Metabolism Of Aquatic Organisms Research Articles

Effects of microplastics and phenanthrene on gut microbiome and metabolome alterations in the marine medaka Oryzias melastigma

Plastic pollution of the oceans is increasing, and toxic interactions between microplastics (MPs) and organic pollutants have become a major environmental concern. However, the combined effects of organic pollutants and MPs on microbiomes and metabolomes have not been studied extensively. In the present study, to evaluate whether MPs and phenanthrene (Phe) act synergistically in the guts of marine medaka (Oryzias melastigma), we performed toxicity assessments, 16 S rRNA gene sequencing, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses. Our investigations revealed increased toxicity induced by Phe, as well as disturbances in gut microbiota (known as dysbiosis) when MPs were present. Furthermore, combined exposure to Phe and MPs resulted in greater alterations to microbiota composition and metabolite profiles. Notably, MP exposure was distinctly associated with the abundance of Shewanella and Spongiibacteraceae, while Phe exposure was associated with the abundance of Marimicrobium. Among key microbiota, Marimicrobium and Roseibacillus were significantly correlated with metabolites responsible for coenzyme A and glycerophospholipid metabolism in medaka. These results suggest that interactions between Phe and MPs may have significant effects on the gut microbiota and metabolism of aquatic organisms and underscore the importance of acknowledging the interplay between MPs and contaminants in aquatic environments.

Excessive use of chemical fertilizers in catchment areas raises the seasonal pH in natural freshwater lakes of the subtropical monsoon climate region

In recent years, the pH of some oligotrophic natural freshwater lakes in the subtropical monsoon climate region has generally reached an extremely high level of approximately 9.0 during the summer and autumn. It has not been proven that the explanation for why carbon assimilation in productive lakes exceeds carbon supply and causes a rise in pH also applies to oligotrophic freshwater lakes. Regardless, this may have been caused by changes in the solute composition of inflowing rivers as a result of changes in land use in catchment areas. Beimiao Reservoir in Baoshan City, Yunnan Province, where pH has increased significantly in summer and fall over the past few years, was chosen for this research in order to verify this hypothesis. This paper evaluates the status quo of water quality and nutrition in this reservoir. In addition, this paper analyzes the effects of water temperature, the metabolism of aquatic organisms, and river input on the horizontal and vertical spatial differences, diurnal variations, seasonal changes, and annual changes in the pH of the reservoir. It was discovered that one of the primary causes of the pH increase in natural freshwater lakes in the subtropical monsoon climate region during summer and autumn can be summarized as follows: A large amount of nitric acid and sulfuric acid are produced in the soil when chemical fertilizers are overused in runoff areas, particularly during intensive horticultural crop cultivation. Therefore, the subtropical monsoon climate region's soil loses calcium and magnesium ions, whose combined equivalent concentrations significantly exceed those of bicarbonate ions. The combined equivalent concentrations of calcium ions and magnesium ions in the inflowing rivers in summer and autumn are also significantly higher than those in the lake, resulting in the depletion of free carbon dioxide caused by calcium carbonate precipitation and an increase in pH. The conclusion of this research casts new light on the preservation and treatment of the ecological environment of lake water with similar issues.

Inhibition of Extracellular Enzymes Exposed to Cyanopeptides.

Harmful cyanobacterial blooms in freshwater ecosystems produce bioactive secondary metabolites including cyanopeptides that pose ecological and human health risks. Only adverse effects of one class of cyanopeptides, microcystins, have been studied extensively and have consequently been included in water quality assessments. Inhibition is a commonly observed effect for enzymes exposed to cyanopeptides and has mostly been investigated for human biologically relevant model enzymes. Here, we investigated the inhibition of ubiquitous aquatic enzymes by cyanobacterial metabolites. Hydrolytic enzymes are utilized in the metabolism of aquatic organisms and extracellularly by heterotrophic bacteria to obtain assimilable substrates. The ubiquitous occurrence of hydrolytic enzymes leads to the co-occurrence with cyanopeptides especially during cyanobacterial blooms. Bacterial leucine aminopeptidase and alkaline phosphatase were exposed to cyanopeptide extracts of different cyanobacterial strains ( Microcystis aeruginosa wild type and microcystin-free mutant, Planktothrix rubescens) and purified cyanopeptides. We observed inhibition of aminopeptidase and phosphatase upon exposure, especially to the apolar fractions of the cyanobacterial extracts. Exposure to the dominant cyanopeptides in these extracts confirmed that purified microcystins, aerucyclamide A and cyanopeptolin A inhibit the aminopeptidase in the low mg L-1 range while the phosphatase was less affected. Inhibition of aquatic enzymes can reduce the turnover of nutrients and carbon substrates and may also impair metabolic functions of grazing organisms.

Effects of vitamin C on oxidative stress parameters in rainbow trout exposed to diazinon

Abstract: : Diazinon (Organophosphorus insecticide) can cause reactive oxidative stresses during metabolism of aquatic organisms. The study presented here aimed to investigate the antioxidant effect of vitamin C on antioxidant enzyme activities and lipid peroxidation in rainbow trout exposed to subchronic dosage diazinon. A total number of 360 Oncorhynchus mykiss were allocated into four treatment groups (with three replicates): control; diazinon (0.1 mg L 1); vitamin C (300 mg kg 1 in diet) plus diazinon (0.1 mg L-1), and vitamin C (1000 mg kg-1 in diet) plus diazinon (0.1 mg L-1). After two and four weeks, blood samples were collected and superoxide dismutase, catalase enzymes, total antioxidant capacity and malondialdehyte index were measured. The specimens exposed exclusively to diazinon showed a significant decrease in superoxide dismutase and total antioxidant capacity activities and also an increase in catalase activity and malondialdehyde index compared to those of the control group. The changes in oxidative stress parameters may be related to destructive free oxiradicals such as superoxide and hydroxyl radicals produced in diazinon metabolism. In conclusion, vitamin C moderated activity of the antioxidant enzyme, increased the total antioxidant capacity, and decreased cellular damages caused by destructive lipid peroxidation process in presence of diazinon. Keywords: Diazinon, antioxidant, vitamin C, enzyme, malondialdehyde, catalase

Open-top static respirometry is a reliable method to determine the routine metabolic rate of barramundi, Lates calcarifer

Closed-system respirometry is a standard technique used to determine aerobic metabolism of aquatic organisms. Open-top systems are rarely used due to concerns of gas exchange across the air–water interface. Here, we evaluated an open-top respirometry system by comparing the mass-specific routine metabolic rate (RMR) of the tropical diadromous finfish barramundi, Lates calcarifer, in both closed-top and open-top respirometers. The RMR of 190 g barramundi was determined across broad temperatures ranging from 18 to 38 °C. There was no significant difference in RMR between barramundi in either closed- or open-top respirometers at any temperature (p > 0.05). To ensure RMR measurements were not an artifact of the respirometry system, barramundi were reciprocally transplanted into either respective closed-top or open-top respirometer and oxygen consumption re-measured at each temperature treatment. The RMR of transplanted barramundi was found to be virtually identical in either respirometer. RMR increased linearly with increasing temperature; the relationship between RMR and temperature (T; 18–38 °C) can be described as 3.658T−36.294 mg O2 kg−0.8 h−1. The daily energetic cost of RMR was 1.193T−11.838 kJ kg−0.8 day−1. Q10 for barramundi increased significantly with increasing temperature (p < 0.0001). Q10(18–28) was the lowest at 1.7 and Q10(28–38) the highest at 1.9, over the whole experiment temp range Q10(18–28) was 1.8. The current study demonstrates that open-top respirometry is a reliable and practical alternative to closed-top respirometry for accurate determination of the aerobic metabolism of barramundi and has potential application for a number of different aquatic organisms.

Quantifying the importance of daily stream water temperature fluctuations on the hyporheic thermal regime: Implication for dissolved oxygen dynamics

• We model the heat transport in the hyporheic zone by using a Lagrangian approach. • We examine the role of the stream water temperature on hyporheic thermal regime . • We examine the role of hyporheic thermal regime on dissolved oxygen (DO) kinetics. • Via a thermal Damköhler number we relate stream morphology and temperature signal. • We show the impact of temperature variation on the evolution of DO concentration. Water temperature is a primary driver of aquatic organism migration, drift, growth and metabolism in both stream and hyporheic zone. Here, we focus on the role of the naturally occurring daily stream water temperature oscillations on the hyporheic thermal regime and on dissolved oxygen (DO) dynamics within the hyporheic zone. We choose DO as target dissolved element because of its importance for aquatic habitat quality and its role in controlling biogeochemical reactions and pool-riffle morphology as bed form because of its ubiquity and ecological relevance. To address the first objective, we introduce a new thermal Damköhler number, Da T , which is the ratio between the median residence time of stream water and the time scale of daily amplitude attenuation of water temperature within the hyporheic zone. Application of the model to a wide range of pool-riffle dimensions shows the dependence of hyporheic water temperature distribution on hyporheic residence time. The latter is a function of the interaction between stream flow and bed form morphology. Our results show that Da T increases with stream size indicating that large streams have more thermally stable hyporheic zones than small streams. To address the second objective, we analytically solve the heat and dissolved oxygen transport equations through the streambed sediment with isotropic and homogeneous hydraulic properties by means of a Lagrangian approach, under the hypothesis that transverse dispersion can be neglected and the DO reaction rate is temperature dependant. We apply these coupled transport models to characterize the distribution of DO concentrations within the hyporheic zone. This analysis shows a relation between the patterns of water temperature and of DO concentrations with important feedbacks on the life and metabolism of aquatic organisms; as well as on the reaction rates, which control the biogeochemical processes within the streambed sediment. We analyze the effects of temperature variations on the kinetics of DO assuming constant and periodic fluctuations of DO concentrations in the stream water. Our results show that for streams with pool and riffle morphology, the latter effect is more important than that of temperature dependent reaction rates.

Investigation of acute toxicity of heavy metals in Artemia salina acclimated to different salinity

Environment plays a vital role in the growth and metabolism of aquatic organisms. Pollutants are known to produce marked changes in the food cycle. In order to study the impact of prey on aquaculture, this study was conducted in live fish feed Artemia salina. Since changes in the culture tank due to environmental factors were mainly responsible for the decline of aquaculture, this study focused on the effect of salinity and heavy metal, including mercury (Hg), copper (Cu), and chromium (Cr), on two life stages of A. salina. Cr-exposed groups showed the highest morality at 0.052 ppm (99%) with the growth of 60%. Percentage mortality was observed to be in the order of Cr>Hg>Cu. Growth was significantly reduced. Artemia was able to accumulate Hg (9–13%), Cu (5.4–5.9%), and Cr (16.4–35%) in the body. The concentrations of heavy metals in water samples were 50–64% of Hg, 52–78% of Cu, and 62% of Cr. Metal stress induced elevated protein content, which may be due to the stress response of the organism against free radicals.

Diurnal dynamic of inorganic carbon and oxygen dissolved in a Nile tilapia (Oreochromis niloticus Linnaeus, 1758) fish pond, São Paulo, Brasil

Natural waters may play the role of sinks or carbon dioxide (CO2) emitters, depending on the physicochemical characteristics of the system (diffusion and reaction of this gas into water) as well as on the pH, and the primary production of micro-organisms as a result of the consumption of such compounds. Evidence suggests that the CO2 concentrations in ponds are mainly governed by the aquatic metabolism, i.e. by the balance between respiration and photosynthesis; AIM: The purpose of this study was to describe aspects of the metabolism of tilapia cultivation based on the dynamic and balance of the oxygen concentrations (DO) and forms of dissolved inorganic carbon (DIC): carbon dioxide (CO2) and bicarbonate (HCO3-). Other variables analyzed are: total phosphorus, water transparency, total alkalinity, water temperature, pH, underwater radiation and quantitative analysis of phytoplankton community; METHODS: Sampling was collected infor 5 consecutive days from 6:00 AM to 8:00 PM (December/2006) every 2 hours; RESULTS: During the test it was observed periodicity in the fluctuations of the DIC concentrations, being CO2 and HCO3- the predominant fractions. The values of DIC were strongly influenced by the fraction of CO2 and it was observed a predominance of the fraction HCO3- in the afternoon. CO2 concentrations ranged from 0.48 µM through 138.94 µM, reaching a daily average of 18.04 µM. The flow of CO2 in the interface atmosphere/water showed variations during the day. In the afternoon (from 12:00 PM until 6:00 PM) the variation pointed to the flow atmosphere/fish pond; however, the balance was 577 µmol.m-2.h-1 in the flow fish pond/atmosphere; CONCLUSIONS: The observed dynamics indicated that under the conditions of this study, the metabolism of aquatic organisms was the main driving force of this system, a fact corroborated by the intense process of euthrophication in the pond.

Analytical characterization of 2-bromo-palmitic acid by gas chromatography–mass spectrometry as a tool for analysis of lipid metabolism in fish

Elucidation of the lipid metabolism of aquatic organisms is important for the progress of aquaculture and its related research activities. 2-Bromo-palmitic acid has been introduced as a metabolically stable inducer of differentiation of adipose tissues [1] and a regulatory factor (inhibitor) in the palmitoylation process of protein dynamics [2–4]. These papers have shown that metabolic or dynamic regulation by the brominated fatty acid is successful. Therefore, it is suggested that 2-bromo-palmitic acid has a significant advantage as a tool for experiments in further investigations on aquatic organisms such as previously described reports showing lipid metabolism in fish [5, 6], in which the detection of the brominated fatty acid will be necessary to infer the potential of this fatty acid as a nonmetabolizable regulatory factor. However, the quantitative properties of the brominated fatty acid have not been elucidated. Thus, this study aims to obtain the analytical profiles of 2-bromo-palmitic acid related to gas chromatography–mass spectrometry (GC–MS). We investigated whether 2-bromo-palmitic acid methyl ester (2-BrC16:0ME) is derived from 2-bromo-palmitic acid, and how the brominated fatty acid methyl ester (FAME) is detected by GC–

Assessment of Activity-Specific Metabolism of Aquatic Organisms: An Improved System

An improved flow-through respirometer capable of assessing activity-specific metabolism of aquatic organisms is presented and assessed. The system is highly sensitive and versatile, since it continuously monitors and records activity-specific oxygen consumption readings for periods up to 72 h and is capable of detecting differences in metabolism of individual specimens of similar weight. Using this system, we demonstrated individual variation and intraspecific differences in metabolism between two size classes of the freshwater leech Nephelopsis obscura and interspecific differences between N. obscura and another freshwater leech, Erpobdella montezuma, and compared these findings with the metabolism of the amphipod Hyalella montezuma.

Measuring the Carbon Dioxide Metabolism of Aquatic Organisms

A method of measuring the carbon dioxide metabolism of aquatic organisms based on the relationship of acidity and carbon dioxide concentration in water is presented. This method is suitable for use in any high school biology laboratory possessing a modern pH meter. Experimental examples of the metabolism of a fish and an aquarium are shown, and three tables of constants are given to aid in the calculations necessary to this method. Additional experiments using the method are suggested.