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Environmental parameters and dissolved substances in the coastal waters of Curacao
No full textThe presence of dissolved substances in coastal waters and their impact on coastal ecosystems depend on influx of substances from land and offshore waterbodies, biological community composition, seasonal changes in environmental conditions, hydrodynamics and topographic factors. The relative importance of these factors is not well known for tropical islands. Here we examined the impact of physical and anthropogenic drivers on spatial and seasonal variability in geochemical properties (concentrations of inorganic nutrients, silicate, inorganic carbon and total alkalinity) of the coastal waters of a Caribbean island (Curaçao), comparing a dry (April 2022) and a wet (January 2024) season. CTD transects were conducted to depths down to 250 m to characterize water column properties offshore, and discrete water samples were collected along the same transects nearshore. Vertical mixing between nutrient-rich Subtropical Under-Water (70–200 m), Western North Atlantic Central Water (below 200 m) and shallow Caribbean Surface Water (<70 m) was observed during the wet season, when coastal waters showed higher Si concentrations, especially at shallow depths, indicating terrestrial runoff. However, despite known high nutrient inputs into coastal waters near urbanized areas from earlier studies, we did not observe a clear relationship between land-based activities and nearby coastal water characteristics. During the dry season, higher N:P ratios were observed, indicating potential P-limitation of primary productivity. Additionally, at specific sites elevated alkalinity and inorganic carbon concentrations suggested enhanced (coral) carbonate dissolution. We discuss how seasonal variability in nutrient inputs and topography-hydrography interactions underlie the temporal fluctuations of observed dissolved substances in Curaçaoan waters
Mineralization of photodegraded polyethylene by the marine-derived fungus Aspergillus terreus
No full textThe microbial processes and kinetics involved in plastic biodegradation in marine environments remain largely unexplored. In particular, the role of marine fungi in this context is largely unconstrained. In this study, we incubated the marine-derived fungus Aspergillus terreus in microcosms with 13C-labelled polyethylene (PE) to trace mineralization and assimilation of plastic-derived carbon. Our assays provide evidence that A. terreus mineralizes UV-treated PE. Over the 22-day period of incubation, fungal-mediated mineralization of photodegraded PE amounted to 0.24% of the initially added PE. NanoSIMS imaging and isotopic analysis of fatty acids demonstrated the limited incorporation of UV-treated PE-derived carbon into fungal biomass. In contrast, incubations with A. terreus and untreated PE for up to 102 days showed no measurable evidence of biotic degradation. These findings underscore the critical role of photodegradation in facilitating subsequent biotic degradation of PE by A. terreus in marine environments
Lower Meuse paleoflood record reveals NAO-driven decadal to multi-centennial variability - XRF-core-scanning Data
No full textThese files contain raw X-ray fluorescence (XRF) core scanning data and line scan data of the Buggenum and Ravenstein cores used in Peng et al. (2025). The abstract of that publication: A central challenge in assessing climate-driven flood regimes is constructing long-term paleoflood records with sufficient temporal resolution to identify both short- and long-term variability. To address this, we performed grain-size and X-ray fluorescence scanning analyses on two cores from paleochannels in the Lower Meuse (the Netherlands). The downcore ln(Zr/Rb) ratio proves to be a reliable grain-size proxy, allowing reconstruction of flood-related sediment input variations. We find the flood intensity record displays a ~300-yr cycle, synchronous to that observed in the North Atlantic Oscillation record, and both records are synchronous at this band. Importantly, a persistent quasi-decadal (7-10 years) oscillation indicate a persistently active flooding regime and hydrological stationarity throughout the Late Holocene. This study advances paleoflood methodology by demonstrating that paleochannel infills provide valuable archives for reconstructing flood histories across multi-annual to millennial intervals, thus enhancing our ability to track hydrological responses to climate variability across multiple timescales
New evidence of small demersal fish in the southern North Sea - data
No full textdata used for manuscript "Small fish biomass in the North Sea is far greater than previously estimated".
Small fish, including species with small adult sizes and juveniles of larger species, play a central role in marine food webs as prey for top predators, such as seabirds, marine mammals, and piscivorous fish. However, reliable data on small fish are lacking as conventional fisheries surveys primarily focus on larger, commercially important species and underestimate small fish. Consequently, little is known about the absolute biomasses, and fine-scale distribution patterns of this important trophic group. Based on 1,307 quantitative Triple-D samples from the Dutch EEZ and the UK sector of the Dogger Bank, biomass densities were estimated for pooled small demersal fish and for the most abundant species individually. Our estimates suggest that small demersal fish biomass is at least twice as high as reported in trawl-based studies. Uniformly distributed species such as dab (Limanda limanda) and plaice (Pleuronectes platessa) contributed most to the overall small fish biomass, while sandeels (Ammodytidae) showed particularly high local densities. These new prey biomass estimates might change our understanding of the North Sea ecosystem’s carrying capacity, and establishes a baseline for monitoring changes in small fish communities driven by climate change and human impacts
Occurrence of nucleoside-bacteriohopanepolyol in high latitude soils: evidence of environmental controls on bacterial lipid membrane distributions
No full textRecently, the analysis of non-derivatised bacteriohopanepolyols (BHPs) by ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS2) revealed a broad structural diversity in this lipid class. Multiple unique BHPs with nucleoside-type polar head groups (Nu-BHPs) were identified in soils. Nu-BHPs had previously been identified in high abundances in soil organic matter, but only by analysing acetylated BHPs, which hindered their structural elucidation. In this study, we apply the UHPLC-HRMS2direct analysis method for the first time to a soil transect to re-examine the distribution of Nu-BHPs, their environmental dependencies, and their proxy potential. The presence and distribution of Nu-BHPs was examined in 17 surface soils along a ~800 km transect in northern Alaska. Our results indicate that certain Nu-BHPs show significant correlation with environmental parameters, such as temperature and soil pH. The variation in 9 Nu-BHPs is captured using a novel ratio, and a regional calibration for warmest quarter soil temperature (WQST) was developed using a linear regression approach (R2 = 0.72). Other calibrations developed for summer air and mean annual temperatures also show strong positive correlations. As BHPs are ubiquitous in soils globally, this study highlights the potential benefit of complementing established organic proxies for soil pH and temperature (e.g., branched tetraether lipids) with calibrations based on Nu-BHPs. Nevertheless, the mechanism behind the environmental dependencies of these BHPs remains unknown. Further work to explore the proxy potential as well as the bacterial sources of these lipids should be undertaken, for instance by sampling soils along relevant (soil pH and temperature) gradients
SEALINK ADCP Coastal Observations on Curaçao 2022
No full textThis dataset contains ADCP (Acoustic Doppler Current Profiler) measurements collected around Curaçao in March 2022. The fieldwork included deployments at multiple reef locations using two ADCP instruments (Nortek AD2CP Signature 1000). This data was collected as a part of the SEALINK project
data for: "Migration of crab plovers Dromas ardeola wintering at Barr Al Hikman, Oman"
No full textCrab plovers Dromas ardeola are shorebirds endemic to the coasts of the Indo-West Pacific biogeographical area. Very little is known about the migration of this enigmatic bird. Here we studied the migratory itineraries of six crab plovers tracked between their wintering grounds in Barr Al Hikman, Oman, and their breeding grounds on islands in the north-west of the Arabian/Persian Gulf in Iran and Kuwait. During spring migration, all tagged birds followed a similar route. On the first leg, birds flew north over desert and mountain areas. After reaching the Arabian/Persian Gulf they followed the northern coastline where most birds had several stops. Birds initiated spring migratory flight between February 28 and May 7, and it took 3–24 days to travel from the non-breeding to the breeding areas. The birds spent between 96–174 days at the breeding colonies. Autumn migratory flights were mostly along the eastern coast of the Arabian/Persian Gulf. Four birds followed a coastal route back to Barr Al Hikman, similar to spring migration. Two birds followed a southerly route and short cut the last stretch of 500 km by crossing the Empty Quarter (Rub Al Khali) desert region. Autumn migratory flights occurred between July 19 and October 24, lasting 3–91 days. Most migratory flights occurred predominantly between 6 pm to 6 am and were almost always less than 25 m altitude from the Earth surface. The maximum height of 1748 m above sea level was measure above the Oman Mountains. Crab plovers were able to cross potential barriers (i.e. the two desert areas, and a mountain range) within single nights. We discuss our result with respect to the migratory connectivity known for this species
Darci Rush
No full textAnaerobic ammonium oxidation (anammox) is an important process in modern global nitrogen cycling. However, the contribution of anammox to ancient nitrogen biogeochemical cycles cannot currently be accounted for because the most characteristic lipid biomarkers of anammox bacteria, ladderane lipids containing concatenated series of cyclobutane moieties, do not preserve as such into the catagenetic window in the sedimentary record. Alternative lipid biomarkers that are more resistant to degradation are needed by the geochemical community to investigate the presence anammox in high maturity sediments and inform on past marine oxygen depletion, nitrogen cycling, and the formation of organic rich sediment such as black shale deposits. Here, we describe novel cyclic hydrocarbons produced by the simulated thermal maturation of anammox bacterial biomass. Alkyl branched tricyclic hydrocarbons were present in pyrolysates generated by hydrous pyrolysis experiments at temperatures >200 °C, in the window of oil generation. Two-dimensional gas chromatography-mass spectrometry revealed that these artificial maturation experiments generated multiple series of cyclic hydrocarbons. A representative product was isolated by preparative gas chromatography, but was shown to be composed of two co-eluting components. Their structures were partially identified, by way of two-dimensional nuclear magnetic resonance (NMR), to be 4-octyl-tricyclo[7.3.0.02,8]dodecanes with the three concatenated rings comprising of 7, 4, and 5 carbons. This ring assemblage was further confirmed through NMR and mass spectral comparisons with four synthesized model compounds. The isolated components had a stable carbon isotopic composition similarly depleted in 13C as the ladderane fatty acids of the original anammox biomass, consistent with a ladderane lipid source. The C20 hydrocarbons could have formed from thermal ether cleavage and ring-opening of the C20-[5]- or [3]-ladderane glycerol ether, common membrane lipids of anammox bacteria. Molecular mechanic calculations were used to generate the relative structural stability of stereoisomers and the possible conversion steps to the formation of these components. These indicated that the 7-4-5 components were the result of the breakdown and rearrangement of bonds in the cyclobutane rings from biosynthetically-derived 4-4-4-4-4 ladderane lipids. These components were not detected in thermally mature sediment and rocks screened using conventional GC-MS analysis, however, by using more advanced chromatography methods these lipids may be still be helpful biomarkers for assessing past anammox in ancient sediments and crude oils
Dataset belonging to "Identifying Saharan dust driven export of biogenic material in the ultraoligotrophic eastern Mediterranean Sea"
No full textTo assess the effects of dust deposition on the strength of the biological pump in the Mediterranean Sea by acting as fertilizer and/or ballasting agent, we analyzed fluxes of mineral dust, particulate organic carbon (POC) and inorganic carbon (PIC), and source-specific lipid biomarkers (i.e., higher plant-derived long-chain fatty acids and phytoplankton-derived alkenones, C30 1,15 diols, and sterols) in sinking particles. Sinking particles were collected at ten-day intervals by a sediment-trap mooring deployed in the Ionian Basin from April 2017 to May 2018 at 2340 m water depth. High POC fluxes occur during summer, when surface ocean primary production is lowest due to thermal stratification. Notably, these high POC fluxes coincide with pulses of substantial dust deposition, suggesting that POC export is primarily driven by dust deposition and subsequent ballasting. However, the lipid composition, and thereby that of the phytoplankton community, differs between dust events. (Seasonal) variations in the properties of the deposited dust, presumably associated with its provenance, likely control the effect of dust deposition on phytoplankton response and export in the Ionian Basin. Although POC export is associated with dust deposition, the net effect of dust deposition on the biological pump is more ambiguous as not all dust events are associated with an increase in POC export, and most dust events are also associated with PIC export that has a counteracting effect on the biological pump. Multi-year time series of dust deposition and biogenic export are required to validate the seasonal variations in dust-driven export of biogenic material observed here, and to account for effects of interannual variations in dust fluxes and phytoplankton production on the strength of the biological pump