Shallow Coastal Waters Research Articles

Feeding strategy and dietary preference shape the microbiome of epipelagic copepods in a warm nutrient‐impoverished ecosystem

AbstractCopepods provide a rich organic microenvironment allowing the settlement and proliferation of microorganisms, forming dynamic microbial hotspots in the oceans. Such symbiotic associations in the plankton were previously hypothesized to be especially developed in warm oligotrophic seas, as they may serve as alternative sources of nutrients in biologically poor waters. Aiming to better understand how copepod microbiomes are shaped in an oligotrophic sea, we characterized microbiota associated with three dominant coastal epipelagic copepod species in the ultra‐oligotrophic Eastern Mediterranean Sea using amplicon sequencing of the 16S rRNA gene. Our results show that copepod‐associated microbial communities were host‐specific rather than determined by seasonal environmental changes. In the filter‐feeding copepod with a tendency to herbivory, Temora stylifera, microbial diversity was low and relatively stable throughout the year. In contrast, omnivorous copepods, the ambush‐feeding Oithona nana, and the mixed‐feeding Centropages ponticus harbored more diverse microbiomes dominated by transient taxa. We suggest that filter‐feeding strategy and narrow food spectrum can limit copepod–microbe interactions, while the ambush and mixed feeding strategies combined with omnivory confer higher microbial diversity. Filter feeders may reduce the recruitment of opportunistic microbes by maintaining high fidelity associations, as indicated by the large number of core taxa in T. stylifera. We underline the importance of the copepod–microbe associations in nutrient‐impoverished ecosystems, based on predicted enrichment of nitrogen metabolism in the core microbiome, mostly during summer when the shallow coastal waters are nitrogen‐depleted.

Impact of the brine discharge on the bottom ecosystem of the Sambia Peninsula coast (South-Eastern Baltic Sea)

The first underground gas storage facility in Russia, built in rock salt deposits, was developed in the coastal zone of the Kaliningrad Region. Since 2018, seawater for erosion of rock salt is taken from the Baltic Sea, and after appropriate treatment, brine is discharged back to the sea. The aim of the work was to assess the impact of the brine discharge on the bottom ecosystem of the coastal shallow area. A comprehensive study was carried out on the possible path of salt brine propagation, including a bathymetric survey, CTD sounding of the water, sampling of bottom sediments and zoobenthos, determination of heavy metals in sediments. The main pathways for the spread of brine along the bottom were determined, and the additional supply of salt to the coastal zone naturally led to local changes in the existing bottom ecosystem of the coastal shallow water, including changed in the structure of zoobenthos.

Probable signature whistle production in Atlantic white‐sided (Lagenorhynchus acutus) and short‐beaked common (Delphinus delphis) dolphins near Cape Cod, Massachusetts

Probable signature whistle production in Atlantic white‐sided (<i>Lagenorhynchus acutus</i>) and short‐beaked common (<i>Delphinus delphis</i>) dolphins near Cape Cod, Massachusetts

THE DYNAMICS OF TREMATODE PREVALENCE IN TWO PERMANENT SETTLEMENTS OF THE PONTO-AZOV MOLLUSK &lt;i&gt;LITHOGLYPHUS NATICOIDES&lt;/i&gt; (C. PFEIFFER, 1828) (GASTROPODA, HYDROBIIDAE) AT THE NORTH-EASTERN BORDER OF ITS RANGE

The freshwater gastropod mollusk Lithoglyphus naticoides (C. Pfeiffer, 1828) is one of the most successful invasive species in waterbodies of the Volga River basin. One of the negative consequences of its spread is range expansion of trematode species, some of which are highly pathogenic for fish, fish-eating birds and mammals. The aim of this study is to analyze the formation features of the trematode fauna in settlements of L. naticoides at the north-eastern border of its range (the Rybinsk Reservoir). It is found that the formation of the first permanent settlement of L. naticoides took place in 2005-2010 in coastal shallow waters in the lower part of the Volga reach of the reservoir. There was no rapid spread of the mollusk throughout the entire water area of the reservoir outside the Volga reach zone with a relatively high mineral content of water. However, in 2011-2019, the formation of a new large settlement of L. naticoides was recorded in the upper part of the Volga reach characterized by faster flow. A relatively low density of mature individuals in the settlements of L. naticoides (up to 50 ind./m) makes it possible for at least five trematode species to complete their life cycle: Apophallus muehlingi (Jägerskiöld, 1899), Apophallus (= Rossicotrema ) donicus (Skrjabin et Lindtrop, 1919), Parasymphylodora markewitschi Kulakowskaja, 1947, Nicolla skrjabini (Iwanitzky, 1928), Sanguinicola volgensis (Razin, 1929). The prevalence of parthenitae of certain species depends on the reservoir water level regime but the overall infection of L. naticoides can exceed 90%. The slow-flowing lower part of the Volga reach is characterized by the dominance of P. markewitschi and trematodes of the genus Apophallus , but N. skrjabini and S. volgensis dominate in the upper section, which is close to the river type. In the future in the Rybinsk reservoir, we can expect naturalization of other trematode species associated with L. naticoides within its range.

Community structure and biomass of larval euphausiids and postlarval mysids in relation to anomalous warming events during a weekly time series (2014–2017) at Cabo Pulmo National Park, Mexico

Euphausiids and mysids are important components of pelagic ecosystems due to their high abundance and tendency to form dense aggregations, swarms, and schools, which concentrate biomass that attracts visual predators. Species richness, abundance, and carbon biomass of euphausiids and mysids were investigated from a weekly daytime surface zooplankton time series from 2014 to 2017, in relation to 15 environmental variables at Cabo Pulmo National Park (CPNP, 23°27′ N, 109°25′ W), Mexico. A marine heatwave (MHW; January–August 2014) and El Niño 2015–2016 (May 2015–May 2016) caused anomalously warm temperatures in relation to the 2002–2018 temperature time series. We tested the hypotheses that CPNP is dominated by a tropical euphausiid and mysid species assemblage and that abundance of both taxonomic groups decreased during the MHW 2014 and El Niño 2015–2016. Euphausiids (7.9 ind. m−3) had a higher mean abundance than mysids (3.4 ind. m−3). Eight euphausiid species, mostly of tropical-oceanic affinity, were collected (98 % larvae). Nyctiphanes simplex decreased and Euphausia distinguenda and Stylocheiron carinatum increased in abundance during El Niño 2015–2016. Five mysid species were collected (juveniles and adults). Mysidium rickettsi alone accounted for 99.98 % of total mysid abundance. Although the euphausiids collected were mainly larval stages, due to sampling in shallow coastal waters during the day, they contributed more biomass than juvenile and adult M. rickettsi in the pelagic habitat, though the abundance of this mysid in its epibenthonic habitat was likely underestimated. A canonical correspondence analysis of euphausiid and mysid abundance as a function of 10 environmental variables explained 77.4 % of the total variability, showing greater seasonal (warm vs cold) than interannual changes. The best correlated environmental variables with euphausiid and M. rickettsi abundance were net primary production (−0.419), zooplankton biovolume (0.3177) and the MEI.v2 (−0.278). We concluded that the most evident changes in community structure and abundance were seasonal (e.g. N. simplex dominated during the cold season while E. distinguenda dominated during the warm season) rather than interannual. Moreover, the abundance and biomass of euphausiids decreased during the MHW 2014 and El Niño 2015–2016; paradoxically the highest abundance and biomass of E. distinguenda and the mysid M. rickettsi occurred during El Niño 2015–2016. This implies higher available biomass for benthonic and nektonic predators in this neritic tropical reef ecosystem, contrasting with decreased abundance of euphausiids observed along the west coast of the Baja California Peninsula during this period.

Foraminiferal Distribution Pattern and its Ecological Implications in the Koswari and Van Islands of the Tuticorin Group of Islands

Objectives: The present investigation attempts to map the foraminiferal distribution pattern, its ecological significance, and the elemental composition of the Koswari and Van islands. Methods: Foraminiferal distribution patterns (both planktic and benthic) were recorded, and textural and geochemical analyses were carried out in the present study. Findings: The coastal environments are generally highly dynamic regions of the earth that possess imprints of global climatic variations. The islands of the Gulf of Mannar emerged during the last interglacial period. These islands are getting eroded due to the long-term impact of coral mining and climatic changes. The excess removal of corals from Koswari Island adversely affected the live coral cover of the Island. The Van island is in proximity to the Tuticorin coastal city and one-fourth of the Island has already become submerged due to several natural and anthropogenic factors. Both the islands are affected by the world coral bleaching event witnessed from 2014-2017. This study is an attempt to record how the foraminiferal assemblages of Koswari and Van islands responded to the world coral bleaching event. In the present investigation, we identified fifteen benthic foraminiferal species and two planktic foraminiferal species from both islands. The foraminiferal assemblages mark the abundance of Neorotalia calcar, Quinqueloculina seminulum, Elphidium crispum, Amphistegina lessonii, and Rotalidium annectens. The main ecological parameters which govern the foraminiferal distribution in these islands are coral reef flats, carbonate environments, and shallow coastal waters. Neorotalia calcar and Quinqueloculina seminulum are recorded as the most abundant species of both Koswari and Van islands. N. calcar prefers macroalgal mat as substratum,while the frequent occurrence of deformed tests and stress-tolerant species such as Q. seminulum indicate the influence of pollution in the coastal area. These recorded species are considered characteristic reef benthic foraminifers which prefer coarse sandy substratum. The other abundant species are Elphidium crispum, Amphistegina lessonii, and Rotalidium annectens, which are widely distributed in the inner shelf sediments of Tamil Nadu and Kerala coasts. Textural attributes of the Koswari and Van islands reflect its high energy environment, and the geochemical signature shows the high calcareous content with typical coral reef foraminifera associated with such sediment nature. Novelty: The study tried to map the effect of the global coral bleaching event of 2016 on Koswari and Van islands of the Tuticorin group of Islands in the Gulf of Mannar using foraminifera as a proxy. Keywords: Foraminifera; Coral reefs; Ecology; Coral bleaching; Gulf of Mannar

A Video Plankton Recorder user guide: Lessons learned from in situ plankton imaging in shallow and turbid coastal waters in the Belgian part of the North Sea

Optical imaging devices such as the Video Plankton Recorder (VPR) harness unique capabilities to perform in situ observations and observe planktonic organisms in their natural environmental context. However, applying this technology in shallow and turbid coastal waters comes with a number of challenges. Depending on the research goal, methodological choices need to be made regarding the appropriate towing procedure and instrument settings, like magnification or field of view. In addition, limitations can be expected related to the physical characteristics of the water column, more specifically regarding suspended matter concentration and turbidity. To inform VPR users on the possibilities and limitations of the device in shallow and turbid coastal waters, this paper evaluates a number of specific deployment procedures in the Belgian part of the North Sea (BPNS). For three different towing procedures the practical feasibility, characteristics and output are assessed and the assets and liabilities for each of the tow types are discussed. A Z-shaped and a clover-shaped tow type are seen as best fit for detailed characterization of the plankton community of a limited geographical area. A straight tow type is more suitable for plankton studies over a larger area, with the potential to capture local plankton abundance peaks and to determine the relation with the spatial variation of the environmental conditions. The capacity of the various VPR magnification settings to capture specific plankton taxa or size groups, was tested during four straight line transects with different magnifications. The highest magnification can be used for organisms from 0.3 to 0.7 mm while the low magnification allows to observe larger organisms within the size range of 1.0 to 3.8 mm. Finally, the boundary conditions for the deployment of the VPR related to the turbidity of the water column were defined and the implications for deployment within the study area were investigated. This study shows that high turbidity values over 6.2 NTU inhibit the collection of useable data, complicating the VPR's application in many coastal and transitional waters.

Development of Survey Methods to Effectively Sample Juvenile Red Snapper along the Atlantic Coast of Florida

AbstractUnderstanding of the early life history of Red Snapper Lutjanus campechanus throughout the U.S. Atlantic Ocean (hereafter, “Atlantic”) is limited, in part, due to the paucity of juveniles (&lt;150 mm TL) collected in long‐term fishery‐independent surveys in the region. This is in sharp contrast to the Gulf of Mexico (hereafter, “Gulf”), where juvenile Red Snapper have been consistently collected in surveys. This apparent regional disparity is poorly understood. Red Snapper nursery habitats may differ between the Atlantic and the Gulf, previous Atlantic surveys may not have included important nursery habitat, or sampling gear used in the Atlantic may not be effective at collecting juveniles. A 2‐year fishery‐independent study was conducted along the Atlantic coast of Florida to test whether juvenile Red Snapper could be effectively sampled with two types of gear not commonly used there: a semi‐balloon trawl like those used in long‐term groundfish surveys in the Gulf and small‐mesh Z‐traps. In total, 194 Red Snapper were collected in the trawl samples and 202 Red Snapper were collected in the Z‐trap samples—mostly juveniles (age 0 and age 1) captured in nearshore waters (&lt;30 m deep). Like the Gulf, shallow coastal waters in the Atlantic likely function as nursery habitat for Red Snapper. Primarily small age‐0 Red Snapper were collected during trawl sampling, which targeted unconsolidated nonreef habitats, whereas larger age‐0 and age‐1 and older Red Snapper were collected during trap sampling, which targeted hard‐bottom reef habitats. Although this study represents the most successful sampling of juvenile Red Snapper in the Atlantic to date, further research is required to delineate the northern and southern extents of Red Snapper nursery grounds. Nevertheless, our results provide a framework for developing a fishery‐independent survey that targets juvenile Red Snapper in the Atlantic to provide valuable data for quantifying recruitment and monitoring the status and recovery of this economically important species.

A new shallow-water mud crab of the genus Hexapanopeus Rathbun, 1898 from Belize (Crustacea: Decapoda: Panopeidae).

A new species of panopeid crab from shallow coastal waters of Belize is formally described and named based upon comparative study of three small specimens obtained in the course of a regional biodiversity survey of decapod crustaceans. The herein designated holotype of Hexapanopeus klausruetzleri n. sp. is a specimen previously included in a comparative molecular phylogenetic analysis that showed it to be closely related to, but genetically distinct from, the western Atlantic species Hexapanopeus angustifrons (Benedict Rathbun, 1891). Hexapanopeus klausruetzleri n. sp. differs from this widely reported warm-temperate species in both its smoother carapace and pereopod surfaces and its generally more lobiform anterolateral teeth. The unique male first gonopod of the new species also strongly supports its morphological separation from all known congeners and other superficially similar western Atlantic panopeids with which it might be confused. To date, mature females have not been found, and the limited available collections are restricted to the vicinity of Carrie Bow Cay and nearby waters. Fourteen additional species of small panopeid and pseudorhombilid crabs, similar to Hexapanopeus klausruetzleri n. sp. in size and general habitus, were taken in the course of our studies in Belize. Most have not been previously reported from these waters, and several warrant further study to confirm their identifications.

Sequencing Bait: Nuclear and Mitogenome Assembly of an Abundant Coastal Tropical and Subtropical Fish, Atherinomorus stipes.

Genetic data from nonmodel species can inform ecology and physiology, giving insight into a species’ distribution and abundance as well as their responses to changing environments, all of which are important for species conservation and management. Moreover, reduced sequencing costs and improved long-read sequencing technology allows researchers to readily generate genomic resources for nonmodel species. Here, we apply Oxford Nanopore long-read sequencing and low-coverage (∼1x) whole genome short-read sequencing technology (Illumina) to assemble a genome and examine population genetics of an abundant tropical and subtropical fish, the hardhead silverside (Atherinomorus stipes). These fish are found in shallow coastal waters and are frequently included in ecological models because they serve as abundant prey for commercially and ecologically important species. Despite their importance in sub-tropical and tropical ecosystems, little is known about their population connectivity and genetic diversity. Our A. stipes genome assembly is about 1.2 Gb with comparable repetitive element content (∼47%), number of protein duplication events, and DNA methylation patterns to other teleost fish species. Among five sampled populations spanning 43 km of South Florida and the Florida Keys, we find little population structure suggesting high population connectivity.

Microplastics in gut content of juveniles of the patagonic silverside fish Odontesthes sp.

Microplastics are among the major environmental problems to be addressed because it is beginning to affect food chains and is also reaching human populations. The present study investigated the size, color, shape and abundance of microplastics in juvenile silversides (Atheriniformes) belonging to the edible species Odontesthes bonariensis, Odontesthes nigricans and Odontesthes argentinensis from shallow coastal waters. While 100 % of the sampled individuals presented microplastics in stomach contents, fibers were 95 %. There is a correlation between the size of the individuals and the maximum particle size ingested ranging from 0.2 to 1.2 mm. There is no significant difference in the number of particles ingested per individual. The plastic particles had a lower density than seawater, which is why they floated on the surface. These results imply that the protected areas of large ocean currents increase the exposure of local fauna to microplastics increasing the risk of ingestion of PMs.

Seagrass Factor in Climate Change Mitigation in the Philippines

Despite their importance, seagrasses are facing a global decline due primarily to increased nutrient loading and sedimentation resulting from deforestation and agriculture, and, more recently, from seawater warming in shallow coastal waters. With the advent of new technology and a concerted understanding of seagrass ecosystems as vulnerable social-ecological systems, there has been a dramatic increase in the number of studies focusing on the effects of climate change on seagrasses. Here, I provide an account of the status, role, and future of Philippine seagrasses in an era of climate-driven environmental change. I have gathered information from published studies and actual accounts to identify potential commonalities in the effects of climate change and the responses of seagrasses across the molecular, community, and ecosystem levels. Occupying 13.3% or 4,826 km of the total length of the Philippine coastline, seagrass species composition and diversity remain relatively stable. The seagrass beds of the Philippines and Southeast Asia are declining at an estimated rate of 2.62% or 391 km2 yr–1. Coupled with the apparent neglect in accounts of global carbon, this decline indicates a potential to lose an effective source of blue carbon useful in mitigating the impacts of climate change. In this study, I evaluate the combined effects of climate change with other environmental stressors on the ecosystem services of seagrasses and emphasize the need to apply the lessons learned from three decades of local studies to provide a more inclusive science-based knowledge of seagrass- climate interaction and a deeper understanding of the ecosystem’s resilience. I conclude by presenting the most significant knowledge and management gaps and future directions for seagrass research in the Philippines.

HISTORY OF CREATION AND CURRENT STATE OF THE OVOSELSKY-ROZHKOVA DAM (KUYALNITSKY LIMAN)

Problems Statement and Purpose. The Kuyalnitskiy estuary is located within the northwestern estuary coastal region, in the interfluve of the Southern Bug and Dniester rivers. This is a closed estuary, which is separated from the sea by an embankment and has no direct connection with it. Nature management in the estuary basin during the 19th‑20th centuries was carried out disregarding the natural territorial regularities and led to a critical condition of the geosystem of the reservoir. Hydrotechnical engineering on the banks and waters of the Kuyalnitsky Estuary was aimed at regulating the hydrological regime in order to create favorable conditions for salt precipitation. One of these structures is an unexplored Novoselsky-Rozhkov dam. Data &amp; Methods Measurements were carried out using geodetic rail 3 m long, being on the rubber boat. Determination of depths and coordinates was carried out after the boat stopped at the measurement point. Аlong with measurements were determined the depths above the flooded crest of the hydrotechnical structure. The surface of the dam was explored by walking routes. The position of the boat and points on the dam was determined by Garmin GPS72H navigator. Depths were determined with an accuracy of 0.01 m. The studies were carried out under conditions of complete calm; during measurements at a temporary water measuring post no level fluctuations were recorded. Results. One of the hydrotechnical objects that exist in the water area of the estuary is the Novoselsky -Rozhkov dam. Dam was built in 1858–1859. to transform the Kuyalnitsky estuary into salt-forming self-sedimentary lake. Initial parameters of the dam: length – 2929 m, width along the top – 6.4 m, width in the lower part – 17.1 m. The height of the structure did not exceed 1 m above the water level due to constant subsidence on soft soils in the estuary. During the 165 years of its existence, the above-water part of the dam was destroyed by floods. The parameters of the underwater part and the axis of the structure remained close to the initial ones: length – 2900 m, average top width –14.2 m. The modern surface profile of the dam has a concave shape and is the same as the bottom profile. The dam affects the natural system of the Kuyalnitsky estuary as an artificial relief form: it causes the accumulation of material at the bottom and near the shore in the southern corners of the structure; water temperature rise in coastal shallow waters and above the surface of the dam by 2–3 0 С was noted in comparison with the water masses of the nearby water area.

The distribution, ecology and predicted habitat use of the Critically Endangered angelshark (Squatina squatina) in coastal waters of Wales and the central Irish Sea.

The angelshark (Squatina squatina) has the northernmost range of any angel shark species, but there is limited information on its distribution, habitat use and ecology at higher latitudes. To address this, Angel Shark Project: Wales gathered 2231 S. squatina records and 142 anecdotal resources from fishers, coastal communities and archives. These spanned the coastal waters of Wales and the central Irish Sea and were dated from 1812 to 2020, with 97.62% of records within 11.1 km (6 nm) of the coast. Commercial, recreational and charter boat fishers provided the majority of S. squatina records (97.18%), with significantly more sightings from three decades (1970s, 1980s and 1990s) and in the months of September, June, August and July (in descending order). The coastal area between Bardsey Island and Strumble Head had the most S. squatina records (n = 1279), with notable concentrations also found in Carmarthen Bay, Conwy Bay and the Outer Severn Estuary. Species distribution models (SDM) identified four environmental variables that had significant influence on S. squatina distribution, depth, chlorophyll‐a concentration, sea surface temperature (SST) and salinity, and these varied between the quarters (Q) of the year. SDM model outputs predicted a larger congruous area of suitable habitat in Q3 (3176 km2) compared to Q2 (2051 km2), with suitability along the three glacial moraines (Sarn Badrig, Sarn‐y‐Bwch and Sarn Cynfelyn) strongly presented. Comparison of modelled environmental variables at the location of S. squatina records for each Q identified reductions in depth and salinity, and increases in chlorophyll‐a and SST when comparing Q2 or Q3 with Q1 or Q4. This shift may suggest S. squatina are making seasonal movements to shallow coastal waters in Q2 and Q3. This is supported by 23 anecdotal resources and may be driven by reproductive behaviour, as there were 85 records of S. squatina individuals ≤60 cm in the dataset, inferred as recently born or juvenile life‐history stages. The results have helped fill significant evidence gaps identified in the Wales Angelshark Action Plan and immediate next research steps are suggested.

Some Like it Hot: The Ecology, Ecosystem Benefits and Restoration Potential of Oyster Reefs in Tropical Waters

Oysters are ecosystem engineers that form biogenic reef habitats in shallow coastal and estuarine waters and provide important ecosystem services. Widespread global declines have triggered a world-wide restoration movement, however a paucity of information on tropical oyster reefs has resulted in their exclusion from existing global assessments and, consequently, restoration. In this review we quantified the known global diversity of native reef-building oysters to compare diversity between temperate and tropical regions and assessed historic oyster reef presence and declines using two tropical case studies. We then summarised the biology, ecology, and benefits of tropical oyster reefs, which have four functional differences to temperate reefs: 1) the diversity of reef-building oysters is over four times higher in tropical than in temperate regions; 2) tropical reef-building oysters can have continuous spatfall throughout the year whereas temperate species have a defined season; 3) tropical reef-building oysters are generally faster growing than temperate reef-building oysters; and 4) tropical oysters commonly create mixed-species oyster reefs whereas temperate oyster reefs are generally formed by a single oyster species. There is evidence of unsustainable and destructive harvesting that has resulted in the decline of tropical oyster reefs, and these reefs should therefore be included in restoration efforts. We highlight knowledge gaps that can guide future research to develop important foundational information that will remove barriers to tropical oyster reef restoration.

DETERMINATION OF 3D WATER TURBIDITY PARAMETER FIELDS FROM LIDAR BATHYMETRY DATA BY VOLUMETRIC DATA ANALYSIS

Abstract. Accurate information on turbidity in water bodies is relevant to numerous limnological and oceanological issues. However, the collection of turbidity parameters using conventional in-situ measurement methods is time-consuming and cost-intensive and therefore usually limited to very small study areas. The use of airborne LiDAR bathymetry data is a promising alternative. However, existing methods for deriving turbidity parameters from airborne LiDAR bathymetry data are limited to the determination of one single turbidity parameter per water column element. The paper presents a novel approach that overcomes the existing limitations enables the determination of 3D water turbidity fields. By volumetric data analysis, the vertical turbidity stratification in the water body can be determined. For validation purposes, the approach was applied to synthetic measurement data generated in a simulation as well as a real measurement data set of a shallow coastal water.

An analytical four-layer horizontal electric current dipole model for analysing underwater electric potential in shallow seawater

The paper presents a new analytical four-layer (air–water–bottom–non-conductive layer) horizontal electric dipole model which allows an accurate approximation of ship's Underwater Electric Potential (UEP) from a sufficient depth in shallow coastal marine waters. The numerical methods, usually Finite Element Method (FEM) or Boundary Elements Method (BEM), are typically used to estimate the electric field and the distribution of static electric components of UEP around the ship. These methods enable analyses with high accuracy but, compared to other point-electrode methods and the proposed analytical model, they are relatively complex and need high computational time. The developed analytical model proposed in this paper allows real-time calculations without significant loss of accuracy of the UEP estimations. In the model, the problem of boundary values at the borders of individual layers is solved using the reflection/image method and applying the idea of continuity of electric potential at a given boundary between two adjacent layers. Its accuracy is verified based on the synthetic data provided by specialised software packages making use of FEM and BEM numerical methods. A dimensionless quantitative analysis of the relationships between basic parameters of the proposed four-layer analytical model and their impact on the accuracy of representation of individual electric field strength components is also delivered. The relationships between water and bottom conductivity and between water depth and bottom thickness are investigated and described. The obtained results show that the developed model allows detailed and reliable analysis of the electric field, especially in shallow coastal waters.

Are fatty acids in fish the evidence of trophic links? A case study from the southern Baltic Vistula Lagoon

Most knowledge on the feeding ecology of fish has been based on the analyses of food remains from the alimentary tracks. This traditional method, however, only provides information about recently consumed food, and is burdened with a risk of incorrect assessment of the role of individual diet components due to the different rates of digestion. A method free from such limitations is the analysis of fatty acids. The objective of our study was to recognise the potential of fatty acid signatures in providing information on the diet and feeding habits of six fish species from the shallow brackish Vistula Lagoon, southern Baltic Sea (Anguilla anguilla, Abramis brama, Rutilus rutilus, Pelecus cultratus, Perca fluviatilis, Sander lucioperca). Multivariate statistical analyses of fatty acid signatures permitted relevant grouping of the fish according to species and their diet, as well as evidenced substantial ontogenetic changes in perch, roach, and bream. They might be caused by dietary changes but can also result from internal regulatory processes. The obtained results confirmed that fatty acids provide useful, time-integrated dietary information, contributing to expanding knowledge regarding the feeding ecology of fish in shallow coastal water ecosystems. They also pointed to the necessity of assessment of the invertebrates and fish's ability to perform endogenous synthesis of polyunsaturated fatty acids, particularly in research on benthic communities. To our best knowledge, this is the first attempt to investigate the feeding habits of fish and food-web relationships in the coastal waters of the Baltic Sea using fatty acids.

Early Prosperity of Iron Bacteria at the End of the Paleoproterozoic Era

AbstractVarious iron formation (IFs) document the interplay between the geosphere and the early biosphere during their co‐evolution. At the transition between the Paleo‐ and Mesoproterozoic eras, the oxidation of the atmosphere and ocean resulted in the waning of the typical marine deposited banded IFs. Here, we report the ∼1.7 Ga Yunmengshan IF at the southern margin of the North China Craton deposited in the intertidal to upper subtidal zone belonging to river delta of coastal environments. The combined REE + Y patterns and negative δ56Fe with positive δ53Cr values reveal terrestrial precipitation of iron oxide and an enhanced continental oxidative weathering at the end of Paleoproterozoic era due to increased atmospheric oxygen level. The oxygen level happened to have facilitated the early prosperity of microaerophilic Fe(II)‐oxidation bacteria on Earth's terrestrial surface, which is recorded by the coastal shallow water iron deposits globally characterized by their small scale and subaerial features.

Microbial Diversity in a North Western Mediterranean Sea Shallow Coastal Lagoon Under Contrasting Water Temperature Conditions

Temperature and light mainly drive seasonal dynamics of microbial planktonic diversity in coastal ecosystems; however, disentangling their effects is challenging because they are always tightly coupled. Shallow coastal lagoons exhibit intense temperature changes throughout the year and high interannual temperature fluctuations, offering the opportunity to study temperature effects on microbial community diversity and succession. Weekly sampling at 16s and 18s rRNA gene OTU diversity associated with high-frequency meteorological and hydrological monitoring was conducted in the northwestern Mediterranean Thau Lagoon (South of France) from winter to spring in 2015 and 2016. While 2015 was a normal climatic year, 2016 had the warmest winter ever recorded in southern France. Water temperature was found to be the main driver of community diversity and succession from winter to spring. During the normal temperature year of 2015, bacterial communities were dominated by Proteobacteria and Bacteroidetes, archaeal community by Thaumarachaeota, and unicellular eukaryotes mainly by picochlorophytes (Bathycoccus prasinos, Micromonas bravo, and Ostreococcus spp.) in winter and diatoms (Chaetoceros spp.) in spring. The unusually warm year 2016 benefited Actinobacteria (ML602J-51), Cyanobacteria (Synechococcus), the picoeukaryote Ostreococcus spp., and several dinoflagellates. Our results suggest that in a warmer ocean, smaller organisms will dominate microbial communities in shallow coastal waters, potentially affecting ecosystem services.