WE have here a comprehensive work embodying the results of a ten years' study of water plants, and dealing in a very practical fashion with the mass of literature that has grown up around the subject. As a book of authority on aquatic plants, it will be ranked with Schenck's work of a generation ago, and it would not receive its due if we did not add that it worthily holds the place. But we must not forget that other industrious investigators have in the meantime filled the gap. Prominent among them are Gluck, Goebel, Henslow, Pond, Sargant, Sauvageau, Willis, and many others. Since Schenck's time, however, new points of view have arisen, and new methods have been in use by numerous inquirers of both sexes, all keen in their desire to take a part in the new era of research. Water Plants: A Study of Aquatic Angiosperms. By Dr. Agnes Arber. Pp. xvi + 436. (Cambridge: At the University Press, 1920.) Price 31s. 6d. net.

Water Plants: A Study of Aquatic Angiosperms

Freshwater snails are used as sensitive biomarkers of aquatic ecosystem pollution. The potential impacts of zinc oxide nanoparticles (ZnONPs) on aquatic ecosystems have attracted special attention due to their unique properties. The present investigation was designed to evaluate the possible mechanisms of ecotoxicological effects of ZnONPs on freshwater snail Biomphalaria alexandrina. ZnONPs showed molluscicidal activity against B. alexandrina snails, and the LC50 was 145 μg/ml. Two tested concentrations of ZnONPs were selected: The first concentration was equivalent to LC10 (7 μg/ml), and the second was equivalent to LC25 (35 μg/ml). Exposure to ZnONPs (7 and 35 μg/ml) for three consecutive weeks significantly induced malondialdehyde and nitric oxide with concomitant decreases in glutathione and glutathione-S-transferase levels in hemolymph and soft tissues of treated snails. Moreover, ZnONPs elicited a significant decrease in total protein and albumin contents coinciding with enhancement of total lipids and cholesterol levels as well as activities of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase in hemolymph and soft tissues of treated snails. This study highlights the potential ecological implications of ZnONP release in aquatic environments and may serve to encourage regulatory agencies in Egypt to more carefully monitor and regulate the industrial use and disposal of ZnONPs.

Toxicological effects of zinc oxide nanoparticles: Ecotoxicological effect of sublethal exposure to zinc oxide nanoparticles on freshwater snail Biomphalaria alexandrina

Environmental toxicology: An overall perspective, or where to from here?

In the next century, global warming, due to changes in climatic factors, is expected to have an enormous influence on the interactions between pathogens and their hosts. Over the years, the rate at which vector-borne diseases and their transmission dynamics modify and develop has been shown to be highly dependent to a certain extent on changes in temperature and geographical distribution. Schistosomiasis has been recognized as a tropical and neglected vector-borne disease whose rate of infection has been predicted to be elevated worldwide, especially in sub-Saharan Africa; the region currently with the highest proportion of people at risk, due to changes in climate. This review not only suggests the need to develop an efficient and effective model that will predict Schistosoma spp. population dynamics but seeks to evaluate the effectiveness of several current control strategies. The design of a framework model to predict and accommodate the future incidence of schistosomiasis in human population dynamics in sub-Saharan Africa is proposed. The impact of climate change on schistosomiasis transmission as well as the distribution of several freshwater snails responsible for the transmission of Schistosoma parasites in the region is also reviewed. Lastly, this article advocates for modelling several control mechanisms for schistosomiasis in sub-Saharan Africa so as to tackle the re-infection of the disease, even after treating infected people with praziquantel, the first-line treatment drug for schistosomiasis.

https://www.mdpi.com/1660-4601/17/1/181/pdf

The Effect of Climate Change and the Snail-Schistosome Cycle in Transmission and Bio-Control of Schistosomiasis in Sub-Saharan Africa.

Phragmites australis (common reed) is one of the most extensively distributed species of emergent plant worldwide The adaptive features of this plant show its competitive character Owing to high intraspecific diversity of common reed, as well as its phenotypic plasticity, the plant shows a broad ecological amplitude Moreover, the plant exhibits a high capacity for acclimatization to environmental conditions which are considered adverse This plant has been used for many years in phytoremediation to purify various types of wastewater Phragmites australis has a high ability to accumulate various nutrients, heavy metals, and micropollutants, and in this respect, it is superior to other aquatic plants This review examines the existing literature on the biological and ecological properties of common reed, the use of common reed in wastewater treatment for removing pollutants and tolerance for metals, and in hydrophyte treatment systems It seems vital to conduct further research on the physiology and biochemistry of the common reed, with the aim of increasing the plant’s efficiency for pollutants removal

The Importance of Biological and Ecological Properties of Phragmites Australis (Cav.) Trin. Ex Steud., in Phytoremendiation of Aquatic Ecosystems—The Review

In this study, the most effective agent was Difenoconazole (Score) followed by Asparagus densiflours then Oreopanax guatemalensis plants against Biomphalaria alexandrina snails. The high concentrations of the three tested agents caused a remarkable reduction in hatchability percent of B. alexandrina eggs than the low concentrations. The sublethal concentrations (LC10 and LC25) of both A. densiflorus and Score have more destructive effect on the survival, growth and reproductive rates of the juvenile snails than the corresponding concentrations of O. guatemalensis plant. Different sublethal concentrations (LCo and LC5) of the three agents caused a remarkable elevation in the activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzymes of the snails after the 1 st week of the exposure. The sublethal concentration LC5 of the three tested agents caused pronounced effect on the alkaline phosphatase (ALP) and acid phosphatase (ACP) activities after the 2 nd weeks of the exposure. Total protein, albumin, globulin and albumin/ globulin (A/G) ratio in hemolymph of snails exposed to sublethal concentration LCo of the three tested agents, are differently affected after the 1 st and 2 nd week of the exposure. The histological examinations demonstrated a severe damage in both secretory cells and digestive cells especially in case of Asparagus densiflours and Score.

Impact of Asparagus densiflours and Oreopanax Guatemalensis plants and Difenoconazole Fungicide on Biochemical Parameters of Biomphalaria Alexandrina Snails

This study aimed to the density and distributions of some freshwater snails collected from eight freshwater streams at Egyptian governorates (Giza, Ismailia, Menoufia and Gharbia). Physical and chemical properties of water quality (i.e. water temperature, pH, dissolved oxygen, total dissolved solids and electrical conductivity), and measuring ammonia, nitrite, nitrate and phosphate was done. Density of aquatic plants was evaluated. Chlorophyll-a content was measured to determine the trophic level of water. The results revealed that Biomphalaria alexandrina was the most enumeration snail spices, where they have the ability to tolerate and adapt to various environmental circumstances. Results proved that the eutrophic state recorded at Giza and Gharbia whereas, hyper-eutrophic state observed at Ismailia and Menoufia. Eichhornia crassipes; Echinochloa sp. (Water grass) and Lemma gibba aquatic plants were the most dominant aquatic plants and almost they were found in all examined sites.

/pdf/impact-of-seasonal-water-quality-and-trophic-levels-on-the-2h29jtmlq1.pdf

Impact of Seasonal Water Quality and Trophic Levels on the Distribution of Various Freshwater Snails in Four Egyptian Governorates

Assessment of the molluscicidal activity of the methanolic seed extracts of Ziziphus spina‐christi and Carica papaya on immunological and molecular aspects of Biomphalaria alexandrina snails

Many chemicals are applied for disinfecting purposes. Although chlorination is the most common procedure, it has many drawbacks. So there becomes an urgent need for new chemicals which are both effective and less harmful to other water fauna. The present work aims at investigating the comparative effects of chlorine and Huwa-san as a new disinfectant on Biomphalaria alexandrina snails which act as bioindicators of toxicity, besides evaluating their miracicidal and cercaricidal activities. The results showed that Huwa-san was more toxic on tested snails than chlorine, where the LC50 values were 21 and 1368.9 ppm, respectively after 24 h. Also, it was found that the activities of catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and glutathione peroxidase (GPX) in snails’ tissues were either induced or inhibited according to the tested disinfectant. Regarding reduced glutathione (GSH) content, it was increased as chlorine concentrations increased, while it reached its minimum content at the highest Huwa-san concentration. Such fluctuations were supported by histopathological examination of digestive and hermaphrodite glands, as prolonged exposure to chlorine led to more detrimental effects than Huwa-san concentrations. Moreover, Huwa-san was more effective on Schistosoma mansoni miracidia than on its cercariae, while the reverse was observed with chlorine. In conclusion, Huwa-san as a newly applied disinfectant can also be used as miracicidal and cercaricidal agent at small concentrations. Despite being more toxic to B. alexandrina snails, the chronic effect of its sublethal concentrations is less harmful than chlorine.

The comparative effect of chlorine and Huwa-san as disinfecting agents on Biomphalaria alexandrina snails and free larval stages of Schistosoma mansoni

Freshwater snails are often used to monitor aquatic pollution. The present study aims to use Biomphalaria alexandrina snails as bio-indicators for three types of NPK fertilisers (high nitrogen, high phosphorus and balanced). Data showed that high phosphorus and high nitrogen fertilisers have a negative impact on the growth rate of juvenile snails. Such observations were supported by determining antioxidant parameters in the digestive gland. Results indicated a significant increase in the catalase activity of snails that were exposed to ½ LC50 concentrations of balanced and high phosphorus fertilisers. Meanwhile, the glutathione S-transferase, glutathione peroxidase and reduced glutathione parameters showed varying results representing an increase or decrease in the activities of all treated groups after both the first and second weeks, according to the type of fertiliser the snails were exposed to.

Sara S. M. Sayed

Papers

Impact of Asparagus densiflours and Oreopanax Guatemalensis plants and Difenoconazole Fungicide on Biochemical Parameters of Biomphalaria Alexandrina Snails

Impact of Seasonal Water Quality and Trophic Levels on the Distribution of Various Freshwater Snails in Four Egyptian Governorates

Assessment of the molluscicidal activity of the methanolic seed extracts of Ziziphus spina‐christi and Carica papaya on immunological and molecular aspects of Biomphalaria alexandrina snails

The comparative effect of chlorine and Huwa-san as disinfecting agents on Biomphalaria alexandrina snails and free larval stages of Schistosoma mansoni

Biomarkers of oxidative stress in Biomphalaria alexandrina snails for assessing the effects of certain inorganic fertilisers