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2 results on '"Marilie Pretorius"'

1. Hatchability and Survival of Lamproglena clariae Fryer, 1956 Exposed to Increasing Concentrations of Aqueous Aluminium

Author

Marilie Pretorius and Annemariè Avenant-Oldewage

Subjects
ectoparasite, aluminium, toxicity, survival, hatching, bioindicator, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999
Abstract

The effect of increased aluminium concentration on the hatchability and survival of Lamproglena clariae is unknown. During October 2019 and October 2020, infected C. gariepinus were collected from the Vaal River and transferred to a controlled aquarium room. Parasite infection was established on acclimated C. gariepinus. Adult female parasites (F2 and F3 generation) on live fish were inspected for egg strings. Viable egg strings were removed, leaving females attached to produce more eggs. Bioassays were performed in varying concentrations of Al (control, 5 µg/L, 30 µg/L, 60 µg/L, and 120 µg/L). Egg development was monitored. In situ physical and chemical water quality parameters were measured, and water samples were collected every 24 h for metal analysis using inductively coupled mass spectrometry. The experiment terminated when all juveniles perished. Five percent of exposed eggs did not hatch in the control solution, compared to 26% in 120 µg/L Al. Hatchability and survival of L. clariae were negatively affected by increased Al concentrations. By removing this ectoparasite from living fish, the need to euthanise the host organism is eliminated, emphasising the usefulness of L. clariae as a bioindicator for metal pollution.

Published
2023
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2. Parasites as Biological Indicators: the Impact of Environmental Quality on the Infections of Lamproglena clariae (Crustacea) on Clarias gariepinus Along the Vaal River, South Africa

Author

Marilie Pretorius and Annemariè Avenant-Oldewage

Subjects
Gill, Pollution, Clarias gariepinus, Geologic Sediments, Endocrinology, Diabetes and Metabolism, media_common.quotation_subject, Clinical Biochemistry, Biochemistry, Freshwater ecosystem, Inorganic Chemistry, South Africa, Rivers, Crustacea, Metals, Heavy, Water Quality, Animals, Parasites, Catfishes, Ecosystem, media_common, biology, Environmental Biomarkers, Biochemistry (medical), Sediment, General Medicine, Total dissolved solids, biology.organism_classification, Salinity, Metals, Environmental chemistry, Environmental science, Water quality, Water Pollutants, Chemical, Environmental Monitoring
Abstract

Anthropogenic activities influence the natural equilibrium of freshwater ecosystems resulting in negative ecological impacts. Differences in the infection variables of Lamproglena clariae in relation to variable water quality influenced by metal pollution were studied at six sites along the Vaal River, South Africa (March 2017 and October 2018). From each sampling site, in situ water quality parameters, water and sediment samples, and a minimum of 10 Clarias gariepinus were collected. Lamproglena clariae specimens collected from the gills of C. gariepinus were used to calculate the prevalence, mean intensity, and mean abundance of the parasite. Metal concentrations in water and sediment were analysed with inductively coupled plasma–optical emission spectrometry and inductively coupled plasma–mass spectrometry. Parasite intensity correlated negatively with some water quality parameters (conductivity, salinity, pH, total dissolved solids, and dissolved oxygen). Negative correlations were found between L. clariae (intensity and prevalence) and metal concentrations (Cu, Cr, Zn, Cd) in water. Parasite infections were influenced negatively at sites with high metal concentrations recorded in sediment and water and high levels of organic pollution. Sites that were found to be more polluted had lower mean intensity and mean abundance of L. clariae, indicating pollution affects the survival of this ectoparasite.

Published
2021

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