Clifford L W JonesRhodes University | RU · Department of Ichthyology and Fisheries Science
Clifford L W Jones
PhD
About
47
Publications
14,337
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394
Citations
Citations since 2016
Introduction
(1) Remediation effluent in algal ponds, constructed wetlands, hydroponics & crop irrigation with a focus on recovering wastewater and nutrients for reuse in aquaculture and small-scale crop farming; (2) Integrating algae into abalone feeds and assessing the biosecurity risk associated with this; (3) Developing technology to farm macro-algae with mussels or abalone in IMTA systems; (4) Mobilising aquaculture/fisheries MSc & PhD students among universities from eight African states.
Additional affiliations
January 2003 - present
Publications
Publications (47)
The potential of pine pollen (PP) to masculinize sexually undifferentiated Nile tilapia was evaluated by feeding graded levels of PP (0.08–3.20 g kg⁻¹ basal diet) to triplicate groups of three-day-old Nile tilapia for 28 days. Masculinization and associated differences in growth were compared to fish individuals fed the same basal diet with no PP (...
Control of prolific reproduction is vital for a profitable tilapia aquaculture enterprise. All‐male tilapia culture is a popular method used to control prolific breeding, because the male individuals grow faster than female and mixed‐sex populations. Presently, most farmers use 17α‐methyl testosterone (MT) to produce all‐male tilapia individuals, a...
A balanced combination of protein sources to partially replace fishmeal in the diets of cultured carnivorous fish can promote optimal fish health and production performance. In the present study, the growth, body condition and gut microbiota of juvenile dusky kob Argyrosomus japonicus fed fishmeal-substituted diets comprising different blends of an...
This study assessed the utility of high rate algal ponds (HRAP) as an alternative to conventional activated sludge (AS) for the secondary treatment of anaerobically digested brewery effluent. Both systems treated post-anaerobically digested brewery effluent to a standard suitable for reuse as bottle washing, boiler feed and aquaculture water. The H...
The use of a crop to remove nutrients from brewery effluent and the influence of pH on these removal rates was evaluated. Cabbage (Brassica oleracea) was grown in recirculating hydroponic systems fed with post-anaerobically digested brewery effluent (BE) either subject to pH adjustment (6.5–7.0) or unaltered pH (8.0–8.5). These were compared with c...
There is an opportunity to anaerobically digest the sludge or algal biomass generated from the activated sludge (AS) and high rate algal pond (HRAP) brewery effluent treatment processes to produce methane, allowing the recovery of the carbon into a valuable product, prior to its disposal. This study evaluated the use of HRAP and AS waste biomasses...
Brewery effluent (BE) can be used as a water and nutrient source for crop irrigation. It contains high levels of nitrogen and phosphorus, which are essential plant nutrients. However, the effluent at Ibhayi Brewery (SAB Ltd) has a high concentration of sodium, which is a constraint for its reuse in agriculture. The objectives here were to determine...
The disposal of waste biomass generated from biological wastewater treatment plants is a costly process and poses environmental threats to the receiving environment. This study aimed to determine the suitability of algae and waste activated sludge (WAS) produced from a brewery effluent treatment system as a fertiliser in agriculture. The change in...
Cabbage (Brassica oleracea), saltbush (Atriplex nummularia) and Japanese millet (Echinochloa esculenta) were grown in recirculating hydroponic systems to determine their capacity to remove sodium from brewery effluent (BE). Each treatment was irrigated with post-anaerobically digested effluent, where the pH was either adjusted to 6.5 or unadjusted....
Soya in formulated diets for abalone, Haliotis midae, can improve somatic growth. However, it may also influence gonad development, thereby limiting the potential benefit of including soya in feed. This is the first study to determine both the effect of dietary soya level on growth and reproduction of abalone and the role of crystalline isoflavones...
Reducing dependency on environmentally unsustainable formulated feeds, most of which include limited reserves of fishmeal as a protein source, is a priority for the aquaculture industry, particularly for intensive culture systems. One approach is to increase nitrogen reuse within the system by feeding nitrogen-rich aquaculture effluent to deposit f...
The ability to utilise carbohydrates is limited for many predatory marine fishes. Graded levels of dietary carbohydrate (4.1–24.6%) were formulated using pregelatinised maize starch, to determine optimal levels for dusky kob Argyrosomus japonicus, an emerging mariculture finfish for which pelleted feeds are being developed. Specific growth rate inc...
Previous research has shown that gut-bacterial populations in farmed abalone are shaped by ontogeny, their macroalgal diet substrates, bacteria present in the environment, and other environmental factors. It has been suggested that weaning postsettlement diatom-fed abalone onto artificial feed may alter the natural succession of bacterial establish...
Brewery effluent (BE) needs to be treated before it can be released into the environment, reused or used in down-stream activities. This study demonstrated that anaerobic digestion (AD) followed by treatment in an integrated tertiary effluent treatment system transformed BE into a suitable solution for crop irrigation. Brewery effluent can be used...
The effect of kelp Ecklonia maxima inclusion in formulated feeds on abalone growth and gut bacterial communities has not been previously investigated in South Africa. An eight-month on-farm growth trial was conducted with sub-adult Haliotis midae (~43 mm shell length) fed graded levels of kelp in formulated feeds. Kelp inclusion (0.44–3.54% of pell...
The treatment of organic wastes remains one of the key
sustainability challenges facing the growing global aquaculture industry.
Bioremediation systems based on coupled bioturbation–microbial processing
offer a promising route for waste management. We present, for the first time,
a combined biogeochemical–molecular analysis of the short-term perfor...
To determine dietary lysine requirement of dusky kob, Argyrosomus japonicus, six isonitrogenous and isoenergetic diets (431 g/kg crude protein, 141 g/kg lipid and 20 kJ/kg) were formulated with graded levels of crystalline L-lysine (18-42 g/kg of the dry diet). The protein source in the basal diet comprised fishmeal and soya, where a combination of...
Deposit-feeding invertebrates are proposed bioremediators in microbial-driven sediment-based aquaculture effluent treatment systems. We elucidate the role of the sediment reduction-oxidation (redox) regime in structuring benthic bacterial communities, having direct implications for bioremediation potential and deposit-feeder nutrition. The sea cucu...
Millions of mega-litres of nutrient-rich effluent are discharged daily with environmental implications and often at considerable financial cost to the primary water user. This research aimed to develop technology that adds value to this liability, by making the effluent available for downstream use in hydroponic crop production.
Brewery effluent su...
Effective and affordable treatment of waste solids is a key sustainability challenge
for the aquaculture industry. Here, we investigated the potential for a deposit-feeding sea cucumber,
Holothuria scabra, to provide a remediation service whilst concurrently yielding a high-value
secondary product in a land-based recirculating aquaculture system (R...
Preliminary research indicates that farmed abalone, Haliotis midae move away from the water surface during rainfall events. This may compromise farm production efficiency due to less contact time with feed that is placed on a feeder plate situated slightly below the surface of the water. The aim was to investigate the effect of simulated rainfall o...
The farming of abalone, Haliotis midae L., can be intensified in serial‐pass systems, but water re‐use increases the concentration of NH3 (free ammonia nitrogen, FAN) and reduces water pH. Changing the percentage dietary protein from 33% to 26% reduced the concentration of FAN (F42, 252 = 2.79; P 1, 12 = 1.09; P = 0.31) or length gain (F1, 12 = 1.0...
The sea cucumber Holothuria scabra, or sandfish, is a commercially valuable aquaculture species; however viable intensive tank-based aquaculture techniques have not yet been developed. This study aimed to assess the role of sand as a substrate and/or dietary component in the intensive tank culture of sandfish in recirculating aquaculture systems (R...
Abalone culture systems are characterised by high water exchange rates as abalone are sensitive to changes in water quality. To reduce the costs of pumping, serial reuse systems have been tested. As water pH can decline in these systems, this study determined the effect of raising pH through the addition of sodium hydroxide (NaOH−) on weight gain,...
South African abalone Haliotis midae farms utilise large volumes of seawater (c. 500–1 500 l s–1) and produce relatively dilute effluents that are potentially suitable for the integrated culture of other species. To test this hypothesis, a marine finfish, silver kob Argyrosomus inodorus, and a detritivorous polychaete, bloodworm Arenicola loveni lo...
Ammonia is a toxic metabolite of protein catabolism that can limit growth and health of aquatic animals. This study investigated the effect of dietary protein level on the average total ammonia (TAN) and free ammonia nitrogen (FAN) concentrations in a serial-use raceway used to farm South African abalone, Haliotis midae Linneaus. Three isoenergetic...
Formulated abalone feeds used by the culture industry are believed to be unsuitable for use at elevated water temperatures (>20 °C). The aim of this study was to develop a feed that could safely be fed to abalone cultured at elevated water temperatures by optimizing dietary protein/energy levels. Abalone (54.90 ± 0.08 mm; 28.99 ± 0.16 g) were cultu...
The aim was to test whether abalone growth and feed conversion ratio (FCR) could be maintained at increased dietary lipid levels if the protein:energy ratio (P:E) was kept constant. Two size classes (25–30 and 65–70 mm) of Haliotis midae were fed diets with graded levels of lipid (4–16%), in which total protein varied (34–39%) to maintain a constan...
To quantify the effects of serial-use of water on abalone growth and feed conversion, this study describes water quality in a serial-use raceway with seven passes. A flow index of 7.2–9.0 L h−1 kg−1 was estimated as the minimum value at which to grow 60–70 mm Haliotis midae, as weight gain (analysis of variance; F6, 14=13.9, P<0.0001) and feed conv...
The effect of dietary protein to energy ratio (P:E) on the growth of dusky kob Argyrosomus japoni-cus was investigated as a first step towards formulating a practical diet for this potential mariculture species in South Africa. The effects of dietary protein and lipid on growth, feed conversion ratio (FCR) and nitrogenous waste production were dete...
Survival of post-settlement abalone when 'weaning' them from diatoms onto macroalgae/artificial feed remains unpredictable for farmers. It is hypothesised that spirulina algae, which are high in protein, may be a suitable feed ingredient for weaning abalone. Over a period of 27 days, the growth and survival of juvenile (4–6 mm shell length) Halioti...
Hecht, T. and Jones, C.L.W. 2009. Use of wild fish and other aquatic organisms as feed in aquaculture – a review of practices and implications in Africa and the Near East.
The relative contribution that solid waste or ‘sludge’, which accumulates at the bottom of abalone (Haliotis midae L.) tanks, makes to dissolved ammonia has not been established. Sludge was allowed to accumulate in 10 fully stocked abalone tanks, fed a formulated feed (Abfeed®; Marifeed, South Africa), for 24 days. Sludge was subsequently siphoned...
Newborn (i.e. neonate) swordtail Xiphophorus helleri Heckel attempted to escape cannibalization attempts in a downward direction more frequently than in any other direction. The downward escape response is likely to be anti-predator behaviour. In addition, neonates were often able to escape cannibalization at the time of birth, despite no previous...
The post-parturition behavioural patterns of adult Xiphophorus helleri (Heckel) were described and quantified by recording their duration and/or frequency in glass tanks. All births occurred in the dark. Female behaviour might increase the chance of newborn juvenile survival: at the top of the tank, where juveniles are more vulnerable to predation,...
— Filial cannibalism has been identified as a constraint to the intensive production of swordtails Xiphophorus helleri. The objective of this study was to quantify the effect of refuge availability and quantity, broodstock population density, and adult sex-ratio on the rate of cannibalism under culture conditions. The availability of shelter had a...
To understand behaviour during filial cannibalism in swordtails (Xiphophorus helleri), the parturition behaviour of eight individually kept females was recorded on videotape. Three levels of female activity (low, medium and high) were quantified by measuring the duration of each. Four additional behavioural events (non-cannibalistic feeding, as wel...
After photography, keeping ornamental fish is the second biggest hobby in the US. It is estimated that the global trade is worth US$1.6 billion annually. Due to the environmental lobby against the harvest of wild fish and the increasing problems of disease and water quality experienced by ornamental fish farmers in Asia, an opportunity exists for S...
Thesis (Ph. D. (Ichthyology))--Rhodes University, 2003.
Projects
Projects (3)
Contribute to improved seed for increased Tilapia productivity and production
This program is about the sustainable utilisation of aquatic resources, through the integration of multitrophic aquaculture and other biological systems. We aim to recover nutrients and water from industrial effluents (e.g. aquaculture, breweries and other food processing industries) so that they can be reused by the primary water user or in downstream activities. We are working with various biological systems that includes integrating various combinations of different systems such as aerobic and anaerobic digesters, high rate algal ponding systems, constructed wetlands, hydroponic vegetable production systems, aquaponics and conventional agriculture and recirculating aquaculture systems systems.
