Bottom Sediment Type Research Articles

The community structure of recent ostracods in the Burullus lagoon, Egypt

This work concentrates on the recent ostracod community from the bottom sediments of Burullus lagoon (BuL), Egypt. It aims to identify the impacts of the environmental factors such salinity, substrate and pH on the ostracod community. Only four ostracod species are identified, Cyprideis torosa, Leptocythere castanea, Loxoconcha elliptica and Cypridopsis vidua. The results reflect the abundance of a sole tolerant species, C. torosa (79.59–100 %, with an average of 94.18 %), in all sites. Actually, this conclusion reflects the dominance of unfavorable conditions for increasing the biodiversity in the lagoon. Moreover, the associated benthic foraminiferal assemblage suffers from the rarity of species and the abundance of one tolerant species, Ammonia tepida. Therfore, there is an urgent need to understand the environmental conditions in the BuL. The measured low salinities are suitable for the survival of only brackish ostracod species. Moreover, the distribution and structure of the ostracod assemblage are mainly controlled by the type of bottom sediments. Actually, as the content of sand increases, particularly at sites near the connection to the sea, low numbers of individuals are recorded, whereas the number of living species increases in muddy substrate. Furthermore, the sites with sandy substrate display thick-walled carapaces, while the others with muddy substrate possess thin-walled carapaces. Also, the occurrence of Cypridopsis vidua is restricted only to the muddy substrate. In terms of the hydraulic conditions, the highest abundance of living species is recorded in the southern part, where the quiet conditions prevail. The lagoon water is alkaline, so pH has no observed effects on the ostracod community. Accordingly, salinity, sediment types and hydraulic conditions play the major role in controlling the abundabce, diversity and distribution of ostracods in the study area. Geographically, the identified ostracod species are broadly distributed in the brackish lagoons of the Mediterranean region.

Aral Environmental Disaster and Its Mitigation Through Forest Plantations

Abstract The drained bottom of the Aral Sea poses a serious threat to all living things in the Aral Sea region because it covers an area of about 6 million hectares. Nearly150 million tons of salt, dust, and sand are released into the air from it annually, which causes significant damage to agriculture and the national economy. It is possible to mitigate the ecological catastrophe by creating forest plantations on the drained bottom from desert plants. Depending on the types of bottom sediments, different technologies for creating forest plantations were tested, which made it possible to obtain highly effective plantations and minimize the negative impact of the dried bottom of the Aral Sea. Globally, the ecological problem of the Aral Sea is regarded as one of the critical issues that require immediate attention, the consequences of which are still being felt on a continental scale.

Changes in the level of biofilm development significantly affect the persistence of environmental DNA in flowing water

As one of the powerful tools of species biomonitoring, the utilization of environmental DNA (eDNA) technology is progressively expanding in both scope and frequency within the field of ecology. Nonetheless, the growing dissemination of this technology has brought to light a multitude of intricate issues. The complex effects of environmental factors on the persistence of eDNA in water have brought many challenges to the interpretation of eDNA information. In this study, the primary objective was to examine how variations in the presence and development of biofilms impact the persistence of grass carp eDNA under different sediment types and flow conditions. This investigation encompassed the processes of eDNA removal and resuspension in water, shedding light on the complex interactions involved. The findings reveal that with an elevated biofilm development level, the total removal rate of eDNA gradually rose, resulting in a corresponding decrease in its residence time within the mesocosms. The influence of biofilms on the persistence of grass carp eDNA is more pronounced under flowing water conditions. However, changes in bottom sediment types did not significantly interact with biofilms. Lastly, in treatments involving alternating flow conditions between flowing and still water, significant resuspension of grass carp eDNA was not observed due to interference from multiple factors, including the effect of biofilms. Our study offers preliminary insights into the biofilm-mediated mechanisms of aquatic eDNA removal, emphasizing the need for careful consideration of environmental factors in the practical application of eDNA technology for biomonitoring in natural aquatic environments.

Spatial distribution of northern shrimp Pandalus eous in the Sea of Japan in relation to the seafloor environment

Abstract To explore relationships between spatial distributions of northern shrimp Pandalus eous and environmental factors along the coastline of Honshu Island in the Sea of Japan, we built delta-type two-step generalized additive models (delta-GAM) based on bottom trawl surveys conducted in 2013–2022. The models provide the first quantitative analysis of the species’ habitat, showing that its distribution is associated with bottom sediment type, depth, slope and topographic position index (TPI) alongside the effects of year and region. From the delta-GAM response plots, species habitat preferences in the Sea of Japan were estimated as follows: seafloor deeper than 283 m; muddy rather than sandy bottoms; gently sloped to flat bottoms (<0.8° in slope); and valleys rather than ridges (TPI < 0.9). These results were reviewed in detail along with previously reported distribution records of northern shrimp. Standardized density (s-density) per fishing grid cell (10′ square latitude–longitude mesh) estimated from the delta-GAM results indicated that this species is widely distributed on the continental slope along the coast of Honshu Island. To test plausibility of the s-density analysis, we compared s-density per fishing grid cell with nominal CPUE (kg per haul) per fishing grid cell based on official logbook data from large offshore trawl fisheries. The two were generally positively correlated by year, and the delta-GAM results were assumed to be fairly robust. Finally, potential fishing grounds were explored based on the delta-GAM results.

Content of Pigments in the Bottom Sediments in a Small Valley Channel Reservoir

This paper presents the first data on the content of plant pigments in the bottom sediments of the Uvod Reservoir (Volga basin, Russia), unique in its hydrological regime, which support the hypothesis of more intensive carbon accumulation in small water bodies. It is established that the average concentration of chlorophyll a and its transformation products at the stations is 62.6 ± 10.0 μg/g of dry sediment, 35.2 ± 4.5 mg/(m2 mm) of wet sediment, and 0.73 ± 0.09 mg/g of organic matter of sediments. The ratio of organic carbon to the pigment concentration varies within 400–6000, depending on the type of bottom sediments, which significantly exceeds the values known for macrophytes and phytoplankton. Despite the features of hydrodynamics and geomorphology of the reservoir, the spatial distribution of sedimentary pigments is consistent with the structure of the bottom sediment complex, which is typical for water bodies of different types. A decrease in differences between the pigment concentrations in the sandy and silty biotopes of the Uvod Reservoir compared to the Upper Volga is noted. The average concentration of chlorophyll a with pheopigments (58.5 ± 6.7 μg/g of dry sediment), calculated considering the areas of bottom sediments of different types, in the Uvod Reservoir is 2.3 times higher than in the Gorky Reservoir (25.3 ± 1.5 μg/g), from which water inflows through the Volga–Uvod Canal. According to the content of sedimentary pigments, the trophic state of the reservoir is mesotrophic. Features of eutrophication in the Uvod Reservoir are more distinctly expressed than in the Gorky Reservoir.

Content of Pigments in the Bottom Sediments in a Small Valley–Channel Reservoir

This paper presents the first data on the content of plant pigments in the bottom sediments of the Uvod Re-servoir (Volga basin, Russia), unique in its hydrological regime, which support the hypothesis of more intensive carbon accumulation in small water bodies. It is established that the average concentration of chlorophyll a and its transformation products at the stations is 62.6 ± 10.0 μg/g dry sediment, 35.2 ± 4.5 mg/(m2 mm) of wet sediment, and 0.73 ± 0.09 mg/g organic matter of sediments. The ratio of organic carbon to the pigment concentration varies within 400–6000 depending on the type of bottom sediments, which significantly exceeds the values known for macrophytes and phytoplankton. Despite the features of hydrodynamics and geomorphology of the reservoir, the spatial distribution of sedimentary pigments is consistent with the structure of the bottom sediment complex, which is typical for water bodies of different types. A decrease in differences between the pigment concentrations in the sandy and silty biotopes of the Uvod Reservoir compared to the Upper Volga was noted. Average concentration of chlorophyll a with pheopigments (58.5 ± 6.7 μg/g of dry sediment), calculated considering the areas of bottom sediments of different types, in the Uvod Reservoir is 2.3 times higher than in the Gorky Reservoir (25.3 ± 1.5 μg/g), from which water inflows through the Volga–Uvod Canal. According to the content of sedimentary pigments, the trophic state of the reservoir is mesotrophic. Features of eutrophication in the Uvod Reservoir are more distinctly expressed than in the Gorky Re-servoir.

Bottom Biocenoses of Taman Bay (Sea of Azov)

In this research, the species composition and structure of macrophytobenthos, macrozoobenthos, and bottom sediments of the Taman Bay, one of the areas of the Sea of Azov where the seagrass Zostera marina L. forms underwater meadows. The material was collected in 2008–2009 before of the Sea of Azov salinization. Three main zones with different types of bottom sediments (sands, sands with shells and silts) were identified, within which four main macrobenthic biocenoses were located (unvegetated coastal biocenosis, mosaic macrophyte communities outside the surf zone, Z. marina underwater meadows and the central regions’ biocenosis with the dominance of mobile forms of macrozoobenthos and a low abundance of macrophytes). The main environmental factor associated with this distribution of macrophytobenthos was the content of silt (with a granule size of less than 0.001 mm). The spatial structure of the macrozoobenthos correlated with the projective cover of Z. marina. Possible reasons for the revealed regularities in the distribution of communities are discussed.

On the limits of distinguishing seabed types via ambient acoustic sound

This article presents a theoretical analysis of optimally distinguishing among environmental parameters from ocean ambient sound. Recent approaches to this problem either focus on parameter estimation or attempt to classify the environment into one of many known types through machine learning. This classification problem is framed as one of hypothesis testing on the received ambient sound snapshots. The resulting test depends on the Kullback-Leibler divergence (KLD) between the distributions corresponding to different environments or sediment types. Analysis of the KLD shows the dependence on the signal-to-noise ratio, the underlying signal subspace, and the distribution of eigenvalues of the respective covariance matrices. This analysis provides insights into both when and why successful hypothesis testing is possible. Experiments demonstrate that our analysis provides insight as to why certain environmental parameters are more difficult to distinguish than others. Experiments on sediment types from the Naval Oceanographic Office Bottom Sediment type database show that certain types are indistinguishable for a given array configuration. Further, the KLD can be used to provide a quantitative alternative to examining bottom loss curves to predict array processing performance.

The effects of sediment types on the structure of bottom invertebrate communities in a small European lowland dam reservoir

The study compares the structure of invertebrate communities inhabiting two types of bottom sediments in Krzynia Reservoir, known also as Lake Krzynia (on the Słupia River, northern Poland). The lake is prone to intensive sedimentation because it is limnic. This limnicity is due to the impact of the river, rather than to surface runoff from the catchment area, where the heavy predominance of natural habitats over transformed ones slows the transport of mineral suspensions from adjacent terrain. In the organic-poor sediments dominated by sand and gravel, the mean density of benthic invertebrates was ten-fold higher than in silty, organic-rich sediments, while invertebrate biomass was only slightly and non-significantly higher in organic-poor sediments than in organic-rich sediments. Simultaneously, the mean invertebrate body weight was markedly lower in organic-poor sediments (0.03 g) than in organic-rich sediments (0.18 g). No significant differences in taxonomic diversity (number and Shannon index of taxa) were found between the studied sediment types in the analysed communities. Among the major invertebrate groups, the Oligochaeta and Mollusca significantly differed in density between sediment types, while the Oligochaeta and Chironomidae differed in biomass. An increased percentage of silt fraction in bottom sediments resulted in a drastic decrease in abundance of benthic fauna, but their biomass declined only slightly. Thus, plans to construct new reservoirs should aim to reduce the rate of silt accumulation in them, in order to preserve their primary function and support biodiversity in transformed river valleys.

Биологическая активность гумусовых кислот донных отложений озер Среднего Приобья

The paper presents the results of studies of the biological activity in the vegetative experiment of preparations of humic acids (GC) and himatomelanic acids (MMC) of bottom sediments of lakes of the Middle Ob region with different paramagnetic activity determined by the "Absolute spins" method and extracted from lakes characteristic of the territory of sapropels. The research was carried out on a test crop - spring wheat variety "Granada". The purpose of this work is to identify the relationship of paramagnetic activity of drugs with the type of initial bottom sediments. It was found that all the preparations had a stimulating effect on the growth processes of wheat seeds "Granada", to a greater extent on the sowing qualities of seeds than on biometric indicators. The greatest effect is achieved at a concentration of 0.01% of the drug. The best results in the vegetative experiment were shown by the HA preparation extracted from clay sapropel silt, which has the highest paramagnetic activity of all samples – 5.90E+13. Keywords: SAPROPEL, BIOLOGICAL ACTIVITY, HUMIC ACIDS, HIMATOMELANIC ACIDS, ELECTRON PARAMAGNETIC RESONANCE, MIDDLE OB

Communities of Benthos Invertebrates of the Kiliya Delta of the Danube River

The communities of benthos invertebrates occurring in various biotopes of the water bodies, watercourses, and coastal zone of the Kiliya delta of the Danube River were distinguished based on the similarity of their species composition. It has been found that mainly water salinity is responsible for the formation of their physiognomy and hierarchic organization in the Kiliya delta of the Danube River, whereas the types of bottom sediments and the types of water bodies are responsible for the formation of their components. The levels of hierarchic organization of benthos communities are as follows: the lowest level is formed by primary mosaic communities occurring in various water bodies and on various types of bottom sediments, the next level is formed by the united communities distributed on various types of bottom sediments in fresh or brackish water bodies, whereas the highest level is formed by the communities of the Kiliya branch and the Danube River delta on the whole. It has been shown that the discreteness and continuality of benthos communities in the Kiliya delta of the Danube River are formed due to the development of both fresh and brackish species.

Regularities of distribution of particulation types of modern bottom sediments and organic carbon by depth in the western part of the Barents sea

In this article, the possibilities of statistical analysis methods were demonstrated on the example of studying modern bottom sediments in the western part of the Barents Sea. As a result of cluster and dispersion analyses, regularities in the distribution of granulometric types of modern bottom sediments and organic carbon dissolved in them with depth within the sublittoral and bathyal zones of the sea were established. Based on the results obtained, it was concluded that the size distribution of sediments was due to the mechanical differentiation of sedimentary material as it was transported by sea currents, as well as the distance from the main sources of drift — Novaya Zemlya, the Kola Peninsula and Svalbard. At the same time, the accumulation of organic carbon in bottom sediments was associated with the peculiarities of the distribution of communities of marine organisms within the considered facies zones. The high content of organic carbon in the bathyal zone of the sea was associated with an increase in primary productivity here, as well as with the transfer by sea currents of the accumulated biogenic material of the littoral and sublittoral zones towards the bathyal.

Coastal barrier morphogenic categories in Mississippi Delta plain development

Coastal barriers are defined as shore-parallel, aggraded-prograded supratidal beach ridge sets and individual single ridge-landforms, composed of sand and/or gravel. Island, spit, and mainland barriers represent the three major topographic subdivisions. In terms of bathymetric and hydrographic characteristics, bottom sediment types and associated habitats, barriers separate the marine offshore from inshore facies. This definition is not uniformly accepted and applied in the literature. Barriers impose reduced salinities inshore, diminish storm impact and moderate inland inundation, protect critical habitats and may mark ancient longshore transport directions, shore and sea-level positions. A wide range of dimensions, topography, and other factors characterize mainland strandplains. Shoal aggradation appears to be the prime island-forming mechanism, followed by accretion around semi-consolidated, elevated cores. Smaller islands may also form by barrier spit fragmentation. Detachment of dune ridges from the mainland shore is an often cited but at best unlikely mode of island genesis. Review of the literature and remote-sensed images created new insights, utilized barrier definitions and genetic theories, as applied in the Mississippi Delta Complex. A three-stage concept, involving dune ridge or barrier spit-detachment by marine encroachment and landward shift of fragmented transgressive islands forms the basis of a recent invited Marine Geology research article. That model assumes spit-growth from delta headlands, followed by splintering into landward-migrating islands. Submerged, they become permanent shoals. For several reasons, this “island-cycle” hypothesis is questionable and a reassessment of the geomorphic and stratigraphic context of this delta coast is required.Contradicting the geomorphic setting of assumed Stage 1, key component of the cycle-model, evidence is lacking for subrecent delta lobes and erosional headland in spawning barrier islands. In addition, the delta headland-flanking islands reveal only progradational (regressive) development and in situ disintegration,. Transgressive landward migrations is known only from the Chandeleur chain's prehistory. Sand from decaying Terrebonne-Lafourche 6 Subdelta headland was the dominant source for the Caminada Strandplain and for the shoal /or island predecessor of Grand Isle. Wave refraction around an inferred Lafourche delta lobe (dated provisionally between ∼2900 - ∼ 2300 yrs. BP) and its decayed erosional headland remnant resulted in diametric reversal of littoral sand transport. An earlier proferred ∼750–300 yrs. BP Caminada Strandplain age range is now replaced by a loosely defined ∼2200- to- ∼800 yrs. BP value, based on ages of Grand Isle and reworked delta hinterland sediments incorporated into the Strandplain.

The Principles of the Distribution of Granulometric Types of the Present-Day Bottom Sediments and Organic Carbon along the Depth in the Western Part of the Barents Sea

The Principles of the Distribution of Granulometric Types of the Present-Day Bottom Sediments and Organic Carbon along the Depth in the Western Part of the Barents Sea

Temporal and spatial patterns of demersal fish assemblages in the coastal water of Sierra Leone

Information on the temporal and spatial patterns of fish community is key to further understand the functioning of marine ecosystem and protect marine organism resources efficiently. 6 demersal trawl surveys were carried out in the coast water of Sierra Leone during Sep 2019∼May 2021. Obvious temporal and spatial heterogeneity of oceanographic condition were observed in the survey area, the water temperature and salinity were usually higher in dry season and lower in rainy season. A total of 195 species belong to 79 families were identified. Offshore Sciaenid sub-community and Inshore sparid sub-community were the 2 common and major groups identified from 6 surveys, but the composition of dominant species may have changed. Less abundant of some traditional economic species (P. Typ, P. qui, Epinephelus, Arius and Lutjanus) and more abundant of T. myo were caught The Offshore sciaenid sub-community distributed mainly in southeast part or closed to shoreline in north part of survey area. The Inshore sparid sub-community distributed mainly in northwest part. Bottom sediment type (Btype) and depth were the common significant factors for the special pattern of fish community in all surveys. Offshore sciaenid sub-community was always associated with mud substrate and shallow water; Inshore sparid sub-community was associated with sand substrate and most of sites distributed in deeper water. The significant effect of sea surface salinity (SSS) were only observed in Oct, Dec, Jan and May. SSS was filtered as significant environment parameter, may not just base on the effect of salinity on fish community, but SSS was also a better characteristic parameter for monthly fluctuation of oceanographic condition. The increasing fishing activities maybe the one of major disturbance factors to the structure change of fish community. In order to promote the biodiversity conservation, strengthen fishery management based on ecosystem approach and developing sustainable fishery should be advocated.

СОДЕРЖАНИЕ ПОЛИЦИКЛИЧЕСКИХ АРОМАТИЧЕСКИХ УГЛЕВОДОРОДОВ В ДОННЫХ ОТЛОЖЕНИЯХ ОЗЕРА БАЙКАЛ В РАЙОНАХ СИЛЬНОГО АНТРОПОГЕННОГО ВОЗДЕЙСТВИЯ

Up-to-date data on the concentration of polycyclic aromatic hydrocarbons (PAHs) in the upper 2-centimeter layer of bottom sediments in the areas of strong anthropogenic impact are presented. These areas are the following: that of the municipal wastewater discharge in the city of Baikal’sk, the impact area of the Baikal-Amur Mainline in the north of the lake, the area at the Selenga River delta front, and the one in the Maloe More region. Based on the results of long-term studies, concentrations of polyarenes in different lithological types of bottom sediments at the controlled test sites were determined. The most severe PAH contamination was observed in the sandy sediments of the test site in the area of municipal wastewater discharge in the city of Baikal’sk. In the other areas, the PAH content does not generally exceed background values.

Polychaeta fauna in the northeastern Barents Sea

The northeast of the Barents Sea (the area between the Franz Josef Land and Novaya Zemlya archipelagos) is one of the little-studied areas characterized by a complex structure of the hydrological regime, bottom relief and bottom sediment structure. This area is characterized by the predominance of brown soils with a large number of foraminifera shells, which affects the species composition and structure of benthic communities. The species composition and quantitative characteristics of polychaetes in the northeastern part of the Barents Sea were analyzed on the basis of material collected in December 2019 during Murmansk Marine Biological Iinstitution expeditions on the r/v Dalnie Zelentsy . Faunal complexes of polychaetes have been identified in the study area depending on environmental conditions (type of bottom sediments, depth, hydrological conditions). In the areas of marginal troughs, the detritophagus Spiochaetopterus typicus dominates in terms of biomass and abundance, forming abundant settlements on soft silty-sandy, silty-clay soils. Low values of biomass and abundance have been noted on brown silts with a large number of foraminifera, dominated by Laonice cirrata . On the slopes of underwater hills, washed more strongly by bottom currents, on rough sandy soils with low nutrient content, the dominance of Nephtys ciliata has been noted. The species Sphaerodoridium kolchaki sp. n. recently encountered in the Barents Sea has been noted in the study area as well. The obtained data complement information on the species composition of the northeastern part of the Barents Sea and make it possible to trace further changes in the composition and structure of benthic communities.

Microplastics distribution in bottom sediments of the Baltic Sea Proper

An abundance of microplastics particles (0.2–5 mm, MPs) in bottom sediments is analyzed based on 53 samples (3 to 215 m deep) obtained in 8 cruises of research vessels across the Baltic Sea Proper in March–October 2015–2016. MPs content varied between stations from 103 up to 10,179 items kg−1 d.w., with the bulk mean of 863 ± 1371 items kg−1 d.w., showing a statistically significant increase with water depth. As many as 74.5% of MPs are of fibrous shape, followed by films (19.8%) and fragments (5.7%). The distributions of fibres, fragments, films, and different types of natural bottom sediments are significantly different, highlighting the specific behaviour of each of these kinds of bottom deposits. A statistically significant correlation between water depth and fibres content is found. Based on the analysis of oceanographic factors and sedimentological principles, an erosion/transition/accumulation pattern for fibres in the Baltic Sea Proper is outlined. Fibres can be considered as a specific type of “synthetic sediment”, while principles of distribution of other MPs are not yet certain.

Mapping and Assessing Commercial Fisheries Services in the Lithuanian Part of the Curonian Lagoon

The spatial distribution of biomass of main commercial fish species was mapped to estimate the supply of a provisioning fishery service in the Curonian lagoon. Catch per unit effort (CPUE) was used as a proxy to estimate the efficiency of commercial fishing and, subsequently, the potential biomass of fishes. The relationship between distinctive characteristics of the fishing areas and corresponding commercial catches and CPUE was analyzed using multivariate analysis. The total catch values and CPUE used in the analyses were derived from the official commercial fishery records. RDE analysis was used to assess the variation of both catch and CPUE of commercial fish species, while the percentages of bottom sediment type coverage, average depth, annual salinity, and water residence time in each of the fishing squares were used as explanatory variables. This distance e-based redundancy analysis allowed for the use of non-Euclidean dissimilarity indices. Fisheries data spatial distribution map indicated the lack of coherence between the spatial patterns of commercial catches and CPUE distribution in the northern part of the lagoon. Highest CPUE values were estimated in the central-eastern part of the lagoon as compared to the western part of the lagoon where CPUE values were substantially lower. Both total catch and CPUE appeared not to be related to the type of bottom habitats statistically while being spatially correlated in-between. However, the impact of salinity and water residence time calculated using the 3D hydraulic circulation model on the distribution of both CPUE and commercial catches was statistically significant.

Lithostratigraphy of the bottom sediments of Pskovsko-Chudskoe Lake in the proposed site of the Ice battle

Abstract. The Ice battle is one of the most famous battles in Russian history. However, there is still no clearly answer as to where the Ice battle took place. Paleogeographic reconstructions can help in finding the place of the battle. The study area is a section of the southern part of Pskovsko-Chudskoe Lake. The works were carried out in the vicinity of Samolva and Kobylie Gorodishche villages of Gdov district of Pskov region, in the Zhelchensky Bay of Pskovsko-Chudskoe Lake. The key methods in this work are bathymetric survey, bottom sediment sampling, and lithological analysis. Three main types of bottom sediments are distinguished: sands at the bottom part of core section, upper it overlain by a thick layer of peat, which covered by gyttja.