Oceanologia最新文献

The 0.5° resolution of many global observational or quasi-observational datasets is not sufficient for the evaluation of current state-of-the-art regional climate models or the forcing of ocean model simulations over Europe. While higher resolved products are available for meteorological data, e.g. ERA5 reanalysis and the E-OBS vs 22 (EOBS22) datasets, they lack crucial information at the land-ocean boundary. ERA5 is frequently used to force regional climate models (RCMs) or ocean models and both datasets are commonly used as reference datasets for the evaluation of RCMs. Therefore, we extended both datasets with high-resolution river discharge for the period 1979–2018. On the one hand, our discharge data close the water cycle at the land-ocean interface so that the discharges can be used as lateral freshwater input for ocean models applied in the European region. On the other hand, the data can be used to identify trends in discharge that are induced by recent climate change as ERA5 and EOBS22 are rather independent datasets. The experimental setup to generate the discharges was chosen in a way that it could be easily adapted in a climate or Earth system modelling framework. Consequently, the recently developed 5 Min. horizontal resolution version of the hydrological discharge (HD) model was used to simulate discharge. It has already been applied in multiple climate modelling studies and is coupled within several global and regional Earth system models. As the HD model currently does not regard direct human impacts of the river runoff, it is well suited to investigate climate change-related discharge trends. In order to calculate the necessary gridded input fields for the HD model from ERA5 and EOBS22 data, we used the HydroPy global hydrological model. For both experiments, we found that the general behavior of discharge is captured well for many European rivers, which is consistent to earlier results. For the EOBS22 based discharges, a widespread low bias in simulated discharge occurs, which is likely caused by the missing undercatch correction in the underlying precipitation data. The analysis of trends over Southeastern Europe was hampered by missing data in EOBS22 after 2004. Using both experiments, we identified consistent trend patterns in various discharge statistics, with increases in low flow characteristics over Northern Europe and general drying trends over Central and Southern Europe. In summary, we introduced an experimental setup that is useful to generate high-resolution river runoff data consistent with the meteorological forcing for historical periods and future scenarios from any climate model data instead of having to rely on observed time series.

This study analyses changes in Normalized Difference Vegetation Index (NDVI) values in the eastern Baltic region. The main aim of the work is to evaluate changes in growing season indicators (onset, end time, time of maximum greenness and duration) and their relationship with meteorological conditions (air temperature and precipitation) in 1982–2015. NDVI seasonality and long-term trends were analysed for different types of land use: arable land, pastures, wetlands, mixed and coniferous forests. In the southwestern part of the study area, the growing season lasts longest, while in the northeast, the growing season is shorter on average by 10 weeks than in the other parts of the analysed territory. The air temperature in February and March is the most important factor determining the start of the growing season and the air temperature in September and October determines the end date of the growing season. Precipitation has a much smaller effect, especially at the beginning of the growing season. The effect of meteorological conditions on peak greenness is weak and, in most cases, statistically insignificant. At the end of the analysed period (1982–2015), the growing season started earlier and ended later (in both cases the changes were 3–4 weeks) than at the beginning of the study period. All these changes are statistically significant. The duration of the growing season increased by 6–7 weeks.

In this paper we highlight the impact of sea-level change on the archaeological record of key developments in human history that took place during the late Pleistocene and the early Holocene. Before modern sea level became established from ∼7 ka onwards, most palaeoshorelines and large areas of coastal hinterland were exposed as habitable land and then drowned again by sea-level rise. We summarise the archaeological implications of this pattern and the conditions in which archaeological and geoarchaeological evidence from these submerged landscapes is preserved despite the potentially destructive erosional impact of sea-level rise. We provide examples of palaeolandscape reconstruction made possible through multi-disciplinary collaboration between archaeology and marine science, drawing on recent underwater research in the North Sea, the Red Sea and on the Cape Coast of South Africa, and discuss evidence of past human responses to sea-level change. We identify the types of modelling procedures that need to be developed to advance this field of research, emphasise the importance of inter-disciplinary collaboration involving two-way exchange of ideas and information between archaeology and marine science, and highlight the value of a long-term perspective in understanding the present and future human impact of sea-level rise.

The study aimed to determine photosynthetic signatures, i.e. photosynthetic energy storage (ES) efficiency and photoacoustic spectra of pigment-containing biofilm communities attached to submerged solid substrates in relation to the temporal variability of the trophic state of natural water. Biofouling phenomenon signatures on artificial solid surfaces, deployed in the shallow Baltic Sea waters (Gulf of Gdańsk, Poland) for a specific period of time, were determined over a three-year period using improved photoacoustic spectroscopy apparatus based on closed cell geometry. Selected chemical parameters (oxygen, nitrogen and phosphorus concentrations) and biological productivity (primary production and Chlorophyll a; hereinafter abbreviated as Chl a) of the water body were obtained from the SatBałtyk System platform (http://satbaltyk.iopan.gda.pl) and used as comprehensive data. As a result, close cross-correlations between photosynthetic energy storage and PAS amplitude spectra and the seawater chemical parameters were demonstrated. As found, ES was negatively correlated with concentrations of biogenic elements (correlation coefficient R given in brackets): O (–0.67), P (–0.81), N (–0.76), and positively correlated with concentrations of Chl a (0.82) and primary production (0.39). As periphyton is believed to respond dynamically to water quality and environmental stresses, its photosynthetic system features can be used as novel, modern and robust indicators in marine bioassessment, in addition to traditional trophic state indices based on chemical analysis.

The longshore realignment of nearshore sandbars is a morphodynamic phenomenon of multiple sandbar systems that has been known about for several decades. However, it is unknown how switching-related nearshore changes influence the evolution of subaerial beaches. This study aims to define the relationship between sandbar switching episodes and the dynamic state of the beach-foredune system along the Curonian Spit coast (Baltic Sea) using decadal satellite-derived and beach profiling data. To define this connection, sandbar switching locations, sandbar cross-shore positions, shoreline positions, and sand volume changes in the beach-foredune system were assessed on interannual and storm-related time scales. Twenty-seven sandbar switching episodes were observed with an average duration of 14.3 months. Most of the switching episodes occurred at preferred locations, coinciding with breaking points of different shoreline orientations where oblique waves and longshore currents prevailed. Shoreline retreat at an average rate of –14.2 m was observed within most of the sandbar switching zones. During major storm events, the average rate of erosion within the sandbar switching zones was significantly higher than the rate outside them. On an interannual time scale, a moderate average rate of erosion was observed within the sandbar switching zones compared to a small accretion rate outside them. Additional case studies of coastal evolution within the switching zones indicated well-correlated rates of switching-determined outer sandbar positions, shoreline positions, and sand volume on the beach and foredune during the switching episodes. The results of this study could be important for the identification of erosional hot spots and coastal prediction.

Endocrine disrupting compounds and in particular estrogenic substances have the ability to interact with the hormone system of organisms. Among them are not only synthetic but also natural substances that potentially stress the aquatic ecosystem. High human population densities such as around the Pearl River Estuary (PRE) are suspected of exerting significant anthropogenic pressure onto coastal areas. In this study, natural and synthetic estrogens as well as estrogen-like substances derived from plants and fungi were investigated in the PRE and at the adjacent northern shelf of the South China Sea. Maximum concentration of 3.6 ng L⁻¹ for estrone (E1), 0.7 ng L⁻¹ for 17α-ethinylestradiol (EE2), 12.9 ng L⁻¹ for genistein (GEN), 11.9 ng L⁻¹ for daidzein (DAI) and 1.9 ng L⁻¹ for zearalenone (ZEN) were observed. While E1 and EE2 were detected in fresh and saltwater samples, GEN, DAI and ZEN were observed only at freshwater sampling sites. During the investigations, the analysis of 17β-estradiol (E2) and EE2 indicated a strong matrix dependence. Additionally, an estrogen screen observation showed estrogenic activity in form of estradiol equivalent quotients up to 0.18 ng L⁻¹.

The paper discusses the factors associated with the sudden outbreak of the nocturnal heterotrophic bioluminescent dinoflagellate Noctiluca scintillans along the Chennai coast. The bloom occurred along a stretch of 16 km following a spell of heavy rain in August 2019. The density of N. scintillans varied from 1000 to 19000 cells/L, with a distinguished distribution pattern. High N. scintillans abundance was recorded at Panaiyurkuppam and Kovalam, with 19000 cells/L and 18000 cells/L, recorded respectively. Adequate nutrients brought by substantial rainfall and a high abundance of the diatom Thalassiosira sp. triggered the N. scintillans bloom. The low wind speed (5 m/sec), lowering of atmospheric temperature (from 24.00 to 31.00°C, 27.5 ± 1.17°C), high rainfall (6 mm within one day), and low sea surface temperature (SST) (from 25.20 to 31.00°C, 29.37± 1.17°C) are probable environmental cues. Local hydrodynamics and the diverging currents governed the presence and dispersion of the bloom in the region.

Chromophoric Dissolved Organic Matter (CDOM) is a vital water constituent in aquatic ecosystems that contributes to water colour, affects light penetration, and impacts primary production. This study aims to determine the spatial and monsoonal variability of CDOM absorption properties in the Likas estuary, characterise the source of CDOM, and investigate the correlations between CDOM absorption properties and salinity. Likas estuary is a small estuary located in Kota Kinabalu city on the west coast of Sabah, facing the South China Sea. A mangrove ecosystem surrounds it with manufactured structures such as residential areas and public facilities. Surface water samples were collected at 19 stations: upstream of rivers to the river mouth and coastal area during spring tides every month, from June 2018 to July 2019, for 14-months. The distribution of a_CDOM(440) in the study area is predictable as a signature in a coastal area with a decreasing gradient from the upstream towards coastal water (0.29 ± 0.19 m⁻¹ to 1.05 ± 0.39 m⁻¹). There are increasing spatial patterns of spectral slopes S_275-295 and S_R. However, S_350-400 and S_300-600 declined spatial gradients from the upstream to coastal water. Thus, S_300-600 indicates a linear relationship between a_CDOM(440), which unconventional results in coastal water. We suspect this is due to a small coverage of the study site with a distance of 0.5 m intervals of each station. This could be why the S_300-600 had constant values throughout the study area (with no statistical difference between stations). In addition, S_300-600 was merely varied in the stations located at the river mouth and coastal water. Based on the spectral slope ratio (S_R), most of the stations located in the Darau, Inanam, and Bangka-Bangka rivers had S_R values less than 1. Hence, CDOM in these stations is a terrestrial-dominated source. Therefore, from our observations during the study period, monsoonal variation could alter the source of CDOM in the study area.

This article provides estimates of the sea spray volume flux using joint statistics of wind and waves. This is achieved by combining the sea spray volume flux parameterization proposed by Xu et al. (2021) with the joint statistics of wind and waves provided by Bitner-Gregersen (2015). Both the sea spray volume flux formula and the joint statistics of wind and waves represent conditions for wind waves from the North-West Shelf of Western Australia. The expected value and the variance of the sea spray volume flux for a range of realistic wind and wave conditions are presented, as well as an illustrative example. Comparison is also made with data from Xu et al. (2021) showing a reasonable agreement for the relevant subset of the data.