Effects Of Un-ionized Ammonia Research Articles

Behavioral Variables to Assess the Toxicity of Unionized Ammonia in Aquatic Snails: Integrating Movement and Feeding Parameters

Behavioral endpoints are important parameters to assess the effects of toxicants on aquatic animals. These endpoints are useful in ecotoxicology because several toxicants modify the animal behavior, which may cause adverse effects at higher levels of ecological organization. However, for the development of new bioassays and for including the behavior in ecotoxicological risk assessment, the comparison of sensitivity between different behavioral endpoints is necessary. Additionally, some toxicants remain in aquatic environments for a few hours or days, which may lead to animal recovery after toxicant exposure. Our study aimed to assess the effect of unionized ammonia on the movement and feeding behaviors of the aquatic gastropod Potamopyrgus antipodarum (Tateidae, Mollusca) and its recovery after exposure. Four treatments were used: a control and three nominal concentrations of unionized ammonia (0.25, 0.5 and 1 mg N-NH3/L). Each treatment was replicated eight times, with six animals in each replicate. Animals were exposed to unionized ammonia for 48 h (exposure period) and, subsequently, to control water for 144 h (post-exposure period). Two movement variables were monitored without food and five feeding behavioral variables were monitored in the presence of food. Some of the feeding behavioral variables showed higher sensitivity (LOEC = 0.25–0.5 mg N-NH3/L) than the movement behavior variables monitored without food (LOEC = 1 mg N-NH3/L). After exposure to unionized ammonia, animals showed a recovery of most behavioral endpoints. The inclusion of post-exposure period and feeding behaviors in bioassays may make studies more realistic, which is crucial for a proper ecotoxicological risk assessment.

Effects of unionized ammonia and suspended solids on rainbow trout (Oncorhynchus mykiss) in recirculating aquaculture systems

This study investigates the individual and combined effects of chronic exposure of rainbow trout to unionized ammonia and suspended solids in a farm-scale recirculating aquaculture system (RAS) over 13 weeks. Unionized ammonia nitrogen concentration was four times (0.05 mg/L) the generally accepted ‘safe’ threshold while total suspended solids (TSS) exceeded the ‘safe’ threshold of 25 mg/L by a factor of >2.5. Still, rainbow trout revealed high survival rates of >99% and no observable detrimental effects of TSS. Bacterial activity showed a close positive linear correlation with solid load and was almost exclusively explained by solid load for TSS concentration > 10 mg/L. However, bacterial activity had no apparent detrimental effect on fish health or performance. Increased unionized ammonia nitrogen concentrations had no relevant detrimental effect on rainbow trout physiology and performance at concentrations of up to 0.05 mg/L. Furthermore, the absent to minor solid-related effects across a wide range of physiological criteria combined with chronic exposure to unionized ammonia demonstrates that chemical or physical irritants are not problematic in RAS if other water and holding parameters are optimal. These findings suggest a greater than expected tolerance of rainbow trout to chronic TSS-related effects which should result in a revision of water quality threshold criteria for RAS.

Dose-dependent effect of un-ionized ammonia on hatching success of fertilized eggs of silver carp Hypophthalmichthys molitrix and bighead carp Hypophthalmichthys nobilis

Ammonia is one of the most common pollutants in aquaculture systems and its elevated concentration in surface water is a critical concern in fish larvae production. The purpose of this study was to assess the effects of un-ionized ammonia (NH3) on hatch success of fertilized eggs of silver carp Hypophthalmichthys molitrix and bighead carp Hypophthalmichthys nobilis, two ecologically and commercially important species in freshwater ecosystems. The results showed total hatch rates and viability of newly hatched larvae 24 h post-hatch decreased significantly with increasing NH3–N concentration for both silver carp and bighead carp, whereas abnormal rate increased significantly with increasing NH3–N concentration. When fitted to the data of total hatch rates and viability of newly hatched larvae 24 h post-hatch, it is clear that the logistic model with three parameters can be fitted to ecotoxicological data well and can describe dose-dependent effects of un-ionized ammonia on hatching success of fertilized eggs of both silver carp and bighead carp. According to the model, the EC50 for the hatch rates of silver carp and bighead carp was 0.98 and 0.86 mg L−1, respectively. Our results should be useful to hatchery managers and fingerling producers in establishing acceptable water quality parameters for the hatchery and nursery ponds.

Peroxidation damage and antioxidative capability of Ceratophyllum demersum under

The current article investigated the effects of ammonia nitrogen concentration and pH on peroxidation damage and antioxidative capability of Ceratophyllum demersum. The pH ranges (7 and 9) were carefully controlled to distinguish between the effects of unionized ammonia (NH3) and ionized ammonia (). The addition of ammonia significantly decreased chlorophyll a content. Peroxidase and superoxide dismutase activities as well as glutathione content under high ammonia conditions (10 mg N/L) significantly increased at pH 7 but were no different or reduced at pH 9. Catalase activity as well as ascorbic acid and malondialdehyde contents significantly increased under all ammonia treatments at pH 7 and 9. C. demersum suffered from stress at pH 9 under high ammonia conditions. Higher pH in water may induce C. demersum to exhibit more severe physiological responses.

A toxicity bioassay study concerning the effect of un-ionized ammonia on the mucus cells response originating from the gills of zebrafish Danio rerio

Ammonia is one of the most common and pervasive pollutants in the aquatic habitat affecting the health of aquatic animals. It affects the number and morphology of mucus producing cells, resulting in excessive and irregular secretion and alterations in quantity of mucus, which can lead to complications in fish health. A toxicity test on the mucus cells localized on the gills (primary lamellae) and inner operculum epithelial lining of zebrafish Danio rerio at different periods of exposure (24, 48 and 72 h) followed by recovery periods was studied using histopathology, scanning electron microscopy and anterior gradient 2 homologue (agr2) gene expression techniques. Fish samples subjected to low, medium and high external toxic ammonia concentrations (L: 17.21 mg/l, M: 25.81 mg/l and H: 38.91 mg/l NH3-N) were observed to display a higher mucus layer production and active secretion compared with the control. Gill cellular alterations were more severe at 48 and 72 h. A high expression of agr2 was detected at 48 h (L and M) recovery periods and a (H) exposure and recovery period indicating an increase in quantity in newly proliferated alcian blue stained mucus cells and excessive secretion observed by histopathology. Such expression decreased at 72 h resulting in a decrease in mucus cell density and secretion.

Incubation and oxidative stress of grass carp (Ctenopharyngodon idella) embryos exposed to different un-ionized ammonia levels

The increase in concentration of ammonia in surface water is a critical concern in aquaculture, especially in fish larvae production. The purpose of this study was to assess the effects of un-ionized ammonia (NH3) on the development and oxidative stress of grass carp (Ctenopharyngodon idella) embryos. The results showed that the rate of embryonic development to hatch was retarded with an increase in NH3–N concentration. Hatch rate of grass carp embryos in the control was greater than 90%, whereas the hatch rate in 0.879 mg L−1 of NH3–N was less than 70%. Viability of newly hatched larvae (24 h post-hatch) significantly decreased with increasing NH3–N concentrations. Viability of newly hatched larvae 24 h post-hatch in the control was 97.8%, whereas in 0.879 mg L−1 of NH3–N, the viability was only approximately 40%. This indicates that although embryos can hatch to larvae under high NH3–N conditions, the larvae were much less tolerant of NH3–N than embryos. NH3–N had a significant effect on superoxide dismutase (SOD) and malondialdehyde (MDA) levels, whereas there was no statistically significant difference in catalase and glutathione activity among different NH3–N levels. Two-way analysis of variance indicated that there was a statistically significant interaction between NH3–N and developmental stage on SOD and MDA. Such changes indicated the presence of oxidative stress when grass carp embryos were exposed in water containing pollutants and SOD plays a key role in removing the free radicals in this case.

Effects of un-ionized ammonia on histological, endocrine, and whole organism endpoints in slimy sculpin ( Cottus cognatus)

Ammonia is known to be an important toxicant in aquatic environments. Although ammonia toxicity has been well studied in many fish species, effects of chronic exposure on slimy sculpin ( Cottus cognatus), a critical biomonitoring species for northern aquatic habitats, are not well known. Further, with increasing mining development in Canada's north, this information is critical to better predict potential effects of mine effluent discharges on northern fish species. Slimy sculpin were exposed to six concentrations of un-ionized ammonia (NH 3) relevant to concentrations found in northern mining effluents: control (0 ppm), 0.278 ppm, 0.556 ppm, 0.834 ppm, 1.112 ppm, and 1.668 ppm. An LC 50 of 1.529 ppm was calculated from mortality data. Histopathological examination of gills indicated significant tissue damage, measured as lamellar fusion and epithelial lifting, at 0.834 ppm, 1.112 ppm, and 1.668 ppm. Using gill endpoints, NOEC and LOEC were calculated as 0.556 ppm and 0.834 ppm, respectively. An EC 50 of 0.775 ppm was determined for lamellar fusion and an EC 50 of 0.842 ppm for epithelial lifting. Hemorrhage of gills was present in mortalities, which occurred at 1.668 ppm of un-ionized ammonia. A significant decrease in liver somatic index (LSI) was seen in both male and female fish at 0.834 ppm and 1.112 ppm, respectively. Gonadosomatic index (GSI) in female fish significantly increased at 1.668 ppm un-ionized ammonia with an associated significant increase in total wholebody testosterone concentrations. GSI in male fish also significantly increased at 1.668 ppm but no differences were seen in testosterone concentrations. No significant differences were seen in gonad histopathological assessments or condition factor. Gill histopathology endpoints may be a more sensitive indicator for detecting effects in slimy sculpin exposed to ammonia than traditional chronic endpoints. Results from this study indicate that ammonia concentrations commonly reported in northern mine effluents hold potential to affect the health of slimy sculpin including acute, chronic, histological and endocrine endpoints.

Decrease of Time for Pathogen Inactivation in Alkaline Disinfection Systems Using Pressure

From field studies conducted by Tulane University (New Orleans, Louisiana), efficiency of advanced alkaline disinfection in closed systems was found to depend on ammonia concentration, pH, exposure time, temperature, total solids content, pretreatment storage time, and mixing effectiveness. In this study of a closed alkaline system, an additional pathogen stressor pressure was tested. The effect of the alkaline dosing has been assessed for dewatered raw and aerobically and anaerobically digested municipal sludge cake that produce un-ionized ammonia at concentrations of 0.05 to 2% on a dry-weight basis. Inactivation of Ascaris suum eggs increased from 50 to 99% as the temperature was increased from 40 to 55 degrees C, thus achieving Class A levels. The systems studied were compared with an alkaline process operated under open conditions, which limited the concentrations of ammonia available because of Henry's Law. Under a closed pressurized system, the effect of un-ionized ammonia was greatly increased, and the resulting time required for inactivation was reduced from hours or days to minutes. In the next few years, it is expected that alkaline disinfection of biosolids will be optimized in relation to the factors stated above, at much lower doses of the alkaline agents. The closed-system alkaline processes that will be developed will be more energy-efficient, cost-effective, and have full control of potential odorous emissions.

Effect of unionized ammonia, viscosity and protozoan contamination on the enzyme activity of the rotifer Brachionus plicatilis

Substrates that are cleaved to yield fluorescent products can be used to quickly quantify enzyme activity in vivo with image analysis or in vitro with fluorometry. This study was carried out to determine whether enzyme activity in rotifers is useful for assessing the physiological condition of rotifers. Neonates of Brachionus plicatilis Müller hatched from cysts were exposed to a concentration series of unionized ammonia ranging from 0 to 9.8 p.p.m., increasing seawater viscosity relative to 1.17 to control sea water by the addition of methyl cellulose and the addition of the protozoan Euplotes sp. to a density of 40 mL−1. Rotifer glucosidase and esterase activities decreased with increasing unionized ammonia and viscosity respectively. Activities of glucosidase and phospholipase decreased with increasing protozoan contamination. There was a significant relationship between enzyme activities and rotifer population growth. In vivo activities of certain rotifer enzymes can therefore serve as biomarkers for the rapid assessment of environmental stressors in rotifer mass cultures.

The effect of external ammonia on growth and food utilization of juvenile turbot ( Scophthalmus maximus L.)

The effect of different concentrations of external un-ionized ammonia (NH 3) on the growth of juvenile turbot ( Scophthalmus maximus L.) was investigated over a period of 20 days. When the concentration of un-ionized ammonia exceeded a threshold level of 0.108 mg NH 3-N l −1, growth was found to be reduced, as indicated by a reduction in body and liver wet and dry weight gain. The observed reduction of growth could partly be explained by less food intake. Efficiency of food utilization was observed to be reduced as indicated by higher food coefficients and relative increases in the faecal amounts produced. No effect of un-ionized ammonia could be observed on the wet weight:dry weight ratio. In fish exposed to high levels of ammonia, the ratio of RNA to DNA in the liver was observed to be reduced. Darkening of skin, and sporadic and fast swimming behaviour were observed among fish exposed to the highest concentrations of un-ionized ammonia.

Study on the unexpected sudden decrease and suppressed growth of the rotifer population in mass culture - I The effect of un-ionized ammonia on the population growth of the rotifer in mass culture.

In mass culture tanks for the rotifer Brachionus plicatilis, the concentrations of inorganic. nitrogen compounds, pH, water temperature and specific gravity were measured daily at the Aqua-culture Research Laboratory of Nagasaki Prefectural Institute of Fisheries from April to July, 1984. The rotifer density decreased with an increased concentration of un-ionized ammonia nitrogen (NH3-N). The highest concentration of NH3-N observed was 3.6ppm. The rotifer densities above 150 rods./ml were observed, only when the pH ranged from 7.3-7.8. Acute toxicity test of NH3-N to rotifers showed that 24h LC50 value was 17.0ppm at 23°C. Chronic toxicity test showed that concentrations of NH3-N at which the population growth and the reproduction reduced by 50% of the controls were 13.2 and 7.8ppm, respectively. The concentrations at which the intrinsic rate of population growth and the net reproduction rate were reduced by l% of those of the control, were adopted as the “no-effect” concentration of NH3-N. They were estimated as 2.1 and 2.4ppm, respectively. The results from mass culture and toxicity tests showed that higher concentration of NH3-Nmight be one of restrictive factors affecting the increase of the rotifer.