Anthropogenic alterations have paramount impacts on the alpha and beta diversity of aquatic resources, and fishes are predominantly susceptible to such impacts. Mahanadi River, one of the major ...peninsular rivers of India, has abundant fish resources, which play a significant role in supporting the fishers’ livelihoods. The exploratory study in the river conducted for three consecutive years recorded 148 species under 53 families. Cyprinids dominated the fish diversity with 41 species, followed by Bagrids (9) and Sciaenids (7). One hundred-one species under 29 families were reported from the freshwater stretch. With a total of 111 species reported under 48 families, the estuarine and tidal freshwater stretch was more speciose, due to marine migrant species which advent the estuarine and tidal freshwaters stretch for breeding and feeding purposes. Tikarpara, a conserved site within a sanctuary, was the most species-diverse as well as a species-even site. The study also recorded the extension of the distributional range of 3 fish species and also 4 exotic species from the river. The seasonal variations in diversity indicated that the deviations were not prominent in freshwater sites, whereas in tidal brackish water sites, species richness was relatively higher in post-monsoon, and species evenness was higher during monsoon. Taxonomic distinctness test showed that the average taxonomic distinctness was high for tidal estuarine locations as they harbour taxonomically distant fishes. The hierarchical clustering of sites showed the inordinate effect of river gradient and fragmentation on the fish community structure. Analyzing the key drivers of the assemblage structure of the entire river, salinity was the major deterministic factor, and within the freshwater stretch, the major influences were depth, transparency, and specific conductivity. The study concluded that, despite all of its ecological stresses, Mahanadi still supports rich fish diversity, yet there is a notable shift in the fish community structure. There is a need for integrating molecular and morphological tools for the taxonomic revision of many genera and species for proper in situ and ex situ conservation measures and to formulate future biodiversity management plans addressing to reduce the impacts of the ecological threats.
ABSTRACT We present luminosity functions derived from a spectroscopic survey of active galactic nuclei (AGNs) selected from Spitzer Space Telescope imaging surveys. Selection in the mid-infrared is ...significantly less affected by dust obscuration. We can thus compare the luminosity functions of obscured and unobscured AGNs in a more reliable fashion than by using optical or X-ray data alone. We find that the AGN luminosity function can be well described by a broken power-law model in which the break luminosity decreases with redshift. At high redshifts ( ), we find significantly more AGNs at a given bolometric luminosity than found by either optical quasar surveys or hard X-ray surveys. The fraction of obscured AGNs decreases rapidly with increasing AGN luminosity, but, at least at high redshifts, appears to remain at % even at bolometric luminosities . The data support a picture in which the obscured and unobscured populations evolve differently, with some evidence that high luminosity obscured quasars peak in space density at a higher redshift than their unobscured counterparts. The amount of accretion energy in the universe estimated from this work suggests that AGNs contribute about 12% to the total radiation intensity of the universe, and a high radiative accretion efficiency is required to match current estimates of the local mass density in black holes.
Rivers get polluted with diverse types of hazardous and toxic substances, pesticides being one of them. The water and sediment of rivers get contaminated with pesticide residues coming through the ...run-off of vast agricultural fields along the catchment area and also from domestic sewage water. The residues get bio-concentrated and bio-accumulated in different aquatic organisms and animals including fishes along the food chain. Fish, one of the important and chief sources of proteins, are consumed by humans. The presence of toxic substances like pesticides in any food item is undesirable for the fear of health hazards. We have monitored the status of pesticide residue in river Gomti, a tributary of River Ganga that passes through the Uttar Pradesh state of India. Water, sediment, and fish samples collected from the different locations along the river stretch were analyzed for 34 targeted pesticide compounds belonging to organochlorines (OC), organophosphates (OP), and synthetic pyrethroids (SP) groups. In 52% of water, 30% of sediment, and 43% of fish samples residues of OCs were detected while the OPs were present in 33%, 25%, and 39% of samples respectively. However, none of the SPs could be recorded in any sample. The concentrations of the pesticides in water indicate stress conditions to some extent to aquatic life, but based on the human health risk assessment it can be concluded that consumption of fishes from the river contaminated with different OC or OP residues would not pose any direct risk to the consumers.
Abstract
We present the C II 158
μ
m line luminosity functions (LFs) at
z
∼ 4–6 using the ALMA observations of 118 sources, which are selected to have UV luminosity
M
1500Å
< −20.2 and optical ...spectroscopic redshifts in COSMOS and ECDF-S. Of the 118 targets, 75 have significant C II detections and 43 are upper limits. This is by far the largest sample of C II detections, which allows us to set constraints on the volume density of C II emitters at
z
∼ 4–6. But because this is a UV-selected sample, we are missing C II-bright but UV-faint sources, making our constraints strict lower limits. Our derived LFs are statistically consistent with the
z
∼ 0 C II LF at 10
8.25
–10
9.75
L
⊙
. We compare our results with the upper limits of the C II LF derived from serendipitous sources in the ALPINE maps. We also infer the C II LFs based on published far-IR and CO LFs at
z
∼ 4–6. Combining our robust lower limits with these additional estimates, we set further constraints on the true number density of C II emitters at
z
∼ 4–6. These additional LF estimates are largely above our LF at
L
CII
> 10
9
L
⊙
, suggesting that UV-faint but C II-bright sources likely make significant contributions to the C II emitter volume density. When we include all the LF estimates, we find that available model predictions underestimate the number densities of C II emitters at
z
∼ 4–6. Finally, we set a constraint on the molecular gas mass density at
z
∼ 4–6, with
ρ
mol
∼ (2–7) × 10
7
M
⊙
Mpc
−3
. This is broadly consistent with previous studies.
We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate active galactic nuclei (AGNs) selected in the mid-infrared. This survey selects both normal and ...obscured AGNs closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L sub(bol) ~ 10 super(10) L sub(middot in circle) to highly luminous quasars (L sub(bol) ~ 10 super(14) L sub(middot in circle)), all with redshifts ranging from 0 to 4.3. Samples of candidate AGNs were selected with mid-infrared color cuts at several different 24 mu m flux density limits to ensure a range of luminosities at a given redshift. The survey consists of 786 candidate AGNs and quasars, of which 672 have spectroscopic redshifts and classifications. Of these, 137 (20%) are type 1 AGNs with blue continua, 294 (44%) are type 2 objects with extinctions A sub(v) > ~ 5 toward their AGNs, 96 (14%) are AGNs with lower extinctions (A sub(v) ~ 1), and 145 (22%) have redshifts, but no clear signs of AGN activity in their spectra. Of the survey objects 50% have L sub(bol) > 10 super(12) L sub(middot in circle), in the quasar regime. We present composite spectra for type 2 quasars and objects with no signs of AGN activity in their spectra. We also discuss the mid-infrared-emission-line luminosity correlation and present the results of cross correlations with serendipitous X-ray and radio sources. The results show that: (1) obscured objects dominate the overall AGN population, (2) mid-infrared selected AGN candidates exist which lack AGN signatures in their optical spectra but have AGN-like X-ray or radio counterparts, and (3) X-ray and optical classifications of obscured and unobscured AGNs often differ.
Deep investigations of host-associated microbiota can illuminate microbe-based solutions to improve production in an unprecedented manner. The poor larval survival represents the critical bottleneck ...in sustainable marine aquaculture practices. However, little is known about the microbiota profiles and their governing eco-evolutionary processes of the early life stages of marine teleost, impeding the development of suitable beneficial microbial management strategies. The study provides first-hand mechanistic insights into microbiota and its governing eco-evolutionary processes in early life stages of a tropical marine teleost model,
.
The microbiota profiles and their dynamics from the first day of hatching till the end of metamorphosis and that of fingerling's gut during the routine hatchery production were studied using 16S rRNA amplicon-based high-throughput sequencing. Further, the relative contributions of various external factors (rearing water, live feed, microalgae, and formulated feed) to the microbiota profiles at different ontogenies was also analyzed.
A less diverse but abundant core microbial community (~58% and 54% in the whole microbiota and gut microbiota, respectively) was observed throughout the early life stages, supporting 'core microbiota' hypothesis. Surprisingly, there were two well-differentiated clusters in the whole microbiota profiles, ≤10 DPH (days post-hatching) and > 10 DPH samples. The levels of microbial taxonomic signatures of stress indicated increased stress in the early stages, a possible explanation for increased mortality during early life stages. Further, the results suggested an adaptive mechanism for establishing beneficial strains along the ontogenetic progression. Moreover, the highly transient microbiota in the early life stages became stable along the ontogenetic progression, hypothesizing that the earlier life stages will be the best window to influence the microbiota. The egg microbiota also crucially affected the microbial community. Noteworthily, both water and the feed microbiota significantly contributed to the early microbiota, with the feed microbiota having a more significant contribution to fish microbiota. The results illustrated that rotifer enrichment would be the optimal medium for the early larval microbiota manipulations.
The present study highlighted the crucial foundations for the microbial ecology of
during early life stages with implications to develop suitable beneficial microbial management strategies for sustainable mariculture production.
ABSTRACT
We present near-IR photometry and spectroscopy of 30 extremely luminous radio and mid-IR-selected galaxies. With bolometric luminosities exceeding ∼1013 $\rm {L_{\odot }}$ and redshifts ...ranging from z = 0.880 to 2.853, we use Very Large Telescope instruments X-shooter and Infrared Spectrometer and Array Camera to investigate this unique population of galaxies. Broad multicomponent emission lines are detected in 18 galaxies and we measure the near-IR lines $\rm {H\,\rm {\beta }}$, $\rm{O\,{\small III}}\, \rm {\lambda }\rm {\lambda }4959,5007$, and $\rm {H\,\rm {\alpha }}$ in 6, 15, and 13 galaxies, respectively, with 10 $\rm {Ly\,\alpha }$ and 5 C iv lines additionally detected in the UVB arm. We use the broad $\rm{O\,{\small III}}\, \rm {\lambda }5007$ emission lines as a proxy for the bolometric active galactic nucleus luminosity, and derive lower limits to supermassive black hole masses of 107.9–109.4 M⊙ with expectations of corresponding host masses of 1010.4–1012.0 M⊙. We measure $\rm {\lambda }_{Edd}$ > 1 for eight of these sources at a 2σ significance. Near-IR photometry and SED fitting are used to compare stellar masses directly. We detect both Balmer lines in five galaxies and use these to infer a mean visual extinction of AV = 2.68 mag. Due to non-detections and uncertainties in our ${\rm H}\, \beta$ emission line measurements, we simulate a broad ${\rm H}\, \beta$ line of FWHM = 1480 $\rm {kms^{-1}}$ to estimate extinction for all sources with measured ${\rm H}\, \alpha$ emission. We then use this to infer a mean AV = 3.62 mag, demonstrating the highly obscured nature of these galaxies, with the consequence of increasing our estimates of black hole masses by a 0.5 orders of magnitude in the most extreme and obscured cases.
Cobia (Rachycentron canadum, Rachycentridae) is one of the prospective species for mariculture. The transcriptome-based study on cobia was hampered by an inadequate reference genome and a lack of ...full-length cDNAs. We used a long-read based sequencing technology (PacBio Sequel II Iso-Seq3 SMRT) to obtain complete transcriptome sequences from larvae, juveniles, and various tissues of adult cobia, and a single SMRTcell generated 99 gigabytes of data and 51,205,946,694 bases. A total of 8609435, 7441673 and 9140164 subreads were generated from the larval, juvenile, and adult sample pools, with mean sub-read lengths of 2109.9, 1988.2 and 1996.2 bp, respectively. All samples were combined to increase transcript recovery and clustered into 35661 high-quality reads. This is the first report on a full-length transcriptome from R. canadum. Our results illustrate a significant increase in the identified amount of cobia LncRNAs and alternatively spliced transcripts, which will help improve genome annotation. Furthermore, this information will be beneficial for nutrigenomics and functional studies on cobia and other commercially important mariculture species.
Populations of
Megalaspis cordyla (horse mackerel) from four areas, two each from the east (Digha and Mandapam regions in the Bay of Bengal) and west (Cochin and Mumbai regions of the Arabian Sea) ...coasts of the Indian peninsula, were studied using body shape morphometrics. A truss box method (
Strauss and Bookstein, 1982) was followed, and 33 distance variables were extracted from digital images of sample specimens using the software platforms tpsDig2 and PAST. The transformed truss measurements were subjected to factor analysis and classification by cross-validation of discriminant analysis. Measurements from the anterior half of the fish body showed meaningful loadings on the first factor, and those from the caudal peduncle gave high loadings on the second factor. The combination of distance variables that produced the minimum amount of misclassification consisted of variables belonging to the middle portion of the body. Our results indicated a clear separation of the Bay of Bengal and Arabian Sea populations. The Mumbai and Cochin populations exhibited obvious mixing, indicating the possible existence of a unique stock along the west coast of India. In the cross-validation of the morphometrics by discriminant analysis, the most well-defined group was the Mandapam population, with only 3.59% of the individuals being misclassified, followed by Digha, indicating limited gene flow in the Bay of Bengal populations of the horse mackerel. The strong morphometric differentiation observed between the Mandapam and Digha populations, in addition to the considerable coral reef features of the Gulf of Mannar region, suggests the existence of separate spawning stock populations of horse mackerel in these regions, which might require distinct stock assessment programs to provide effective management strategies for the east coast.
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![The ALPINE-ALMA [C II] Surv...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X/small "The ALPINE-ALMA [C II] Survey: [C II] 158 μm Emission Line Luminosity Functions at z ∼ 4–6")
