pCO2 sensors (nominal depths: 67m, 236m; sampling interval 2h) and two Sunburst SAMI-pH sensors (nominal depths: 67m, 236m; sampling interval 3h). The mooring also included two McLane RAS water samplers (nominal depths: 67m, 236m) and two sediment traps (nominal depths: 449m, 522m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: This dataset contains gas concentrations (CH4, CO2) in high spatial resolution from surface waters in September 2021 in a lake in the Mackenzie Delta ("Swiss Cheese Lake"). We measured surface water gas concentrations from small boats using a Microportable Greenhouse Gas Analyzer connected to a Dissolved Gas Extraction Unit (Los Gatos Research). The measurements were part of the "Mackenzie Delta Permafrost Field Campaign" (mCan2021) within the "Modular Observation solutions for Earth Systems" (MOSES) program.

Description: This dataset contains gas concentrations (CH4, CO2) in high spatial resolution from surface waters in September 2021 in a lake in the Mackenzie Delta ("Lake 3"). We measured surface water gas concentrations from small boats using a Microportable Greenhouse Gas Analyzer connected to a Dissolved Gas Extraction Unit (Los Gatos Research). The measurements were part of the "Mackenzie Delta Permafrost Field Campaign" (mCan2021) within the "Modular Observation solutions for Earth Systems" (MOSES) program.

Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset describes the environmental conditions for 64 tundra and glacier sites (〉=60°N latitude) across the Arctic, for which in situ measurements of surface energy budget components were harmonized (see Oehri et al. 2022). These environmental conditions are (proxies of) potential drivers of SEB-components and could therefore be called SEB-drivers. The associated environmental conditions, include the vegetation types graminoid tundra, prostrate dwarf-shrub tundra, erect-shrub tundra, wetland complexes, barren complexes (≤ 40% horizontal plant cover), boreal peat bogs and glacier. These land surface types (apart from boreal peat bogs) correspond to the main classification units of the Circumpolar Arctic Vegetation Map (CAVM, Raynolds et al. 2019). For each site, additional climatic and biophysical variables are available, including cloud cover, snow cover duration, permafrost characteristics, climatic conditions and topographic conditions.

Description: At the end of the two year incubation of a subantarctic E. huxleyi culture (2015-11-20 to 2017-12-01), a temperature response experiment was performed using the Now (Day 747) and Future (Day 725) populations. Now and Future populations were grown in triplicate 28 ml Nalgene Oak Ridge-style centrifuge tubes (Sigma) in Now or Future medium, respectively. The tubes were held in an aluminium temperature gradient block similar to Thomas et al. (1963), that was heated at one end and cooled at the other using water maintained at constant temperature by refrigerated circulators (Julabo GmbH). The temperature regime resulted in a range of 10 temperatures along the length of the block from 6.2°C at one end to 16.5°C at the other, with a range within replicates at each temperature of 0.1 – 0.2°C. The block was lit from below which achieved a light level of 62 +/- 7 μmol m⁻² s⁻¹ at the bottom of the tubes in a 12 hour: 12 hour light: dark cycle. To ensure uniform light each replicate was manually rotated through the row holes at the set temperature during the incubation period. Measurements of in vivo chl-a were made daily and growth rates calculated from the least squares regression of the natural logarithm of in vivo fluorescence, versus time.

Description: Time-series data of physical oceanography and ocean current velocities were obtained from mooring SCO1-1 in the Fram Strait from Aug 2018 to Aug 2022. The mooring was deployed during RV MARIA S. MERIAN expedition MSM76 and recovered during RV POLARSTERN expedition PS131. The attached archive contains raw data files of four Seabird SBE16 SeaCATs (nominal depths: 410m, 472m, 538m, 609m; sampling interval 1h), three SBE56 temperature logger (nominal depths: 442m, 502m, 630m; sampling interval 20s) and two AADI RCM11 current meter (nominal depths: 411m, 610m; sampling interval 2h). Auxiliary information such as sensor calibration sheets, mooring diagrams, and schedule files are also provided, if applicable. The data of one SBE16 (472m) could not be obtained because the instrument did not connect.

Description: Time-series data of physical & biological oceanography, ocean current velocities, nutrient biogeochemistry, molecular biology and carbon/particle export were obtained from mooring HG-EGC-7 in the Fram Strait from June 2021 to July 2022 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS126 and recovered during PS131. The attached archive contains raw data files of three Seabird SBE37 MicroCATs (nominal depths: 38m, 232m, 484m; sampling interval 1h), three AADI RCM11 current meters (nominal depths: 45m, 239m, 487m; sampling interval 1h), one AADI Seaguard current meter (nominal depth: 993m, sampling interval 1h), one Wetlabs ECO PAR sensor (nominal depth: 38m; sampling interval 1h), one Wetlabs ECO Triplet fluorometer (nominal depth: 38m; sampling interval 2h), two Satlantics SUNA nitrate sensors (nominal depths: 38m, 232m; sampling interval 4h), two Sunburst SAMI-pCO2 sensors (nominal depths: 38m, 232m; sampling interval 1h) and two Sunburst SAMI-pH sensors (nominal depths: 38m, 232m; sampling interval 3h). The mooring also included two McLane RAS water samplers (nominal depths: 38m, 232m; data archived elsewhere), one sediment trap (nominal depth: 480m; data archived elsewhere), and four PE samplers (nominal depths: 51m, 239m, 482m, 893m; data archived elsewhere). Auxiliary information such as sensor calibration sheets, mooring diagrams, and schedule files are also provided, if applicable. The pH sensor at 38 m, the ECO Triplet at 38 m and the SUNA at 232m had issues and did not record any valid data.

Description: Time-series data of physical oceanography, ocean current velocities and ocean acoustics were obtained from mooring F4-20 in the Fram Strait from June 2021 to July 2022 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS126 and recovered during PS131. The attached archive contains raw data files of seven Seabird SBE37 MicroCATs (nominal depths: 76m, 153m, 253m, 402m, 502m, 727m, 1204m; sampling interval 15m/1h), four Seabird SBE56 temperature loggers (nominal depths: 53m, 103m, 203m, 323m; sampling interval 60s), one RDI Workhorse 300kHz ADCP (nominal depth: 53m; sampling interval 60s), one RDI Longranger ADCP (nominal depth: 382m; sampling interval 1h) and two AADI RCM11 current meter (nominal depths: 726m, 1205m; sampling interval 1h). The mooring also included an ASL Acoustic Zooplankton Fish Profiler (nominal depth: 103m, data archived elsewhere) and a Develogic Sonovault (nominal depth: 805m, data archived elsewhere). Auxiliary information such as sensor calibration sheets, mooring diagrams, and schedule files are also provided, if applicable. The SBE37 at 253m had power issues and stopped recording after ~5 months.

Description: Time-series data of physical oceanography and ocean current velocities were obtained from mooring SCO3-1 in the Fram Strait from Aug 2018 to Aug 2022. The mooring was deployed during RV MARIA S. MERIAN expedition MSM76 and recovered during RV POLARSTERN expedition PS131. The attached archive contains raw data files of two Seabird SBE16 SeaCATs (nominal depths: 246m, 405m; sampling interval 1h), one SBE37 MicroCAT (nominal depths: 296m; sampling interval 10m), two SBE56 temperature logger (nominal depths: 326m, 366m; sampling interval 20s) and one RDI Longranger ADCP (nominal depth: 404m; sampling interval 2h). Auxiliary information such as sensor calibration sheets, mooring diagrams, and schedule files are also provided, if applicable. One SBE56 (366m), the ADCP (404m) and one SBE16 (405m) were lost during recovery.

Description: Time-series data of physical oceanography and ocean current velocities were obtained from mooring F2-20 in the Fram Strait from July 2020 to July 2022 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV MARIA S. MERIAN expedition MSM93 and recovered during RV POLARSTERN expedition PS131. The attached archive contains raw data files of three Seabird SBE37 MicroCATs (nominal depths: 17m, 251m, 777m; sampling interval 30m/1h), 10 Seabird SBE56 temperature loggers (nominal depths: 17m, 32m, 52m, 95m, 145m, 200m, 301m, 351m, 402m, 453m; sampling interval 60s), one RDI Longranger ADCP (nominal depth: 401m; sampling interval 2h) and one Nortek Aquadopp current meter (nominal depth: 726m; sampling interval 1h). Auxiliary information such as sensor calibration sheets, mooring diagrams, and schedule files are also provided, if applicable. The SBE56 at 402m was lost. The SBE37 at 251m had power issues and stopped recording after 2 months.

Description: Time-series data of ocean current velocities and carbon/particle export were obtained from mooring F4-W-3 in the Fram Strait from June 2021 to July 2022 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS126, and recovered during PS131. The attached archive contains raw data files of one AADI RCM11 current meter (nominal depth: 143m; sampling interval 1h) and a profiling underwater winch (nominal depth: 114m). The mooring also included one BioOptical Platform (nominal depth: 420m; data archived elsewhere). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable. The winch had issues and did not record valid data, but the available files are included here for completeness.

Description: Time-series data of ocean acoustics were obtained from mooring F4-OZA-2 in the Fram Strait from July 2020 to July 2022 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV MARIA S. MERIAN expedition MSM93 and recovered during RV POLARSTERN expedition PS131. The mooring included an ASL Acoustic Zooplankton Fish Profiler (nominal depth: 167m; data archived elsewhere), an MTE Aural M2 underwater recorder (nominal depth: 300m; data archived elsewhere) and a Develogic Sonovault (nominal depth: 836m; data archived elsewhere). The attached .zip file only contains the mooring diagrams and folder structure.

Description: A total of 556 samples (3 cm average sample spacing) were collected from the 12 m long Winsenberg section in order to reconstruct a floating timescale using cyclostratigraphic methods and to investigate paleoclimatic dynamics using selected elemental ratios. Samples were measured as a powder covered with Chemplex film on a Bruker S1 Titan 800 portable XRF at the University of Münster with the following settings: 40 kV, 20 mA, no filters, 75 s. Spectra were deconvoluted in Bruker Artrax software, and linearly calibrated using a set of 10 sedimentary standards of known composition and 11 calcite-quart mixtures. The composition of these standards is also included. Selected elemental ratios were tuned via the methods described in the accompanying manuscript, and are included in this dataset as well.

Description: Time-series data of physical & biological oceanography, nutrient biogeochemistry and molecular biology were obtained from mooring F4-W-1 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS114, and recovered during PS121. The attached archive contains raw data files of a profiling SBE19plus system on an NGK winch (nominal depth: 153m), two Seabird SBE37 microcats (nominal depths: 157m, 252m; sampling interval 1h), one Satlantics SUNA nitrate sensor (nominal depth: 252m; sampling interval 4h), one Sunburst SAMI-pCO2 sensor (nominal depth: 252m; sampling interval 1h) and one Sunburst SAMI-pH sensor (nominal depth: 252m; sampling interval 3h). The mooring also included a McLane RAS water sampler (nominal depth: 252m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: On five occasions during the two year incubation of a subantarctic E. huxleyi culture (2015-11-20 to 2017-12-01), triplicate cultures of Now (11°C and pH 8.1) and Future (14°C and pH 7.8) cells, and also the crossover experiments - Future cells inoculated into Now medium and incubated under Now conditions (Future in Now), and Now cells incubated in Future medium under Future conditions (Now in Future) were prepared. Growth rates of each culture were monitored by measuring the in vivo chl-a of subsamples daily with a Turner 10AU fluorometer and calculating the least squares regression of the natural logarithm of in vivo fluorescence, versus time during exponential growth.

Description: Emiliania huxleyi was incubated for two years (2015-11-20 to 2017-12-01) under two conditions: present-day subantarctic water during summer (11°C and pH 8.1; Now), and projected conditions for subantarctic water by 2100 (14°C and pH 7.8; Future; Law et al. 2018). The pH was reduced by 0.3 units by bubbling 10% CO₂ through the medium prior to the addition of coccolithophore cells and confirmed using a spectrophotometric method (DOE 1994). One culture of each treatment was maintained in a semi-batch style to ensure the cells remained in exponential growth, with cell concentration maintained at low levels (〈80000 cells ml⁻¹) to maintain pH at the target value. The pH of the medium after cell growth was checked periodically using a spectrophotometric method (DOE 1994) and was always found to be at the target pH. The in vivo fluorescence of the cultures was measured with a Turner 10-AU fluorometer and the growth rate of the cultures was calculated from the least squares regression of the natural logarithm of in vivo fluorescence, versus time during exponential growth (Strzepek et al. 2011).

Description: In situ measurements were undertaken during two non-upwelling periods (15 days in June 2012 and 7 days in May-June 2013) at a water depth of 1.5 m. pH, pCO2 and seawater temperature were measured with two Submersible Autonomous Moored Instruments (SAMI-pH and SAMI-CO2, deployed at the pier of Marina Papagayo (10.64154,-85.65571). Discrete water samples were used to validate the sensors, and salinity values were obtained from discrete water samples and used for correction of pH values. Wind speed data was obtained from a station of the Instituto Metereológico Nacional (National Metereological Institute of Costa Rica) located at the nearby Liberia airport. Tidal data was provided by Módulo de Información Oceanográfica of the University of Costa Rica.

Description: To quantify chronic stress levels in milkfish cultured within a typical commercial mariculture setting, we measured ontogenetic (OG) scale cortisol of milkfish sampled from four cage systems (F1-F4) with different geographic locations and management strategies. Sampling stations were located within a mariculture area (approx. 2.2 x 0.6 km) of the Guiguiwanen Channel, Bolinao (Philippines). Each station was sampled twice (time point I and II) with an intermediate time interval of 15 days. According to Aerts et al. (2015), ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) was used to analyze OG scale cortisol. Additional to the stress-physiological data, environmental parameters (oxygen concentration, salinity) were recorded, and the gut content of the fish and the fish feed were analyzed for their carbon (C) and nitrogen (N) content, CN stable isotope signatures, presence of antibiotics (LC-MS/MS), organic matter (pyrolysis-GCMS, MetaboLights accession MTBLS1438), microbial community composition (16S amplicon sequencing, PRJEB33594, OTU table available here), and abundance of the virulence factor gene thermolabile hemolysin of Vibrio sp. (qPCR, primers: tlh-G-vibrio-0515-a-S-22: 5'-GCTGGTTCTTRGGDCAYTTCTC-3', tlh-G-vibrio-0750-a-A-22: 5'-TGGAACGCYACGGTTRTAGTTC-3'). Furthermore, the sampling took place as part of a larger sampling campaign within the ACUTE project (AquaCUlture practice in Tropical coastal Ecosystems: Understanding ecological and socio-economic consequences; funding: Leibniz SAW-2015-ZMT-4), during which also sediment microbial communities and environmental parameters were surveyed (sediment: doi: 10.1093/femsec/fiz006, SRA accession: SRP155505, doi:10.1594/PANGAEA.900758).

Description: This study was undertaken as part of a collaborative project titled Biotechnological Applications of Marine Biofilms developing on solid surfaces in the Arabian Gulf funded by research grant (SQU-GCC/CL/17/02). The succession of marine biofouling communities (mature biofilms) on plastic panels were investigated over a period of six months in four locations in the Arabian Gulf (Fintas and Salmiya marinas in Kuwait, and Bandar Rowdha and Al Mouj marinas in Oman). Monthly assessment of the physico-chemical parameters of the seawater at each location was done using portable meters (thermometer, refractometer, pH meter, turbidity meter and conductivity/TDS meter). The concentrations of nutrients and elements were analysed using ion chromatography (IC) and inductively coupled plasma optical emission spectrometry (ICP-OES), respectively. After each month, the developed biofilm on each panel was quantitatively and qualitatively analyzed as follows; total wet weight, abundance of bacteria using epifluorescence microscopy, chlorophyll a concentrations using spectrophotometry, percent coverage of macrofoulers, and presence or absence of signs of grazing based on visual observations and/or photodocumentation (using Image J software), which was also used to assess the presence/absence and dominance of macrofouling species. Additionally, the composition of the microbial community was investigated using 16S amplicon sequencing, resulting in supplementary data sets for bacterial community composition, predicted bacterial metabolic pathways (Bowman and Ducklow 2015, doi:10.1371/journal.pone.0135868), and presence/absence of microalgae based on their chloroplast 16S.

Description: The development of a mature biofouling community on solid surfaces in the marine environment primarily involves the availability of colonizing bacterial communities and their ability to persist over time in any given environment. This study was undertaken as part of a collaborative project titled Biotechnological Applications of Marine Biofilms developing on solid surfaces in the Arabian Gulf funded by research grant (SQU-GCC/CL/17/02). The succession of marine biofouling communities (mature biofilms) on plastic panels were investigated over a period of six months in four locations in the Arabian Gulf (Fintas and Salmiya marinas in Kuwait, and Bandar Rowdha and Al Mouj marinas in Oman). Monthly assessment of the physico-chemical parameters of the seawater at each location was done using portable meters (thermometer, refractometer, pH meter, turbidity meter and conductivity/TDS meter). The concentrations of nutrients and elements were analysed using ion chromatography (IC) and inductively coupled plasma optical emission spectrometry (ICP-OES), respectively.

Description: The Universität Hamburg is part of the environmental studies in the INDEX (Indian Ocean Exploration) program, which was established by the BGR (Federal Institute for Geosciences and Natural Resources), Hanover. The INDEX license area is located in the oligotrophic subtropical gyre of the South Indian Ocean. Sinking particulate matter samples were collected by sediment trap mooring 01-01 to measure vertical particle flux quantitatively and qualitatively. Mooring 01-01 was deployed during cruise MSM59-2 (RV Maria S. Merian) and recovered during cruise SO259 (RV Sonne).

Description: Double oblique zooplankton net tows from 200 m water depth to the sea-surface were carried out using a 0.7 m diameter Bongo frame with paired 200 µm mesh nets, a General Oceanics Flow meter affixed to each net to measure the volume of water filtered, and a temperature-depth recorder. Tows were conducted at least twice daily (day and night), with one additional day per cycle of sampling every 2-3 hours for further studies of diel patterns. A quantitative subset of salp specimens were identified to species using keys (Foxton 1965, doi:10.1017/S0025315400016519; Bone 1998), classified into oozooid or blastozooid stage, and measured for total length and corrected to oral to atrial (OAL). For plots and calculations, Salpa thompsoni lengths were divided into 5 mm bins, and abundance was calculated for each size bin.

Description: This dataset provides abundance data for macrofaunal taxa determined from sediment samples collected in the Weddell Sea (mostly South-Eastern). A minimum of three samples (cores) were collected at each station with a MUC10 multicorer or a giant box corer during PS96. Sediment cores were sliced into depth layers (stations 017, 026, 061, 072: 0–2cm, 2–5cm, 5– bottom; stations 001, 037, 048: 0–1cm, 1–2cm, 2–3cm, 3–4cm, 4–5cm, 5– bottom) and preserved in 4%-borax-buffered formaldehyde solution prior to sieving (sieve size 500 µm, 1000 µm) and counting (detailed methods in Säring et al. submitted). Abundance is presented per depth layer (note different slice volume) as ind./m². Data from different size fractions are available upon request. Macrofauna communities included individuals from 18 higher taxa. The macrofauna abundance data are part of a larger ecological study on meio- and macrofauna communities and their relation to environmental conditions and remineralisation at the sediment-water interface (see Related to below). For the larger study, sediment cores from which macrofauna abundance data are deposited here were also used for microcosm incubations: Untreated incubations (Benthic ecosystem Function Experiments BEFEx), and incubations with and without microalgae addition (Algae Feeding Experiment AFEx). Cores from BEFEx and AFEx without algae are labeled with NT (not treated), cores from AFEx with algae are labeled as T (treated).

Description: This dataset contains abiotic and biotic data from sediment samples from nine sites in the Weddell Sea (mostly South-Eastern). Data are provided for sediment pigments (chlorophyll a and phaeopigment content through fluorometry), total organic carbon (TOC), total nitrogen (TN), stable isotope values of carbon and nitrogen (δ13C, δ15N) and grain size (silt&clay 〈 32 µm, very fine sand 63–125 µm sand, fine sand 125–250 µm, medium sand 250–500 µm, coarse sand 500–1000 µm, larger coarse sand 〉 1000 µm). Before the TOC and carbon isotope analysis the sediment samples were acidified to eliminate inorganic carbon. A minimum of three replicate samples (cores) were collected using a MUC10 multicorer or giant box corer. Sediment cores were subsampled with a 60-ml syringe (inner diameter 2.7 cm) for stations 017, 026, 061, 072, and with a 10-ml syringe (inner diameter 1 cm) for stations 001, 037, 048, 104, 115. Subsamples were sliced in 1-cm steps down to 5 cm depth. Detailed methods are described in Säring et al. (submitted) except for stable isotopes: Flash combustion in a Flash 2000 (Thermo) elemental analyser to a Delta V advantage (Thermo) isotope ratio masspectrometer. δ values are reported relative to atmospheric N2 (δ15N) and Vienna PeeDee Belemnite (δ13C). Reference materials for stable isotope analysis: IAEA-N1, IAEA-N2, IAEA-N3, NBS 22, IAEA-CH-3 and IAEA-CH-6; calibration material: Acetanilide (Merck). The analytical precision for both stable isotope ratios was 〈±0.2‰. Cores with the label -e (Environment) were only used to collect the above data. Environmental and fauna data were collected from cores with the label -i (Incubation). This data table is part of a larger study analysing the role of environmental parameters for meio- and macrofaunal community composition (see Related to below).

Description: Around the Antarctic Peninsula (North-Western Weddell Sea, Bransfield Strait, Drake Passage) water samples for measurements of chlorophyll-a were collected with Niskin bottles mounted on a CTD rosette. At each station samples were taken at two depths, the chlorophyll-a maximum (Cmax, defined as the water depth with maximum fluorescence detected during in-situ profiles) and close to the seafloor (bottom). Water samples were poured over a 100-µm sieve to remove larger particles and filtered over glass fibre filters GF/C at approximately 250 mbar. Colouring of filters determined the amount of sea water used (3–5l). Filters were stored at −80°C. Chloroplastic pigments were extracted with 10ml acetone (90%), determined using a fluorimeter and expressed in µg/l. For details see Hauquier et al. (2015) and Veit-Köhler et al. (2018).

Description: We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. Dissolved inorganic nitrogen and phosphate in pore water were collected as an indicator of eutrophication. We took one sediment pore water sample per transect from each site/sampling event using 30 cm PVC cores. The cores were pushed into the sediments, and after extraction an Eijkelkamp rhizon connected to a 20 ml syringe was placed in a hole corresponding to a depth of 5 cm below the sediment surface. Making vacuum with the syringe, the water was pulled out of the sediment cores. These samples were immediately filtered (0.45 µm pore size, Whatman GF/F filters) in pre-rinsed polyethylene bottles, frozen (−20°C) and transported to the Leibniz Centre for Tropical Marine Research. Analysis was performed using a continuous flow injection analyzing system (Skalar SAN++-System). The measuring procedure had a relative standard deviation 〈 3.5% with reference to the linear regression of an equidistant 10-point calibration line from NIST standards. Final concentrations are given in micromolar.

Description: We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. δ15N was collected as an indicator of eutrophication. We took one 50ml surface sediment sample per transect for delta 15 nitrogen analysis. The samples were stored at −20°C and transported frozen to the Leibniz Centre or Tropical Marine Research. They were then dried at 50°C in a forced air oven until constant DW, ground to a fine powder with mortar and pestle, and weighed into tin capsules prior to analysis for nitrogen stable isotope composition (δ15N ) with a gas isotope ratio mass spectrometer (Thermo Finnigan Delta Plus). Results are expressed in delta notation (‰) where the standard for delta 15 nitrogen is atmospheric nitrogen.

Description: We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. Macroalgae biomass was collected as an indicator of eutrophication. Macroalgae biomass was quantified along five 50-m transects per site/sampling event, set perpendicular to the coast and parallel to each other, separated by ~50 meters. We collected the macroalgae present in three random 0.25x0.25 meters quadrats per transect. The macroalgae samples were cleaned of sediments and rinsed with water. They were then dried at 50°C in a forced air oven until constant dry weight. The macroalgae biomass was calculated as the grams of dry weight divided by the area of the quadrat (grams of dry weight per square meter).

Description: We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. Seagrass cover was quantified along five 50-m transects per site/sampling event, set perpendicular to the coast and parallel to each other, separated by ~50 meters. Seagrass cover was quantified as the percent area occupied per species within seagrass plots of 0.5 x 0.5 m marked by PVC quadrats, randomly placed along each transect (n = 9 per transect, 45 per site/sampling event).

Description: We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. We considered nine traits reportedly correlated to light and inorganic nutrients preemption, namely, leaf maximum length (cm), leaf maximum width (cm), vertical rhizome length (cm), leaves per shoot, rhizome diameter (cm), roots per meter, root maximum length (cm), leaf mass area (grams per square centimeter), and shoots per meter. To quantify the seagrass traits at each site/sampling event, we defined four zones of ~2500 m2 per site/sampling event, within which we sampled five ramets (defined as a train of at least two shoots) per species, amounting to a total of approximately 20 ramets per species and site/sampling event. The ramets were transported frozen at -4°C to the Leibniz Centre for Tropical Marine Research for trait measuring. We measured rhizome diameter and root maximum length with a ruler to the nearest millimeter. Number of shoots and number of roots were visually counted, and divided by the length of the ramet.

Description: We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. We considered nine traits reportedly correlated to light and inorganic nutrients preemption, namely, leaf maximum length (cm), leaf maximum width (cm), vertical rhizome length (cm), leaves per shoot, rhizome diameter (cm), roots per meter, root maximum length (cm), leaf mass area (grams per square centimeter), and shoots per meter. To quantify the seagrass traits at each site/sampling event, we defined four zones of ~2500 m2 per site/sampling event, within which we sampled five ramets (defined as a train of at least two shoots) per species, amounting to a total of approximately 20 ramets per species and site/sampling event. The ramets were transported frozen at -4°C to the Leibniz Centre for Tropical Marine Research for trait measuring. We measured leaf maximum length, leaf maximum width and vertical rhizome length with a ruler to the nearest millimeter. Leaves per shoot were visually counted.

Description: We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. Chlorophyll a in the water column was collected as an indicator of eutrophication. In the proximities of each transect, we collected five ~3-liter seawater samples from each site/sampling event and kept them in a cooler box until filtration. Seawater was immediately filtered upon arrival in the Institute of Marine Sciences (IMS, Stone Town, Zanzibar) under constant pressure onto pre-combusted (5 h, 450°C) and pre-weighed Whatman GF/F filters (0.45 µm pore size). The filters were stored at −20°C and transported frozen to the Leibniz Centre for Tropical Marine Research in Bremen (Germany). Chlorophyll-a was extracted from the filters in 8 ml of 96% ethanol in glass vials heated for 5 min at 80°C, covered with aluminum foil, and placed in a rotor at room temperature for approximately 24 h. Extracts were subsequently centrifuged at 5000 rpm for 20 min. Chlorophyll-a samples were determined in a photometer Shimadzu UV-1700, and calculated as micrograms per liter.

Description: We sampled the archaeological and modern-day snapper otoliths used for this analysis from sites in the Hauraki Gulf, on the east coast of the North Island of New Zealand. Long Bay (AL) samples were radiocarbon dated using Bayesian modelling to between 1430-1485 AD, while the Omaha (AO) samples were dated to between 1530-1640 AD (Campbell et al. 2004, 2019). For comparison we acquired modern samples from as close as possible to the archaeological middens. Kawau Island (MO, 2016 AD) served as the modern comparison to the Omaha midden and outside of the current Long Bay marine reserve (ML, 2020 AD) provided samples to compare with the Long Bay midden. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis was conducted to measure Barium (138Ba) and Strontium (88Sr) compositions along an ablation path though the core to the proximal tip of each otolith. For each of the four sites, ten sagittal otoliths were transverse-sectioned and then mounted on a geological slide for laser ablation. Instrumentation was an Applied Spectroscopy RESOlution M-50 laser ablation system powered by a Coherent 193 nm ArF excimer laser and an Agilent 7900 quadrupole ICP-MS, located in the Centre for Trace Element Analysis in the Department of Chemistry, University of Otago (Dunedin, New Zealand). Slides with mounted otoliths were placed in an ablation cell in an atmosphere of pure helium to minimize any possibilities of experiencing re-condensation of ablated materials and elemental fractionations (Eggins et al. 1998). The video imaging system had suitable magnification to identify the core and was used for mapping transect pathways. Prior to obtaining measurements the 75 µm diameter transects were pre-ablated from core to the edge of the otolith to remove surface contaminants. The spot size employed for the transects was selected as a compromise between spatial sensitivity and detection power of the overall system (Taddese et al. 2019). The ablation with a laser firing frequency of 10 Hz and an on-sample fluence of 2.5 J/cm2 was operated along the pre-ablated transects with the sample stage moving at 10 µm/s, for determining elemental concentrations in correspondence to life cycle of the fish. The ICP-MS instrument was tuned to minimize oxide formation, double charge formation and mass fractionation. Signal intensities of Ba and Sr were maximized after carrying out gas tuning processes on software-controlled gas flows of He and N2 along with ICP-MS controlled Ar. Standards were run regularly with NIST610, NIST 612 and MACS3 used for instrument calibration, verification and matrix matched quality control respectively. Data reduction of the raw count data to molar ratios (element of interest/Ca) was conducted using Iolite 3.63 (School of Earth Sciences, University of Melbourne) which subtracts gas backgrounds and corrects for any drift in instrument response (Paton et al. 2011). Accuracy and precision of the analyses were assessed using NIST 612 and the MACS-3 otolith reference material (United States Geological Survey - USGS). For the glass control precision was excellent RSD 〈3% and the accuracy was within ± 5% for all elements. For the otolith reference material precision was better than 5% with recoveries percentages of 97% and 96% for Sr and Ba, respectively.

Description: Seismic reflection data collected on the Amundsen Sea shelf during cruise PS104 with RV Polarstern in 2017. 2 GI-guns were used a seismic source, the data were recorded with a 600 m (active length) long streamer. The data are fully processed to time migration. No gain, filter or mute have been applied. The data are in SEGY format. See cruise report of PS104 or 20170013_segy_info.txt file for more information on acquisition and processing parameters.

Description: Seismic reflection data collected on the Amundsen Sea shelf during cruise PS104 with RV Polarstern in 2017. 2 GI-guns were used a seismic source, the data were recorded with a 600 m (active length) long streamer. The data are fully processed to time migration. No gain, filter or mute have been applied. The data are in SEGY format. See cruise report of PS104 or 20170014_segy_info.txt file for more information on acquisition and processing parameters.

Description: Time series data of physical oceanography (seawater conductivity, temperature, pressure, salinity), ocean current velocities and hydroacoustics were obtained from mooring F4-18 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during Polarstern expedition PS114, and recovered during PS121. The attached archive contains raw data files of 6 Seabird SBE37 microcats (nominal depths: 63m, 150m, 250m, 500m, 731m, 1202m; sampling interval 1h), one RDI Workhorse Longranger ADCP (depth: 380m; sampling interval: 1h) and two AADI RCM11 current meters (depths: 730m, 1208m; sampling interval: 2h). The mooring also included a Develogic Sonovault (nominal depth: 800m; data archived elsewhere). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time-series data of physical oceanography, nutrient biogeochemistry, molecular biology, and carbon/particle export were obtained from mooring F4-S-3 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS114, and recovered during PS121. The attached archive contains raw data files of two Seabird SBE37 microcats (nominal depths: 23m, 50m; sampling interval 1h), one Wetlabs ECO PAR sensor (nominal depth: 23m; sampling interval 1h), one Wetlabs ECO Triplet fluorometer (nominal depth: 23m; sampling interval 2h), one Satlantic SUNA nitrate sensor (nominal depth: 23m; sampling interval 4h), one Sunburst SAMI-pCO2 sensor (nominal depth: 23m; sampling interval 1h) and one Sunburst SAMI-pH sensor (nominal depth: 23m; sampling interval 3h). The mooring also included a McLane RAS water sampler (nominal depth: 23m), a McLane PPS phytoplankton sampler (nominal depth: 25m) and two sediment traps (nominal depths: 204m, 613m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time series data of physical oceanography (seawater conductivity, temperature, pressure, salinity) and ocean current velocities were obtained from mooring F1-17 in the Fram Strait in September 2018 - July 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV MARIA S. MERIAN expedition MSM76 and recovered during MSM93. The attached archive contains raw data files of one Seabird SBE37 microcat (nominal depth: 345m; sampling interval 20 min) and one RDI Quartermaster ADCP (nominal depth: 345m; sampling interval 1h). Although the mooring was recovered in July 2020, data is only available until July 2019 due to instrument power failures. The records show also evidence that the mooring was moved at the end of November 2018, most likely by a bottom trawler. Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time series data of physical oceanography (seawater conductivity, temperature, pressure, salinity), ocean current velocities, hydroacoustics and multi-frequency acoustic backscatter were obtained from mooring F5-18 in the Fram Strait in September 2018 - July 2020 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV MARIA S. MERIAN expedition MSM76 and recovered during MSM93. The attached archive contains raw data files of three Seabird SBE37 microcats (nominal depths: 46m, 247m, 731m; sampling interval 20 min), one RDI 600kHz ADCP (nominal depth: 34m; sampling interval 30min), one RDI Longranger ADCP (nominal depth: 403m; sampling interval 1h) and one AADI RCM11 current meter (nominal depth: 730m; sampling interval 2h). The 600kHz ADCP wasn't aligned correctly in the water column due to issues with the attached flotations. Therefore, the data is likely not usable. The mooring also included one ASL Acoustic Zooplankton Fish Profiler (nominal depth: 135m; data archived elsewhere) and one Develogic Sonovault (nominal depth: 790m; data also archived elsewhere). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time series data of physical oceanography (seawater conductivity, temperature, pressure, salinity) and ocean current velocities were obtained from mooring F3-18 in the Fram Strait in September 2018 - July 2020 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV MARIA S. MERIAN expedition MSM76 and recovered during MSM93. The attached archive contains raw data files of four Seabird SBE37 microcats (nominal depths: 54m, 200m, 250m, 760m; sampling interval 20 min), one RDI Longranger ADCP (nominal depth: 400m; sampling interval 1h) and two AADI RCM11 current meters (nominal depths: 759m, 1067m; sampling interval 2h). The ADCP suffered from a compass calibration issue. Both RCMs only measured for one year due to early power failures. Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: Time series data of hydroacoustics and multi-frequency acoustic backscatter were obtained from mooring F4-OZA in the Fram Strait in September 2018 - July 2020 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV MARIA S. MERIAN expedition MSM76 and recovered during MSM93. The mooring included one ASL Acoustic Zooplankton Fish Profiler (nominal depth: 155m; data archived elsewhere) and one Develogic Sonovault (nominal depth: 836m; data also archived elsewhere). The attached .zip file only contains the mooring diagrams.

Description: Time-series data of physical oceanography and carbon/particle export were obtained from mooring HG-IV-FEVI-38 in the Fram Strait in July 2018 - August 2019 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS114, and recovered during PS121. The attached archive contains raw data files of four Seabird SBE37 microcats (nominal depths: 52m, 253m, 1200m, 2526m; sampling interval 1h), two AADI RCM11 current meters (nominal depths: 203m, 1230m; sampling interval 1h), one Nortek Aquadopp current meter (nominal depth: 750m; sampling interval 20 min), one RDI Longranger ADCP (nominal depth: 409m; sampling interval 1h) and two AADI Seaguard current meters (nominal depths: 2348m, 2524m; sampling interval 1h). The mooring also included three sediment traps (nominal depths: 196m, 1223m, 2341m) and one BioOptical Platform (565m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

Description: To measure CO₂ we used a CO₂ sampling data logger from the company CO2Meter, Inc. (https://www.co2meter.com/). The model was a CM-0002 gas detector handheld which has a measurement range of 0 – 10.000 ppm (0-1%) CO₂ with an accuracy of ± 30ppm ± 3%. The handheld is using the non-dispersive infrared (NDIR) method to determine CO₂ concentrations. Before each measurement the CO₂ data logger were calibrated to outdoor air which was assumed to have a CO₂ concentration of 400 ppm. At each sampling plot at low tide three CO2-Meters were positioned adjacent to each other but not covering pneumatophores or crab holes to avoid extra respiration not from the sediment-air interface. A chamber with 305 ml of volume was installed on the sediment and shaded to maintain temperature inside the chamber steady. Furthermore the chamber was darkened to prevent any respiration of ecosystems (Reco). Inside the chamber a HOBO temperature logger was positioned, with a logging interval of one minute. After setting up the instruments for measurements we waited between approximately 10 minutes until we started the logging. This was because the logging needed to start after any sediment disturbance has occurred. Each measurement took between 17 and 25 minutes. Data was considered to be obtained under steady state conditions if the temperature did not change more than 1.5 °C (Chojnicki et al., 2009).

Description: In Lac Bay a 10 m by 10 m plot was established and within each plot tree characteristics were identified and measured. The perimeter at breast height (or 1.3 m) of each tree inside the plot was noted, except for the perimeter of R. mangle species, where measurements were taken at the height of the highest prop root. From the perimeter the diameter at breast height (DBH) was calculated.

Description: In Lac Bay a 10 m by 10 m plot was established and within each plot tree characteristics were identified and measured. The perimeter at breast height (or 1.3 m) of each tree inside the plot was noted, except for the perimeter of R. mangle species, where measurements were taken at the height of the highest prop root. From the perimeter the diameter at breast height (DBH) was calculated.