Mean Abundance Research Articles

Searching for common patterns in parasite ecology: species and host contributions to beta-diversity in helminths of South African ungulates and fleas of South American rodents

We searched for common patterns in parasite ecology by investigating species and host contributions to the beta-diversity of infracommunities (=assemblages of parasites harboured by a host individual) in helminths of three species of South African ungulates and fleas of 11 species of South American rodents, assuming that a comparison of patterns in distinctly different parasites and hosts would allow us to judge the generality or, at least, commonness of these patterns. We used data on species’ composition and numbers of parasites and asked whether (i) parasite species’ attributes (life cycle, transmission mode, and host specificity in helminths; possession of sclerotized combs, microhabitat preference, and host specificity in fleas) or their population structure (mean abundance and/or prevalence) and (ii) host characteristics (sex and age) affect parasite and host species’ contributions to parasite beta-diversity (SCBD and HCBD, respectively). We found that parasite species’ morphological and ecological attributes were mostly not associated with their SCBD. In contrast, parasite SCBD, in both ungulates and rodents, significantly increased with either parasite mean abundance or prevalence or both. The effect of host characteristics on HCBD was detected in a few hosts only. In general, parasite infracommunities’ beta-diversity appeared to be driven by variation in parasite species rather than the uniqueness of the assemblages harboured by individual hosts. We conclude that some ecological patterns (such as the relationships between SCBD and parasite abundance/prevalence) appear to be common and do not differ between different host-parasite associations in different geographic regions, whereas other patterns (the relationships between SCBD and parasite species’ attributes) are contingent and depend on parasite and host identities.

Parasites Infestation on Cultured Barramundi (Lates calcarifer) and the Impact of Fish Health

Barramundi Lates calcarifer is one of the leading marine aquaculture commodities in Indonesia, therefore fish health should be observed. This study was conducted to determine the type and number of parasites present in barramundi, the prevalence, mean intensity and mean abundance of parasite and the number of leukocytes in each individual, based on the level of infestation. This study used a quantitative descriptive method, using a total of 30 fish with two different sizes of host of ± 20 cm (large) and ±5 cm (small) each as many as 15 individuals. The results showed that size of host samples influenced the number of parasites infested with the prevalence of 40%, while ectoparasite 20%. This may due to differences in the living environment as well as the larger host provides more space to the parasites. The ectoparasites found in barramundi, namely Trichodina sp, Cryptocaryon sp, Benedenia sp, Diplectanum sp and endoparasites, namely Camallanus sp. Ectoparasites Trichodina sp. has the highest mean intensity of 20%. The highest mean abundance on large fish was 3.2 ind/fish on ectoparasite and endoparasites was 0.07 ind/fish. The lowest leukocytes were 179.82 103/μl (19.6 cm) and the highest in sample number three was 218 103/μl (20 cm), all exceeded the normal amount of leucocytes cells for fish was uninfected.

Studies on Insect Pollinator Fauna and Behaviour of Honeybees in Indian Mustard, [Brassica juncea (L.) Czern. and Coss

Understanding honeybee foraging behaviour optimizes pollinator usage, increasing crop yield, quality, and ecosystem biodiversity, benefiting mustard and other crops. The present investigations were carried out in the experimental field of mustard crop and the apiary at RVSKVV- Krishi Vigyan Kendra, Morena, Madhya Pradesh, during 2021-22. Results revealed that a total of 36 species belonging to 8 orders viz., Hymenoptera (12), Diptera (9), Lepidoptera (6), Coleoptera (3), Hemiptera (2), Orthoptera (2), Neuroptera (1) and Odonata (1). The comparative mean abundance among the various bees appearing on mustard flowers revealed that Apis mellifera (15.29 bees/m2/5 min) was the predominant visitor followed by A. dorsata (11.57 bees/m2/5 min) and A. cerana indica (6.81 bees/m2/5 min. It was found that A. mellifera, A. dorsata and A. indica constituted 45.40, 34.37 and 20.23 per cent, respectively. The maximum mean foraging speed during different day hours varied from 3.33 to 8.66 seconds for A. cerana indica 1200 hrs to 1600 hrs, respectively and for A. mellifera it varied from 1.46 to 3.66 seconds at 1800 hrs to 1400 hrs, respectively. Additionally, the highest mean foraging rate during different day hours varied from 10.71 to 21.43 flowers visited/min for A. mellifera during 1800 to 1200 hrs, respectively and the mean foraging rate was lowest for A. cerana indica varied from 5.14 to 12.29 flowers visited/min during 1800 to 1200 hrs, respectively

MbDecoda: a debiased approach to compositional data analysis for microbiome surveys.

Potentially pathogenic or probiotic microbes can be identified by comparing their abundance levels between healthy and diseased populations, or more broadly, by linking microbiome composition with clinical phenotypes or environmental factors. However, in microbiome studies, feature tables provide relative rather than absolute abundance of each feature in each sample, as the microbial loads of the samples and the ratios of sequencing depth to microbial load are both unknown and subject to considerable variation. Moreover, microbiome abundance data are count-valued, often over-dispersed and contain a substantial proportion of zeros. To carry out differential abundance analysis while addressing these challenges, we introduce mbDecoda, a model-based approach for debiased analysis of sparse compositions of microbiomes. mbDecoda employs a zero-inflated negative binomial model, linking mean abundance to the variable of interest through a log link function, and it accommodates the adjustment for confounding factors. To efficiently obtain maximum likelihood estimates of model parameters, an Expectation Maximization algorithm is developed. A minimum coverage interval approach is then proposed to rectify compositional bias, enabling accurate and reliable absolute abundance analysis. Through extensive simulation studies and analysis of real-world microbiome datasets, we demonstrate that mbDecoda compares favorably with state-of-the-art methods in terms of effectiveness, robustness and reproducibility.

Earthworms as soil health indicators in no-tillage agroecosystems

No-tillage (NT) and no-tillage systems (NTS) are widely used conservation agriculture practices in Brazil, and in the state of Paraná, nearly 80% of annual crops are cultivated using these methods. Compared with NT, NTS sites permanently include: minimum soil disturbance, soil cover (straw and living vegetation) and crop rotation and diversification with cover crops. These practices often increase earthworm populations, that can be used to indicate soil health. Herein, we review soil health classification of NT sites, and the species found in Paraná state. We compiled information from 130 sites with NT or NTS, located in 29 counties, of which 93 had biomass and 91 had species richness data, aiming to compare NT with NTS sites, and the effect of the age of these practices on earthworm populations. Overall, 29 earthworm species were recorded, of which 17 were native, including many new to science. Mean abundance and biomass in NT + NTS were 104 ind m−2 and 2.5 g m−2, respectively, and richness 2.5 species per site. Abundance was significantly higher in NT than NTS in the initial phase of adoption, and both abundance and biomass decreased with increasing age of NT. Earthworm abundance and species richness were positively correlated with clayey soils and phosphorus content, while higher biomass was associated with soil carbon content and pH. A new classification system was proposed, with the categories poor (<50 ind. m−2, 1 species), moderate (≥50 to <100 ind m−2, 2 species), good (≥100 to <150 ind m−2, 3 species), very good (≥150 to 200 ind m−2, 4 species) and excellent (≥200 ind m−2, ≥5 species) soil health, using earthworm abundance and species richness, respectively. Most of the sites sampled showed poor or moderate soil health, with few displaying very good or excellent health, indicating the need for improved management practices, in order to promote earthworm populations and their potential benefits to soil fertility and plant production.

Assessment of microplastic contamination in some commercial fishes of the southern Caspian Sea and its potential risks.

This study examined the occurrence of microplastics (MPs) in the gastrointestinal tract (GIT) of 384 fishes classified into four species from 11 sites in 2022 from the southern part of the Caspian Sea. GITs of fishes were collected and digested in H2O2 and KOH at 45°C for 72h. After filtration, extracted MPs were observed under a stereomicroscope, and selected MP particles were identified using FTIR. Presence of MPs was 68.98% in the GIT of the investigated fish. The mean abundance of MPs was 5.9 ± 0.9 MPs/GIT in Rutilus kutum, 9.2 ± 1.2 MPs/GIT in Chelon auratus, 3.6 ± 0.7 MPs/GIT in Alosa braschnikowi, and 2.7 ± 0.5 MPs/GIT in Vimba vimba. The predominant form of MPs was fiber (58.21%), followed by fragment (34.77%). Black (34.4%), white (19.07%), and blue (14.58%) were the most frequently detected colors of MPs. Overall, 6 MP polymers were identified, dominantly polypropylene (42.86%), polystyrene (17.86%), and cellophane (14.28%). The western part of the Caspian Sea (mostly tourist spots and urban areas) showed more MP pollution in fish compared to the eastern part. Polymer hazard index (PHI) revealed alarming microplastic contamination in the southern Caspian Sea. The PHI value of the present study showed that PES (PHI = 8403.78) and PS (PHI = 535.80) were "Extreme danger" and "Danger" risk categories, respectively.

Niche position accounts for the positive occupancy–abundance relationship of lake fishes

AbstractAimIf the positive occupancy–abundance relationship prevails, locally abundant species are widely distributed. Although broadly supported, studies on lake fishes have thus far contributed little to this topic, especially at intermediate and small spatial scales. Here, the main objective was to investigate the relationship between occupancy and abundance of lake fish species within a large lake, as well as examine the relative importance of ecological niches, functional traits and phylogenetic relatedness in forming the relationship.LocationPoyang Lake, China.TaxonFishes.MethodsWe calculated occupancy and mean abundance for 78 fish species and estimated niche position and niche breadth for each species based on a set of environmental variables. Additionally, we generated four functional trait vectors and one phylogenetic vector, describing trait similarity and phylogenetic relatedness, respectively. Linear models, hierarchical partitioning analyses and boosted regression trees were used in combination to explore the relative role of niche position, niche breadth, trait vectors and phylogenetic relatedness in determining fish occupancy, abundance and their relationship.ResultsOccupancy and mean abundance of fish species in Poyang Lake showed a significantly positive and rather strong interspecific relationship. Interspecific variations in fish occupancy and abundance were well accounted for by niche position, followed by niche breadth. Nonetheless, trait vectors and phylogenetic relatedness were of minor importance in affecting fish occupancy and abundance. Additionally, occupancy was better explained than abundance by the predictor variables used, which was shown by both linear models and boosted regression trees.Main ConclusionsThis study suggests that the positive correlation between occupancy and abundance also occurs in lake fish species. Furthermore, ecological niche features, especially niche position, were more important than functional traits and phylogenetic relatedness in accounting for occupancy and abundance of fish species in Poyang Lake.

Floating marine debris in two pelagic ecosystems of the southwestern Atlantic off Argentina

In 2012 and 2013, observational surveys from seismic vessels were conducted to evaluate the abundance and composition of floating marine debris (FMD) in the east of Tierra del Fuego (TDF), Argentina, and the Brazil/Malvinas Confluence zone (BMC), respectively. The mean abundance of FMD varied significantly between sampled ecosystems, with higher loads in TDF (mean abundance = 6.15 ± 8.84 items) when compared to BMC (3.31 ± 6.83 items). Plastics dominated the composition of FMD at both ecosystems (&gt; 80%), followed by foamed plastics. Within the plastic category, bags were the most abundant item, followed by wrappers, and bottles, among others. According to its color, white/clear, and multicolor debris were the most abundant. The main presumed source of FMD was domestic activities, followed by fisheries-related, and construction. This is the first study demonstrating the utility of using seismic vessels as a platform for monitoring FMD in waters within the Argentine continental shelf and adjacent waters.

Hooded Vultures Necrosyrtes monachus are still declining in West Africa: a nearly 50-year assessment study (1969–2019)

Large-scale declines in vulture populations have been recorded in West Africa. One concern is that the current trend in Hooded Vulture Necrosyrtes monachus populations in West Africa is poorly known. To help fill this knowledge gap, we conducted nationwide road counts in Burkina Faso, Mali and Niger, using (where possible) the same routes and methods as counts conducted in 1969–1973 and 2003–2004 (46–50 years later). Use of exactly the same routes was unfortunately possible only in Burkina Faso as a result of the security situation in sub-Saharan West Africa at the time of this study. Our results reveal that Burkina Faso remains a stronghold for Hooded Vultures with a mean abundance of 62 individuals per 100 km, reaching a peak of 217 per 100 km in the highest abundance areas. A comparison between early and recent studies shows that populations of Hooded Vulture are still declining in the West African sub-region. In Burkina Faso, the number of Hooded Vultures per 100 km decreased from 122 to 75 (a decline of 38%) over the last five decades. In the West African sub-region, under both ‘best-case’ and ‘worst-case’ scenarios, Hooded Vultures seem to have declined by 58% to 65% between the 1970s and 2019. The main causes of this population decline in West Africa are unintentional poisoning, decreasing food availability, and the trade in vulture body parts for Traditional Medicine. Conservation actions for Hooded Vultures in West Africa could include the implementation of supplementary feeding sites (also known as ‘vulture restaurants’) and decreasing the demand for vulture body parts (for use in Traditional Medicine and mystical practices) by offering relevant alternatives such as plants and their derivatives.

Accumulation, tissue distribution, health hazard of microplastics in a commercially important cat fish, Silonia silondia from a tropical large-scale estuary

The current knowledge regarding the presence of microplastics (MPs) in the digestive tracts of fish, particularly the non-edible parts, provides limited assistance in assessing the risk to human health and establishing guideline values for policy-making purposes. Therefore, we conducted the first investigation into MPs within the commercially significant catfish species S. silondia, form a major tropical estuary assessing their accumulation, characteristics, and associated risks in various tissues, particularly the consumable muscle. A sum of 132 MPs were identified, and the mean abundance of MPs were 7.40 ± 4.12 item/DT, 3.20 ± 1.69 item/gill and 2.60 ± 1.65 item/muscle found in digestive tract (DT), gill and muscle of the fish, respectively. The strong relationships of MPs among three different tissues (y = 0.6069x - 22.69, R2 = 0.7589) indicated the pathways and how MPs were influenced by the physiology of organisms. The prevalence of MPs in fish muscle demonstrated their trophic transmission to humans. Moreover, fishes with higher weight had higher MPs in their gill, and DT. The dominant type, color and size of MPs were fibrous (89.67%), violet (41%) and &amp;lt; 0.5 mm sized (94%), respectively. The high percentage of fibers suggests that they might have come from ropes, fishing nets or sewage. FTIR chemical composition analyses of microplastics (MPs) identified three primary polymer types: PET (44.5%), PE (33.3%), and PP (22.2%) in fish. These polymers are commonly associated with packaging materials, household wastes and plastic pipes. Contamination level assessment by CF (CF = 2.76) and PLI (PLI &amp;gt; 1) indicated moderately to highly contaminated fish with MPs ingestion. While the complete understanding of the direct negative effects of microplastics (MPs) on human health remains elusive, their presence in estuarine fish raises concerns for both human and ecosystem health. The findings will be useful for assessing the hazards to human health from exposure to MPs and for creating effective risk management plans to reduce those risks.

Spatial Distribution Pattern of the Mesozooplankton Community in Ross Sea Region Marine Protected Area (RSR MPA) during Summer

The Ross Sea region Marine Protected Area (RSR MPA) is one of the most productive regions in the Southern Ocean. Mesozooplankton intermediates the primary product to the higher predators, such as penguins and seals, in this ecosystem. In this study, the mesozooplankton community structure and spatial pattern in the RSR MPA in January were investigated by using 505 μm-mesh-size bongo net samples. As a result, 37 mesozooplankton taxa with a total mean abundance of 35.26 ind./m3, ranging from 2.94 to 139.17 ind./m3, were confirmed. Of the 37 taxa, 7 occupied almost 84% of the total abundance, with copepods being the main dominant taxa. As shown by our hierarchical analysis, the mesozooplankton community was divided into four groups, each associated with a specific geographical distribution. Group A was composed of stations around Terra Nova Bay and showed relatively low abundance. Group B included stations around the continental slope region. Group D was composed of the Ross Sea continental shelf stations, while group C consisted of stations geographically located between those of groups B and D. These four groups were influenced by various environmental factors, such as water temperature, salinity, and nutrients. In summary, the mesozooplankton community can be separated according to geographical pattern. This pattern is related to several environmental factors.

Niche position and niche breadth effects on population abundances: A case study of New World Warblers (Parulidae).

Species abundance patterns are influenced by a myriad of factors, including habitat availability and ecological niche characteristics. However, the evidence concerning the specific impact factors such as niche position and niche breadth on mean and maximum abundances in vertebrates at a broad geographical scale remains inconclusive. In this study, we investigated the influence of niche position and breadth on the abundance of 47 species of birds belonging to the Parulidae family, commonly known as New World Warblers. We obtained data on abundance and presence records spanning the reproductive distribution of these species and employed the outlying mean index analysis to calculate niche position and niche breadth. We assessed the relationship between abundance metrics and niche descriptors using phylogenetic regressions to account for the non-independence resulting from phylogenetic ancestry. Initially, we developed individual models for each predictor and subsequently formulated a multi-predictor model encompassing niche position, niche breadth, and their interaction. Our findings revealed a negative relationship between niche position and both mean and maximum abundance, while niche breadth exhibited a positive relationship with these niche characteristics. Notably, the results of the multi-predictor models indicated that niche position exerted the most substantial influence on both mean and maximum abundance. Additionally, the interaction between niche position and niche breadth had the most positive and significant contribution to mean population abundance. This study underscores the need for future research in other vertebrates to delve into the mechanisms underlying these patterns. Such endeavors will not only enhance our understanding of ecological dynamics but also equip us with predictive capabilities to anticipate population responses to environmental changes effectively.

Digenea community structure of the Salema, Sarpa salpa (Linnaeus, 1758) (Teleostei, Sparidae), from the Central coast of Algeria.

The main goal of the current work was to describe and analyse the Digenean community structure in Sarpa salpa. A total of 114 specimens of S. salpa were collected from the Central Coast of Algeria at six localities. The fish were immediately transported to the laboratory to be examined for digeneans. From 107 of the 114 S. salpa examined, a total of 8,722 specimens of seven species belonging to three families were recovered. Among them, Robphildollfusium fractum and Mesometra orbicularis were the most prevalent and abundant species. Moreover, Lepocreadium album was found for the first time in S. salpa from the coast of Algeria, and Centroderma spinosissima and Wardula capitellata represent new parasites to the Algerian digenean fauna that infect teleost fish. The component community of these Digeneans is characterised by R. fractum as its dominant species representing 62% of the total number of collected Digeneans, as well by a Shannon diversity index (H') and Dominance Simpson index (D) of 1.03 and 2.23, respectively. According to Spearman's correlation test, Mesometra brachycoelia and W. capitellata were negatively correlated to the host biological factors. On the other hand, R. fractum showed a positive correlation between its mean abundance and the total length of the fish. With these findings, we provided the component structure of the Digenean fauna of S. salpa and highlighted their diversity, contributing to the biodiversity of the parasitic Platyhelminthes in Algeria.

Poetry of G.A. Levin on the pages of Saratov publications in the 20s of the XX century

The purpose of this article is to analyze the poetic works of the Saratov poet G.A. Levin, published on the pages of the periodicals «Artistic Saratov» and «Sarrabis» in Saratov in the 20s of the past century. The scientific novelty of the study lies in the fact for the first time the poems of G.A. Levin «The air shines with a blessed blue», «I know, a dark, beloved voice», «Chernyshevsky’s Monument», «The early coolness has been drained to the dregs», «Shakespeare» are mentioned. The article focuses on the aesthetic side of these poems, emphasizing their extreme lyricism and abundance of figurative means. In addition, this study notes the relevance of the poetry of G.A. Levin on the pages of these publications not only because of their external artistry, but also because of their ideological expressiveness. The editorial board of the magazines «Art Saratov» and «Sarrabis» considered the poems of G.A. Levin worthy of understanding, since the goal was to instill good taste in the Saratov reader of the 1920s and teach him to appreciate genuine literary works. As a result, the following was revealed: (a) G.A. Levin gives the images greater ideological and artistic capacity and expressiveness; (b) the poet uses metaphors and epithets not only as conventional methods of expressiveness, but also as forms of holistic knowledge of the essence of the Universe; (c) the poet paid special attention to love lyrics, intertwined Russian and Italian themes in individual poems, and resorted to Shakespearean heroes. The article notes the versatility of the poetic image, and the analysis of the poems is carried out taking into account the influence of the lyrics of famous poets of the Silver Age on Levin’s poetry.

Ecological and social factors influence interspecific pathogens occurrence among bees

The interspecific transmission of pathogens can occur frequently in the environment. Among wild bees, the main spillover cases are caused by pathogens associated with Apis mellifera, whose colonies can act as reservoirs. Due to the limited availability of data in Italy, it is challenging to accurately assess the impact and implications of this phenomenon on the wild bee populations. In this study, a total of 3372 bees were sampled from 11 Italian regions within the BeeNet project, evaluating the prevalence and the abundance of the major honey bee pathogens (DWV, BQCV, ABPV, CBPV, KBV, Nosema ceranae, Ascosphaera apis, Crithidia mellificae, Lotmaria passim, Crithidia bombi). The 68.4% of samples were positive for at least one pathogen. DWV, BQCV, N. ceranae and CBPV showed the highest prevalence and abundance values, confirming them as the most prevalent pathogens spread in the environment. For these pathogens, Andrena, Bombus, Eucera and Seladonia showed the highest mean prevalence and abundance values. Generally, time trends showed a prevalence and abundance decrease from April to July. In order to predict the risk of infection among wild bees, statistical models were developed. A low influence of apiary density on pathogen occurrence was observed, while meteorological conditions and agricultural management showed a greater impact on pathogen persistence in the environment. Social and biological traits of wild bees also contributed to defining a higher risk of infection for bivoltine, communal, mining and oligolectic bees. Out of all the samples tested, 40.5% were co-infected with two or more pathogens. In some cases, individuals were simultaneously infected with up to five different pathogens. It is essential to increase knowledge about the transmission of pathogens among wild bees to understand dynamics, impact and effects on pollinator populations. Implementing concrete plans for the conservation of wild bee species is important to ensure the health of wild and human-managed bees within a One-Health perspective.

Heavy metal pollution in the nearshore surface sediments north of the Shandong Peninsula and the Western Miao Islands, China

Surface sediment samples (N = 94) were obtained from the west Miao Islands, northern Shandong Peninsula, China, and analyzed for grain size and elements. Based on the classification by Folk and Ward, surface sediments were dominated by silt-sized components, sandy silt, and silt. The mean abundance of heavy metals could be ordered according to Cr > Zn > Ni > Cu> Pb > As> Cd > Hg. According to sediment quality guidelines, surface sediments have a 21 % probability of being toxic. The potential ecological risk index indicates low potential ecological risk, while the enrichment factor and geo-accumulation indices indicate slight to moderate pollution across most of the study area. Pollution load indexes indicate that 38 % of sites are moderately metal contaminated and 62 % of sites are not polluted. The study area was classified according to the level of heavy metal contamination and its sources.

Description of the helminth community structure from two populations of Plains Viscacha (Rodentia: Chinchillidae) in semi-captive and wild conditions

Lagostomus maximus is a native rodent of South America that presents economic and biological importance. However, few studies on parasites of this rodent are available throughout its geographic distribution. The aim of this study was to explore, describe and compare the structure of helminth communities from 2 populations of L. maximus in semi-captive (SCHP) and wild (WHP) conditions in Buenos Aires Province, Argentina. The structure of helminth communities was studied considering ecological data at different levels. Seven helminth taxa were collected. Graphidioides spp. and Lagostonema ecasiense were the most prevalent species in SCHP, and Viannella viscaciae in WHP. This last species showed the highest values of mean intensity and mean abundance in both host populations. Helminths from SCHP showed higher values of abundance, mean intensity, mean abundance, diversity, and evenness, and lower values of specific richness and dominance than WHP. Specific richness, evenness and dominance allowed separating the 2 host populations. The abundances of V. viscaciae and Graphidioides spp. distinguished both host populations, suggesting possible influences of human intervention and/or environmental characteristics, as consequence of semi-captive and wild conditions.

Microplastics Prevalence in Different Cetaceans Stranded along the Western Taiwan Strait.

Microplastics (MPs) pollution is of global concern, which poses serious threats to various marine organisms, including many threatened apex predators. In this study, MPs were investigated from nine cetaceans of four different species, comprising one common dolphin (Delphinus delphis), two pygmy sperm whales (Kogia breviceps), one ginkgo-toothed beaked whale (Mesoplodon ginkgodens), and five Indo-Pacific humpback dolphins (Sousa chinensis) stranded along the western coast of the Taiwan Strait from the East China Sea based on Fourier transform infrared (FTIR) spectroscopy analysis. Mean abundances of 778 identified MPs items were 86.44 ± 12.22 items individual-1 and 0.43 ± 0.19 items g-1 wet weight of intestine contents, which were found predominantly to be transparent, fiber-shaped polyethylene terephthalate (PET) items usually between 0.5 and 5 mm. The abundance of MPs was found at a slightly higher level and significantly correlated with intestine contents mass (p = 0.0004*). The MPs source was mainly likely from synthetic fibers-laden sewage discharged from intense textile industries. Our report represents the first study of MPs in pelagic and deep-diving cetaceans in China, which not only adds baseline data on MPs for cetaceans in Asian waters but also highlights the further risk assessment of MPs consumption in these threatened species.

Microplastic pollution in high-altitude Nainital lake, Uttarakhand, India

Microplastics (MPs) contamination has been reported in all environmental compartments, but very limited information is available at higher-altitude lakes. Nainital Lake, located at a high altitude in the Indian Himalayas, has various ecosystem services and is the major source of water for Nainital town, but the MP abundance is still unknown. This study presents the first evidence of the abundance and distribution of MP in Nainital Lake. Surface water and sediment samples were analysed from 16 different sites in and around the catchment area of Nainital Lake. The MP were observed in all the samples, and their abundance in surface water was 8.6–56.0 particles L−1 in the lake and 2.4–88.0 particles L−1 in hotspot sites. In the surface sediment, MP abundance ranged from 0.4–10.6 particles g−1, while in the hotspot sediment, the mean abundance was 0.6 ± 0.5 particles g−1. Fibers were the dominant MP, while 0.02–1 mm were the predominant size of MP particles. The results of chemical characterization showed the presence of six polymers, among which high-density polyethylene was the most abundant. The Polymer Hazard Index assessment classified the identified polymers as low-to high-risk categories, with a higher abundance of low- (polypropylene) and medium- (polyethylene)-risk polymers. Tourist activities and run-off catchments can be considered the major sources of MP, which can affect the ecosystem. Minimal concentrations of MP were observed in the tube well and drinking water, which depicts the direct risks to humans and, thus, the need for remedial measures to prevent MP contamination in drinking water. This study improves the knowledge of MP contamination in the higher-altitude freshwater lake, which can be the major pathway for the transport of MP to the rivers, and also emphasizes the need for waste management in Nainital town.

Site-specific Parasitism of Crustaceans on the Black Pomfret, Parastromateus niger (Carangidae) from Indian Waters

An extensive parasitic survey on the Black Pomfret Parastromateus niger (Bloch) (Carangidae) was carried out along the coastal waters of India. A total of 162 host fish (P. niger) were collected, in which 72.2% of the fish were infested with parasitic crustaceans. Six species of parasitic crustaceans were collected, including one species of cymothoid isopod Cymothoa eremita (Brünnich, 1783), and five species of copepods belonging to five different families such as Bomolochus megaceros Heller, 1865 (Bomolochidae), Lernaeenicus stromatei Gnanamuthu, 1953 (Pennellidae), Lernanthropus koenigii Steenstrup and Lütken, 1861 (Lernanthropidae), Synestius caliginus Steenstrup and Lütken, 1861 (Caligidae) and Thysanote appendiculata. (Steenstrup and Lütken, 1861) (Lernaeopodidae). Even though six species of parasitic crustaceans were recovered from the host fish, simultaneous multiple parasitism seldom occurred (only 10%). The prevalence, mean intensity, and mean abundance of each parasite were calculated. The taxonomic account, host, site, and niche-specific parasitization of each species, are discussed. The present study also reviewed and discussed the simultaneous multiple co-occurrence of parasitic crustaceans.