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Data from: Establishing cordgrass plants cluster their shoots to avoid ecosystem engineering
No full text1. Vegetated coastal ecosystems such as salt marshes, dunes and seagrass meadows occur at the land-sea interface ? a dynamic environment typified by harsh growing conditions. These ecosystems are known as biogeomorphic landscapes because their functioning depends on biophysical interactions by which organisms engineer landforms to their own benefit. The strength of such biogeomorphic feedbacks depends on plant traits, such as stem flexibility and shoot density.
2. Recent work demonstrated that dune grasses with similar morphological traits can build contrasting landscapes due to differences in their spatial shoot organization. However, in contrast to dune grasses that trap and stabilize sand particles in aeolian landscapes, flow attenuation in aquatic environments can generate scouring around plant stems and cause uprooting, leading to establishment thresholds for young plants.
3. Yet, it remains unknown how findings from aeolian landscapes translate to aquatic systems and how young clonally expanding plants in hydrodynamically exposed conditions overcome these establishment thresholds by optimizing shoot placement.
4. Here, we measured shoot patterns of 90 establishing cordgrass patches (Spartina anglica) at 18 European field sites that cover a broad range of hydrodynamic conditions. Next, we carried out a field experiment to investigate how observed spatial shoot patterns affect plant-sediment feedbacks.
5. Surprisingly, field survey analyses reveal highly consistent clustered shoot patterns, regardless of environmental conditions. Experimental results demonstrate that this clustered pattern minimizes scouring compared to densely clumped organizations typically observed in established patches.
6. Synthesis. In contrast to earlier findings highlighting that establishing dune grasses optimize their landscape engineering capacity via a flexible shoot placement strategy, we find that cordgrass instead follows a fixed strategy that minimizes engineering effects in its early life stages. We suggest that marsh grasses avoid physical stress and associated establishment thresholds in their early life stage, and switch to an ecosystem engineering strategy once established. These findings shed new light on how plant traits interact with their environment to shape the landscape and pave the way for improved restoration designs by mimicking the natural shoot organization of establishing vegetation
Full EGC-DrIFT 6h interpolated dataset
No full textThis dataset contains drifter data from 5 deployments at the East Greenland shelfbreak, in 2019, 2020 and 2021. The deployments were done at the latitudes of : 65N (August 2019), 79N (September 2019), 60N (July 2020), 66N (August 2021) and 70N (August 2021). The netcdf file contains the positions, speeds, and measurements (Temperature and Salinity when available) of both CARTHE and SVP drifters. Drifter positions are interpolated every 6h from August 14th 2019 to November 15th 2022
Demand-resource mismatch in the high-Arctic explains two decades of body shrinkage in red knots
No full textAnimal body shrinkage appears correlated with climate warming, but the mechanism remains unclear. For an Arctic-breeding shorebird, the red knot, we demonstrate why juvenile body size at its West-African non-breeding grounds has decreased over two decades. Over this period, stable-isotope ratios sampled from juvenile feathers - grown as chicks on their Arctic breeding grounds 9,000 kilometers away - reveal a decline in the dietary contribution of crane flies, their key food source on the tundra. With crane fly phenology advancing with earlier snowmelt dates but red knot breeding timing not, this has caused an increasing mismatch with the demands of growing chicks, leading to slower growth and smaller final body sizes. Our results imply that body shrinkage may come about rapidly via plasticity during development
Supplementary data
No full textNanoSIMS measurements of R. mucilaginosa cells, where we analyzed three sample sets: (i) the original inoculum, (ii) after incubation with 13C-labelled polyethylene without and (iii) with UV-treatment. We measured a total of 1144 regions of interest (ROIs, i.e., corresponding to 1144 individual cells)
Development of ?13C-CO2 values in incubations with R. mucilaginosa (RM) and with 13C-polyethylene (PE), with prior UV-treatment (+UV) and without (-UV) as the sole carbon source as well as in incubations without R. mucilaginosa
Hydrography and velocity data from the Long-term Ocean Circulation Observations (LOCO) mooring in the central Irminger Sea: Deployment nine (LOCO2_9) July 2011 to August 2012
No full textThe data set under this specific DOI contains data from the ninth LOCO2 deployment (LOCO2_9), from 29 July 2011 to 1 August 2012.
Data from other deployments can be found through the related identifyers.
The LOCO2 mooring was started as part of the Dutch Long-term Ocean Circulation Observations project. LOCO2 was moored in the central Irminger Sea at approximately 59.2N, 39.5W from summer 2003 until summer 2018. It was equipped with Acoustic Doppler Current Profilers for the upper ocean (2500m) circulation, a near bottom SBE37 to record the temperature and salinity of the Denmark Strait Overflow Water and (from the 10th deployment onwards) another SBE37 at around 150m. A McLane Moored Profiler (MMP) equipped with a CTD was programmed to make profiles along the mooring cable between ~150m depth and ~2400m depth.
LOCO2 was positioned in the center of the Irminger Gyre, underneath the strong atmospheric forcing of the Greenland Tip Jet, in order to study deep winter convection in the Irminger Sea. Data and results are described in the following publications:
- de Jong, M. F., van Aken, H. M., V?ge, K., and R. S. Pickart (2012). Convective mixing in the central Irminger Sea: 2002-2010. Deep-Sea Research I, 63, 36-51. https://doi.org/10.1016/j.dsr.2012.01.003
- van Aken, H. M., and M. F. de Jong (2012). Hydrographic variability of Denmark Strait Overflow Water near Cape Farewell with multi-decadal to weakly time scales. Deep-Sea Research I, 66, 41-50. https://doi.org/10.1016/j.dsr.2012.04.004
- de Jong, M. F. and L. de Steur (2016). Strong winter cooling over the Irminger Sea in winter 2014-2015, exceptional deep convection, and the emergence of anomalously low SST. Geophysical Research Letters, 43, 13, 7106-7113. https://doi.org/10.1002/2016GL069596
- de Jong, M.F., M. Oltmanns, J. Karstensen, and L. de Steur (2018). Deep convection in the Irminger Sea observed with a dense mooring array. Oceanography 31(1):50?59. https://doi.org/10.5670/oceanog.2018.109
- de Jong, M.F., Fogaren, K.E., Le Bras, I., Trafford, L. and H. Palevsky (submitted 2023). Convection in the central Irminger Sea; insights into variability and the roles of surface forcing and stratification from 19 years of high resolution mooring data
Tissue- and diet-dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species
No full textIn ecology, stable-isotope ratios are widely used to determine diets of organisms and reconstruct food webs. This is usually done by analyzing the stable-isotope ratios of nitrogen (?15N), which increase with increasing trophic level, and those of carbon (?13C), which correlate with the ?13C value of food source(s) and generally differ between terrestrial and marine food sources. Assimilation of food changes stable-isotope ratios, resulting in different values between the food source and its consumer. These differences are known as isotope trophic discrimination factors and, if known, can be used to determine from the stable-isotope ratios in the consumer?s tissue what the consumer has been eating. What is often ignored is that discrimination factors can differ between consumer?s food sources and also between tissue types. Therefore, we performed a controlled feeding study in red knots Calidris canutus to determine discrimination factors between different food sources and red knot tissues. We kept two groups of red knots in captivity on a stable diet, one group feeding on mudsnails and the other on Trouvit pellets, for several months, during which the birds molted their feathers. We analyzed ?13C and ?15N in both food sources and in five red knot tissues (blood cells, blood plasma and three feather types) and subsequently calculated the isotope discrimination factors. We confirmed that the discrimination factors differed between tissues, and also between diets. Our values deviated from general averages reported in reviews on a wide range of animals/birds, but were very similar to values from previous red knot and dunlin studies. We therefore think that our discrimination factors can be used in future stable isotope studies, not only on red knots, but also on other marine shorebird species and plea for careful consideration of using the right discrimination factors
Prince Edward Islands Biodiversity 2016-2017
No full textCommunity composition is one of the main factors influencing the function of any given ecosystem, with a more diverse community providing a larger set of services. Benthic community composition can vary at a spatial and temporal scales, with primary production dynamics and benthic food availability being main factors to determine the structure of a given system. Studies have indicated shifts in benthic community composition at Sub-Antarctic Islands over a period of 30 years, linked to variability in food availability driven by climate change. Here we aim to evaluate possible short-term variability in benthic community composition at the Sub Antarctic archipelago Prince Edward Islands (PEIs), sampling stations located across three regions over two consecutive years. The results indicated significant higher species richness and abundances in 2017 than 2016, and some taxa also showed variation among regions around the PEIs. Such effects can be linked to different substratum type of the station sampled or to sampling effort. This study further contribute to understand how benthic communities may change in the near future, an essential information to develop efficient management strategies for this vulnerable marine system
Hydrography and velocity data from the Long-term Ocean Circulation Observations (LOCO) mooring in the central Irminger Sea: Deployment twelve (LOCO2_12) July 2015 to August 2016
No full textThe data set under this specific DOI contains data from the twelfth LOCO2 deployment (LOCO2_12), from 19 July 2015 to 2 August 2016.
Data from other deployments can be found through the related identifyers.
The LOCO2 mooring was started as part of the Dutch Long-term Ocean Circulation Observations project. LOCO2 was moored in the central Irminger Sea at approximately 59.2N, 39.5W from summer 2003 until summer 2018. It was equipped with Acoustic Doppler Current Profilers for the upper ocean (2500m) circulation, a near bottom SBE37 to record the temperature and salinity of the Denmark Strait Overflow Water and (from the 10th deployment onwards) another SBE37 at around 150m. A McLane Moored Profiler (MMP) equipped with a CTD was programmed to make profiles along the mooring cable between ~150m depth and ~2400m depth.
LOCO2 was positioned in the center of the Irminger Gyre, underneath the strong atmospheric forcing of the Greenland Tip Jet, in order to study deep winter convection in the Irminger Sea. Data and results are described in the following publications:
- de Jong, M. F., van Aken, H. M., V?ge, K., and R. S. Pickart (2012). Convective mixing in the central Irminger Sea: 2002-2010. Deep-Sea Research I, 63, 36-51. https://doi.org/10.1016/j.dsr.2012.01.003
- van Aken, H. M., and M. F. de Jong (2012). Hydrographic variability of Denmark Strait Overflow Water near Cape Farewell with multi-decadal to weakly time scales. Deep-Sea Research I, 66, 41-50. https://doi.org/10.1016/j.dsr.2012.04.004
- de Jong, M. F. and L. de Steur (2016). Strong winter cooling over the Irminger Sea in winter 2014-2015, exceptional deep convection, and the emergence of anomalously low SST. Geophysical Research Letters, 43, 13, 7106-7113. https://doi.org/10.1002/2016GL069596
- de Jong, M.F., M. Oltmanns, J. Karstensen, and L. de Steur (2018). Deep convection in the Irminger Sea observed with a dense mooring array. Oceanography 31(1):50?59. https://doi.org/10.5670/oceanog.2018.109
- de Jong, M.F., Fogaren, K.E., Le Bras, I., Trafford, L. and H. Palevsky (submitted 2023). Convection in the central Irminger Sea; insights into variability and the roles of surface forcing and stratification from 19 years of high resolution mooring data
Chapter 5 - Tidal flat transitions signaled by self-organized algal patterns
No full textTo understand the establishment of vegetated coastal wetlands, we combined mathematical modelling and a field study to investigate the emergence of algal-covered sedimentary ridges that constitute distinct spatial patterns on tidal flats. Strikingly, these patterned bedforms appear to facilitate the establishment of saltmarsh vegetation. We measured plant seedling densities in the field, which showed that seedling densities are higher on elevated bedforms colonized by the filamentous algae Vaucheria. Based on these field measurements and earlier laboratory experiments, we developed a mathematical model under the hypothesis that the bedform patterns are self-organized due to algal-induced scale-dependent feedbacks (filaments increase sediment strength, creating elevated ridges where algal growth is further improved; algal growth is inhibited adjacent to ridges due to scour and inundation). Model simulations confirmed this hypothesis, as they reproduced the wide range of observed Vaucheria patterns, varying from no cover to parallel ridges and from branching networks to full algal cover. Moreover, we used the model to explain the observation that large mudflat areas remain topographically smooth and bare (i.e., no algal mats nor plants) for years despite the development of algal-covered bedform patterns elsewhere on the mudflat at similar elevation. We found that the scale-dependent feedbacks make both the configurations with smooth mud and with algal bedforms highly resilient to changes in environmental conditions, such that these two configurations can coexist as alternative stable state under a range of mudflat elevations. Furthermore, we showed that changes in the spatial complexity of the algal pattern indicate imminent tipping points that lead to ecosystem collapse or establishment. Our study sheds light on processes that might be highly relevant for wetland restoration and conservation projects. Such projects could benefit from ecosystem engineers like Vaucheria and the signaling value of their spatial patterns
Effects of offshore wind farms on suspended particulate matter derived from satellite remote sensing
No full textThe impacts of offshore wind farms on water quality remain to be quantified. This study examines the water quality in and around four offshore wind farms in the Dutch part of the North Sea using suspended particulate matter (SPM). Satellite-derived SPM was used in a Before-After-Control-Impact (BACI) analysis to assess changes in water quality caused by wind farm construction. In addition, relationships between satellite retrieved SPM and environmental variables from models (i.e., salinity, temperature and current velocity from the hydrodynamical GETM model, and wind speed from ERA-5 re-analysis meteorological data) were investigated to identify the drivers of SPM
change in each of the four sites. Results show that SPM concentrations (as well as temperature and salinity) changed significantly when comparing a period of ca 6 years before and after wind farm construction, while no significant changes were observed when comparing control and impact treatment. The BACI analysis thus did not reveal a significant effect on SPM in response to construction of the wind farms. Scatterplots showed a complex interaction of hydrodynamic and meteorological variables on SPM changes, superimposed on a clear seasonal variation; when analysed by season, surface water temperature correlated most with SPM variations. Our results suggest
that the combination of BACI and the visualization of satellite-derived and model derived data provide insight in the potential impact of wind farms. Satellite imagery was crucial in providing SPM data at relevant spatio-temporal scales; however, the satellite data may be biased by sampling under clear sky and low wind speed conditions, while the environmental variables were retrieved disregarding the wind farms in the hydrodynamical model. Despite these drawbacks, such information provides an understanding of the possible environmental impacts of offshore wind farms that can be used in policy making, and in general terms, these results may aid the planning of new wind farms