M.Sc. (Zoology) / The Limpopo Province covers an area of 12.46 million hectares and these accounts for 10.2 per cent of the total land area of the Republic of South Africa. The province is endowed with abundant agricultural resources and it is one of the country’s prime agricultural regions noted for the production of fruits and vegetables, cereals, tea, and sugar. A key feature of the agricultural industry of Limpopo Province is its dualism. There are two distinct types of agricultural production systems. The large scale commercial farming system occupies approximately 70% of the total land area. The smallholder farms are located mostly in the former homeland areas and they cover approximately 30% of the provincial land surface area. The town of Thohoyandou, with its surrounding villages, is the area of greatest human concentration in the Luvuvhu Catchment and subsistence farming is about a third of the total agricultural component. It is important to study the effects of agricultural inputs (e.g. fertilizers and sediment loads) on aquatic ecosystems in order to fully understand the processes involved of these stresses on aquatic ecosystems. Knowledge of these impacts toward the environment and human health is often limited due to lack of capacity building, especially among small scale farmers. Ten bio-monitoring sites were studied on five systems in the Vhembe district. The sites were sampled during the low flow period of November 2011 and the high flow period of April 2012. Sampling sites were selected to present conditions in the Mutale, Mutshindudi and Tshinane Rivers upstream and downstream of the potential influence of small scale agricultural activities...

M.Sc. / There are 39 known species of Lamproglena to date. A review of all species including the species name, the author, as well as an accompanying sketch and information regarding the distribution, pathology and host preference is given. Lamproglena clariae is a copepod gill parasite found on Clarias gariepinus. It has been observed that they cause extensive gill tissue proliferation, which may interfere with respiration. It is uncertain on which tissue type Lamproglena feeds, as red blood is never apparent in the gut of Lamproglena monodi, whereas in the cases of both L. clariae and L. barbicola they undoubtedly feed on blood, proven by the frequently blood-filled gut. Even thought the mouthparts are not fully understood as yet, it is deduced that feeding involves only the maxillae and maxillipedes. Many poecilostomes lacks mandibles. Also, in the lernaeids the mandible is appendage is the smallest and from the 39 known Lamproglena species, the mandibles are described in only eight species. This study examines the digestive tract and the structure of the mouthparts using both light and scanning electron microscopy and tracts the nerves to establish if L. clariae does possess mandibles. Specimens were collected from Clarias gariepinus in the Vaal Dam after the fish were euthanised and the gills removed. The samples were fixed in an aceto formaldehyde alcohol solution and preserved in 70% ethanol prior to dehydration and embedding in resin. Serial section were made at 5 pm and stained with a trichrome stain. A schematic as well as graphic reconstruction of the digestive system is presented. The digestive system consist of three predominant parts, the fore, mid and hindguts. The foregut has a cuticularised epithelium. The oesophagus has a muscle layer iv which stretched and contracts in order to aid feeding and it extends into the midgut via a funnel-like structure. There are four designated zones within the midgut. The hindgut is a simple, cuticle lined tube. Cell structures are discussed. The bilobed protocerebrum in L. clariae is present. The deutocerebrum innervates the antennules. The tritocerebrum consist of two lobed parts and innervates the antennules. The ventral nerve cord is situated posterior to the cephalon. It protrudes dorsally, from where the posterior commissures innervates. The anterior commissures innervates closer to the tritocerebrum. The nerves leading to the mandibles are innervated from the anterior commissure. The more posteriorly located commissure innervates the nerve to the seta located between the antennae and the maxillae. Both the nerves to the maxillae and the endopodite to the maxillae are innervated from this commissure. Mandibles were left out of previous species descriptions of L. clariae. Other Lamproglena species descriptions, showing the mandibles, revealed slender looking mandibles located in close proximity to the mouth opening. This is contrary to the stout mandibles of L. clariae. Future research topics are highlighted and discussed

M.Sc. Zoology / Only a few species of the family Diplozoidae have previously been described from Africa, from various Labeo and Barbus species. An investigation was undertaken respectively in the Vaal Dam and Vaal River Barrage in the Vaal River system, South Africa to determine aspects of the morphology, taxonomy and ecology of specimens of this family collected from the gills of Barbus aeneus. Various fish species, namely B. aeneus, Barbus kimberleyensis, Labeo capensis, Labeo umbratus, Cyprinus carpio, Clarias gariepinus and Micropterus salmoides, were collected with the aid of gill nets. The fish were killed and the length, weight and sex determined. The gills were removed from the left and right gill chambers, placed in separate, marked petri dishes and covered with water from the dam. Gills (from first to fourth pair) were examined with the aid of a dissection microscope. The position of attachment and the region on the gill namely dorsal, median or ventral, was noted. Parasites were removed, fixed between a cover slip and glass slide in steaming hot aceto-formaldehyde alcohol and preserved in 70 % ethanol. A morphological study was undertaken. Results of a Scanning Electron Microscopy study illustrated the following external characteristics namely a round opisthohaptor with four pairs of clamps, while study of whole mounts revealed larval hooks, a round-ended intestine and eggs without filaments. Graphic reconstruction of serial sections of the reproductive system of parasites embedded in resin revealed that the vas deferens of one individual opens into the common vitelline duct of the other. Parasites were identified as belonging to the genus Paradiplozoon. The morphological characteristics, namely the round opisthohaptor, intestine with rounded ending, egg without filament and morphological measurements, of various structures (for example, total body length) that differ from other species of this genus, led to the establishment of a new species, that is, P. alwinii.

Powdered laundry detergents are consumed in high volumes worldwide. Post use, they are directed toward water resources via wastewater treatment works or, as is the situation in many rural areas of South Africa, they enter the environment directly as a result of laundry washing activity undertaken alongside surface waters. Within wastewater treatment works, the main ingredient in powdered laundry detergents, the narcotic toxin linear alkylbenzene sulfonate (LAS), is mostly removed, rendering the waste stream a negligible risk to the aquatic biota of receiving waters. In contrast, the biological and ecological impacts of direct LAS input to the aquatic environment, as a consequence of near-stream laundry washing, are yet to be fully realised. Consequently, this thesis posed two research questions: 1) 'What are the LAS concentrations in a small rural South African river'? and 2) 'Is the in-stream biological community negatively affected at these concentrations?' The chosen study area, the community of Balfour in the Eastern Cape Province, is like many rural areas of South Africa where inadequate provision of piped water to homesteads necessitates laundry washing alongside the nearby Balfour River. The first research question was addressed in two ways: by predicting LAS concentrations in Balfour River water by assessing detergent consumption and laundry washing behaviour of residents living alongside the river; and measuring actual in- stream LAS concentrations on different days of the week and during different seasons. Results indicated that LAS concentrations were highly variable temporally and spatially. High peak concentrations of LAS occurred infrequently and were limited to the immediate vicinity of near-stream laundry washing activity with the highest measured concentration being 342 μg.L ⁻¹ and the average 21 μg.L ⁻¹ over the sampling period. The second research question was addressed by integrating the chemical evidence, determined from the first research question, with the biological evidence of stress responses measured in macroinvertebrates collected downstream of near-stream laundry washing activity on the Balfour River. Predicted and measured LAS exposure concentrations from the Balfour River were compared to a water quality guideline for LAS (304 μg.L ⁻¹), specifically derived in this thesis. Biological stress responses were measured at different levels of organisation: two sub-cellular responses (lipid peroxidation and cholinesterase activity); three measures of macroinvertebrate tolerance to water quality impairment; five measures of community composition; three measures of community richness; and a surrogate measure of ecosystem function (functional feeding groups). Weight-of-evidence methodology was utilised to assess, integrate and interpret the chemical and biological evidence, and at its conclusion, determined no effect on the in-stream biological community of the Balfour River downstream of laundry washing activity.