Coastal Sites Research Articles

Direct effects of ocean alkalinity enhancement in the Baltic Sea–results from in-silico experiments

To achieve carbon neutrality, ocean alkalinity enhancement (OAE) is currently being researched as a marine option for carbon dioxide removal (CDR). The approach of releasing calcite near the sediments and using the effect of enhanced mineral solubility in the pore water for more efficient dissolution may be promising in the Baltic Sea. The Baltic Sea is considered a potential application site for this method, as, in contrast to other seas, it is partly undersaturated in calcite even at shallow depths. However, the possible implications of this method, specifically if applied in coastal settings, are still poorly understood. Therefore, using a coupled hydrodynamic and biogeochemical ocean model of the Baltic Sea, we simulated the release of calcite near the sediment as a possible strategy for OAE. Simulations were run with and without enhanced solubility in the pore water for two release locations, one in shallow coastal water and one in a deep basin. While enhanced solubility by oxic mineralisation did not make a difference for the deep basin, it substantially changed the achievable calcite dissolution rates at the coastal site and therefore the potential CO2 removal. Here, our simulations provide a lower and an upper limit of the effectiveness of calcite dissolution. The release locations differed considerably in magnitude and timescales of CO2 uptake. As the saturation level of calcite appears to be the main limiting factor of the method, the CO2 removal potential of a release location cannot be upscaled infinitely by adding more calcite. Our results demonstrate a potential for OAE using calcite in the Baltic Sea. We used the model results on average and maximum changes in alkalinity and pH to reflect on potential environmental impacts based on a review of the existing literature. However, safe and responsible deployment of this CDR method in the Baltic Sea requires further research on localized dissolution rates, the alkalinity budget of the Baltic Sea and the environmental implications of OAE using calcite.

Tropical Cyclone Response in Annual Tree Growth at Three Different Coastal Sites Along the Gulf of Mexico, USA

Coastal forests are highly vulnerable to disturbances from tropical cyclones (TCs), yet the long-term impacts of storm surges on tree growth remain understudied. This study examines the relationship between TC-induced storm surges and annual tree-ring growth in Pinus elliottii at three coastal sites along the northern Gulf of Mexico. Using dendrochronological methods, we analyzed total ring width, earlywood, and latewood growth patterns to assess suppressions in response to past TC activity. Our results indicate that storm surge events consistently cause growth suppression, with recovery periods averaging two to three years. However, suppression patterns vary by site, with trees in more protected locations displaying stronger correlations with TC storm surge events, while those in chronically stressed environments exhibit frequent growth limitations independent of TCs. For example, only 38% of suppression events at the unprotected Gulf State Park correspond with TC storm surge events, and this increases to 67% at the protected Weeks Bay NERR site. Additionally, latewood ring width corresponds with TC storm surge events more than total or earlywood ring width. These findings highlight the complexity of TC impacts on coastal tree growth, emphasizing the importance of site-specific factors such as topographic position and hydrological conditions. Understanding these interactions is critical for improving paleotempestology reconstructions and informing forest management strategies in coastal environments facing increasing TC activity due to climate change.

Tidal dynamics and seasonal hydrological variations influencing organic carbon distribution in the Yangtze River estuary.

Tidal dynamics and seasonal hydrological variations influencing organic carbon distribution in the Yangtze River estuary.

Two sides of the same coin: Weathering differences of plastic fragments in coastal environments around the globe.

Two sides of the same coin: Weathering differences of plastic fragments in coastal environments around the globe.

Tracing microplastics in environmental sources and migratory shorebirds along the Central Asian Flyway.

Tracing microplastics in environmental sources and migratory shorebirds along the Central Asian Flyway.

Widespread Distribution of chs-1 Mutations Associated with Resistance to Diflubenzuron Larvicide in Culex pipiens Across Italy, Reaching Virtual Fixation in the Venetian Lagoon.

Control interventions against mosquito larvae are the primary measure to reduce the adult abundance and risk of arbovirus outbreaks in Europe. One of the most commonly used larvicides in Italy is diflubenzuron (DFB), which targets chitin synthase 1 (chs-1), interrupting the normal development of larvae into adults. Recent studies identified high levels of DFB resistance in Culex pipiens populations from Emilia-Romagna (Italy) associated with I1043L/M/F mutations at position 1043 of the chs-1 gene. The aim of the present study was to assess the circulation of 1043 resistance alleles in Cx. pipiens populations across Italy, outside Emilia-Romagna, with a focus on the Veneto region. Overall, 1032 specimens were genotyped. The 1043L allele was found in all examined Italian regions (Trentino-Alto Adige 19-36%; Veneto 0-91%; Piemonte 11%; Liguria 28%; Lazio 0-8%; Puglia 5%). The highest frequencies (up to >90%) were observed in the Venetian lagoon, where 1043M was also detected (6-11%). Overall, the relatively low frequencies of 1043 mutations despite extensive and longstanding use of DFB in Italy suggest a high fitness cost worthy of further investigations, while their extremely high frequencies in coastal touristic sites point to these sites as the most relevant for resistance monitoring and larvicide rotation.

Damage triggered by bioerosion and surface residence time in Holocene shell beds from Brazil

Holocene shell beds along the Brazilian coast provide critical records of sea level variations influenced by climatic changes. This study examines the taphonomic implications of bioerosional traces in bioclastic accumulations from coastal sites in Rio de Janeiro State, Brazil. By integrating sedimentological, taphonomic, and taxonomic data, the relationship between bioerosion and shell damage signatures was explored, focusing on three Quaternary localities rich in mollusk shell remains. Detailed analyses using thin sections, X-ray microtomography, and compaction tests identified four distinct bioerosion incipient- traces: Entobia, Caulostrepsis, Meandropolydora, and Oichnus. The results show that the one active depositional site has a higher proportion of bioclasts with bioerosion but fewer shells with taphonomic damage compared to two Holocene sites. The higher fragmentation rates at Holocene sites are linked to longer exposure times of bioeroded shells before final burial. These differences suggest that shorter exposure times lead to lower fragmentation rates despite higher bioerosion levels. Mechanical tests confirmed that bioeroded shells are more fragile, breaking into angular fragments, thereby contributing significantly to shell damage. Thus, bioerosion coupled with moderate surface residence times, plays a crucial role in shell fragmentation, with hydrodynamic conditions being a secondary agent of shell damage in high-energy environments.

Role of microbial mats in the genesis of soft‐sediment deformation structures in a siliciclastic environment

ABSTRACTThis study addresses gaps in existing knowledge about what triggers deformation structures in soft sediments and the siliciclastic rocks that form from them. These structures are extremely diverse due to the variety of processes and agents that cause them, although several studies have been carried out to disentangle the triggering mechanisms of their formation. This study considers the role of microbial mats (with characteristic millimetre to centimetre‐heterolithic lamination) in the formation of soft sediment deformation structures, and proposes what processes are involved in their formation. It is hypothesized that wet microbial mats exhibit extremely flexible and plastic deformation that may be analogous to some structures found in sedimentary rocks. The present study documents convoluted sedimentary structures characterized by deformation, which were identified at a depth of 10 to 15 cm in a coastal sedimentary supratidal flat subject to flooding during storm surges and studied using morphological and petrographic analysis. The research was conducted at a modern coastal site characterized by sediments colonized by thick microbial mats. Currents during storm surges create deformed microbially‐induced sedimentary structures, such as metre‐scale microbial roll‐ups, in which the laminated microbial mats exhibit multiple folds. Additionally, microbial folds and gas domes, characterized by a convex‐upward microbial mat, have a cavity when they form that is filled with sand due to liquefaction and/or fluidization during subsequent flooding by storm surges. These processes are related to the incoming seawater and the height of the water column (up to 70 cm) above the microbial surface, which is also influenced by wave action. The results may help to provide new insights into the genesis of some soft‐sediment deformation structures in the coastal environment, documenting a non‐seismic mechanism of formation in siliciclastic deposits.

Strengthening the evidence for seasonal intertidal exploitation in Mesolithic Europe and new insights into Early Holocene environmental conditions in the Bay of Biscay from the oxygen isotope composition of Phorcus lineatus (da Costa, 1778) shells

Strengthening the evidence for seasonal intertidal exploitation in Mesolithic Europe and new insights into Early Holocene environmental conditions in the Bay of Biscay from the oxygen isotope composition of Phorcus lineatus (da Costa, 1778) shells

Resilience of coastal upland vegetation post-Hurricane Sandy

Hurricane Sandy hit the coastal urbanized matrix of Jamaica Bay, New York in October 2012 resulting in damage to its fringing coastal upland vegetation. Sand deposition and residual standing water from flooding tested the resilience of these habitats. Three years post-Sandy, we conducted detailed vegetative surveys in 24 sites around the bay where sand deposition and flooding occurred. We compared the damaged locations with paired adjacent undisturbed areas to evaluate the differences in vegetative resilience. Our surveys in the coastal upland sites disturbed by sand deposition and flooding showed no differences in non-native plant species richness, percent cover, or composition compared with their undamaged counterparts. Further, there was no evidence that the hurricane facilitated further invasion of non-native plant species, either as an increase in abundance of existing non-native species or invasion of new non-native plant species. We found trends in a few specific survey areas, where site conditions allowed for a higher degree of damage as measured by a decrease in vegetative percent cover. We conclude that even hurricane level disturbances did not change the vegetative character of our study area’s shore and that the upland vegetation in this area demonstrated resilience despite substantial storm damage.

Spatial and temporal predictability drive foraging movements of coastal birds

BackgroundTemporal and spatial predictability of food resources are critical to the foraging efficiency of central place foragers. While site fidelity is often assessed in this context, route fidelity, or the repeated use of the same path while traveling, and temporal aspects of habitat predictability have received less attention. We examined how the use of urban, coastal, and offshore habitats influenced spatiotemporal predictability in the foraging patterns of herring gulls (Larus argentatus) and great black-backed gulls (L. marinus). Since gulls show higher site fidelity when foraging in urban habitats, we predicted that these trips would also show higher route fidelity. Similarly, we predicted that gulls foraging in coastal habitats would adapt the timing of foraging trips relative to tides.MethodsWe analyzed GPS tracks of herring gulls (n = 79) and great black-backed gulls (n = 37)—between 2016–2022 from four nesting colonies whose surrounding areas varied in their degree of urbanization. Fréchet distance, which is defined as the repeated use of the same path while traveling, was used to assess route fidelity, within colonies and between habitat types. We also compared the consistency of foraging trip timing relative to tidal stage and day of week, respectively, across habitat types.ResultsNeither herring nor great black-backed gulls showed higher route fidelity in urban habitats. Herring gulls showed direct travel between urban foraging sites but revisited sites in different orders, suggesting that a mosaic map may be used to navigate between known urban foraging sites. Herring and great black-backed gulls that foraged at coastal sites exhibited patterns in trip timing in relation to the tidal cycle, with foraging primarily occurring at or around low tide. Herring gulls in urban environments foraged more on Fridays and weekends, possibly due to increased or altered human activities on these days.ConclusionsOur results demonstrate the importance of spatial memory and spatiotemporal predictability of gull foraging habitats and highlight the extent to which gulls adjust their movements based on their foraging habitats.

Study on the Influence of Heat Exchange of Static Drill Rooted Energy Pile on the Consolidation of Coastal Soft Soil Site

ABSTRACTThe use of static drill‐rooted energy piles in deep soft soil foundations causes thermal exchange between the piles and the surrounding soil, resulting in excess pore pressure and consolidation settlement in the soft soil layer around the piles, which affects the long‐term deformation of the site. To investigate the impact of the operation of this novel energy pile on the consolidation of the soil around the pile, a simulation analysis was conducted using the ABAQUS software to assess the soil temperature, pore pressure, and consolidation settlement around the static drill rooted energy pile group under a 120‐day heating and cooling cycle. The research findings indicated that the temperature change decreased as the distance between the soil and the pile increased, resulting in less thermal consolidation settlement and pore pressure variations. Heating conditions (ΔT = 18.7°C) resulted in a 17°C increase in the soil temperature below the center of the pile group, with temperature changes becoming negligible beyond 8D. The maximum pore pressure variations in the soil occurred at 2D and 6D distances from the pile, with values of 1.24 and 1.12 kPa, respectively. Under heating conditions, the surface settlement at a 2D distance from the pile group was 6.19 mm, which increased to about 10 mm under heating–cooling cycles. These research findings provide a foundation for analyzing the environmental impact of novel energy piles in coastal areas.

Location and natural history are key to determining impact of the 2021 atmospheric heatwave on Pacific Northwest rocky intertidal communities

IntroductionIn late June 2021, the Pacific Northwest region of the United States and Canada experienced an unprecedented atmospheric heatwave that co-occurred with one of the lowest day-time tide series of the year. Several consecutive days of air temperatures 10-20°C above normal, coupled with mid-afternoon low tides proved deadly for many rocky intertidal organisms, which live at the margin of land and sea.MethodsTo assess short (weeks) and longer-term (1 year) impacts of the heatwave on rocky intertidal communities, we used long-term monitoring data collected annually at 16 sites throughout Washington State.Results and discussionOur findings indicate that impacts were most severe at sites within the Salish Sea region of WA, where peak low tides occurred during the hottest, mid-afternoon hours. Focal species assemblages at Olympic coast sites, where low tides occurred in the morning, were largely spared. In addition, while the heatwave was associated with substantial short-term changes in acorn barnacle, rockweed, and California mussel assemblages, lasting impacts (1 year) were only observed in the mussel assemblage at the one Salish Sea site where this species is common. These findings will aid in forecasting both short-term and longer lasting impacts of future heatwave events and help direct potential mitigation efforts to regions and species assemblages where impacts will likely be greatest.

Multiple eco-regions contribute to the seasonal cycle of Antarctic aerosol size distributions

Abstract. In order to reduce the uncertainty of aerosol radiative forcing in global climate models, we need to better understand natural aerosol sources which are important to constrain the current and pre-industrial climate. Here, we analyse particle number size distributions (PNSDs) collected during a year (2015) across four coastal and inland Antarctic research bases (Halley, Marambio, Dome C and King Sejong). We utilise k-means cluster analysis to separate the PNSD data into six main categories. “Nucleation” and “bursting” PNSDs occur 28 %–48 % of the time between sites, most commonly at the coastal sites of Marambio and King Sejong where air masses mostly come from the west and travel over extensive regions of sea ice, marginal ice and open ocean and likely arise from new particle formation. “Aitken high”, “Aitken low” and “bimodal” PNSDs occur 37 %–68 % of the time, most commonly at Dome C on the Antarctic Plateau, and likely arise from atmospheric transport and ageing from aerosol originating likely in both the coastal boundary layer and free troposphere. “Pristine” PNSDs with low aerosol concentrations occur 12 %–45 % of the time, most commonly at Halley, located at low altitudes and far from the coastal melting ice and influenced by air masses from the west. Not only the sea spray primary aerosols and gas to particle secondary aerosol sources, but also the different air masses impacting the research stations should be kept in mind when deliberating upon different aerosol precursor sources across research stations. We infer that both primary and secondary components from pelagic and sympagic regions strongly contribute to the annual seasonal cycle of Antarctic aerosols. Our simultaneous aerosol measurements stress the importance of the variation in atmospheric biogeochemistry across the Antarctic region.

Importance sampling of seismic tsunami sources with near-field emphasis for inundation PTHA: benchmarking with complete ensembles

SUMMARY Site-specific Probabilistic Tsunami Hazard Assessment (PTHA) is a powerful tool for coastal planning against tsunami risk. However, its typically high computational demands led to the introduction of a Monte Carlo Stratified Importance Sampling (SIS) approach, which selects a representative subset of scenarios for numerical inundation simulations. We here empirically validate this sampling approach, for the first time to our knowledge, using an existing extensive data set of numerical inundation simulations for two coastal sites in the Mediterranean Sea (Catania and Siracusa, both located in Sicily, Italy). Moreover, we propose a modified importance sampling function to prioritize seismic tsunami scenarios based on their arrival time at an offshore point near the target site, in addition to their wave amplitude and occurrence rate as leveraged in the previous work. This sampling function is applied separately in each earthquake magnitude bin, and allows denser sampling of near-field earthquakes to whose variations tsunamis are very sensitive. We compare the confidence intervals of the offshore PTHA estimates obtained with the new and the original importance sampling functions. Then, we benchmark our onshore PTHA estimates obtained with both functions against the inundation PTHA calculated using the full set of scenarios. We also test the assumption that onshore random errors follow a normal distribution, as found previously for the offshore case. As a result of the benchmarks, we find that the SIS approach works satisfactorily. Introducing the arrival time as an additional sampling factor enhances the precision of the estimates of both the mean and the percentiles for the two coastal sites considered. With this modification it is possible to deal efficiently with heterogeneous near-field earthquake sources involving coastal deformation at Catania and Siracusa, in addition to regional crustal and subduction sources. By comparing the sampling errors with the model (epistemic) uncertainty, an optimal trade-off between the number of simulations employed and the uncertainty of the PTHA model can be found, even for such a complex situation. A relatively small number of scenarios, on the order of a few thousand, is sufficient to perform site-specific PTHA for practical applications. These numbers correspond to 4–8 per cent of the already reduced ensembles used in previous assessments at the same sites.

An Interhemispheric Difference in Atmospheric Gaseous Elemental Mercury Isotopes Reveals a New Insight in Oceanic Mercury Emissions

AbstractOceanic emission of gaseous elemental mercury (Hg0 or GEM) is an important source for atmospheric mercury (Hg), but existing estimates of global gross oceanic Hg0 emissions are highly variable (800–7,220 Mg yr−1). This study measured atmospheric GEM concentrations and isotopic compositions at two coastal sites in Terengganu, Malaysia, a region that receives air masses from both hemispheres, during 2019–2021 to diagnose the amount of oceanic Hg0 emissions. Significantly lower mean (±1sd) concentration (1.28 ± 0.20 ng m−3), Δ199Hg (−0.23 ± 0.03‰), and Δ200Hg (−0.066 ± 0.018‰) and significantly higher δ202Hg (0.43 ± 0.12‰) were observed during the wet season when air masses were predominantly from the Southern Hemisphere, compared with those (mean concentration, Δ199Hg, Δ200Hg, and δ202Hg of 1.77 ± 0.09 ng m−3, −0.17 ± 0.03‰, −0.045 ± 0.023‰, and 0.25 ± 0.11‰, respectively) during the dry season when air masses were predominantly from the Northern Hemisphere, suggesting interhemispheric difference in GEM concentrations and its isotopic compositions. Using a Δ200Hg mass balance model, we estimated that the oceanic Hg0 emissions from HgII reduction should be below 2,250 ± 891 Mg yr−1 (±1sd), which is at the low‐end range of the literature reported values. We then used the constrained value as emission input to a three‐dimensional atmospheric Hg isotope model and reproduced well the global distributions and interhemispheric gradient of atmospheric GEM Δ200Hg. The findings from the present study will help to better understand Hg0 emissions from global oceans and their roles in global atmospheric Hg cycling.

Three thousand years of oyster fisheries: a view from Southeast Queensland, Australia

Oysters are an almost ubiquitous presence in coastal archaeological sites globally. Southeast Queensland is no exception, with oysters frequently the dominant taxon in midden deposits. It has been estimated the total number of oysters at Booral Shell Mound in the Great Sandy Strait to be more than 5.9 million individuals. This paper moves beyond just the number of oysters to examine the structure of populations within the deposits at two Southeast Queensland sites, Booral Shell Mound and White Patch 3, from an Applied Historical Ecology approach. In doing so, the nature and sustainability of First Nations marine resource exploitation may be determined. Additionally, environmental factors influencing molluscan population dynamics can be elucidated. Historical accounts provide insights into observed collection practices in the early colonial period, as well as the persistence of First Nations oystering and other marine resource exploitation in the mid-late 19th century in response to participation in the wider economy of early Brisbane. Reasons for the late nineteenth-early Twentieth century collapse of Southeast Queensland oyster populations are examined and attempts to revive the oyster industry reviewed.

Strategic Participatory Planning and Social Management for Clustering Maritime Cultural Heritage: A Case Study of the West Pagasetic Gulf, Greece

Maritime cultural heritage (MCH) in Greece remains poorly explored and underutilized due to several key challenges, including the dispersed locations of heritage sites, limited community engagement in decision-making, and the absence of a well-structured decentralized governance framework. This paper addresses these issues by focusing on strategic planning and social management to better integrate coastal and maritime heritage sites into both tourism development and the everyday life of local communities. Our research examines the creation of local social networks and participatory decision-making processes, as well as the adoption of innovative solutions such as maritime spatial planning (MSP) and soft projects to connect scattered cultural sites into cohesive, integrated clusters. The aim is to foster tourism and economic development through collaboration with local stakeholders. The findings emphasize the establishment of a social network for cultural heritage management in the West Pagasetic region of Magnesia, Greece, which culminated in a strategic plan to link cultural sites through soft projects and consultations. This process included a participatory workshop and the creation of a Community of Practice (CoP) that brought together professionals from the heritage, tourism, and planning sectors.

Significant Impact of a Daytime Halogen Oxidant on Coastal Air Quality.

Chlorine radicals (Cl·) are highly reactive and affect the fate of air pollutants. Several field studies in China have revealed elevated levels of daytime molecular chlorine (Cl2), which, upon photolysis, release substantial amounts of Cl· but are poorly represented in current chemical transport models. Here, we implemented a parametrization for the formation of daytime Cl2 through the photodissociation of particulate nitrate in acidic environments into a regional model and assessed its impact on coastal air quality during autumn in South China. The model could reproduce over 70% of the high Cl2 level measured at a coastal site, revealing a discernible presence of Cl2 and released Cl· in coastal and adjacent areas. Abundant Cl2 alters the oxidative capacity of the atmosphere, consequently increasing O3 (6-12%) and PM2.5 (10-16%) concentrations in high-NOx areas and reducing O3 (3%) concentration in low-NOx areas. Accounting for chlorine chemistry shifts the O3 - precursor relationships from VOC limited to mixed or NOx -limited regimes, enhancing the benefits of NOx emission reduction in mitigating O3 pollution. Our findings suggest that tightening emission control for two acidic pollutants, NOx and SO2, would alleviate reactive Cl· production and its adverse impact on air quality.

Survival and growth of three boreal conifer species transplanted to warm sites: Implications for responses to global warming and extreme climatic events

Understanding the responses of boreal conifers to climate change are essential for future mitigation and adaptation. In this study, three-year-old seedlings of three Japanese boreal conifers including Sakhalin fir, Yezo spruce, and Sakhalin spruce, naturally found in Hokkaido, Japan, were transplanted in spring 2016 to a cool control and two warm (air-dried interior and humid coastal) sites. We investigated survival, height, and ecophysiological traits based on three parameters: stable carbon isotope discrimination (δ13C), specific leaf area (SLA), and leaf mass specific nitrogen concentration (N) of seedlings during experiments. The survival rates of two spruce species were gradually significantly lower in warm sites, while that of Sakhalin fir did not significantly differ among sites. The relative growth rate (RGR) of two spruce species was significantly lower in the warm-interior site than in both cool control and warm-coastal sites in 2018, although in 2017 the RGR of two spruce species was lower in the warm sites than in cool control site. The less negative δ13C value in 2018 revealed that a vapor pressure deficit might decrease the spruces’ RGR via stoma closure in the warm-interior site. We found that Sakhalin fir would be less sensitive to climate change than two spruce species.