Maximum Abundance Research Articles

NEW DATA ON THE DISTRIBUTION AND ISOTOPIC CHARACTERISTICS OF WOOLLY MAMMOTH REMAINS, <i>MAMMUTHUS PRIMIGENIUS</i> (PROBOSCIDEA, ELEPHANTIDAE), IN THE LATE PLEISTOCENE OF THE MINUSINSK DEPRESSION (SOUTH SIBERIA)

Radiocarbon dating of woolly mammoth remains from the Minusinsk Depression allows for the patterns of its distribution in southern Siberia in the Late Pleistocene to be specified. In the south of Siberia, mammoths are shown to have been most abundant in cold periods, the species having reached its maximum abundance in LGM. So far, there is no single mammoth record that would confidently refer to the warm time interval. During the warm intervals of the Late Pleistocene, the environment in southern Siberia could possibly have not favorable for the permanent habitation of the species Mammuthus primigenius. In general, the mammoths from the Minusinsk Depression retain species-specific features of the content of carbon and nitrogen stable isotopes (δ13C and δ15N) in bone collagen compared to other large herbivores. They show the highest δ15N values with the lowest δ13C, vs reindeer that, on the contrary, demonstrate the lowest δ15N values and a high δ13C. The isotopic signal of other herbivorous mammal species lies between the values of mammoths and reindeer. A comparison of the obtained data on carbon and nitrogen stable isotopes (δ13C and δ15N) of the woolly mammoth remains from the Minusinsk Depression with similar parameters in animals from the north of eastern Siberia reveals significant differences. One of the possible reasons may lie in differences in the diet of animals of the Minusinsk Depression from mammoths of other populations. However, similar trends, i.e. a relatively lower δ15N and higher δ13C content in the Late Pleistocene, are characteristic of both reindeer and woolly rhinoceroses of the Minusinsk Depression. This suggests that the differences in the carbon and nitrogen isotope composition in the Minusinsk Depression mammoths from those from the northern territories are due not only to the type of food, but also to a slightly different isotopic background of the region, associated with the local environment.

Abundance of radioactive technetium in Przybylski's star revisited

AbstractWe have searched for lines of the radioactive element technetium (Tc) in the spectrum of Przybylski's star (HD 101065). The nuclei of this chemical element are formed in the slow process of capturing thermalized neutrons. The possible lines of Tc I are heavily blended. We have synthesized the profile of one resonance line at 4297.06 Å , which is also a part of the complex blend, and we arrived at a decision that it is not visible in the spectrum (as was first noted by Ryabchikova), casting doubt on the existence of technetium in the atmosphere of the Przybylski's star. Therefore, based on our calculated combined profile, which has been adjusted to the observed blend profile at 4297.2 Å (that may possibly contain the resonance technetium line 4297.06 Å), we reduce the maximum technetium abundance to (Tc/H) = 2.5. This value can be considered only as an upper limit of the technetium abundance in the Przybylski's star.

Abundance, Distribution, and Characterization of Microplastics on Two Recreational Beaches in Kota Kinabalu, Sabah, Malaysia

Currently, there is a lack of assessment of the level of microplastics (MPs) pollution on recreational beaches around the world. Therefore, this study was conducted to determine the current state of MP pollution on two popular recreational beaches of Kota Kinabalu, Sabah, namely, (1) Tanjung Aru Beach and (2) UMS ODEC (Outdoor Development Center) beach. MPs from the sediments were extracted using the density separation method and analyzed through a stereoscopic microscope. The overall MPs abundance, weight, size, colors, and polymer types were recorded. Tanjung Aru beach recovered higher numbers of MPs particles for all stations, with 857 MPs/kg dry sediment with a total mass concentration of 57.72 g/kg, while UMS ODEC recorded 160 MPs/kg particles with a total mass concentration of 17.96 g/kg. The maximum MPs abundance was observed in the size of <1 mm with a high proportion of white/transparent coloring. Micro Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed that polypropylene (PP:60%) and polyethylene (PE:43%) were the two most common plastic polymers found on both beaches, followed by polyethylene terephthalate (PET), and the least common was polystyrene (PS). Metals (arsenic, chromium, copper, and nickel) were found within the MPs collected. The present study demonstrated an alarming quantity of MPs on two recreational beaches in Kota Kinabalu, Sabah, Malaysia. However, information concerning the primary sources, local dynamics, and repercussions of MPs in this location is still limited; thus, further research is required.

Benthic biota (nummulites) response to a hyperthermal event: Eccentricity-modulated precession control on climate during the middle Eocene warming in the Southern Mediterranean

Earth's future environment depends critically on how the marine ecosystems react to the current greenhouse conditions. Past warming events from the Middle Eocene can shed light on the nature of these reactions. Middle Eocene sedimentary archives from the Tethyan margins record the Middle Eocene Climatic Optimum (MECO) with varying carbon isotope excursions from site to site. The present study integrates stable isotopes, the abundance of benthic fauna, and astrochronology to look for the timing of the MECO peak warming and the maximum abundance of nummulites in the Southern Mediterranean (Tunisia). A mesotrophic environment during the lower Bartonian with high eustatic sea level promotes the formation of a shallow water carbonate platform in central Tunisia from 40.6 Ma to 39.8 Ma. Nummulites occur in low abundance in the Lower Reneiche Limestone unit (LRL, Bey et al., 2015) from 40.6 to 40.2 Ma, then increase, reaching maximum abundance at the Upper Reneiche Limestone unit (URL, 40.1 to 40 Ma). Maximum accumulation of nummulites and negative excursion of δ18O in the URL occurred during the MECO's warming peak (40.07 to 40 Ma), 200 kyr after the middle Eocene third-order maximum flooding surface. The nummulitic beds represent warmer climates and higher sea levels (arid to semi-arid climate), and the short marl intervals reflect enhanced detrital input (humid climate and lower sea level). The eccentricity modulations were extracted using a lowpass filter applied on a wide-band precession filter then we computed the instantaneous amplitude using Hilbert Transform. The Spearman-rank correlation assesses the potential introduction of amplitude modulations during tuning. Power Decomposition Analysis (PDA) indicates a dominant short eccentricity forcing on the regional climate during the MECO with a minor obliquity component. Variations in magnetic susceptibility and CaCO3 content suggest a combined control of climate and sea-level cycles controlled by eccentricity-modulated precession cycles.

Endophytic bacterial taxonomic and functional diversity in the seeds of wheat genotypes from different agroecologies

ABSTRACT Plant genotype and agroecology influence the composition and functionality of seed endophytic bacterial communities. Taxonomic analysis of 123 wheat seeds endophytic bacteria classified these into 23 genera predominantly under Firmicutes followed by Actinobacteria and Proteobacteria. Genus Bacillus was most abundant (30.7%) followed by Streptomyces (18.4%) with other representative genera such as Stenotrophomonas, Paenibacillus, Mixta, Enterobacter, Micrococcus, Pantoea, Alkalihalobacillus, Cortiobacterium, and more. Across agroecologies, the core microbiota of seeds consists of Bacillus, Streptomyces, Paenibacillus, and Stenotrophomonas, with maximum diversity and abundance observed in seeds of the North Western Plain Zone of India. Seed endophytic bacteria had PGP traits; nitrogen fixation (n = 101), production of IAA (n = 65), siderophores (n = 43), ammonia (n = 82) and solubilization of phosphate (n = 47), potassium (n = 37), and zinc (n = 8). The isolates produced HCN and hydrolytic enzymes and displayed antagonism against fungal pathogens. Overall, the information generated on wheat seeds’ endophytic bacterial taxonomy and beneficial traits may pave the path for the development of novel bioinoculants. Key message Wheat seeds from various agro-ecologies of India harbor diverse endophytic bacteria. Firmicutes were dominant followed by Actinobacteria and Proteobacteria. Genus Bacillus, Stenotrophomonas, Streptomyces, and Paenibacillus were core endophytic bacteria in different agro-ecologies. The endophytic bacterial strains were displaying diverse functional traits.

Temperature dependence of parasitoid infection and abundance of a diatom revealed by automated imaging and classification

Diatoms are a group of phytoplankton that contribute disproportionately to global primary production. Traditional paradigms that suggest diatoms are consumed primarily by larger zooplankton are challenged by sporadic parasitic "epidemics" within diatom populations. However, our understanding of diatom parasitism is limited by difficulties in quantifying these interactions. Here, we observe the dynamics of Cryothecomonas aestivalis (a protist) infection of an important diatom on the Northeast U.S. Shelf (NES), Guinardia delicatula, with a combination of automated imaging-in-flow cytometry and a convolutional neural network image classifier. Application of the classifier to >1 billion images from a nearshore time series and >20 survey cruises across the broader NES reveals the spatiotemporal gradients and temperature dependence of G. delicatula abundance and infection dynamics. Suppression of parasitoid infection at temperatures <4 °C drives annual cycles in both G. delicatula infection and abundance, with an annual maximum in infection observed in the fall-winter preceding an annual maximum in host abundance in the winter-spring. This annual cycle likely varies spatially across the NES in response to variable annual cycles in water temperature. We show that infection remains suppressed for ~2 mo following cold periods, possibly due to temperature-induced local extinctions of the C. aestivalis strain(s) that infect G. delicatula. These findings have implications for predicting impacts of a warming NES surface ocean on G. delicatula abundance and infection dynamics and demonstrate the potential of automated plankton imaging and classification to quantify phytoplankton parasitism in nature across unprecedented spatiotemporal scales.

Structure and Spatial Distribution of Mesozooplankton Communities in the Atlantic Sector of the Southern Ocean

In this paper, the composition and patterns of spatial distribution of mesozooplankton communities in the waters of the Bransfield Strait, the Antarctic Sound, the Powell Basin of the Weddell Sea and the waters off the Antarctic Peninsula and South Orkney Islands during the austral summer of 2022 are presented. Among the mesozooplankton communities two groups were found to be the most abundant: copepods Calanoides acutus, Metridia gerlachei and Oithona spp., and euphausiids Euphausia superba. The maximum abundance and biomass of the mesozooplankton were found in the warm Antarctic surface deep-sea water off the South Orkney Islands. The minimum values, respectively, were found in the cold modified Weddell Sea waters off the Antarctic Peninsula. Copepods was concentrated in the Bransfield Strait near the South Shetland Islands with sea surface temperature (SST) of –0.5–0.5°С and sea surface salinity (SSS) of 34.5–34.6‰; and the krill E. superba eggs and larvae at different development stages was concentrated in the waters off the South Orkney Islands with SST values of 1–2°С and SSS values of 34.3–34.5‰. Four groups of mesozooplankton communities at different composition, abundance, and taxa dominance were identified. The results of this and future study have practical implications for monitoring the state of the changing ecosystem of the Southern Ocean.

Oribatid mites in different Mediterranean crop rotations fertilized with animal droppings.

Unsustainable soil management is one of the drivers of soil degradation, but impact assessment requires the development of indicators. Oribatids might be considered as early indicators of disturbances due to the stability of their community. The aim of this study was to investigate the feasibility of oribatids as bioindicators of sustainable agricultural practices. Under a dry Mediterranean climate, three fertilization experiments - two under a two-crop rotation system and one under maize monoculture and established 12 years earlier - were sampled 3× for oribatid identification during the last annual cropping cycle. The hypothesis was that different nutrient and crop managements affect the number of oribatid species and individuals present, and these parameters could be used as indicators of soil degradation. In total, 18 oribatid species were identified, and 1974 adult individuals were recovered. Maximum abundance was found prior to sowing. Pig slurry (PS) vs. control, and dairy cattle manure (CM) vs. mineral fertilization increased oribatid abundance. This increase was evident when the average applied rates with PS were ca. 2 Mg of organic matter (OM) ha- 1 yr- 1, or higher than ca. 4 Mg OM ha- 1 yr- 1 for CM. When the preceding crop was wheat and PS or CM were used, Oribatula (Zygoribatula) excavata (which reproduces sexually) predominated. In maize monoculture fertilized with CM, Tectocepheus sarekensis and Acrotritia ardua americana (which can reproduce through parthenogenesis) prevailed vs. Oribatula, which indicated a heavily disturbed soil. Under this specific Mediterranean environment, the predominance of certain parthenogenic oribatid species and the number of individuals provide advanced warning on soil degradation.

Fire activity across Cretaceous/Paleogene transition: Evidence from pyrogenic biomarkers preserved in the Mahadeo-Cherrapunji section, Meghalaya, India.

Previous studies on high concentrations of polycyclic aromatic hydrocarbon (PAHs) present in the shallow-marine Um-Sohryngkew River (USR) Cretaceous/Paleogene Boundary (KPB) section suggested regional fire incidences and biotic stress on life. However, such observations at the USR site have not been confirmed so far anywhere else in the region, we, therefore, do not know whether the signal was local or regional. Thus, to find out charred organic markers associated with the shelf facies KPB outcrop (at a distance of over 5 km) of the Mahadeo-Cherrapunji road (MCR) section, PAHs were analyzed using gas chromatography-mass spectroscopy. Data show a notable rise in the PAHs and exhibit maximum abundance in the shaly KPB transition layer (in biozone P0) and the immediately underlying layer. The PAH excursions match well with the major incidences of the Deccan volcanic episodes and convergence of the Indian plate with the Eurasian and Burmese plates. These events were responsible for seawater disturbances and eustatic and depositional changes, including the retreat of the Tethys. The incidence of high amount of pyogenic PAHs unrelated to the total organic carbon content is suggestive of wind-blown or aquatic system transportation. A down-thrown shallow-marine facies of the Therriaghat block was responsible for an early accumulation of PAHs. However, the spike of perylene in the immediately underlying KPB transition layer is plausibly linked to the Chicxulub impact crater core. Anomalous concentrations of combustion-derived PAHs together with the high fragmentation and dissolution of the planktonic foraminifer shells show marine biodiversity and biotic distress. Significantly, the pyrogenic PAH excursions are restricted to either the KPB layer itself or strictly below or above it, indicating regional fire incidences and attendant KPB transition (66.016 ± 0.050 Ma).

Taxonomy and abundance of epibenthic Prorocentrum (Dinophyceae) species from the tropical and subtropical Southwest Atlantic Ocean including a review of their global diversity and distribution

In the tropical and subtropical South Atlantic Ocean, studies on the taxonomy and abundance of benthic harmful algae are scarce and the region has been largely under investigated. In this study, morphological descriptions, molecular (LSU rDNA and ITS region) and abundance data of benthic Prorocentrum species from the tropical and subtropical Southwest Atlantic and three oceanic islands are presented. Moreover, a review of global benthic Prorocentrum species richness and distribution is presented. Eleven benthic Prorocentrum species were found in Brazil. Morphological and molecular data on P. borbonicum, P. hoffmannianum, P. lima species complex and P. rhathymum were provided. Prorocentrum panamense, P. cf. caipirignum, P. cf. concavum, P. cf. norrisianum, P. emarginatum/fukuyoi/sculptile complex and two not identified species were observed using scanning electron and/or light microscopy, and morphological descriptions are presented. Prorocentrum lima species complex was found at all investigated sites, in abundances up to 2 × 104 cells g−1 FW at the Northeast Brazil, while maximum abundance of all the remaining species did not exceed 1 × 103 cells g−1 FW. The Fernando de Noronha archipelago can be considered a hotspot of benthic Prorocentrum species diversity, with ten species registered. Data compiled in the literature review shows a clear latitudinal gradient with higher species richness in tropical and subtropical regions relative to temperate areas. It is also evident that there is a bias caused by taxonomic impediment and an uneven sampling effort, with many regions still to be investigated using a combined morphological and molecular effort. Therefore, the current knowledge on the global distribution of benthic Prorocentrum species is likely underestimated.

Local variability, human factor or vague procedure? Searching for the reasons of excessive mortality in free living aquatic insects, resulting from biological monitoring

During the analysis of the biomonitoring data of Polish watercourses, it was found that the vast majority of aquatic insects (83–95% of more than 8.8 million individuals collected between 2012 and 2019) die unnecessarily during sampling, as a result of the sub-sampling procedure. Great, in some cases 30-fold differences in the mortality of insects, including those belonging to protected taxa, were observed between the samples analyzed by various regional laboratories. The most important reason for these differences appears to be factors that can be collectively referred to as the ‘human factor’, related to removing insects from the sphere of ethical protection, makes their killing an activity ethically neutral. This kind of attitude, which does not attach any importance to the life and suffering of insects interacts with the lack of precise requirements for the sampling equipment used. Those factors seem to be the most important in explaining the causes of excessive mortality of aquatic insects during sampling and the huge differences between laboratories. Principal component analysis and the analysis of variability measures showed that ecological differences between sampling sites can only be considered as a secondary determinant.Implications for insect conservationImproperly planned and conducted monitoring procedures, through excessive mortality of free-living aquatic insects, have or may have a negative impact on the environment and biodiversity. Therefore, it seems very important to promote alternative solutions that reduce such mortality in biological monitoring, such as: non-lethal methods of animal sampling, the use of pre-sampling areas to estimate the density of animals before sampling and estimation of the maximum abundance of a sample necessary for a reliable estimate of taxonomic richness using rarefaction.

Clinical application of ctDNA detection in Chinese pediatric patients with soft tissue sarcoma (STS).

10041 Background: Circulating tumor DNA (ctDNA) is an effective and noninvasive supplementary approach for assessing minimum tumor burden in a range of solid tumors; however, studies on pediatric soft tissue sarcoma (STS) are limited. The purpose of the study was to assess the utility of ctDNA detection in predicting patient response and recurrence, and to inform treatment strategies through dynamic monitoring of ctDNA during the treatment of various types of pediatric STS. Methods: From January 2022 to January 2023, a total of 27 tissues and 112 plasma samples were obtained at baseline and during treatment. Utilizing the next-generation sequencing approach, ctDNA profiling was performed on tissue and plasma samples from 48 pediatric STS ( &lt; 18 years old) with a panel of 481 sarcoma-specific genes (Nanjing Geneseeq Technology Inc.). Results: The study included thirty patients with rhabdomyosarcoma, nine Ewing sarcoma, and nine other subtypes of sarcoma, with 52.1% (n = 25) female. Seven patients were stages I-II, and 24 were stages III-IV. At baseline, ctDNA was identified in 56.25 % (18/32) of plasma before chemotherapy and 87.50 % (14/16) of plasma before surgery. Comparable mutational burdens were seen in baseline tissue and plasma samples, with an average of 3.8 and 3 mutations per sample, respectively. The concordance of detected mutations between tissue and plasma was 64.3%. The average plasma abundance (p = 0.007), maximum abundance (p = 0.0045), ctDNA concentration (hGE/ml) (p = 0.0005), and relative ctDNA abundance (p = 0.0083) of stage IV patients (n = 5) were higher than those of stage I-III patients (n = 6). Following surgical resection, four patients (25 %, 4/16) had detectable ctDNA. In the longitudinal monitoring, we found a high correlation (75.86 %, 22/29) between ctDNA trend and clinical response. Notably, ctDNA positive in Ewing sarcoma had the strongest correlation with clinical response. The inconsistency between ctDNA detection and clinical response could be attributed to the presence of bone lesions (57.1%, 4/7). One patient was observed to have positive ctDNA before any radiological findings. Conclusions: Our findings showed that it is feasible to use ctDNA to dynamically monitor tumor burden in pediatric soft tissue sarcoma, especially Ewing sarcoma. ctDNA may serve as a safe, non-invasive option complementary to imaging assessment of sarcoma, and further clinical benefits are being investigated.

Search for lithium-rich giants in 32 open clusters with high-resolution spectroscopy

Context. Lithium-rich giant stars are rare and their existence poses a challenge to our understanding of stellar structure and evolution. In particular, open clusters aptly constrain the mass and age of their members, offering a unique opportunity to understand the evolutionary stage where Li enrichment occurs. Aims. We take advantage of the high-quality sample gathered for the search for planets in open clusters with HARPS and UVES to look for Li-rich giants and to identify the Li enrichment mechanisms responsible. Methods. We derived stellar parameters for 247 stars belonging to 32 open clusters, with 0.07 Ga &lt; ages &lt; 3.6 Ga. We employed the spectral synthesis technique code FASMA for the abundance analysis of 228 stars from our sample. We also determined the ages, distances, and extinction using astrometry and photometry from Gaia and PARSEC isochrones to constrain their evolutionary stage. Our sample covers a wide range of stellar masses from 1 to more than 6 M⊙ where the majority of the masses are above 2 M⊙. Results. We find 14 canonical Li-rich giant stars that have experienced the first dredge-up. This corresponds to 6% of our total sample, higher than what is typically found for field stars. The majority of the stars (11/14) are located at the red clump, two lie on the red giant branch, and we could not conclude on its evolutionary stage for one. Apart from the canonical limit, we used the maximum Li abundance of the progenitor stars as a criterion for Li enrichment and found 12 Li enriched stars (five appearing in the red clump, five at the upper red giant branch, and two that are inconclusive). We find Li enhancement also among eight stars that have passed the first dredge-up and show strong Li lines based on the fact that stars at the same evolutionary stage in the same cluster have significantly different Li abundances. We confirm that giants with higher Li abundances correspond to a higher fraction of fast-rotating giants, suggesting a connection between Li enhancement and stellar rotation, as predicted by stellar models. Conclusions. Our Li-rich giants are found in various evolutionary stages, implying that no unique Li production mechanism is responsible for Li enrichment. Instead, there are different intrinsic or external mechanisms that are simultaneously at play.

Stabilization of γ-/α-Fe nanocrystalline phases inside carbon nanotube buckypapers and functionalization with Gd

The stabilization of γ-Fe inside carbon nanotubes (CNTs) and its magnetic-coupling with α-Fe or Fe3C has attracted a great interest for the possible control of the hysteresis-loss processes in magnetic hyperthermia. Being interested in exploring further the stabilization-dynamics of this phase (γ-Fe), we have performed novel investigations on the fabrication and manipulation of filled CNTs films (buckypapers) with major focus on the effects of vapour-flow- and cooling-rate synthesis-parameters. X-ray diffractograms (XRD) and Rietveld refinements evidence an unusual stabilization of γ-Fe upon cooling, with a maximum relative abundance of 26 % after a slow-cooling step of 30 min. In-situ post-growth manipulation of the CNT-structure, in presence of tris(tetramethylcyclopentadienyl)‑gadolinium (III), allows for a particularly efficient functionalization of the CNT-walls, with in-situ surface-deposition of an amorphous Gd-phase. The rapid-cooling approach employed in the post-growth Gd-functionalization-step is found to have beneficial effects on the γ-Fe stabilization, with an enhanced relative abundance of 30 %, as extracted from Rietveld refinements. Extended characterization through magnetometry, evidence a dependence of the coercive-field value on both cooling and flow-rate parameters. The reported dataset confirms the existence of a magnetic-coupling within the encapsulated nanocrystals, with the unit-cell-volume being in the order of 45.9 Å3.

Copepod community structure in the highly turbid innermost part of Ariake Bay in the 2000s with special reference to high abundances of &lt;i&gt;Oithona davisae&lt;/i&gt;

Ariake Bay has Japan’s biggest nori seaweed farming field in the innermost part and has suffered from environmental degradation since the late 1990s. To elucidate the seasonal patterns in the copepod community structure in the inner bay, we examined monthly plankton-net samples collected in the top 2-m layer at 11 stations for 5 years from April 2002 to March 2007. Of the 11 stations, 7 were at the high-turbidity site (HTS) representing the nori farming field and 4 in the offshore low-turbidity site (LTS) for comparison. The copepod community in the HTS was dominated almost year round by Oithona davisae, whose 5-year mean abundance of 203 ind. L−1 comprised 84% of copepods and was more than double that in the LTS. O. davisae became extremely abundant in summer with the maximum monthly mean abundance in the HTS of 2756 ind. L−1 and the maximum sample-specific abundance of 10116 ind. L−1. The following predominant copepods in the HTS were Parvocalanus crassirostris in summer–autumn, Microsetella norvegica in summer, Acartia omorii in spring, and Paracalanus parvus s.l. irregularly. Possible causes for high abundance of O. davisae in the HTS are assumed to be sufficient food resources, water temperature over 21°C, and a wide salinity tolerance range of the species.

Microbial community dynamics and performance of simultaneous anammox and denitrification (SAD) process at varying substrate loadings during long-term operation

The simultaneous anammox and denitrification (SAD) process has attracted more and more attention due to its low energy consumption and high-efficiency, but its optimal operating conditions and the interspecies interactions between the main functional microorganisms anaerobic ammonia oxidation bacteria (AnAOB) and denitrifying bacteria (DNB) have not been fully elucidated. In this study, SAD was achieved by enriching DNB through the addition of sodium acetate to anammox granular sludge. Furthermore, the pollutant removal effect and the composition of the main functional microbial community under different organic loads were investigated by manipulating the influent C/N ratio. The results indicated that the reactor achieved the highest total nitrogen removal efficiency of 89.05% at a C/N ratio of 1 and the activity of AnAOB was inhibited on a higher C/N ratio, leading to the deterioration of effluent quality. Candidatus_Brocadia was the dominant genus of AnAOB, reaching a maximum relative abundance of 0.49% at a C/N ratio of 1. DNB was also significantly enriched after the addition of sodium acetate, and the synergistic effect of the two functional bacteria contributed the simultaneous nitrogen and carbon removal of the SAD process.

Abundance does not predict extinction risk in the fossil record of marine plankton

A major premise of ecological neutral theory is that population size is inversely related to extinction risk. This idea is central to modern biodiversity conservation efforts, which often rely on abundance metrics to partially determine species extinction risk. However, limited empirical studies have tested whether extinction is indeed more probable for species with low abundances. Here we use the fossil record of Neogene radiolaria to test the relationship between relative abundance and longevity (time from first to last occurrence). Our dataset includes abundance histories for 189 polycystine radiolarian species from the Southern Ocean, and 101 species from the tropical Pacific. Using linear regression analyses, we show that neither maximum nor average relative abundance are significant predictors of longevity in either oceanographic region. This suggests that neutral theory fails to explain the plankton ecological-evolutionary dynamics we observe. Extrinsic factors are likely more important than neutral dynamics in controlling radiolarian extinction.

Abundance and distribution of subsurface microfibres and seabed macrolitter in Thoothukudi, Gulf of Mannar, South-east coast of India

Aim: Considering the potential harm caused by plastic pollution to the marine ecosystem, the present study was conducted to elucidate the status of microfiber and macrolitter in the selected areas of Thoothukudi on the South-east coast of India. Methodology: The abundance and distribution of subsurface microfibers in four locations of Tuticorin inshore waters were estimated by filtering subsurface waters using a 250µm mesh epineuston net. The non-biodegradable macrolitter on the seabed at three locations of Thoothukudi was estimated by swept area method. Results: Among the four selected stations, a higher quantity of microfibres was observed in the subsurface waters at 5m depth close to nearshore areas, with the highest mean numerical abundance of 3.13±0.3 nos.m l-1. The annual difference in the subsurface microfibre abundance varied significantly between stations (p&lt;0.05). Plastics were the most dominant litter constituents on the sea beds among three stations. A significant seasonal variation (p&lt;0.05) with maximum mean total macrolitter abundance was noticed on the seabed at Kayalpattinam (45.81± 9.3 kg km-2). The estimated mean macrolitter abundance at all the stations was higher than the reported national average of 10.95±3.05 kg km-2. Interpretation: This study revealed variations in the abundance and distribution of microfibers and macrolitters in the selected areas of Tuticorin. The study emphasises the role of land and marine-based anthropogenic activities in the plastic pollution of this region. Key words: Abundance, Gulf of mannar, Microfibres, Macrolitter, Subsurface waters, Seabed

Effects of Biotic and Abiotic Factors on the Spatiotemporal Distribution of Round Scad (Decapterus maruadsi) in the Hainan Island Offshore Area

Fishery resource and environmental data from four surveys conducted in the Hainan Island offshore area from March 2021 to June 2022 were used to investigate the spatiotemporal distribution of round scad (Decapterus maruadsi). A generalized additive model was applied to explore the relationships among abundance and distribution, also biotic and abiotic factors (i.e., temperature, salinity, chlorophyll-a concentration, water depth, phytoplankton abundance, zooplankton abundance, and jack mackerel (Trachurus japonicas) abundance). Round scad abundance (average 67.17 kg/km2) showed distinct spatial and seasonal differences around Hainan Island, with highest abundance in summer (171.72 kg/km2) and lowest abundance in spring (3.06 kg/km2). The optimal model revealed that jack mackerel abundance, sea bottom temperature, sea surface temperature, and latitude very significantly (p &lt; 0.01) affected round scad distribution. Jack mackerel abundance (mainly in the range 0–50 kg/km2) was positively correlated with round scad distribution. The distribution showed a dome-shaped relationship with bottom water temperature in the range 18–30 °C, with maximum abundance at 24 °C. The distribution was negatively correlated with surface water temperature in the range 22–30 °C. Sea surface chlorophyll-a concentration and longitude were significantly correlated (p &lt; 0.05) with round scad distribution. The results provide theoretical support to further investigate the formation mechanism of round scad fishing grounds and to enrich knowledge of pelagic fish abundance in the continental-shelf waters of the northern South China Sea.

First Record of the Alien Tintinnid Ciliate Rhizodomus tagatzi Strelkow and Wirketis 1950 in the Adriatic Sea

The tintinnid ciliate Rhizodomus tagatzi has spread rapidly in recent decades in neritic areas of the Mediterranean and adjacent seas, where it is classified as a non-indigenous species. The present study documents the first finding of the species in the Adriatic Sea, in the transitional waters of the Neretva River estuary. Zooplankton material was collected with 5 L Niskin bottles in three layers (1, 5 and 7 m) at two stations, at the mouth of the Neretva River and 16 km upstream, in the period from May 2022 to January 2023. In addition to the morphological characteristics of R. tagatzi, we discuss the state and variability of the populations based on the abundance of the species and the influence of abiotic environmental factors (temperature and salinity) and possible pathways of entry into the Adriatic Sea. The maximum abundance of R. tagatzi in the Neretva River estuary of ~2 × 103 cells L−1 is among the highest in the Mediterranean Sea, and the species has a significant contribution to the tintinnid community (&gt;80%), indicating successful establishment of the population in the estuary and intense influence on ecosystem functioning until the strong river flow completely displaces the wedge from the seabed. Statistical methods confirm the differences between stations in the total abundance of tintinnids and differences in their vertical distribution at the upstream station.