SEGH Articles

Aquaculture: Pathway to food security in Kenya

16 July 2018
Dr Andrew Marriott (Centre for Environmental Geochemistry, BGS) and Prof Odipo Osano (University of Eldoret) tell us about their recent voyage on Lake Victoria as part of an exciting project looking into aquaculture and food security in Kenya

In late December we were successful in obtaining funding through a Newton International Links bid with the British Council. This project aims to investigate problems of food insecurity and the implications of anthropogenic pollutants for food safety, the impact on the health and nutritional quality of aquaculture farmed fish, and the potential of fisheries aquaculture to boost food security and sustainability in Lake Victoria, Kenya. Having been successful in the bid, I was looking forward to working with fish again and using the knowledge gained from my years as a Marine Biologist at Bangor University. The project brings together my experiences working on fisheries aquaculture and from knowledge gained working within the Inorganic Geochemistry team in exploring micronutrients, pollution pathways and the associated problems of food security and nutrition in Aquaculture fish. This collaborative project involves the Inorganic Geochemistry team (IG) at BGS with our old friend Prof Odipo Osano from the School of Environmental Sciences at the University of Eldoret (UoE) with whom we have worked closely for over 2 years. This grant funded project also collaborates with Dr Tracey Coffey and Dr Sharon Egan from the School of Veterinary Science (University of Nottingham), and the experienced research team led by Dr Christopher Mulanda Aura at the Kenyan Marine Fisheries Research Institution (KMFRI) based in Kisumu, Kenya.  

 stakeholder discussions

Stakeholder discussions at KMFRI headquarters between the project team and aquaculture producers

 

Stakeholder discussions were hosted at KMFRI headquarters between the project team and aquaculture producers explaining how the project will address questions related to pollution pathways (Food Safety-human and ecological health), through studying problems associated with sedimentation rates in water from erosion, or changes in land-use and water quality, as well as the effects of toxic metals as drivers of antimicrobial resistance (AMR). Expanding on this, and linking to other BGS activities (http://britgeopeople.blogspot.co.uk/search?q=watts+kenya) and interests of the Ministry for Agriculture, Livestock and Fisheries, data will be generated to understand the potential for aquaculture to address ‘hidden hunger’ (deficiencies of essential micronutrients for human and animal health). Questions came quick and fast from those attending, with the fisheries-licence holders and the cage-culture representative being extremely interested in what we were intending to do. However, transparency and open talks through public engagements such as this alleviated any concerns they may have had, and their subsequent assistance in locating sites and communicating with local cage managers proved invaluable.

 

 Team and Stakeholders

The team and the stakeholders

 

Attention turned to the fieldwork, which was based on KMFRIs main research vessel R.V. Uvumbuzi (Discovery) based on the Winam Gulf in Kisumu. This allowed us direct access and quicker travel between sampling sites within the Winam Gulf to view and sample the intensity of aquaculture cages along the shores of Lake Victoria (Kenyan side).

 aquaculture cages

Aquaculture cages along the shores of Lake Victoria (Kenyan side)

 

Cage sizes ranged from a few meters (2x2) to the medium 6x4 meters up to the larger 20x20 meters and housing fish from a few thousand to over 20,000 for the larger 20x20 m cages. Most of the fish (Tilapia) are sold at local markets after growing for 6 months (plate size) or in the case of the larger cages (>10m) sold to merchants after growing for up to 8 months for re-sale as fillets. Involving the representative for the aquaculture operators in the stakeholder meeting hosted by KMFRI, provided invaluable as they were able to help in the design of sampling locations, and assist in gaining the trust and co-operation of the managers of each cage site. With the local manager informed in advance of our visit, sampling fish from both within the cages, and from the wild went smoothly and efficiently. Sampling involved all the experience of the project team. Water parameters such as pH, temperature, conductivity and dissolved oxygen were measured either directly from the vessel or from the small canoe brought along for closer inshore work.

 KMFRI Team

The KMFRI team on the canoe

 

After measurements of the water were obtained, the process of collecting water samples from just below the surface (approx. 1 m), and from depth, was completed using a niskin water sampler system. The collected water was then filtered using 0.45 um filters. Water samples were observed to be slightly discoloured around the shores of Winam Gulf which isa possible indication of high sedimentation rates from land erosion. This colouration cleared when we moved further out to the main channel at Rusinga in the Lake. Finally the collection of a sediment sample was taken using the Van Veen Grab Sampler for both biogeochemical analysis in the UK, and benthic microbiological analysis by the team at KMFRI.

 Van Veen Grab Sampler

The Van Veen Grab Sampler

 

Most of the sediment collected near the Winam Gulf area near the shore had a strong H2S aroma indicating possible eutrophic conditions in that area. Fish were sampled both from the cages and also where possible from the wild, using fish locally caught by the local fishermen.

 Sampled caged Talapia

Sampled caged Tilapia fish

 

Fish were processed on board the R.V. Uvumbuzi, and measurements were taken to record the biological data. Finally sub-samples of muscle tissue were taken and vacuum sealed for subsequent analysis of trace metals, and tissue for DNA extraction and Anti-Microbial Resistance studies.

 

 Marriott fish sampling

Andy Marriott sub-sampling muscle tissue

 

After 3 long days working on the Lake, the water, sediment and fish tissue samples were finally off-loaded from the RV Uvumbuzi and transported to the School of Environmental Sciences (University of Eldoret). Here sediment samples were partially dried and excess water removed for transportation back to the Inorganic Geochemistry labs in the UK for ICP- MS analysis. Similarly, fish tissue will be measured for trace metals and DNA and AMR analyses at the School of Veterinary Science (University of Nottingham).

Water, fish tissue and sediment geochemistry data in addition to ongoing studies by UoE and KMFRI will help to identify possible pollution pathways from anthropogenic activities, and sediment loading from erosion or changes in land-use for design of further investigation in the Winam Gulf and shores of Lake Victoria. Bio-geochemistry data from this and subsequent investigations will be invaluable to KMFRI in advising on the future siting of aquaculture cages to ensure food safety for human and ecological health. Given that ‘wild’ fish catches are unsustainable in Lake Victoria, aquaculture/farming of fish through sustainable methods is an important approach to food sufficiency and in addressing ‘hidden hunger’ along the shoreline of Lake Victoria and further inland.

Acknowledgements:

I would like to thank the Newton International Links programme and the British Council for funding the project. I would also like to thank the BGS-ODA programme and Center for Environmental Geochemistry for financial support and technical expertise.

Keep up to date

SEGH Events

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Distribution pattern and health risk assessment of polycyclic aromatic hydrocarbons in the water and sediment of Algoa Bay, South Africa 2018-11-11

    Abstract

    Polycyclic aromatic hydrocarbons are amongst the pollutants of major concern in the terrestrial and aquatic habitats. They are mostly characterised by carcinogenic and non-carcinogenic effects. Distribution and potential health risks of sixteen priority PAHs in the water and sediment samples collected between December 2015 and June 2016 from Algoa Bay, South Africa, were evaluated. Water and sediment samples collected were extracted with liquid–liquid and soxhlet extraction methods, respectively, and then cleaned up using glass column loaded with silica gel. Final concentrations of the target PAHs were determined by gas chromatography interfaced with flame ionization detector. Results indicated that individual PAH concentrations in surface water, bottom water and sediment samples ranged from not detected (ND) to 24.66 µg/L, ND to 22.81 µg/L and ND to 5.23 mg/kg correspondingly. Total PAHs concentrations varied as 12.78–78.94 µg/L, 1.20–90.51 µg/L and 1.17–10.47 mg/kg in the three environmental matrices in that order. The non-carcinogenic risk was generally below 1, whereas risk indices (dermal contact) were above the acceptable limit of 1 × 10−4 in the water column, suggesting possible carcinogenic effects to humans, with adults being the most vulnerable. Similarly, highest contributions to TEQs and MEQs in the sediments were made by benzo(a)pyrene and dibenzo(a,h)anthracene, the two most toxic congeners, signifying the possibility of carcinogenicity and mutagenicity in humans. Diagnostic ratios of PAHs reflect a prevailing pyrogenic input all through. The pollution was albeit moderate, yet regular check is recommended to ensure safe and healthy environment for human and aquatic lives.

  • Potential exposure to metals and health risks of metal intake from Tieguanyin tea production in Anxi, China 2018-11-10

    Abstract

    The metal content of Tieguanyin tea from Anxi, Southeast China, was studied. Leaching experiments were designed based on the local tea-drinking habits, and tea infusions were prepared using three types of water and two methods of soaking tea. Twelve metals (Cd, As, Cr, Pb, Se, Sb, Ag, Tl, Cu, Zn, Be, and Ba) were measured by inductively coupled plasma mass spectrometry (ICP-MS), and a human health risk assessment was performed. The results showed that the quality of water used for steeping tea has a direct effect on the leaching concentrations of metals in the tea infusion and this effect can be reduced by using pure water or commercially available drinking water. Further, the two tea-soaking methods used by local residents can reduce the metal intake. The health risk assessment determined that the carcinogenic risk values of Cr, As, and Pb (Cr > Pb > As) were within an acceptable range (10−7–10−4); therefore, the concentrations of these metals in tea infusions do not pose substantial carcinogenic risk to tea drinkers. The results also indicate that the high concentrations of Tl in the tea infusions pose a substantial noncarcinogenic risk and may result from the dissolution characteristics of Tl and the water quality.

  • Health risk assessment and source apportionment of polycyclic aromatic hydrocarbons associated with PM 10 and road deposited dust in Ahvaz metropolis of Iran 2018-11-09

    Abstract

    The objective of this study was to compare the characteristics of polycyclic aromatic hydrocarbons (PAHs) in PM10 and road dust samples, as well as to identify and quantify the contributions of each source profile using the positive matrix factorization (PMF) receptor model. Health risk assessment was carried out using toxic equivalency factors and incremental lifetime cancer risk (ILCR), which quantitatively estimate the exposure risk for age-specific groups. PM10 samples were collected on PTFE filters in the metropolitan area of Ahvaz. Road dust samples were also collected from all over the urban areas with different land uses. Total PAH concentrations in PM10 and road dust samples were 0.5–25.5 ng/m3 and 49.3–16,645 µg/kg, respectively. Pyrene was the highest PAH in the PM10 profile, whereas fluoranthene became the highest PAH in the road dust. Abundance of benzo[ghi]perylene at PM10 and road dust samples suggested a source indicator for traffic emissions. The results demonstrate that in 36.5% of samples, PM10 concentrations exceed the maximum concentration level recommended by EPA. A multiple linear regression model was used to estimate the influence of meteorological parameters (temperature, wind speed, and relative humidity) on buildup of PAHs. All of PAH species show higher concentrations during the cold and typical days rather than the dust event days and warm periods. PMF analysis showed that vehicular emissions (50.6%) and industrial activities (especially steel industries) (30.4%) were first two sources of PAHs bounded with PM10, followed by diesel emissions (11.6%) and air–soil exchange (7.4%). For road dust samples, three common sources were also identified: vehicular traffic (48%), industrial activities (42.3%), and petrogenic sources (9.7%), in line with that of diagnostic molecular ratios results. According to the results of health risk assessment model, the ILCR of exposure to PAHs associated with PM10 and road-deposited dust was higher than the guidelines of USEPA, indicating high carcinogenic risk.