A “most remarkable” monster’s fossilized remains from Jurassic Germany is a never-before-seen species, a new study reports.
The marine reptile, which swam in prehistoric oceans about 183 million years ago, has been given the name Plesionectes longicollum, which translates to “long-necked near-swimmer.”
P. longicollum is a type of plesiosauroid, an extinct group of long-necked, carnivorous marine reptiles that swam in Earth’s oceans during the time when dinosaurs dominated terrestrial environments. This specimen lived during the early Toarcian age (183 million to 174 million years ago) during the Early Jurassic.
The fossilized specimen is about 10 feet (3 meters) long, similar to the length of an alligator, with its neck accounting for slightly less than half of its total span.
The nearly-complete skeleton of the animal contained remnants of fossilized soft tissue and bone, which enabled scientists to determine that P. longicollum is indeed a newly-discovered species — a conclusion past studies were hesitant to make.
The reptile’s bones were originally excavated in 1978 from a quarry in Germany, part of the Posidonia Shale formation, which is known for its “exquisitely preserved fossils,” according to the study. “This specimen has been in collections for decades, but previous studies never fully explored its distinctive anatomy,” study lead author Sven Sachs, a vertebrate paleontologist at the Natural History Museum of Bielefeld in Germany, said in a statement from the museum.
Related: Oldest tadpole on record was a Jurassic giant
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The findings were published in the journal PeerJ on Aug. 4.
The fossilized skeleton of Plesionectes longicollum, the oldest known plesiosaur from the Posidonia Shale formation. (Image credit: Staatliches Museum für Naturkunde Stuttgart)
“Our detailed examination revealed an unusual combination of skeletal features that clearly distinguish it from all previously known plesiosaurs,” Sachs said. The work demonstrated that the Posidonia Shale beds contained a higher degree of reptile diversity than previously thought.
The new specimen is the oldest known plesiosaur from the town Holzmaden in southwest Germany, according to the statement. The animal was not yet an adult when it died, but based on its anatomy, researchers were able to classify it into a new genus and species.
Five other almost complete Plesionectes skeletons have been identified at the Posidonia Shale and include examples of all three major plesiosaur lineages.
“This discovery adds another piece to the puzzle of marine ecosystem evolution during a critical time in Earth’s history,” study co-author Daniel Madzia, a paleobiologist at the Polish Academy of Sciences, said in the statement. The period when P. longicollum lived “was marked by significant environmental changes, including a major oceanic anoxic event that affected marine life worldwide,” he said. The event, which depleted oxygen and spiked acidification in the water, led to a severe loss of marine biodiversity, including an extinction event killing around 5% of global families on land and in the sea.
This fossil is permanently housed at the Stuttgart State Museum of Natural History in Germany.
As long as you’re looking at the night sky, August has a ton of cool stuff going on this year. Among those is the full moon, also known as the Sturgeon Moon. It’s the last full moon of the summer, and it’s coming on Aug. 9.
According to The Old Farmer’s Almanac, the full moon will reach its peak brightness at 3:55 a.m. ET on Aug. 9. Thus, if you want to see the moon at its brightest, you’ll want to look up the evening of Aug. 8 and on into the next morning. It’s not a big deal if you miss it, as the moon will be over 90% full from Aug. 6 through Aug. 11, so you’ll have plenty of chances to look up and see it.
A lot is going on during this full moon, so if you want to make a night of it, you have other things you can look for. Saturn, Venus, Mercury, Uranus and Neptune will all be in the south and eastern sky, lining up nicely in preparation for the planet parade coming in late August. Venus and Jupiter don’t make an appearance until much later in the evening, but they’ll be visible with the naked eye. The other three will require some sort of magnification.
The Perseids meteor shower is also active, so you may spy a shooting star or two, depending on how dark it is outside. The Perseids come from the Perseus constellation. On the morning of Aug. 9, it’ll be in the eastern sky alongside Venus and Jupiter, so everything will be in the same general area.
Why is it called the Sturgeon Moon?
The Sturgeon Moon is named after the humble sturgeon fish. According to The Old Farmer’s Almanac, sturgeon were a staple food for Native Americans in the Great Lakes region, and the fish used to be a lot more abundant during mid- to late summer. Of all the bony fish, the sturgeon is the most primitive, dating back to the Cretaceous period over 120 million years ago. Thus, scholars often refer to the fish as a living fossil. It’s also a long-lived fish, with an average lifespan of 50 to 60 years. Females of the species can get as old as 150 years.
Other names for August’s full moon include the Corn Moon, Ricing Moon, Black Cherries Moon and Mountain Shadows Moon. It’s also been called a Harvest Moon, splitting the name with September’s full moon.
The performance of the SNAD-IFAS hybrid process at different phases is shown in Figs. 1 and 2. The first phase was the start-up of the SNAD-IFAS hybrid process. The influent was the diluted THP-AD liquor, in which NH4+-N and COD concentrations were 445.0 and 715.0 mg/L, respectively. From day 0 to day 12, the ammonium removal efficiency increased from 85.1% to 100% and the total inorganic nitrogen (TIN) removal efficiency increased from 74.4% to 89.9% (Figs. 1b and 2b). During the stable operation of the start-up, the average NH4+-N, NO2−-N, and NO3−-N concentrations were 0, 10.9, and 50.3 mg/L in the effluent of the hybrid process, respectively (Fig. 1a, c, d). COD was removed with an average COD removal efficiency of 20.7%, and the average COD concentration was 355.6 mg/L in the effluent during the whole phase I (Fig. 2c, d). When the TIN removal efficiency of the hybrid process was 89.9%, the TIN removal efficiencies of SIR1 and SIR2 were 63.1% and 23.7%, respectively, indicating that the nitrogen removal of the hybrid system mainly depended on SIR1 and SIR2. The SNAD-IFAS reactors in the hybrid system can be quickly started in 12 days because the inoculated activated sludge and carriers were taken from a full-scale SNAD reactor.
Fig. 1: Nitrogen conversion at different phase in the hybrid process.
a Influent (Inf.) and effluent (Eff.) concentration of NH4+-N. b NH4+-N removal efficiency. c Effluent (Eff.) concentration of NO2−-N. d Effluent (Eff.) concentration of NO3−-N.
Fig. 2: Total inorganic nitrogen (TIN) and COD removal performance at different phase in the hybrid process.
a Influent (Inf.) and effluent (Eff.) concentration of TIN. b TIN removal efficiency. c Influent (Inf.) and effluent (Eff.) concentration of COD. d COD removal efficiency.
In Phase II (13–106 d), the concentration of NH4+-N in the influent was ranged from 736.0 mg/L to 1347.7 mg/L (except for the fluctuation point) by progressively decreasing the dilution ratio, and the C/N ratio of the influent was kept at 1:1. To maintain the nitrogen removal efficiency of SIR1 and SIR2, the values of DO and pH were adjusted to cope with the increase in the NH4+-N concentration in the influent. It was shown that the NH4+-N concentration in the influent of SIR1 was approximately 736.0–1347.7 mg/L, which is significantly higher than that of SIR2 (98.8-553.9 mg/L) (Fig. 1a). Thus, more DO was needed for nitrosation in the SIR1, which can not only provide a substrate for AnAOB but also reduce the inhibitory effect of FA on AnAOB activity, while the SIR2 was controlled under low DO conditions to ensure the activity of AnAOB. A previous study also demonstrated that the DO is usually maintained at about 0.30 mg/L in order to sustain the partial denitrification process. Similarly, to maintain the activity of AnAOB, DO was controlled at around 0.10 mg/L19. Therefore, the DO concentrations of SIR1 and SIR2 were controlled at 0.15–0.35 mg/L and 0.10–0.20 mg/L, respectively (Table 1). Although the DO of SIR1 was only 0.05–0.15 mg/L higher than that of SIR2, even subtle differences in DO concentration could show different treatment effects due to the extremely strong activity of the AOB enriched in the SNAD-IFAS system (Fig. S1). At the same time, it was also this extremely strong activity of AOB that ensured that a higher partial denitrification process could be achieved even under low DO conditions, providing a reaction substrate for anammox bacteria.
Table 1 Operational parameters of two-stage tandem-type SNAD-IFAS process
In addition to adjusting the DO, it was also necessary to adjust the pH of SIR1 and SIR2, which could adjust the concentrations of FA in the two reactors to ensure the nitrogen removal efficiency of the two reactors. The reason for controlling the concentration of FA was that different functional bacteria had different tolerance capacities for FA. It was reported that the activity of AOB would be inhibited when the concentration of FA was in the range of 10–120 mg/L, while it was 0.1–1.0 mg/L for NOB24,25. NOB was more sensitive to FA than AOB25. If the concentration of FA was greater than 30 mg/L, the activity of AnAOB was also inhibited26. Therefore, the pH of SIR1 and SIR2 was controlled at 7.7–7.8 and 8.0–8.1 (adjustment by adding potassium bicarbonate), respectively (Table 1), to ensure that the FA concentrations of SIR1 and SIR2 were about 16-23 mg/L and 3 mg/L, respectively. Through the adjustment of the above two process parameters, on the 48th day, the TIN concentration of the influent reached more than 1000 mg/L, and the TIN removal efficiencies of SIR1 and SIR2 were 76.2% and 14.0%, respectively (Figs. 2a, 3b). The TIN removal efficiency of the SNAD-IFAS hybrid process was 92.3% (Fig. 2b). On the 96th day, SIR1 and SIR2 can already treat the undiluted THP-AD liquor. The average TIN removal efficiencies of SIR1 and SIR2 were 70.6% and 15.4%, respectively (Fig. 2a, b). The average TIN removal efficiency of the SNAD-IFAS hybrid process was 89.9% (Fig. 2b), which was higher than the one-stage and two-stage PN/A process11,12,13,14. During phase II, the average COD removal efficiencies of SIR1 and SIR2 were 43.1% and 8.4%, respectively (Fig. 2c, d).
Fig. 3: Specific anammox activity (SAA) of SNAD-IFAS process.
a SAA of suspended sludge in SIR1. b SAA of biofilm in SIR1. c SAA of suspended sludge in SIR2. d SAA of biofilm in SIR2. Error bars represent the standard deviation around the mean.
From day 49 to 53, the NH4+-N concentration in the influent of SIR1 increased to 1313.7–1604.9 mg/L (Fig. 1a). The excessive increase in NH4+-N concentration caused the decrease in TIN removal efficiency of SIR1 from 70.3% to 37.3% due to the high concentration of FA (72-88 mg/L), resulting in an increase in the influent NH4+-N concentration of SIR2 from 338.6 mg/L to 897.1 mg/L. Nevertheless, the TIN removal efficiency of the whole system has not been greatly affected, and the TIN removal efficiency can still be maintained at 86.5–93.7%. This was because, although the TIN removal efficiency of SIR1 decreased, TIN can still be removed by the following SIR2 and A2O2 units, and the TIN removal efficiency of SIR2 can be maintained at 25.2–41.3%. The influent was ceased on the 54th day and lasted for 3 days to alleviate the inhibitory effect of the high concentration of FA on AnAOB. The SNAD-IFAS process was restored by reducing the influent ammonia nitrogen concentration. From day 57 to 65, the performance of the whole system recovered instantly, with the influent ammonia increasing from 678.7 to 1000.0 mg/L, and the TIN removal efficiency was restored to 94.5%. The SNAD-IFAS hybrid system returned to stabilization in just one week. Actually, it was the speedy adjustment of the hybrid process in the period of break-in that showed excellent practicability since the characteristics of actual wastewater were always complicated and shifty.
Throughout phase II, the A2O2 process can ensure that the effluent NH4+-N and NO2−-N concentrations of the hybrid system were kept at a low level. However, the TIN and COD removal efficiency of the A2O2 process was relatively low. This was because when the wastewater entered the A2O2 unit, most of the bioavailable organic matter in wastewater had been consumed, and most of the remaining organic matter was non-bioavailable organic matter, which makes the denitrification activity and COD removal efficiency of the A2O2 unit low. The total nitrogen in the effluent is further reduced if a small additional carbon source is supplemented. In summary, when the undiluted THP-AD liquor was treated by the SNAD-IFAS hybrid process with the average NLR of 0.85 kg N/(m3·d), the average NRR of 0.76 kg N/(m3·d) was maintained, which was higher than the PN/A process12,13. The average removal efficiencies of NH4+-N, TIN, and COD were 94.0%, 89.9%, and 66.8%, respectively. The removal process of TIN and COD in the THP-AD liquor mainly occurred in SIR1 and SIR2.
Specific anammox activity in SNAD-IFAS reactors
From the above results, most of the nitrogen removal in the SNAD-IFAS hybrid process was completed by SIR1 and SIR2. Therefore, it was necessary to detect the activity of AnAOB, which played a leading role in nitrogen removal in the SNAD-IFAS reactors. Through a series of batch tests, the results showed that strong anammox activity was detected on the biofilm of SIR1 and SIR2, and the SAA of SIR1 and SIR2 was 68.72 and 42.15 mg N/(g VSS·h), respectively (Fig. 3b, d). The SAA inside the SNAD-IFAS process was 7-11 times higher than that inside the PN/A process (6.0 mg N/(g VSS·h))27, which ensured that the SNAD-IFAS process had a higher nitrogen removal loading rate than the PN/A process. No significant anammox activity was detected in the suspended sludge of the two SNAD-IFAS reactors (Fig. 3a, c). However, strong aerobic ammonia oxidation activity can be detected in the suspended sludge of SIR1 and SIR2, and the SAOB can reach 28.04 and 3.55 mg NO2−-N/(g VSS·h), respectively (Fig. S1a, c). The biofilm of the two SNAD-IFAS reactors had weaker aerobic ammonia oxidation activity, with the SAOB of SIR1 and SIR2 being 2.36 and 0.52 mg NO2–-N/(g VSS·h), respectively (Fig. S1b, d).
The above specific activity results indicated that AnAOB mainly grew on the biofilm and AOB mainly grew on the suspended sludge. The main agents responsible for nitrogen removal in the SNAD-IFAS process are AnAOB and AOB. This result was consistent with previous studies21,28,29. Besides, the SAA of the SNAD-IFAS reactors was much higher than previous research reports18,29,30,31. Two main reasons can be used to explain this phenomenon. One was that the NLR of SNAD-IFAS reactors was much higher than previous studies, and the influent NH4+-N concentration can reach 1347 mg/L, which can provide sufficient substrate for AOB and AnAOB. AnAOB usually had high anammox activity under higher influent substrate conditions32. The other was that a large amount of AnAOB was retained in the reactor to prevent the elapse of AnAOB by adding the biological carriers. The biomass concentration was also a key factor leading to the super high anammox activity32.
Shifts in compositions of microbial community and nitrogen metabolism bacteria
High-throughput sequencing analysis was carried out to further investigate the variation of microbial community structure in the SNAD-IFAS reactors. As shown in Table S1, a total of 257,248 effective sequences were obtained from six samples of suspended sludge and biofilm. These effective sequences were clustered into OTUs, and 3,431 OTUs were obtained. The bacteria coverage of six samples described as the Good’s value was between 99.6% and 99.8% (Table S1). The Ace index and Simpson index were used to analyze the community richness and diversity of suspended sludge and biofilm from different reactors. Compared with inoculated sludge (S0, B0), the Ace index decreased, but the Simpson index increased in SIR1 (S1, B1) and SIR2 (S2, B2), indicating that the microbial richness and diversity in SIR1 and SIR2 were reduced (Table S1). This suggested that non-adapted bacteria in inoculated sludge were eliminated because of changes in the water quality characteristics of the influent. These results agreed with previous studies33,34. Venn diagrams can be used to tally the number of unique and common OTUs in multiple samples, as well as to visually represent the similarity and overlop of the samples’ OTU composition. According to Venn diagrams (Fig. S2), the unique OTU numbers of the inoculated sludge S0 sample and B0 sample were 360 and 623, respectively. The unique OTU numbers of S1, B1, S2, and B2 samples were 71, 22, 65, and 16, respectively. The inoculated sludge samples had the largest number of unique OTUs, indicating the highest bacterial diversity, which was also consistent with the above Simpson index results. In addition, the different contaminant concentrations of influent in different reactors resulted in a different number of unique OTUs. The unique OTUs in SIR1 were higher than those in SIR2, both in suspended sludge and biofilm. The influent types had a noticeable impact on the microbial community and functional characteristics35.
Apart from generating alterations in microbial richness and diversity, the compositions of microbial community also changed. Bacteroidetes, Patescibacteria, and Fimicutes decreased from 24.44%, 24.03%, and 8.53% in S0 to 13.48%, 0.44%, and 0.99% in S1, respectively (Fig. 4a). The same changes could also be observed in biofilms (B0, B1). However, Planctomycetes, Chloroflexi, and Deinococcus-Thermus significantly increased in SIR1 and SIR2 compared to inoculated sludge. Chloroflexi and Deinococcus-Thermus increased from 1.55% and 1.79% in S0 to 29.08% and 23.26% in S1, respectively. Planctomycetes increase from <0.01% and 9.52% in S0 and B0 to 1.88% and 22.35% in S1 and B1, respectively. Proteobacteria (20.51–38.09%) were dominant in inoculated sludge, SIR1 and SIR2 (Fig. 4a). Proteobacteria were widely detected in a variety of anammox-based processes such as PN/A process and SNAD process14,21,27. The variations in microbial communities were also mediated using the principal component analysis (PCA) according to all the sequences at OTU levels for qualitative analysis of clustering behavior. The microbial community in both suspended sludge and biofilm was changing after treating THP-AD liquor (Fig. 4b). According to the matrix distances, the biggest differences were between seeding sludge (S0, B0) and activated sludge in both SNAD-IFAS reactors (S1, S2, B1, B2). Further, this evidence was analyzed using a ternary diagram at genus level (Fig. 4c, d). Here, genera from the family Burkholderiaceae, Saprospiraceae, and Ruminococcaceae were significantly enriched in S0 and B0, whereas Truepera, Limnobacter, Nitrospira, Turneriella, Denitratisoma, Thermomonas, SM1A02, Candidatus Kuenenia, and Candidatus Brocadia were mostly detected in S1, S2, B1, and B2. Previous study reported that Limnobacter, Nitrospira, Denitratisoma, and SM1A02 were the common companion bacteria of AnAOB in anammox-based processes21,28. Truepera and Thermomonas were main decomposers for organic matters36,37. These results indicated that when the SNAD-IFAS process was used to treat the THP-AD liquor, the microbial community of the inoculated sludge changed dramatically. Some microorganisms adapted to the THP-AD liquor could grow in the SNAD-IFAS reactors, while some microorganisms that were not suitable for the environment were eliminated from the SNAD-IFAS reactors, thus forming a specific microbial community structure in the SNAD-IFAS reactors.
Fig. 4: Microbial community characterization of suspended sludge and biofilm.
a Community structure at phylum level. b Principle coordinate analysis over long-term operation. c, d Ternary plot representing the relative occurrence of individual genus (circles) in S1, B1 and S2, B2 compared with S0, B0 (genera enriched in different compartments are colored by the taxonomy of the families and the size of the circles is proportional to the mean abundance in the community). e Community structure at genus level. S0: inoculated suspended sludge; S1: SIR1 suspended sludge; S2: SIR2 suspended sludge; B0: inoculated biofilm; B1: SIR1 biofilm; B2: SIR2 biofilm.
Studies have shown that many key nitrogen removal microorganisms belong to Proteobacteria and Planctomycetes, such as Nitrosomonas, Thauera, and Ca. Kuenenia, the model bacteria of nitrogen removal. Therefore, the genus-level compositions of the microbial community were discussed in detail (Fig. 4e, Table 2). The relative abundance of AnAOB (Ca. Kuenenia and Ca. Brocadia) was very low in suspended sludge (<0.01%, S1, S2), whereas it was high in biofilms of the SNAD-IFAS reactors (13.49–20.94%, B1, B2). These results were consistent with the SAA experiment in “Reactor configuration and experimental procedure”. Previous studies also demonstrated that AnAOB mainly existed in the biofilm rather than in the suspended sludge during the operation of the SNAD-IFAS and SNADRP-SBBR processes21,28. The relative abundance of AnAOB in the SNAD-IFAS process was much higher than that in one stage or two stage PN/A process for treating the THP-AD liquor (10–17%)11,14. Moreover, Ca. Kuenenia and Ca. Brocadia were the dominant AnAOB in the biofilms of inoculated sludge. However, Ca. Brocadia decreased from 2.66% (B0) to 1.65% (B1), while Ca. Kuenenia increased from 6.22% (B0) to 19.29% (B1), indicating that the dominant AnAOB in SIR1 was Ca. Kuenenia. In contrast, in SIR2, Ca. Brocadia increased from 1.65% (B1) to 4.45% (B2), while Ca. Kuenenia decreased from 19.29% (B1) to 9.04% (B2). The composition of the anammox bacterial community can be significantly influenced by the unique niches that various environments offer. There is a considerable correlation between the composition of the anammox bacterial community and certain environmental factors, including pH, temperature, the contents of nitrogen species, organic carbon and salinity38,39. A previous study also has demonstrated that Ca. Kuenenia preferred to live in high dissolved inorganic nitrogen level conditions40. Consequently, due to the high dissolved inorganic nitrogen level in SIR1, Ca. Kuenenia dominated in SIR1 and had a high relative abundance. However, as the inorganic nitrogen concentration decreased in SIR2, the relative abundance of Ca. Kuenenia decreased, whereas the relative abundance of Ca. Brocadia, which is highly adaptable to low concentrations, increased. The dominant AnAOB in SIR2 was Ca. Kuenenia and Ca. Brocadia. But overall, Ca. Kuenenia was still the dominant AnAOB in the SNAD-IFAS process. In addition, Nitrosomons and Nitrospira appeared in SIR1 and SIR2 (Table 2). According to reports, Nitrosomons and Nitrospira are the major AOB and NOB in anammox-based process11,14,19,21,27. Nitrosomons and Nitrospira were mainly present in the suspended sludge of both SIR1 and SIR2. The relative abundance of Nitrosomons in SIR1 was higher than that in SIR2, whereas the relative abundance of Nitrospira in SIR1 was lower than that in SIR2. This result explained the reason why the nitrate in the effluent of SIR2 was higher than that in the effluent of SIR1 (Fig. 1d). Although the relative abundance of Nitrosomons was very low in the SNAD-IFAS process, the activity of AOB was high (Fig. S1) and had played an important role in anammox-based process11,14,21,27. The relative abundance of Nitrospira was also lower than that in PN/A process27. Simultaneously, bacteria related to heterotrophic denitrification were found to be enriched in the identified genera, including Thauera, Denitratisoma, Thermomonas, Arenimonas, and Dokdonella (Table 2). Thauera is a common genus of denitrifying bacteria in wastewater treatment plants, and some studies have demonstrated that Thauera is the main partial denitrification bacteria27,41. Denitratisoma is a type of denitrifying bacteria that often detected in SNAD-IFAS process21. Furthermore, Thermomonas, Arenimonas, and Dokdonella are also found to be a heterotrophic denitrifying bacterium and have been observed in partial nitrification-denitrification system for treating landfill leachate and simultaneous nitrification and denitrification process for the treatment of domestic wastewater42,43. The relative abundances of denitrifying bacteria in SIR1 and SIR2 were 24.75% and 29.43%, respectively. The denitrifying bacteria mostly existed on biofilm in both SIR1 and SIR2, which was also consistent with our previous study21. The enrichment of these denitrifying bacteria in SNAD-IFAS reactors further improved the TIN removal efficiency, resulting in a higher TIN removal efficiency than the PN/A process for treating THP-AD liquor. These denitrifying bacteria might also have a certain contribution to the removal of COD in the THP-AD liquor.
Table 2 Phylogenetic classification and comparisons of key nitrogen removal functional groups involved in the suspended sludge (S) and biofilm (B) within IS, SIR1 and SIR2 at genus level
Co-occurrence network analysis and organic metabolic functions
In the bioreactor, ecosystem stability depends on relationships between co-existing individuals of microbial communities as well as on the composition of the community as a whole44. Co-occurrence networks show more complexity in resistance and resilience of microbial populations than community composition45. The co-occurrence patterns (at the genus level) revealed that there were series of positive correlations in bacterial communities of SNAD-IFAS reactor (Fig. 5a). This result indicated that when bacterial communities were exposed to THP-AD liquor containing high concentration of ammonium and complex organics, they inclined to cooperate and weaken competition. The denitrification core genera, Candidatus Kuenenia and Candidatus Brocadia, displayed positive correlations with the cluster of nodes represented by some heterotrophic bacteria, including norank Anaerolineaceae, norank AKYH767, norank Desulfarculaceae, norank SBR1031, norank SJA-28, and Limnobacter. Previous studies reported that most species of the Anaerolineae were responsible for the decomposition of carbohydrates and protein in THP-AD liquor, alleviating the inhibition of complex organics on AnAOB27,46. The enrichment of Limnobacter was able to consume oxygen and organic matter under organic conditions after long-term operation21. Therefore, these heterotrophic bacteria can help AnAOB resist adverse environmental factors such as oxygen and organics. In addition, there were more genera associated with Nitrosomonas in the co-occurrence network, and the relationship was more complex (Fig. 5a). Although the relative abundance of Nitrosomonas (0.21–1.67%) was much lower than other bacteria, Nitrosomonas was central genus in the co-occurrence network. This ecological network characteristic of AOB also explained why predecessors emphasized the importance of AOB in the PN/A process during the treatment of THP-AD liquor14,27. On the one hand, AOB can provide the important substrate (nitrite) for AnAOB, and on the other hand, AOB occupies an important position in the microbial ecological network and maintains close contact with other microorganisms (Fig. 5a).
Fig. 5: Microbial network and functional predictions.
a Network analysis based on genus correlation analysis with a 50% cutoff of co-occurrence. The number of the nodes represents the number of genera. Various node colors indicate different phylum. The size of the nodes represents the abundance of genera. The color of the edges indicates the positive (red) and negative (green) of the correlation given Speraman. b, c Sankey diagram indicating the relative contribution of predicted enzymes (ECs) by PICRUSt2.
More importantly, to resist and survive various environmental stresses, which represents an evolutionary challenge for microorganisms, complex defensive mechanisms are necessary for microbial communities47. In fact, the THP-AD liquor contains complex organic matters, which would affect the activity of AOB and AnAOB27. However, during the operation of the SNAD-IFAS process, the activity of AOB and AnAOB was high, and the average removal efficiency of COD could reach 43.1%, which was higher than the PN/A process (Figs. 2, 4). This result showed that, compared with the PN/A process, a part of the refractory organics might be degraded in the SNAD-IFAS process. The degradation mechanism of refractory organics might be attributed to the co-metabolism process of organics. Therefore, PICRUSt2 analysis was employed to predict potential co-metabolism mechanisms of organics in the SNAD-IFAS process. As shown in Fig. 5b, the predicted pathways associated with degradation of refractory organics in suspended sludge and biofilm mainly include pyridine degradation, dioxin degradation, cyclohexane degradation, urease degradation, and fatty acid (FAME) degradation. An overall high proportion for enzymes (gabD, EC: 1.2.1.16, 1.2.1.79, 1.2.1.20) involved in the pyridine degradation pathways in suspended sludge and biofilm. The succinate-semialdehyde dehydrogenase (gabD) was mostly involved in the pyridine degradation process’s following stages48. Moreover, Truepera was significantly enriched in suspended sludge (S1, S2) and biofilm (B1, B2). Especially in suspended sludge, the relative abundance of Truepera in inoculated suspended sludge was only 1.78%, rapidly increased to 23.36% (S1) and 21.48% (S2), and became the dominant bacteria in suspended sludge (Fig. 4e, Fig. S3). Previous studies reported that Truepera was the dominant species in the biodegradation system treating coking wastewater containing pyridine and an electricity-assisted bio-photodegradation system for high-concentration pyridine removal49,50. Thus, in this study, the relatively high abundance of Truepera in the SNAD-IFAS system contributed to the removal of pyridine in THP-AD liquor. Apart from the enrichment of specific strains, co-metabolic processes were also effective pathways for pyridine degradation. Some of the carbon-hydride degrading enzymes, including beta-glucosidase (EC: 3.2.1.21) and beta-galactosidase (EC: 3.2.1.23), were anticipated to be present in the SNAD-IFAS process (Fig. 5c). Both enzymes can create easily broken-down small molecules like glucose. Glucose can supply a lot of carbon nutrients and improve energy provision, which encourages the production of extracellular enzymes and/or their secretion, increasing the variety of the microbial community for the co-metabolic of pyridine51,52. Meanwhile, the creation and secretion of non-specific enzymes that can degrade both substrates can be stimulated by structural analogs of the targeted refractory compounds53. For instance, ammonia can trigger non-specific enzymes, like ammonia monooxygenase, that contribute to the oxidation of refractory materials54. Thus, the high ammonia concentration within the SNAD-IFAS system might also promote pyridine co-metabolism. In addition, enzymes that biodegrade with polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated dibenzofurans (PCB) were also predicted in large numbers, as were enzymes that degrade with cyclohexane, uric acid, fatty acids, and proteins (Fig. 5b)55,56,57,58,59, explaining the high COD removal efficiency of the system. Importantly, these organic degradation enzymes can eliminate the influence of complex organic matter in the system on AOB and AnAOB, and the presence of urease can also decompose urea to provide ammonia nitrogen matrix for AOB and AnAOB. In summary, the complex microbial ecological network formed by the bacteria and the co-metabolism process of refractory organic matter ensure the stable operation of the process.
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A collection of stone tools has provided an insight into the spread of early human species.
Long before our species arrived in the region, our distant relatives were crossing deep water on the way to new lands.
A human species arrived on a major Indonesian island more than 800,000 years earlier than previously known.
Stone tools have been found on one of the world’s largest islands, Sulawesi, which is part of a distinct region known as Wallacea. This scattering of islands between Borneo and Australia have a unique roster of animals and plants that is different from the continents that lie either side.
Wallacea’s distinct biodiversity has developed because of the deep-water channels that separate it from the larger landmasses nearby, providing hard barriers that few species can cross. This included our own, Homo sapiens, which only overcame them in the past 100,000 years.
But a recently discovered archaeological site on Sulawesi known as Calio shows that other human species made this journey much earlier. The tools found there have been dated at between 1–1.5 million years old, much older than the next oldest tools from about 194,000 years ago.
Professor Adam Brumm, who co-authored the new research, says that the region plays an important part in understanding how our distant relatives spread across the world.
“This discovery adds to our understanding of the movement of extinct humans across the Wallace Line, a transitional zone beyond which unique and often quite peculiar animal species evolved in isolation,” Adam says.
“It’s a significant piece of the puzzle, but the Calio site has yet to yield any hominin fossils. So, while we now know there were toolmakers on Sulawesi a million years ago, their identity remains a mystery.”
The findings of the study were published in the journal Nature.
What was found on Sulawesi?
Calio was first excavated in 2019 after a large stone flake was found in a cornfield near the village of Ujung. Digs over the following years revealed that the area was a place where ancient humans lived, hunted and made tools.
In total, seven tools were discovered at the site, which are thought to have been made from large pebbles found in nearby riverbeds. Though they might look natural at first glance, closer study reveals that these tools have been specifically shaped by removing certain parts of the stone to make them useful for a range of purposes.
Eventually, the tools ended up in a nearby river, where they were quickly buried in the sediment alongside crocodile and shark teeth and the jawbone of a pig-like animal called Celebochoerus. This jawbone was crucial to help date the site through methods known as uranium series dating (USD) and electron-spin resonance (ESR).
USD uses the proportion of uranium isotopes in the bone to provide an age for a fossil, but only provides a minimum estimate. ESR helps to narrow it down by examining the radiation dose that the fossil has experienced while it’s been buried.
The Celebochoerus was found to have lived at some point from 1.04–1.48 million years ago. This means that ancient humans must also have been living in Sulawesi at this time.
Who made the Calio tools?
The discovery of these artefacts brings Sulawesi into line with the island of Flores to its south, where million-year-old tools have also been discovered. Both sets of tools show that ancient humans were living in Wallacea in the distant past, but identifying a species is difficult without fossils.
While miniature human species such as Homo floresiensis and Homo luzonensis once lived on the islands of southeast Asia, they were around too recently to have made these tools. However, Professor Chris Stringer, one of our experts in human evolution, explains that their relatives are a possible candidate.
“Over one million years ago, it’s possible that the ancestors or relatives of species like H. floresiensis and H. luzonensis might have been living on Sulawesi,” Chris says. “Although it’s often thought that H. floresiensis’ ancestors dispersed via Java, ancient oceans currents would probably have favoured dispersal from northern islands such as from Sulawesi.”
“Alternatively, a species known as Homo erectus was living in regions like Java when those Sulawesi toolswere produced. So, they could have made them as well.”
Just as the identity of the toolmakers remains a mystery, so does the way these humans got to Sulawesi in the first place. It’s possible they had some knowledge of raft building to make the journey between islands and built up resources to survive the trip.
Alternatively, they might have been carried across on rafts of vegetation during severe storms or tsunamis, which is believed to have helped other animals and plants disperse across the region.
To find out more about these ancient pioneers, the next step would be to find human fossils on Sulawesi from over a million years ago. Though the humid climate generally stops remains being preserved, the island’s mountainous interior contains many caves that could have allowed teeth and bone to survive.
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The speaker for this event will be Dr. Walt Alvarado, from the Space Biosciences Research Branch at the NASA Ames Research Center.
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In a groundbreaking scientific breakthrough, researchers have successfully reconstructed the prehistoric atmosphere using fossilized dinosaur teeth. This achievement could reshape our understanding of Earth’s ancient climate. Led by geochemist Dingsu Feng of the University of Göttingen, the international team analyzed oxygen isotopes preserved in the enamel of teeth from the Cretaceous and Jurassic periods. Their findings reveal not only the composition of the air dinosaurs once breathed but also hint at sudden, massive CO2 spikes likely linked to volcanic activity. The results provide a new method to study climate dynamics over deep time and understand extinction events.
How dinosaur teeth preserve ancient atmospheric clues
The study focused on the analysis of oxygen-17, a rare isotope that leaves behind telltale chemical signatures when inhaled by air-breathing vertebrates. Over millions of years, these signals remain preserved in durable tissues such as tooth enamel. Because teeth are less susceptible to environmental contamination, they serve as reliable time capsules of ancient biology and atmospheric conditions.Researchers examined previously collected tooth enamel powders from museum specimens across Europe, including those of Tyrannosaurus rex and Kaatedocus, a sauropod dinosaur. These samples held valuable information about oxygen ratios, which correlate with atmospheric CO2 concentrations.
CO2 levels in the age of dinosaurs
Based on the isotope readings, scientists determined that atmospheric CO2 levels were far higher during the Mesozoic era than today. In the late Jurassic, CO2 concentrations reached about 1,200 parts per million (ppm). During the late Cretaceous, this figure dropped slightly to around 750 ppm. For comparison, modern atmospheric CO2 levels hover around 430 ppm.This confirms previous models suggesting that dinosaurs lived in a hotter, more carbon-rich world, largely influenced by natural processes such as plate tectonics and sustained volcanic activity.
Volcanic activity and sudden climate changes
A particularly fascinating discovery was the spike in isotope anomalies in two specific teeth—one from a T. rex and another from a Kaatedocus. These anomalies suggest short-lived but significant surges in atmospheric CO2. Scientists believe these may be linked to massive volcanic eruptions, such as flood basalt events, which released enormous amounts of CO2 in a short geological timeframe.Such findings support the idea that volcanic CO2 emissions played a major role in driving rapid climate changes, which may have affected ecosystems and evolutionary pressures on land-dwelling vertebrates.
Implications for modern climate science
The ability to reconstruct prehistoric air with such precision opens new doors for understanding both past and future climate patterns. By identifying CO2 fluctuations during the age of dinosaurs, researchers can refine models that predict how modern ecosystems might respond to accelerated carbon emissions.This study also highlights the potential of fossilized remains as archives of environmental data, giving scientists tools to trace how life and climate have co-evolved over hundreds of millions of years.
Next target: The Great Dying
Buoyed by their success, the team now plans to apply the same method to fossils from the Permian-Triassic extinction event, known as the Great Dying, which occurred 252 million years ago. This catastrophic period saw the extinction of over 90% of marine species and 70% of terrestrial life, likely due to prolonged volcanic eruptions in what is now Siberia.By analyzing teeth from this period, researchers hope to uncover how atmospheric CO2 behaved before, during, and after this global extinction, offering new clues into Earth’s resilience and recovery mechanisms.From volcanic eruptions to global extinction events, dinosaur teeth have revealed more than just what these creatures ate. They’ve opened a window into the very air they breathed. This pioneering research underscores the power of modern geochemistry and paleontology to unravel the secrets of Earth’s deep past, with implications that stretch far into the planet’s uncertain climatic future.
Climate change is starving the Arctic Ocean of essential nutrients, with the region’s six largest rivers now delivering far less of the type of nitrogen that marine ecosystems need to survive, according to new research in one of Earth’s most vulnerable regions.
The study, led by Bridger J. Ruyle of NYU Tandon School of Engineering, is published in Global Biogeochemical Cycles, where it has been selected as an Editor’s Choice. Ruyle completed the research as a Postdoctoral Fellow at the Carnegie Institution for Science.
The study found that warming temperatures and thawing permafrost are fundamentally altering the chemistry of Arctic rivers. The result is that coastal food webs that have sustained Indigenous communities for millennia are being deprived of inorganic nitrogen, an essential nutrient, potentially triggering cascading effects throughout the Arctic Ocean ecosystem.
“This is a red flag for the Arctic,” said Ruyle, who joined NYU Tandon in the summer of 2025 as an Assistant Professor in the Civil and Urban Engineering Department. “Rapid changes in river nitrogen chemistry could completely transform how these marine ecosystems function.”
The research analyzed 20 years of data from six major Arctic rivers — the Yenisey, Lena, Ob’, Mackenzie, Yukon, and Kolyma — which collectively drain two-thirds of the land area flowing into the Arctic Ocean. These rivers transport nitrogen that supports up to 66% of the ecosystem’s primary production in coastal Arctic regions.
Between 2003 and 2023, Ruyle and colleagues documented declines in inorganic nitrogen accompanied by simultaneous increases in dissolved organic nitrogen, a far less bioavailable form of the element, in four of the six rivers. The findings reveal that warmer temperatures and increased precipitation caused by climate change are driving the shift in nitrogen composition through their effects on river discharge and permafrost thaw.
Using sophisticated statistical modeling, the researchers identified permafrost loss as the key factor explaining the diverging trends between organic and inorganic nitrogen in these rivers. The study combined 20 years of water chemistry data with environmental variables including temperature, precipitation, land cover, and permafrost extent to pinpoint the climate drivers behind the chemical shifts.
This Arctic rivers research represents Ruyle’s broader research mission to understand how human activity, climate change, and natural processes interact to affect water quality globally. Among other areas of focus, his work includes tracking “forever chemicals” and pharmaceuticals in wastewater.
“Whether we’re looking at PFAS contamination in drinking water or nitrogen cycling in Arctic rivers, the common thread is understanding how environmental changes propagate through water systems,” Ruyle explained. His research explores how human activity, the biosphere, and climate change affect water quality, with particular focus on developing analytical tools to quantify chemical contamination and developing models using remote sensing data to assess climate impacts.
The Arctic findings have implications for ecosystem management and climate adaptation strategies. River transport of nitrogen is estimated to support up to 66% of primary production in Arctic coastal regions, making these compositional changes important for marine food webs and the Indigenous communities that depend on these resources.
The research also highlights the interconnected nature of global environmental challenges. As Ruyle noted in previous work on pharmaceutical contamination, climate-driven water scarcity could exacerbate water quality problems, as there’s less dilution of contaminants during drought conditions. The Arctic study similarly shows how temperature and precipitation changes cascade through complex biogeochemical systems, resulting in water quality and ecosystem impacts
“This work demonstrates why we need to think about water quality and climate change as fundamentally linked challenges,” Ruyle said. ” As climate change intensifies, we must understand these interconnections to protect both human health and ecosystem integrity.”
Along with Ruyle, the paper’s authors are Julian Merder of the University of Canterbury, New Zealand; Robert G.M. Spencer of Florida State University; James W. McClelland of the Marine Biological Laboratory, Woods Hole; Suzanne E. Tank of the University of Alberta; and Anna M. Michalak of Carnegie Institution for Science.
The study was supported by the National Science Foundation through grants for the Arctic Great Rivers Observatory.
Journal
Global Biogeochemical Cycles
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
Changes in the Composition of Nitrogen Yields in Large Arctic Rivers Linked to Temperature and Precipitation
Article Publication Date
24-Jul-2025
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