Offshore Areas Research Articles

Behaviour of a laterally loaded short-finned pile located on sloping ground

Finned piles are considered a novel solution to replace large-diameter piles supporting transmission towers, bridge abutments and so on and are often implemented beneficially for mooring dolphins in offshore areas. This experimental investigation was attempted to examine the lateral response of short-finned piles installed in the proximity of a typical slope of 1V:2H. The 1g model testing of regular and finned piles at different load eccentricities comprised three lateral load tests on horizontal ground and 24 lateral load tests on the slope with the pile at varying distances from the crest. The fin efficiency was observed to decrease with an increase in load eccentricity due to the poorer mobilisation of soil resistance on fins at higher load eccentricities. The finned pile installed at a distance of two pile diameters away from the crest exhibited a net efficiency closer to unity, indicating its ability to improve the receptible subgrade reaction near a loose and steeper sandy slope. An in-depth study of soil resistance developed in the finned pile located at the crest reveals that the fins effectively reduced the soil resistance, specifically in the region above the pivot point.

Evidence of new diapiric structures in the southern Adria Plate (Eastern Margin of Tethyan Ocean): Implications for Triassic paleogeography and evaporites remobilization during subduction/collision (Northern Ionian Sea, Central Mediterranean)

It has long been recognized that the Adria Plate, as well as the Dinaric-Hellenic sector, contains a large volume of Triassic salt associated with diapirism, and it is well known that Triassic evaporites in the Mediterranean Sea region were deposited over epicratonic platforms surrounding the Mesozoic passive margin of Tethys Ocean. However, the real extent of these evaporites is still unknown; especially in the deep-water offshore area where publicly available seismic reflection profiles are scarce and petroleum exploration wells are missing. Several authors highlighted the presence of Triassic salt structures, mostly triggered by Meso-Cenozoic compressions and associated with fold-and-thrust belts. Both the lack of data and the later compressions contribute to hiding how a diapiric structure, formed in a passive margin and characterized by dome's geometry, is remoulded to assume a teardrop geometry typical of diapirs in fold-and-thrust belts. Two end members of diapiric structures are discussed: extensional structures formed in a passive margin, and compressional structures formed in a fold-thrust belt. The transformation of one end-member into the other is not well known. In the Northern Ionian Sea, the Apulian foreland, belonging to the southernmost termination of the Adria Plate and considered one of the largest preserved Mesozoic passive margin block of the Tethys Ocean, is a deep-water area associated with the opposing fronts of the nearby Calabrian Arc/Apennines and Dinaric-Hellenic Chains since the Cretaceous. Therefore, it represents an ideal area for investigating both the real extent of Triassic evaporites and the transformation of the diapiric structures under different regional geodynamic contexts.Based on seismic reflection profiles but no petroleum exploration wells, we present evidence of Triassic evaporites in the deep-water portion of the Apulian foreland, as indicated by the interpretation of two diapiric structures never described previously. These two new diapirs likely formed from inherited Mesozoic salt structures such as pillows and/or salt domes. The identification of halokinetic-related sequences affecting the Plio-Quaternary foreland sediments allows constraining the polyphaser evolution of the two diapirs. We suggest they are reactivated in response to the compressive stresses transmitted by the nearby Calabrian Arc/Southern Apennines and Hellenides. But, after the Middle Pleistocene, extensional tectonics, related to Adria Plate flexuring, acted again, and the diapirs were cross-cut by normal faults. These observations and findings are integrated into the geological context that controls the fundamental features of the diapirs, providing new insights on the fate of diapiric structures formed in a passive margin, later involved in a subducting and colliding plate, and before they become part of a fold-and-thrust belt. Furthermore, the study provides new constraints on the Triassic paleogeographic reconstruction of the Northern Ionian and Central Mediterranean Seas at the continental margin of the Tethys Ocean.

Monitoring Suspended Sediment Concentration in the Yellow River Estuary and Its Vicinity Waters on the Basis of SDGSAT-1 Multispectral Imager

Suspended sediments have profound impacts on marine primary productivity and the ecological environment. The Yellow River estuary and its vicinity waters, with a high dynamic range of suspended sediment concentration (SSC), have important eco-environmental functions for the sustainable development in this region. The multispectral imager (MI) on board China’s first Sustainable Development Goals Science Satellite 1 (SDGSAT-1) features seven high-resolution bands (10 m). This study employs multispectral imagery obtained from SDGSAT-1 with single-band and band-ratio models to monitor the SSC in the Yellow River estuary and its vicinity waters. The results show that SDGSAT-1 images can be used to estimate the SSC in the Yellow River estuary and its vicinity waters. The overall pattern of the SSC exhibits a notable pattern of higher concentrations in nearshore areas and lower concentrations in offshore areas, and the retrieved SSC can attain values surpassing 1000 mg/L in nearshore areas. The R2 values of both the single-band and the band-ratio models for SSC inversion exceed 0.7. The single-band model R(854) demonstrates superior performance, achieving the highest R2 value of 0.93 and the lowest mean absolute percentage error (MAPE) of 44.04%. The single-band model based on SDGSAT-1 R(854) tends to outperform the band-ratio models for waters with algal blooms, which may be used for inversions of SSC and/or suspended particulate matter (SPM) in the waters full of algal blooms and suspended sediments. The monitoring results by SDGSAT-1 suggest that the complex SSC distributions in the Yellow River estuary and its vicinity waters were highly impacted by the river sediments discharge, tide, currents and wind-induced waves.

Acoustic ecology of harbour porpoise (Phocoena phocoena) between two U.S. offshore wind energy areas

Abstract Offshore wind energy is set to develop rapidly in waters off the east coast of the United States. There is considerable overlap between areas proposed for offshore wind development and harbour porpoise habitats in the Gulf of Maine (GOM) and Southern New England waters. Baseline data on the occurrence and foraging activity of porpoises was collected using 10 echolocation-click detectors (F-PODs) from 2020 to 2022. Porpoises were present year-round in the GOM with peak detections in the summer and fall. In line with previous reported distribution patterns, porpoise occurrence in Southern New England was high in fall, winter and spring, but porpoises were largely absent in the summer. One site in the GOM, Mount Desert Rock (MDR), was an anomaly as porpoise detections here were highest in the winter. On average, foraging was identified in 29% of all porpoise detections, with the most foraging occurring at MDR (53%). Results from generalized additive models suggest that time of year, hour of day, lunar illumination, and temperature are significant contributors to porpoise presence and/or foraging effort. European studies show that harbour porpoises exhibit behavioural changes, disruption of foraging and displacement due to wind energy development. Therefore, early identification of areas of importance, mitigating impacts, and monitoring changes is essential for the protection of this species in US waters.

Comparison of Extreme Wind and Waves Using Different Statistical Methods in 40 Offshore Wind Energy Lease Areas Worldwide

With the ongoing global drive towards renewable energy, several potential offshore wind energy lease areas worldwide have come into focus. This study aims to estimate the extreme wind and wave conditions across several newly designated offshore wind lease sites spanning six continents that are crucial for risk assessment and the design of offshore wind turbines. Firstly, the raw data of wind speeds and wave heights prevailing in these different lease areas were obtained. Following this, an in-depth extreme value analysis was performed over different return periods. Two principal methodologies were applied for this comparative study: the block-maxima and the peaks-over-threshold (POT) approaches. Various statistical techniques, including the Gumbel method of moments, Gumbel maximum likelihood, Gumbel least-squares, and the three-parameter GEV, were employed under the block-maxima approach to obtain the distribution parameters. The threshold for the POT approach was defined using the mean residual life method, and the distribution parameters were obtained using the maximum likelihood method. The Gumbel least-squares method emerged as the most conservative estimator of extreme values in the majority of cases, while the POT approach generally yielded lower extreme values compared to the block-maxima approach. However, the results from the POT approach showed large variations based on the selected threshold. This comprehensive study’s findings will provide valuable input for the efficient planning, design, and construction of future offshore wind farms.

Marine resistome of a temperate zone: Distribution, diversity, and driving factors across the trophic gradient

Marine and ocean environments are the most widespread habitats in the world but are still the least studied from the aspect of antibiotic resistance. The indigenous and tetracycline (TET)- and sulfamethoxazole (SXT)-resistant planktonic bacterial communities were simultaneously investigated for the first time along a trophic gradient of a temperate zone, regarding their taxonomic and functional structures as well as biotic and abiotic factors affecting their dynamics as vehicles of antibiotic resistance genes (ARGs), thus impacting the ARGs distribution at seasonal and spatial scales.A total of 80 microbiomes, recovered seasonally from bottom layer and surface waters along a 68-km transect from wastewater-impacted estuary to coastal and pristine open sea in the central Adriatic (Mediterranean Sea), were analysed using 16S rRNA amplicon sequencing, PICRUSt2 bioinformatics and extensive biostatistics. Eighty-one bacterial phyla were identified, with majority (n = 49) in summer when communities were found to be more species enriched across the gradient. Microbial diversity was more site-specific and pronounced in surface microbiomes in winter. Nevertheless, both richness and community diversity decreased with distance from the coast. Although the microbiomes from human-influenced sites significantly differed from those in oligotrophic offshore area, Proteobacteria were still the most abundant phylum during both seasons at the surface and seabed along the gradient, and the major contributors to the marine resistome regarding native and TET- and SXT-resistant microbial communities. Resistome structure was more diverse in winter, whereas peptide, vancomycin and multidrug resistance modules predominated regardless of season, trophic status, or antibiotic. However, multidrug, beta-lactam resistance modules as well as macrolide, phenicol, aminoglycoside, and particularly imipenem resistance genes were much more frequent in winter, suggesting that the diversity of indigenous resistomes is highly dependent on seasonal variations of the water column, driven by thermohaline stratification and nutrients. Moreover, several pathogenic genera stood out as important carriers of multiple resistance traits in TET- and SXT-related resistomes in both seasons, particularly Acinetobacter, Vibrio, Bacillus and Pseudomonas, beside which Proteus, Serratia and Bacteroides prevailed in native resistomes.This study evidenced seasonal and spatial variations of the marine microbiome and resistome and their driving forces along the trophic gradient, providing a comprehensive insight into the diversity and distribution of antibiotic resistance in the marine ecosystem of a temperate zone.

METOCEAN SPECIFICATIONS FOR WIND DATA BASE ON THE BLACK SEA

In this paper we present the steps to establish a design of floating wind turbine in offshore area. In order to be able to design a floating wind turbine in the offshore area of the Black Sea, data about the wind potential, the potential of waves and sea currents are needed, as well as wave-wind cross-data and other atmospheric data. It is assumed that the location of the floating turbine is the area of the Galata platform, Varna, Bulgaria, located at 25 km south-east of the city of Varna in the South-West Black Sea area. The wind dataset can downloaded from a server in NetCDF file form. The spatial data are used to generate wind maps showing the distribution of the mean wind speed for the full-time distribution (i.e. total time) and for the four seasons, respectively.

Seismic Identification and Hydrocarbon Accumulation Characteristics of Submarine Fan in offshore Suriname

In recent years, oil and gas fields have been continuously discovered in the Suriname-Guyana Basin of South Atlantic, the reservoir of which is submarine turbidite sandstone and become one of the hot exploration objectives in the world. Based on the interpretation and analysis of 2D seismic and well data, this paper presents the integrated geological and geophysical evaluation of the Suriname-Guyana basin within Suriname and describes the identification characteristics and hydrocarbon accumulation process of submarine fan in offshore Suriname. The tectonic evolution of this region can be divided into four stages, breakup of Pangea, intracontinental rift, regional uplift and drifting over the South Atlantic. The Upper Cretaceous marks the transition of a transgressive to a regressive system with increasing sediment input from the south west, creating a broad delta plain environment across the shallow offshore area. It has been confirmed that multi-stage submarine fans have developed from Upper Cretaceous to Neogene in offshore Suriname, with overlapping characteristics of multiple erosive surfaces. It is suggested that erosive surface forming local unconformity is the important identification mark of submarine fan. Among them, the Paleogene and Upper Cretaceous submarine fans are the most widely distributed and have the most obvious characteristics on seismic profiles. The bottom of the Paleogene and Upper Cretaceous fans are identified by the erosive surfaces. The fan root has obvious characteristics of cutting valley, forming inter-bedded with the deep-sea facies toward the outer fan, along with litho-logic granularity thinning and scope expansion. The distal parts of the submarine fan are surrounded by abyssal shale, which can form a good source, reservoir and cap configuration. Therefore, turbidite fan sandstone with good source rock and cap configuration is the favorable reservoir.

Characterization and Modeling of Doppler Spectra for Offshore UHF-Band Sea Clutter at Low Grazing Angles

The Doppler spectra of sea echoes, which contain abundant information on floating scatterers, are important for exploring the characteristics of sea clutter. Using sea clutter data at low grazing angles observed by a coherent ultra-high frequency (UHF) radar located on Lingshan Island in the Yellow Sea, China, this study conducted detailed research on the characteristics of Doppler spectra with multiple ocean parameters, including grazing angle, significant wave height (SWH), and wave directions. The effect of sea echoes with different local normalized intensities on short-time Doppler spectra was further studied. The results indicate that with increasing sea states, the bimodal behavior of Doppler spectra, an evident phenomenon of Bragg scattering, gradually weakens. The frequency shifts of the mean spectra increased linearly with increasing SWH and wind speed, decreased linearly with increasing grazing angle, and decreased with the cosine value of the relative wave direction angles. In comparison, frequency shifts of the short-time spectra increased with increasing sea states and local echo intensities but fluctuated around a fixed value after reaching a certain extent. For spectral widths, the grazing angle is a significant influencing factor, with its broadening trend evident with a decrease in the grazing angle, whereas other ocean parameters, such as wave direction and wind direction, have no apparent influence. Considering the major contributions of the parameters, semi-empirical models for the mean spectral frequency shifts, mean spectral widths and short-time spectral frequency shifts were proposed. By verifying the measured data and predicted results, the models exhibited good prediction accuracy and applicability. The proposed inferences and models are helpful for understanding low grazing angle UHF-band sea clutter characteristics and improving target detection algorithms in offshore areas. These findings supplement previous studies on sea clutter Doppler spectra.

Estimation of Coastal Area and Lake Water Level Changes Using High-Resolution Altimetry

Radar satellite altimeters are widely used in offshore areas, whereas they are underutilized in coastal areas due to a number of interference factors. Altimeter satellite data can be used to summarize elevation information at 1 Hz for offshore areas, but for areas close to land, it is more effective to utilize imagery with a resolution of 20 Hz to provide a more detailed representation. The use of highresolution satellite altimeter data is expected to increase the amount of data available for hydrological data such as complex coastlines and small lakes. Therefore, in this study, we investigated the applicability of 20 Hz altimeter data in the Korean Peninsula. First, the accuracy was analyzed by comparing the 20 Hz altimeter data from the Jason-3 satellite with the Ulleungdo tide data. Second, we compared the 20 Hz altimeter data from the Sentinel-3A satellite with the water level data of Soyang Lake to see if it can be applied to land areas. In the case of inland lakes, the water level is estimated to be affected by the discharge volume due to heavy rainfall in summer, and it was determined that the satellite altimeter data can be utilized. Therefore, utilizing the data from this study is expected to improve the accuracy of hydrological analysis in coastal and lake environments.

Environmental gradients shape microbiome assembly and stability in the East China sea

Microbiomes play a key role in marine ecosystem functioning and sustainability. Their organization and stability in coastal areas, particularly in anthropogenic-influenced regions, however, remains unclear compared with an understanding of how microbial community shifts respond to marine environmental gradients. Here, the assembly and community associations across vertical and horizontal gradients in the East China Sea are systematically researched. The seawater microbial communities possessed higher robustness and lower fragmentation and vulnerability compared to the sediment microbiomes. Spatial gradients act as a deterministic filtering factor for microbiome organization. Microbial communities had lower phylogenetic distance and higher niche breadth in the nearshore and offshore areas compared to intermediate areas. The phylogenetic distance of microbiomes decreased from the surface to the bottom but the niche breadth was enhanced in surface and bottom environments. Vertical gradients destabilized microbial associations, while the community diversity was enhanced. Multivariate regression tree analysis and canonical correspondence analysis indicated that depth, distance from shore, nutrient availability, temperature, salinity, and chlorophyll a, affected the distribution and co-occurrence of microbial groups. Our results highlight the crucial roles of environmental gradients in determining microbiome association and stability. These results improve our understanding of the survival strategies/adaptive mechanisms of microbial communities in response to environmental variation and provide new insights for protecting the ecosystems and maintaining the sustainability of ecological functions.

Suspended sediment change along the Zhejiang-Fujian coast revealed using MODIS 250-m imagery

Suspended sediment concentration (SSC) is one of the important parameters in the ecological environment evaluation of marine water bodies, as it provides an important basis for research on the ecological environment of nearshore sea areas, shoreline beach erosion and deposition, water quality of coastal zones and nearshore sedimentation zones. In recent years, the amount of sediment carried by the Yangtze has declined dramatically due to the Three-Gorges Dam (TGD), which might change the sediment supply to the sea and thus affect sediment transport to the coasts of Zhejiang and Fujian. This study aims to both develop specific algorithms and reveal the interannual and seasonal dynamics of the suspended sediment belt from the Yangtze Estuary to the Zhejiang-Fujian provincial shoal using MODIS 250 m data from 2000 to 2020. MODIS time-series analysis shows that the suspended sediments were originally from the Yangtze Estuary and formed a suspended sediment belt in the winter season. Moreover, driven by monsoon winds and coastal current dynamics, the sediment belt has obvious seasonality. Furthermore, we also suggest that the coastal sediment area has a tendency to shrink in winter, and the lifetime of the sediment belt also shortens, showing early disconnection in spring and delayed recovery in autumn, in response to the decline in sediment discharge from the Yangtze River basin to the sea. Impressively, the impact of the TGD in 2003 led to a drop in the sediment concentration in the coastal area. In addition, further analysis confirms that a sudden decrease in suspended sediment concentration was observed at Zhoushan (S2), Wenling (S4), Minjiang River Mouth (S7), Pingtan Island (S8), and many other stations along the coast in 2003, and the closer to the Yangtze Estuary, the more serious this phenomenon becomes, on the basis of monthly SSC analysis. These findings can assist us in better understanding the new pattern of the sediment belt from the Yangtze Estuary to the Zhejiang-Fujian coastal area. The findings of this study have theoretical and practical implications for the study of the hydrological sediment field in offshore areas, the protection of the marine ecological environment, changes in the shoreline and mudflats, and the maintenance of waterways and ports in estuaries.

Basin development and petroleum prospectivity of the hybrid turbidite-contourite system in the east Pande area, offshore Tanzania

2D seismic reflection and wellbore data were used to investigate the structure and stratigraphy of the East Pande block, offshore Tanzania, allowing an assessment to be made of basin development and the occurrence of petroleum system elements. Interpretation of the 2D seismic data showed that patterns of sedimentation were controlled by the Cretaceous- Quaternary oceanic circulation (including bottom currents) together with sea level changes and the basin-ward input of detrital material from the Tanzania mainland, resulting in the development of at least five reservoir-seal combinations. The identified reservoir rocks include hybrid turbidite-contourite deposits together with channel sands and their associated levee successions which have moderate porosity and a low shale volume. Regionally, the hybrid turbidite-contourite deposits have not been studied in detail; their presence in the East Pande area may be of interest to both local and regional researchers. Potential structural traps in the study area include faults and local folds; another trapping mechanism is provided by stratigraphic pinch-outs which are characterized in seismic data by flat spots indicative of hydrocarbon accumulations. Deep-rooted faults and erosive channel bases are interpreted to have allowed petroleum migration from underlying source rocks to shallower reservoir intervals. The mapped faults in the study area have N–S to NNW-SSE trends which conform to the Permo-Triassic fault systems of the coastal Tanzania basin. This suggests that the locations and orientations of younger faults was controlled by the pre-existing structural grain linked to Karoo (Permo-Triassic) faulting. The results of this study suggest that the East Pande area offshore Tanzania may have significant petroleum prospectivity.

A cross-scale modeling framework for simulating typhoon-induced compound floods and assessing the emergency response in urban regions

The cities within the Pearl River Delta (PRD), known as the Greater Bay Area (GBA), are flood-prone areas that faced frequent threats from typhoon-induced storm surges and rainfall in recent decades. To assess the potential consequences of a typical typhoon event, fine-scale simulations of inundation induced by both pluvial and fluvial flooding (known as compound flooding) are crucial for policymakers and concerned stakeholders to develop proper measures. In this study, we develop a cross-scale framework for modeling city inundation arising from typhoon-induced surges and torrential rainfall–runoff by coupling a three-dimensional ocean model (FVCOM) and a one-dimensional and two-dimensional coupling river analysis system (HEC-RAS). The ocean model is applied to capture the mesoscale behavior of surge and tide propagation from the deep sea to shallow offshore areas near the PRD. The river analysis system can simulate storm wave propagation along rivers, overtopping banks on floodplains and rainfall–runoff-induced flooding in urban regions at gradually refined scales. Second, the framework integrates GIS components (network analysis) with these hydraulic models. Through this framework, the urban emergency service coverage can be assessed under various potential flood scenarios during typhoon landfalls. Super Typhoon Mangkhut in 2018, the most devastating typhoon in the last decade in the PRD, is used as a case study in simulating and studying the flooding process. The simulated results show that in this typhoon event, pluvial and fluvial flooding play different roles in hindering the accessibility of emergency resources. Moreover, the interaction between pluvial and fluvial flooding significantly affects some urban regions.

Evaluation and Comparison of Multi-Satellite Aerosol Optical Depth Products over East Asia Ocean.

The atmosphere over the ocean is an important research field that involves multiple aspects such as climate change, atmospheric pollution, weather forecasting, and marine ecosystems. It is of great significance for global sustainable development. Satellites provide a wide range of measurements of marine aerosol optical properties and are very important to the study of aerosol characteristics over the ocean. In this study, aerosol optical depth (AOD) data from seventeen AERONET (Aerosol Robotic Network) stations were used as benchmark data to comprehensively evaluate the data accuracy of six aerosol optical thickness products from 2013 to 2020, including MODIS (Moderate-resolution Imaging Spectrometer), VIIRS (Visible Infrared Imaging Radiometer Suite), MISR (Multi-Angle Imaging Spectrometer), OMAERO (OMI/Aura Multi-wavelength algorithm), OMAERUV (OMI/Aura Near UV algorithm), and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) in the East Asian Ocean. In the East Asia Sea, VIIRS AOD products generally have a higher correlation coefficient (R), expected error within ratio (EE within), lower root mean square error (RMSE), and median bias (MB) than MODIS AOD products. The retrieval accuracy of AOD data from VIIRS is the highest in spring. MISR showed a higher EE than other products in the East Asian Ocean but also exhibited systematic underestimation. In most cases, the OMAERUV AOD product data are of better quality than OMAERO, and OMAERO overestimates AOD throughout the year. The CALIPSO AOD product showed an apparent underestimation of the AOD in different seasons (EE Below = 58.98%), but when the AOD range is small (0 < AOD < 0.1), the CALIPSO data accuracy is higher compared with other satellite products under small AOD range. In the South China Sea, VIIRS has higher data accuracy than MISR, while in the Bohai-Yellow Sea, East China Sea, Sea of Japan, and the western Pacific Ocean, MISR has the best data accuracy. MODIS and VIIRS show similar trends in R, EE within, MB, and RMSE under the influence of AOD, Angstrom exponent (AE), and precipitable water. The study on the temporal and spatial distribution of AOD in the East Asian Ocean shows that the annual variation of AOD is different in different sea areas, and the ocean in the coastal area is greatly affected by land-based pollution. In contrast, the AOD values in the offshore areas are lower, and the aerosol type is mainly clean marine type aerosol. These findings can help researchers in the East Asian Ocean choose the most accurate and reliable satellite AOD data product to better study atmospheric aerosols' impact and trends.

Performance of European oysters (Ostrea edulis L.) in the Dutch North Sea, across five restoration pilots

IntroductionThe European flat oyster (Ostrea edulis) is a biogenic reef former, internationally recognised as threatened and declining in the NE Atlantic by OSPAR and one of the focal species in nature inclusive designs in offshore windfarms in The Netherlands. Oyster reefs offer habitat to many other benthic hard substrate and fish species and provide ecosystem functions such as shelter and feeding grounds. European flat oyster reefs have disappeared from the Dutch North Sea in the early 1900s due to overfishing and diseases but are now subject of nature restoration under the Dutch Marine Strategy.MethodSince 2018, pilot projects have started in the Dutch North Sea to restore European flat oysters at suitable locations, such as offshore windfarms or natural reefs, which are protected from bottom trawling. We compared European flat oyster performance in five pilot projects, using translocated adult oysters sourced from Ireland, Norway, and the Netherlands. The aim of this research was to assess the performance of translocated oysters between pilots, to assess the installation and monitoring techniques, and to come forward with recommendations for future pilot projects.ResultsWe found that translocation of both foreign sourced flat oyster populations (Ireland and Norway in nearshore and offshore areas) and local oysters (in nearshore areas) result in good oyster performance. Oysters were able to grow (max 3.67 mm/month) and reproduce (larvae present) in their new environment. We found that growth rate was explained by origin and average water temperature, to a lesser extent by number of months, location and salinity and not to other environmental factors such as pH and O2. Correlations between growth and environmental conditions need to be considered with caution, since not all pilots were sampled just before and after the growing season. Oysters were Bonamia-negative at the start and end of the pilots, indicating that the offshore Dutch North Sea is still Bonamia-free.Discussion, conclusions, recommendationsBy the year 2050 more than ten new offshore farms will be constructed in the Dutch North Sea and some sites will be suitable for oyster restoration. We conclude that local and foreign sourced oysters performed well at all locations. Based on the success and failure of the different outplacement and monitoring techniques, we provide recommendations on good practice for the future, including developing standardized monitoring protocols. This will enable better inter-site comparisons in upcoming oyster restoration pilots.

Two new species of Travisiidae (Annelida, Sedentaria) from Thailand.

Two new species of Travisiidae, Travisia satunensis sp. nov. and T. thailandensis sp. nov., were collected from different locations in Thailand waters. Travisia satunensis sp. nov. was collected in the Andaman Sea, at 214 m water depths. Travisia thailandensis sp. nov. was collected from offshore petroleum concession areas in the Gulf of Thailand, at 5080 m water depths. Travisia satunensis sp. nov. differs from all other species by having branched annulated branchiae on chaetigers 235, each annulated with a single filament, chaetae throughout the body and pygidium with 10 anal cirri, six digitiform and four short cirri, alternately arranged. Travisia thailandensis sp. nov. differs from all other species by having 21 pairs of cirriform, annulated branchiae from chaetiger 2, a mid-ventral groove along body, two last segments achaetous, and nephridiopores on chaetigers 714. A key for Travisia species from the Indo-Pacific region is also provided.

The importance of C3 and C4 grasses and CAM shrubs in the Greater Cape Floristic Region under contemporary and Last Glacial Maximum climates

Southern Africa’s Greater Cape Floristic Region (GCFR) – a hotspot of biological diversity and palaeo-anthropological evidence for modern human evolution – is a climatically complex region where broad climatic gradients influence the relative importance of plant photosynthetic types in local vegetation. This mix of photosynthetic pathways imprint an isotopic signature on palaeo-records, thereby allowing for the reconstruction of historical climate and vegetation. Here, we use vegetation plot data, coupled with the photosynthetic-type affinities of plant genera, to relate their relative cover to bioclimatic drivers and use these to create spatial distribution models of C3 and C4 grasses and CAM shrubs across the contemporary GCFR. We then use palaeodistribution modelling, drawing on downscaled climate models for the Last Glacial Maximum (LGM), to hindcast the LGM distributions of photosynthetic types for the GCFR and its then-exposed offshore areas. In addition, we construct a model to account for the effect of lower atmospheric CO2 concentration ([CO2]) during the LGM on the competitive interactions between C3 and C4 grasses and use this model to hindcast relative C4-grass cover across the glacial-era GCFR. Our palaeodistribution models suggest that, even though there were some reductions in CAM cover and shifts in C3-/C4-dominated grass layers between the LGM and Holocene, these were mostly localised, with changes at the regional scale being relatively muted. For C3/C4 grasses, distributional shifts were even more subtle once sub-ambient glacial [CO2] was accounted for. Our hindcasts of glacial, [CO2]-adjusted grass cover show agreements and inconsistencies with various sedimentary and herbivore-diet records in the palaeo-archive: both lines of evidence suggest the dominance of C3 species in the strongly winter-rainfall western GCFR; in the eastern GCFR, with muted rainfall seasonality, hindcasts of relative C3:C4 cover and δ13C signals from palaeo-records vary, with greater disparities between them. The lack of significant upheavals in the distribution of photosynthetic types suggests that the GCFR presented a relatively stable and dependable resourcescape for hunter-gatherer populations through the glacial–interglacial cycle of the LGM–Holocene transition. Our maps of relative C3-/C4-grass and CAM-shrub cover provide a reasonable surrogate for relative biomass of different photosynthetic types in local vegetation at a landscape scale and depict an independent estimate of carbon isoscapes across the GCFR – under both an interglacial (Holocene) and glacial (terminal Pleistocene) climate – against which palaeo-records can be assessed.

Seawater temperature changes in the southern Baltic Sea (1959–2019) forced by climate change

The study included the analysis of changes in sea surface and water column temperature and air temperature in the years 1959–2019 in the southern Baltic Sea based on in situ measurement (CTD probe), satellite data, and model data (ERA5). SST increased on average by 0.6°C per decade. Analyses at different depths showed that the highest temperature increase per decade at 0.60–0.65°C characterised the layers from 0 to 20 m. The smallest increase (0.11°C) was recorded at a depth of 70 m, below which the temperature change per decade increases again to 0.24°C. The results from satellite observations covering 1982–2019 were consistent with measurement data. The most intense water warming occured in the spring – summer (0.8–1°C per decade); in the winter, the change did not exceed 0.2°C. In the offshore area, in 1951–2020, air temperature increased by approx. 2°C, with an average increase of 0.37°C per decade. The average increase in seawater temperature in the coastal zone was 0.2°C per decade. The most intense warming characterised March to May (0.25–0.27°C). The average annual air temperature increase on the coast from 1951 to 2020 was 0.34°C per decade. The results represent an important contribution to research and prediction of changes in the marine environment caused by global climate change.

INFLUENCE OF ATMOSPHERIC PRECIPITATION AND SURFACE RUNOFF ON PHYTOPLANKTON CHARACTERISTICS IN THE NORTHERN PART OF THE BLACK SEA

The joint dynamics of the Black Sea phytoplankton parameters (primary production, specific growth rate, biomass) and the amount of precipitation over the period from 1998 to 2015 was studied in coastal areas and the open coast of the northern part of the Black Sea. The analysis used satellite data (SG) (GPCPMON) GPCP Version 3.2, TRMM TMPA (3B42RT), as well as SeaWiFS from 1998 to 2010, MODIS-Aqua from 2002 to 2015 and MODIS-Terra from 2000 to 2015. Phytoplankton indicators were calculated according to 46 КОВАЛЕВА, СУСЛИН LOMONOSOV GEOGRAPHY JOURNAL. 2023. VOL. 78. NO. 4 the models developed earlier by the authors. The average monthly values of all considered values were evaluated, as well as bi-weekly and daily values for atmospheric precipitation. As a result of the study, it was revealed that the role of atmospheric precipitation for the variability of phytoplankton characteristics is not significant in vast water areas over long time intervals, and it could be neglected. In some cases in the presence of large rivers and coastal runoff it increases up to 30% in the offshore areas. There was also a more noticeable effect of atmospheric precipitation on the biological productivity of phytoplankton in small, limited water areas over short time intervals. According to our data during the 18-year period there was a more noticeable correlation between the specific growth rate and precipitation in winter than in other seasons for the open coast of the Black Sea. The correlation of biomass and primary production with atmospheric precipitation is less pronounced. The specific growth rate correlated more than other studied phytoplankton indicators with the amount of precipitation. In three districts, an increase in the amount of precipitation relative to the previous level with monthly averages above 0,6 mm/day led to an increase in the specific growth rate, or maintained it at the same level. The increase in the specific growth rate was not the same everywhere and was not proportional to the amount of atmospheric precipitation. This indicates the influence of many factors on phytoplankton characteristics; however, precipitation could have an additional stimulating role.