Production of Labile Protein-Like Dissolved Organic Carbon Associated With Anaerobic Methane Oxidization in the Haima Cold Seeps, South China Sea

Cold seeps where methane-rich fluids escape from the seafloor generally support enormous biomass of chemosynthetic organisms and associated fauna. In addition to transporting a great amount of methane toward the seafloor, cold seeps also contribute to the aged, dissolved organic carbon (DOC) pool in the deep ocean. Here, two sediment cores from the “Haima cold seeps,” northern South China Sea and a nearby reference core were analyzed for pore-water sulfate and DOC concentrations, δ13C of DOC, and optical properties of dissolved organic matter (DOM). High DOC concentrations (0.9–3.7 mM) accompanied by extremely low δ13C values (−43.9 to −76.2‰) suggest the conversion of methane into sedimentary DOC pool in the seep sediments. Parallel factor analysis (PARAFAC) of the fluorescence excitation-emission matrices shows higher fluorescent intensities of labile protein-like components (C2 and C4) and lower fluorescent intensities of refractory humic-like components (C1 and C3) in the seep cores compared to the reference core. The intensity of C2 is positively correlated with DOC concentrations and δ13C-DOC in the seep sediments, suggesting that the labile protein-like DOM was produced by the anaerobic oxidation of methane (AOM). Moreover, low humification index (HIX) and high biological index (BIX) values also indicate intensified production of relatively labile DOM with lower degradation degree in the seep cores compared to the reference core. Hence, we highlight that methane-derived DOC may serve as important carbon and energy sources for heterotrophic microbial communities due to its relatively labile nature.

Brain Entropy Study on Obsessive-Compulsive Disorder Using Resting-State fMRI

Object: Brain entropy is a potential index in the diagnosis of mental diseases, but there are some differences in different brain entropy calculation, which may bring confusion and difficulties to the application of brain entropy. Based on the resting-state function magnetic resonance imaging (fMRI) we analyzed the differences of the three main brain entropy in the statistical significance, including approximate entropy (ApEn), sample entropy (SampEn) and fuzzy entropy (FuzzyEn), and studied the physiological reasons behind the difference through comparing their performance on obsessive-compulsive disorder (OCD) and the healthy control (HC).Method: We set patients with OCD as the experimental group and healthy subjects as the control group. The brain entropy of the OCD group and the HC are calculated, respectively, by voxel and AAL region. And then we analyzed the statistical differences of the three brain entropies between the patients and the control group. To compare the sensitivity and robustness of these three kinds of entropy, we also studied their performance by using certain signal mixed with noise.Result: Compare with the control group, almost the whole brain's ApEn and FuzzyEn of OCD are larger significantly. Besides, there are more brain regions with obvious differences when using ApEn comparing to using FuzzyEn. There was no statistical difference between the SampEn of OCD and HC.Conclusion: Brain entropy is a numerical index related to brain function and can be used as a supplementary biological index to evaluate brain state, which may be used as a reference for the diagnosis of mental illness. According to an analysis of certain signal mixed with noise, we conclude that FuzzyEn is more accurate considering sensitivity, stability and robustness of entropy.

Diversity of Planktonik Diatom at Bengkalis Waters, Riau Province

This research was carried out in August to September 2019 at Bengkalis Waters, Riau Province. This study goals to describe the water quality statues and to determine the species composition, abundance and biological index of planktonic diatom in the Bengkalis waters. Survey method was applied in this research which are 5 stations established, with 3 sampling points in each station. The stations were determined purposively based on antrophogenic activities conducted in that area. Diatom samples were filtered from surface water as much as 100 liters by using plankton net number 25, and the samples were then observed using an Olympus CX 21 microscope (magnification 10 x 10 and 10 x 40) and were identified. The value of water quality at each station indicates that the water is in normal range and it may support the growth of diatoms. There were 20 spesies of planktonic diatoms recorded in the Bengkalis waters. There were 2 species, namely Coscinodiscus sp. and Navicula sp. that were found in each station. Meanwhile, the abundance of plankatonic diatoms ranged from 23,041.80 to 286,693.18 ind/l. The average of biological indices values are as follows: diversity index 1.39-2.32, dominance index 0.24 to 0,48 ind / l, and the uniformity index 0.55 to 0.87 ind / l. The biological indices values indicated that the Bengkalis Waters can be categorized as moderate polluted water and there is no dominant species.

The condition of reef fish (family Chaetodontidae) in Krueng Raya and Ujong Pancu waters, Aceh Besar District

This study aims to determine the condition of reef fish of the Chaetodontidae family in Krueng Raya and Ujong Pancu waters, Aceh Besar District. The study was conducted in October 2019, where six observation locations were representing the two regions. Fish observations were carried out using the Underwater Visual Census (UVC) method. The results of the study found four genera of Chaetodontidae fish consisting of 21 species. Benteng Inong Balee Station is the location with the highest number of individuals and species of Chaetodontidae fish, 38 individuals belonging to 11 species. On the other hand, Lhok Mee Station is the location with the least number of individuals and species of Chaetodontidae fish found, only 13 individuals belonging to 6 species. The highest abundance of Chaetodontidae fish was found at Ahmad Rhang Mayang Station (521.11 ind/ha). Meanwhile, the least abundance of Chaetodontidae fish was found at Lhok Mee Station, ( 115.38 ind/ha). The number of species, Krueng Raya waters have a higher number of Chaetodontidae fish species than Ujong Pancu waters. On the other hand, the abundance value Ujong Pancu waters have a higher average abundance value of Chaetodontidae fish than Krueng Raya waters. Overall, based on the biological index, the community structure of reef fish of the Chaetodontidae is still stable. Compared to previous study, the present study shows that, within a period of 6 years, the condition of Chaetodontidae fish in Aceh Besar waters has increased in the number of species, abundance, and diversity of fish.

Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences

The Ross Sea, one of the most productive regions in the Southern Ocean, plays a significant role in deep water formation and carbon cycling. Dissolved organic carbon (DOC) concentrations and chromophoric dissolved organic matter (CDOM) absorption and fluorescence (FDOM) properties were studied in conjunction with biophysical properties during austral summer. Elevated values of both DOC (mean 47.82 ± 5.70 μM) and CDOM (absorption coefficient at 325 nm, acdom325: mean 0.31 ± 0.18 m–1) observed in the upper shelf waters in the southwest (SW), north of the Ross Ice Shelf (RIS), the northwest and along a transect inward of the shelf break, suggested in situ production and accumulation linked to the productive spring/summer season. However, regional differences were observed in CDOM with acdom325 higher (0.63 ± 0.19 m–1) and its spectral slope S275–295 lower (24.06 ± 2.93 μm–1) in the SW compared to other regions (0.25 ± 0.08 m–1 and 28.92 ± 2.67 μm–1, respectively). Similarly, the specific UV absorption coefficient or SUVA254 determined at 254 nm was greater (1.85 ± 0.55 m2 mg–1 C) compared to other regions (1.07 ± 0.24 m2 mg–1 C), indicating CDOM of greater molecular weight and aromaticity in the SW. Phytoplankton absorption spectra indicated the shallow mixed layer of SW Ross Sea to be dominated by diatoms (e.g., Fragilariopsis spp.), a preferential food source for grazers such as the Antarctic krill, which in large numbers have been shown to enhance CDOM absorption, a likely source in the SW. Excitation-emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC) retrieved one protein-like and two humic-like FDOM fractions commonly observed in the global ocean. In contrast to acdom325 which was uncorrelated to DOC, we observed weak but significant positive correlations between the humic-like FDOM with salinity and DOC, high value of the biological index parameter BIX and an instance of increasing FDOM with depth at a location with sinking organic matter, suggesting autochthonous production of FDOM. The absorption budget showed a relatively higher contribution by CDOM (70.7 ± 18.3%) compared to phytoplankton (22.5 ± 15.2%) absorption coefficients at 443 nm with implications to ocean color remote sensing. This first study of DOM optical properties provides additional insights on carbon cycling in the Ross Sea.

Using the benthic macroinvertebrates as indicators of the water quality in the “Cachoeira do Paraíso” waterfall (Itinguçu State Park, Peruíbe, SP, Brazil) / Uso de macroinvertebrados bentônicos como indicadores de qualidade da água na Cachoeira do Paraíso (Parque Estadual do Itinguçu, Peruíbe, SP, Brasil)

Rivers protection is fundamental for the socioecological systems, and the benthic macroinvertebrates communities can be used to assess the quality of river waters. This study aimed to assess the water quality at the “Cachoeira do Paraíso” waterfall, Peruíbe, SP, based on the benthic macrofauna. Sampling took place at 3 sampling sites, under different levels of anthropic influence. Water physical-chemical and sedimentological parameters were evaluated, as well as macrobenthic organisms. Samplings were done by kick sampling technique. The organisms were identified at the lowest possible taxonomic level and points were attributed to each group according to their respective sensitivity and tolerance to pollutants. Then, a biological index was calculated to indicate the water quality. Ecological indices were calculated and compared using ANOVA. The water physical-chemical parameters showed to be within the legal standards. 13 taxonomic groups of benthic macroinvertebrates were identified, with the Shannon diversity indices indicating similar taxonomic diversity. The score given to each taxa generated biological indices for each sample, ranging from regular to excellent. Diptera (with head) I was the most representative taxon, and sensitive taxonomic groups, were found in all the sampling sites, suggesting a good quality of the water body during the period of study.

Fluorescence Characteristics of Chromophoric Dissolved Organic Matter in the Eastern Indian Ocean: A Case Study of Three Subregions

Comprising one of the major carbon pools on Earth, marine dissolved organic matter (DOM) plays an essential role in global carbon dynamics. The objective of this study was to better characterize DOM in the eastern Indian Ocean. To better understand the underlying mechanisms, seawater samples were collected in October and November of 2020 from sampling stations in three subregions: the mouth of the Bay of Bengal, Southern Sri Lanka, and Western Sumatra. We calculated and evaluated different hydrological parameters and organic carbon concentrations. In addition, we used excitation emission matrix (EEM) spectroscopy combined with parallel factor analysis (PARAFAC) to analyze the natural water samples directly. Parameters associated with chromophoric DOM did not behave conservatively in the study areas as a result of biogeochemical processes. We further evaluated the sources and processing of DOM in the eastern Indian Ocean by determining four fluorescence indices (the fluorescence index, the biological index, the humification index, and the freshness index β/α). Based on EEM-PARAFAC, we identified six components (five fluorophores) using the peak picking technique. Commonly occurring fluorophores were present within the sample set: peak A (humic-like), peak B (protein-like), peak C (humic-like), and peak T (tryptophan-like). The fluorescence intensity levels of the protein-like components (peaks B and T) were highest in the surface ocean and decreased with depth. In contrast, the ratio of the two humic-like components (peaks A and C) remained in a relatively narrow range in the bathypelagic layer compared to the surface layer, which indicates a relatively constant composition of humic-like fluorophores in the deep layer.

Non-Linear Visualization and Importance Ratio Analysis of Multivariate Polynomial Regression Ecological Models Based on River Hydromorphology and Water Quality

Multivariate polynomial regression (MPR) models were developed for five macrophyte indices. MPR models are able to capture complex interactions in the data while being tractable and transparent for further analysis. The performance of the MPR modeling approach was compared to previous work using artificial neural networks. The data were obtained from hydromorphologically modified Polish rivers with a widely varying water quality. The modeled indices were the Macrophyte Index for Rivers (MIR), the Macrophyte Biological Index for Rivers (IBMR), and the River Macrophyte Nutrient Index (RMNI). These indices measure the trophic and ecological status of the rivers. Additionally, two biological diversity indices, species richness (N) and the Simpson index (D), were modeled. The explanatory variables were physico-chemical properties depicting water quality and river hydromorphological status indices. In comparison to artificial neural networks, the MPR models performed similarly in terms of goodness of fit. However, the MPR models had advantages such as model simplicity and ability to be subject to effective visualization of complex nonlinear input–output relationships, as well as facilitating sensitivity analysis using importance ratios to identify effects of individual input variables.

Benthic Community and Assessment of Water Quality Using Biological Index in RAMSAR, Ninh Binh

Van Long, the largest wetland RAMSAR in delta areas of northern Vietnam, is a famous destination for tourists, which might influence on water quality and biodiversity. Two surveys in September 2019 and May 2020 aimed to determine species composition of macrozoobenthos and build biological indicators to assess the water quality for biodiversity conservation. Present findings report a list of 41 species in 27 genera, 14 families of macrozoobenthos (Gastropoda, Bivalvia, Crustacea - Decapoda) in Van Long. Of which, Gastropoda is the most abundant, accounting for 58.5% of the total number of species, followed by Crustacean (26.8%) and Bivalvia (14.6%). Both Shannon-Weiner biodiversity (H') and Margalef indices “d” in rainy season are higher than those in dry season (H '= 2.565 vs. 2.466 and d = 4.987 vs. 3.286, respectively). For water quality assessment, based on TCVN 7220-2: 2002, the water in Van Long RAMSAR is in low level of pollution. According to ASPT index on average (3.42), this parameter was under medium to heavily polluted. The results recommend utilizing family taxon of macrozoobenthos with the recorded scales to assess quality of aquatic environments of freshwater bodies in northern Vietnam.