Transect Study Research Articles

P0654 Switching from intravenous to subcutaneous infliximab: physicians’ practice and patients’ satisfaction - Results from a nationwide transectional study

Abstract Background Subcutaneous (SC) infliximab is efficient and safe in inflammatory bowel diseases (IBD), but no guidelines exist regarding practical modalities of switching from IV to SC infliximab. This study aimed to describe current practice in France, assess patients’ experience, and identify factors associated with higher satisfaction levels. Methods Two questionnaires were created for this nationwide cross-sectional study. Each practitioner completed a physician questionnaire and provided a patient questionnaire to all consecutive patients receiving infliximab (IV or SC) over an 8-weeks period. Factors associated with a higher satisfaction following switch, assessed using a 10 points numerical scale (10=completely satisfied) were explored using a multivariate analysis. Results Among 48 responding physicians, the switch was proposed more readily for patients in deep remission (97.9%), after infusion-related reactions (91.7%), or for cost-saving reasons (52%). Perianal lesions did not discourage the switch (83.3%), contrary to concerns about reduced infusion unit activity (68.9%) and poor adherence (52.1%). The first SC injection was mainly performed instead of the next IV infusion (77.3%). Immunosuppressive therapy was maintained (87.5%) for patients treated with combination therapy, generally for 6 months. Among 241 enrolled patients, 33.6% had switched to SC infliximab including 14 (17.3%) receiving an intensified SC dose immediately after the switch. Most of these patients (13/14) were on IV infliximab ≥ 10mg/kg/8-weekly prior to switch, had Crohn’s disease (13/14), had received IV infliximab for more than 5 years (10/14) and did not receive concomitant immunosuppressive therapy at the time of switch (10/14). Patients who did not switch cited absence of information regarding the SC option (22.0%), concern over altered medical follow-up (15.2%), and fear of disease relapse (11.4%) as most frequent reasons. Among those who switched, the median satisfaction score was 10/10 [8.0-10.0], even in patients immediately switched to optimized SC infliximab (10/10 [9.0-10.0]). The switch was felt as improving disease activity in 43/77 (55.8%) of patients. 60.5% reported no apprehension before SC injection, whereas 16.0% rated their apprehension above 4/10. No serious adverse events were reported; local injection site reactions (erythema or oedema) were reported only in 7.4% of cases. Multivariate analysis showed that patients’ satisfaction was correlated with the duration of prior IV infliximab treatment (p=0.040). Conclusion This nationwide study provides an overview of current physicians’ practices for switching from IV to SC infliximab that could help for editing guidelines and demonstrates high level of patients’ satisfaction after switch.

Forecasting range shifts using abundance distributions along environmental gradients

Globally, many species’ distributions are shifting in response to contemporary climate change. However, the direction and rate of shifts remain difficult to predict, impeding managers’ abilities to optimize resource allocation. Here, we developed a new approach for forecasting species range‐limit shifts that requires only abundance data along environmental (for example, elevational) gradients. We posited that the distribution of species’ abundances could offer insights into the potential for future range‐limit shifts. We then tested this prediction using data from several transect studies that compared historical and contemporary distributions. Consistent with our prediction, we found that strong asymmetry in abundance distributions (that is, “leaning” distributions) indeed preceded species’ lower‐limit range shifts. Accordingly, surveying abundances along environmental gradients may represent a promising, cost‐effective method for forecasting local shifts. Ideally, this approach will be incorporated by practitioners into species‐specific management planning and will inform on‐the‐ground conservation efforts.

Mangroves and Associated Flora of Vashista Godavari Estuary from Darbharevu to Biyyaputippa, West Godavari District, AP, India

Mangrove ecosystem is one of the productive ecosystems in aquatic environment. Mangrove populations occurring along the Vashista branch of Godavari River were studied using line transect with 16 m² quadrates and the quadrate samples were analyzed. In the present investigation a total of 16 mangrove species were reported, out of which four are true mangrove species, six associated mangroves and six halophytes were reported. Transect studies revealed that mangroves were distributed up to 10 to 20 meters in Darbharevu and 30 to 40 meters in Biyyaputippa region. Most of the forest in Darbharevu is in form of long strip and in Biyyaputippa forest extends and density of species was high than Darbharevu. In both study sites (Darbharevu and Biyyaputippa) the species with the highest density was Suaeda monoica whereas the species with lowest density was Sonneratia caseolaris. The maximum height in these two stations varied from 5 to 10 meters only. Percentage frequencies of DBH (Density at Breast Height) classes were estimated. In the present study only two diameter classes in Darbharevu and 4 classes in Biyyaputippa were reported. This is an indicative of the small and bushy mangrove vegetation in station 1 and little bit larger canopy was reported in station 2. Anthropogenic and aqua industry play a critical impact on the survival of this mangrove ecosystems.

Alcohol addiction treatments for home resident in Switzerland: review and results of a transectional study

IntroductionIn Switzerland, alcohol consumption is even decreasing, with an exception for old people after retirement.35%of them have a heavy or addictive consumption (OFSP, consommation d’alcool en Suisse, fait et chiffres. 01.2023). This is also the case for home residents.The alcohol consumption by old poeple has negatives consequences on the health (falls, fractures, cognitives disorders). The autors conduct a crossectionnal enquiry in the homes of Fribourg area to identify addictive behaviour and different existing supports. After a review, the authors present the results of their enquiryObjectivesIdentify how much home-residents have a problematic or an addictive alcohol problemIdentify if there is existing supportHinghligthing the training need for the staffMethodsCrossectionnal enquiry was sent in 42 Home of the Fribourg area, with 3 relancesResultsThe premliminary result will be completed at the end of 2023:-Every home identify at leat 4-5 residents with a problematic alcohol consumption-Most of them, the staff have no specific addictive trainig and no needs for it-The staff authorise alcohol consumption in the home, to avoid alcohol withdrawal-The psychiatric consultant in the home can help the staff to manage the counter-attitudesHome residents are not eligible for specialized addictive care, whil the generally respond well to motivationnal interviewing or to controlled consumption. The lack of staff training could be an hypothesis. The lack of interest in the neagtives conséquences oh alcool on th health of people at the enf of their lives is anothers hypothesisConclusionsNursing home residents are not eligible for specialized addictive care. The enquiry results are astonishing: no need of specialized training, authorization of continous drinking in the different homes, while the literature points the effectivnesse of motivationnal interviewing or controlled approaches by old people with addictive disorders.Further studies are needed, ethical consideration on the management of alcohol addiction in the elderly should be proposed.Disclosure of InterestNone Declared

Patterns and mechanisms of belowground carbon responses to changes in precipitation

Abstract It is well known that aboveground productivity usually increases with precipitation. However, how belowground carbon (C) processes respond to changes in precipitation remains elusive, although belowground net primary productivity (BNPP) represents more than one-half of NPP and soil stores the largest terrestrial C in the biosphere. This paper reviews the patterns of belowground C processes (BNPP and soil C) in response to changes in precipitation from transect studies, manipulative experiments, modeling and data integration and synthesis. The results suggest the possible existence of nonlinear patterns of BNPP and soil C in response to changes in precipitation, which is largely different from linear response for aboveground productivity. C allocation, root turnover time and species composition may be three key processes underlying mechanisms of the nonlinear responses to changes in precipitation for belowground C processes. In addition, microbial community structure and long-term ecosystem processes (e.g. mineral assemblage, soil texture, aggregate stability) may also affect patterns of belowground C processes in response to changes in precipitation. At last, we discuss implications and future perspectives for potential nonlinear responses of belowground C processes to changes in precipitation.

Soil Mineral-Associated Organic Carbon and Its Relationship to Clay Minerals across Grassland Transects in China

The purpose of this study was to determine the mineral-associated organic carbon (MOC) and its relationship to clay minerals under different temperatures and precipitation. We selected three typical grassland transects in China: Titanium Plate (TP), Mongolian Plate (MP), and Loess Plate (LP) with natural temperature gradients. Along the transect, there is a gradient in the precipitation between the various types of grasslands. The surface soil (0–10 cm) was sampled to determine the MOC. Clay minerals were charactered by X-ray diffraction (XRD). According to the findings, the MOC content increased with decreasing temperature (5.41–14.89 g/kg). MOC had a positive correlation (r = 0.67) with the amount of clay mineral content. In the large-scale study of transects, precipitation masks the effect of temperature change on the MOC to a certain extent. It indirectly affected the MOC content by affecting the mixed-layer illite/smectite (I/Sme) content, and this effect was strongest at the lowest temperature TP (r = −0.73). Except for precipitation, CaO in the soil can affect soil organic carbon (SOC) stability by influencing the pH and I/Sme. The amount of bacteria increased as a result of I/Sme, and the influence of bacteria on the MOC was surpassed only by the soil pH. Climate and clay mineral composition characteristics affected the MOC to a certain extent. Among them, the effect of precipitation change on the MOC is higher than temperature, but it has little effect on soil with a higher weathering degree and CaO content.

Innovation in the services sector and its complex relationship with business survival

This article provides empirical evidence of a complex relationship between the types of innovation undertaken by micro and small restaurant enterprises (MSEs) and their specific factors of business survival (SFOBS). It is a quantitative, non-experimental, transectional, and correlational study, with a probabilistic sample carried out with an ad hoc instrument validated by experts. The SEM structure established allows us to consider that innovating in the tangible elements of the service and in those that improve the empathy of the service generate positive impacts on the SFOBS, especially the size of the company by revenue. Likewise, the different intervening factors are interrelated, generating a synergy of business survival.

Precipitation consistently promotes, but temperature oppositely drives carbon fluxes in temperate and alpine grasslands in China

Temperate grassland (TG) and alpine grassland (AG) are two distinct grassland types with different climatic backgrounds and adaptation patterns. Little is known about the universal and divergent responses of TGs and AGs to climate change, particularly with regard to the carbon (C) fluxes. The large-scale responses of the C fluxes in different grasslands to climate change remain unclear, with only a few comparative studies of distinct responses of the C fluxes in TGs and AGs to climate change hinders our understanding of this subject. In this study, we conducted a large-scale transect study across the Mongolian, Loess, and Tibetan Plateaus in China to reveal the similarities and differences in the responses of the C fluxes in TGs and AGs to climate change. We used C flux data measured by eddy covariance from ChinaFLUX and published literature, covering the period from 2003 to 2020. The results showed that TGs and AGs in China were weak C sinks. Net ecosystem productivity in TGs and AGs exhibited opposite trends with increasing latitude, longitude, and altitude. Elevated water (mean annual precipitation and soil water content) consistently increased the C fluxes. Conversely, increased temperature (mean annual temperature and mean annual soil temperature) reduced the C fluxes in TGs and increased the C fluxes in AGs. The water factors promoted the C fluxes in both TGs and AGs by improving the leaf area indices. Conversely, the temperature factors had a strong direct, negative effect on the C fluxes in TGs and a weak direct, positive effect on the C fluxes in AGs, emphasizing the divergent patterns of the C fluxes in TGs and AGs and their responses to climate change. Overall, this study enhances our knowledge on C sinks and various grassland hydrothermal sensitivities.

Pedogenesis of soils formed on jurassic calcareous sedimentary rock formations: A transect study in northern semi-arid highlands of Ethiopia

With the objective of examining soil characteristics, pedogenic processes and classification in association to local environmental and landscape attributes, a transect study was carried out in Hnitalo Wajerat district of Northern Ethiopia. Six pedons beded on shale and dolerite parent rocks were investigated. The soils were sandy loam to clay in texture, moderately porous, neutral to strongly alkaline, nonsaline, base-rich and calcareous. The dominant pedogenic processes prominent in soils of the area were calcification, vertization, argilluviation, melanization and colloidal eluviations. Mollic and ochric horizons were noticed on surface horizons, while cambic, calcic and vertic horizons were found to be the dominant subsurface horizons. Steep upslope areas were characterized by shallow gravelly soils with continuous hard rock. Shrink-swell cracks, colluvic materials and deep soils were prominent on flat areas. The soils of the area were classified as Leptosols/Entisols, Cambisols/Inceptisols, Calcisols/Aridisols and Vertisols. The study evidenced that the pedogenic processes and soil development were largely patterned by terrain positions, lithology and land use type.

Experimental evidence suggests dominance of species effect on the variability in hydrogen isotope fractionation between leaf wax compounds and source water

Quantifying the hydrogen isotope fractionation between leaf wax compounds and source water (εapp) is a prerequisite for hydrogen isotopic composition (δD) based paleo-hydrological studies. However, characterization of the εapp values, mostly done in field-based studies, are predominantly carried out in northern mid-latitude regions, as compared to that in the tropics. Further, the εapp values estimated in field-based studies are often associated with inherent uncertainties which could stem from (i) incorrect source water δD values, (ii) a species-effect, and (iii) varying climatic conditions (as in transect studies). Hence, to characterize the εapp values in tropics and to decouple the factors affecting the variability of εapp, we conducted an outdoor experiment wherein four evergreen and three deciduous angiosperm trees were grown under similar climatic conditions for 85 days with water of known δD value (−2‰). The εapp values in the studied species were −119 ± 23‰ (n = 14) for n-alkanes and −126 ± 27‰ (n = 12) for n-alkanoic acids of chain lengths C31 and C30, respectively. We observed inter-species variabilities in εapp values that are consistent with previous field and transect studies. As the plants were grown under similar climatic conditions and irrigated with water of the same δD value, the variability in εapp values observed here suggested that the species-specific hydrogen isotopic fractionation likely has a dominant control over the uncertainty in the community-averaged εapp values. Further, the εapp values of deciduous and evergreen species showed no systematic differences, suggesting that changes in the relative proportion of these taxa may not affect the community-averaged εapp and the reconstructed δD values of paleo-precipitation in angiosperm tree dominated catchments.

Holocene forest and land-use history of the Erzgebirge, central Europe: a review of palynological data

Abstract. The ongoing ecological conversion of mountain forests in central Europe from widespread Picea monocultures to mixed stands conceptually also requires a historical perspective on the very long-term, i.e. Holocene, vegetation and land-use dynamics. Detailed sources of information for this are palynological data. The Erzgebirge in focus here, with a maximum height of 1244 m a.s.l., represents an extreme case of extensive historical deforestation since the Middle Ages due to mining, metallurgy, and other industrial activities, as well as rural and urban colonisation. For this regional review we collected and evaluated 121 pollen diagrams of different stratigraphic, taxonomic, and chronological resolution. This number makes this region an upland area in central Europe with an exceptionally high density of palynological data. Using well-dated diagrams going back to the early Holocene, main regional vegetation phases were derived: the Betula–Pinus phase (ca. 11 600–10 200 cal yr BP), the Corylus phase (ca. 10 200–9000 cal yr BP), the Picea phase (ca. 9000–6000 cal yr BP), the Fagus–Picea phase (ca. 6000–4500 cal yr BP), the Abies–Fagus–Picea phase (ca. 4000–1000 cal yr BP), and the anthropogenic vegetation phase (ca. 1000–0 cal yr BP). Some diagrams show the presence or even continuous curves of potential pasture and meadow indicators from around 2000 cal BCE at the earliest. Even cereal pollen grains occur sporadically already before the High Medieval. These palynological indications of a local prehistoric human impact also in the higher altitudes find parallels in the (geo-)archaeologically proven Bronze Age tin placer mining and in the geochemically proven Iron Age metallurgy in the Erzgebirge. The pollen data show that immediately before the medieval clearing, i.e. beginning at the end of the 12th century CE, forests were mainly dominated by Fagus and Abies and complemented by Picea with increasing share towards the highest altitudes. According to historical data, the minimum of the regional forest cover was reached during the 17th–18th centuries CE. The dominance of Picea in modern pollen spectra is caused by anthropogenic afforestation in the form of monocultures since that time. Future palynological investigations, preferably within the framework of altitudinal transect studies, should aim for chronologically and taxonomically high-resolution and radiometrically well-dated pollen diagrams from the larger peatlands.

PEMETAAN PHYLUM ECHINODERMATA (KELAS ASTEROIDEA) DI ZONA LITORAL PANTAI PASIR PUTIH SITUBONDO

Class Asteroidea is a member of the phylum Echinodermata Asteroidea with high diversity, diversity will be found the similarities and differences that can be used as a key identification and classification. Pasir putih Situbondo beach has many invertebrate animals, particularly Asteroidea class that can be used to research about their abundance. The problems that arise are animals Echinodermata (classes Asteroidea ) What are some which can be found on the shore of Pasir Putih Situbondo beach can be used as a source data about their abundance. The results showed that the white sand beach Situbondo is found one type of the class Asteroidea namely Linckia laevigata acquisition this study of transects 1 to 15 only one transect contained starfish is on transect 14 wherein the transects , measuring 100 m sea littoral zone. Reason discovery of starfish on the shore of Pasir Putih Situbondo beach slightly due to limited types of starfish Asteroidea because in this month is going east wind season so that the starfish is hard to find.

Terrestrial transect study on pattern and driving mechanism of ecosystem services in the China–Mongolia–Russia Economic Corridor

This study quantified the gradient characteristics, trade-off/synergy relationships, and spatiotemporal changes in five key ecosystem services on the meridional (east-west transect of the Siberian Railway (EWTSR) and zonal (north-south transect of Northeast Asia (NSTNEA)) transects of the China–Mongolia–Russia Economic Corridor from 1992 to 2020. The results showed significant regional differentiation of ecosystem services. The improvement in ecosystem services in the EWTSR was significantly greater than in the NSTNEA, and the synergy between water yield and food production in the EWTSR improved the most from 1992 to 2020. The relationship between ecosystem services and different levels of dominant factors was significant, and population expansion had the greatest impact on the trade-off between habitat quality and food production. The leading drivers of ecosystem services in the NSTNEA were normalized vegetation index, population density, and precipitation. This study helps reveal regional differentiation characteristics and drive factors of ecosystem services in Eurasia.

Birds pre-adapted to a road in a heterogeneous and contiguous old-growth forest: a point transect study

Roads are present globally across all habitats and their negative impacts on the landscape are being increasingly reported. Yet often more is known about the identity of roadkill than how avian assemblages are impacted by roads. This study used 100 paired point counts by the road and 400 m into the forest interior to assess if the assemblages were different and determine what species may be impacted by the road. The study was undertaken along a highway cut through one of the world’s tallest forests – old-growth karri (Eucalyptus diversicolor) forest of south-western Australia. There was no overall significant difference in species richness and abundance between road and forest interior sites, although a small number of species (4.3%) did demonstrate preferences. Overall, we suggest that the limited significant differences resulted from: (1) the narrowness of the road with the forest canopy frequently extended fully across and (2) the natural variation found in eucalypt forests, which has aided the birds as a pre-adaptation to the presence of this road – because eucalypt forests are a heterogeneous array of streams and forest heterogeneity.

Spatial distribution of elephant populations and habitat characteristics in the Serbajadi-Lokop forest area of Aceh Indonesia

Understanding the factors influencing the spatial distribution of elephants can provide insight into the dynamics of their populations, thus helping elephant and habitat conservation efforts. Elephant habitat selection is an important key to knowing the existing conditions for the potential availability of elephant feed. This study aims to determine the spatial distribution of elephant populations and the characteristics of habitat selection as a route in the all-around forest area of Aceh Timur district. This research was carried out in the Serbajadi-lokop forest area. We observed areas that had high activity. The method used is direct observation of the 500 m long transect path on each transect and literature study to obtain information about the selection of elephant habitat areas. The results show that 22 areas are used as resting sites and elephant habitat areas. In the area, several types of plants with forest cover range from 25%-90%, the height of the land varies from 0-400 meters above sea level and the vegetation type consists of 14 primary forest locations, 6 secondary and 2 Plantation Areas . Overall, it can be concluded that the ecology of wild elephants in all-around forest areas has diverse characteristics and is in the lowlands and elephants have the selection of certain areas to rest within the forest area.

The influence of near-surface sediment hydrothermalism on the TEX86 tetraether-lipid-based proxy and a new correction for ocean bottom lipid overprinting

Abstract. The diversity and relative abundances of tetraether lipids produced by archaea and bacteria in soils and sediments are increasingly used to assess environmental change. For instance, the TetraEther indeX of 86 carbon atoms (TEX86), based on archaeal isoprenoidal glycerol dialkyl glycerol tetraether (iGDGT) lipids, is frequently applied to reconstruct past sea-surface temperatures (SSTs). Yet, it is unknown how the ratio fully responds to environmental and/or geochemical variations and if the produced signals are largely the adaptive response by Thaumarchaeota to oceanographic effects associated with climate or seasonal temperature changes in the upper water column. We present the results of a four push-core transect study of surface sediments collected along an environmental gradient at the Cathedral Hill hydrothermal-vent system in Guaymas Basin, Gulf of California. The transect crosses a region where advecting hydrothermal fluids reach 155 ∘C within the upper 21 cm below the seafloor (cm b.s.f.) close to the vent center to near-ambient conditions at the vent periphery. The recovered iGDGTs closest to the vent center experienced high rates of turnover with up to 94 % of the lipid pool being lost within the upper 21 cm b.s.f. Here, we show that the turnover is non-selective across TEX86 GDGT lipids and does not affect the ratio independently. However, as evident by TEX86 ratios being highly correlated to the Cathedral Hill vent sediment porewater temperatures (R2=0.84), the ratio can be strongly impacted by the combination of severe lipid loss coupled with the addition of in situ iGDGT production from archaeal communities living in the vent sediments. The resulting overprint produces absolute temperature offsets of up to 4 ∘C based on the TEX86H calibration relative to modern climate records of the region. The overprint is also striking given the flux of iGDGTs from the upper water column is estimated to be ∼ 93 % of the combined intact polar lipid (IPL) and core GDGT lipid pool initially deposited on the seafloor. A model to correct the overprint signal using IPLs is therefore presented that can similarly be applied to all near-surface marine sediment systems where calibration models or climate reconstructions are made based on the TEX86 measure.

Seasonal and Spatial Variations in Synechococcus Abundance and Diversity Throughout the Gullmar Fjord, Swedish Skagerrak.

The picophytoplankton Synechococcus is a globally abundant autotroph that contributes significantly to primary production in the oceans and coastal areas. These cyanobacteria constitute a diverse genus of organisms that have developed independent niche spaces throughout aquatic environments. Here, we use the 16S V3–V4 rRNA gene region and flow cytometry to explore the diversity of Synechococcus within the picophytoplankton community in the Gullmar Fjord, on the west coast of Sweden. We conducted a station-based 1-year time series and two transect studies of the fjord. Our analysis revealed that within the large number of Synechococcus amplicon sequence variants (ASVs; 239 in total), prevalent ASVs phylogenetically clustered with clade representatives in both marine subcluster 5.1 and 5.2. The near-surface composition of ASVs shifted from spring to summer, when a 5.1 subcluster dominated community developed along with elevated Synechococcus abundances up to 9.3 × 104 cells ml–1. This seasonal dominance by subcluster 5.1 was observed over the length of the fjord (25 km), where shifts in community composition were associated with increasing depth. Unexpectedly, the community shift was not associated with changes in salinity. Synechococcus abundance dynamics also differed from that of the photosynthetic picoeukaryote community. These results highlight how seasonal variations in environmental conditions influence the dynamics of Synechococcus clades in a high latitude threshold fjord.

Pesticides in the atmosphere and seawater in a transect study from the Western Pacific to the Southern Ocean: The importance of continental discharges and air-seawater exchange

The global oceans are known as terminal sink or secondary source for diffusive emission of organochlorine pesticides (OCPs) and selected current used pesticides (CUPs) into the overlaying atmosphere. Many pesticides have been widely produced worldwide, subsequently applied, and released into the environment. However, information on the occurrence patterns, spatial variability, and air-seawater exchange of pesticides is limited to easily accessible regions and, hence, only few studies are reported from the remote Southern Ocean. To fill this information gap, a large-scale ship-based sampling campaign was conducted. In the samples from this campaign, we measured concentrations of 221 pesticides. Both gaseous and aqueous samples were collected along a sampling transect from the western Pacific to the Southern Ocean (19.75° N-76.16° S) from November 2018 to March 2019. Twenty-seven individual pesticides were frequently (≥ 50%) detected in gaseous and aqueous samples. Tebuconazole, diphenylamine, myclobutanil, and hexachlorobenzene (HCB) dominated the composition profile in both phases. Spatial trends analysis in atmospheric and seawater concentrations showed a substantial level reduction from the western Pacific towards the Southern Ocean. Back-trajectory analysis showed that atmospheric pesticide concentrations were strongly influenced by air masses origins. Continental and riverine inputs are important sources of pesticides in the western Pacific and Indian Oceans. Atmospheric and seawater concentrations for the target pesticide residues in the Southern Ocean are low and evenly distributed due to the large distance from potential pollution sources as well as the effective isolation by the Antarctic Convergence (AC). Air-seawater fugacity ratios and fluxes indicated that the western Pacific and Indian Oceans were secondary sources for most pesticides emitted to the atmosphere, while the Southern Ocean was still considered to be a sink.

Post-Nourishment Changes of an Artificial Gravel Pocket Beach Using UAV Imagery

Monitoring and analysis of changes in the volume and area of nourished beaches is crucial to inform any beach renourishment programme. The aim of this study is to utilise UAV surveys and SfM photogrammetry to assess the beach nourishment performance of an artificial gravel beach exposed to a range of external forcing, including storms. The paper presents results from nineteen UAV surveys conducted between January 2020 and January 2021 at Ploče, an artificial beach in Rijeka (Croatia). The beach was nourished twice and eleven storm events, ranging from weak to strong, were recorded during this period. The Agisoft Metashape software was used to obtain point clouds and digital elevation models (DEMs) from UAV images; Matlab and CloudCompare were used for further analysis of the DEMs. The accuracy and precision of the DEMs was assessed and uncertainty levels of ±5 cm were applied to all derived DEMs. The study provides new insights into the response of the emerged part of the beach to storms. Predictably, the largest changes were recorded after the first storm following beach nourishment. The longshore variability in the beach response to storms was identified from full 3D point clouds. Most of the lost sediment was from the east side of the beach, while the rest of the beach aligned with the predominant wave direction through cross-shore and longshore processes. Offshore/onshore sediment exchange between the lower and upper beach face on the western side manifested itself in beach profile steepening and berm formations. Overall, changes in beach volume and area were small, indicating that this artificial beach is relatively stable. The embayed layout following the natural coastal configuration appears to be effective in retaining nourished sediment on the beach. This work highlights the need to consider pocket embayed beaches in three dimensions, as traditional transect studies can overlook the three-dimensional behaviour. This study also highlighted the wider potential of UAVs and SfM for studies of high-resolution elevation changes on natural and artificial beaches, as well as for coastal monitoring of beach nourishment.

Holocene variability in sea‐ice conditions in the eastern Baffin Bay‐Labrador Sea – A north–south biomarker transect study

Reconstructions of sea‐surface conditions during the Holocene were achieved using three sediment cores from northeastern Baffin Bay (GeoB19948‐3 and GeoB19927‐3) and the Labrador Sea (GeoB19905‐1) along a north–south transect based on sea‐ice IP25 and open‐water phytoplankton biomarkers (brassicasterol, dinosterol and HBI III). In Baffin Bay, sea‐surface conditions in the Early Holocene were characterized by extended (early) spring sea ice cover (SIC) prior to 7.6 ka BP. The conditions in the NE Labrador Sea, however, remained predominantly ice‐free in spring/autumn due to the enhanced influx of Atlantic Water (West Greenland Current, WGC) from 11.5 until ~9.1 ka BP, succeeded by a period of continued (spring–autumn) ice‐free conditions between 9.1 and 7.6 ka BP corresponding to the onset of Holocene Thermal Maximum (HTM)‐like conditions. A transition towards reoccurring ice‐edge and significantly reduced SIC conditions in Baffin Bay is evident in the Middle Holocene (~7.6–3 ka BP) probably caused by the variations in the WGC influence associated with the ice melting and can be characterized as HTM‐like conditions. These HTM‐like conditions are predominantly recorded in the NE Labrador Sea area shown by (spring–autumn) ice‐free conditions from 5.9–3 ka BP. In the Late Holocene (last ~3 ka), our combined proxy records from eastern Baffin Bay indicate low in‐situ ice algae production; however, enhanced multi‐year (drifted) sea ice in this area was possibly attributed to the increased influx of Polar Water mass influx and may correlate with the Neoglacial cooling. The conditions in the NE Labrador Sea during the last 3 ka, however, continued to remain (spring–autumn) ice‐free. Our data from the Baffin Bay–Labrador Sea transect suggest a dominant influence of meltwater influx on sea‐ice formation throughout the Holocene, in contrast to sea‐ice records from the Fram Strait area, which seem to follow predominantly the summer insolation trend.