Environmental and natural resources management in the South

published in: 2021 - 2019 - 2018 - 2017 - 2016


Isolation of quercetin-3-O-sulfate from guava leaves

Nguyen P-D, Hérent M-F, Le T-B, Bui T-B-H, Bui T-B-H, Do T-T-H, Nguyen T-P, Scippo M-L, Kestemont P, Quetin-Leclercq J. 2023. Isolation of quercetin-3-O-sulfate and quantification of major compounds from Psidium guajava L. from Vietnam. Journal of Food Composition and Analysis 115:104928. DOI: 10.1016/j.jfca.2022.104928.

In Vietnam, Guava, Psidium guajava, has a high economic value, mostly for fresh fruit, but also for products from guava leaves for tea or leave extracts. P. guajava leaves show a wide range of pharmacological activities such as anti-diabetes, anti-oxidant, anti-microbial, anti-cancer, anti-diarrhea, and anti-inflammatory. This study identifies the major phenolic compound of a crude ethanol extract of P. guajava leaves and develops methods for quantification of phenolic and triterpenic components by HPLC-PDA-HRMS. The major phenolic compound was determined as quercetin-3-O-sulfate which is isolated and quantified for the first time in P. guajava. Validated HPLC-DAD quantification methods were developed to quantify the major triterpenic and phenolic derivatives of this extract and found to be accurate in the concentration range of 2–50 μg/mL for phenolic, and 5–100 μg/mL for triterpenic compounds. Four crude ethanol extracts of guava leaves collected at different periods of the year were analyzed using the developed methods and were found to be richer in triterpenic than phenolic derivatives. It is notable that weather or rainfall influenced the richness in bioactive compounds in guava leaves.

Co-management approach & mangrove conservation

Gnansounou SC, Sagoe AA, Mattah PAD, Salako KV, Aheto DW, Glèlè Kakaï R. 2022. The co-management approach has positive impacts on mangrove conservation: evidence from the mono transboundary biosphere reserve (Togo-Benin), West Africa. Wetlands Ecology and Management. DOI: 10.1007/s11273-022-09894-0.

Literature on conservation science has documented the increasing use of the co-management approach to effectively conserve natural resources. Although some studies found the co-management approach as highly effective, others also reported some uncertainties associated with the use of this conservation approach. Using the mono transboundary biosphere reserve (MTBR) as a case study, this work assessed the effectiveness of the co-management approach for mangrove conservation in West Africa. Data was collected in two protected sites of the reserve (one in Togo and the other in Benin). Results showed that the co-management approach has lowered anthropogenic stressors to mangroves in the reserve. Under the co-management approach, all the mangroves located in the Benin side of the reserve are identified as under low risk whereas 42% of the mangrove cover are considered under low risk and 58% under medium risk in Togo. Local perception also portrayed the reduction of mangrove degradation in the study sites following the adoption of the co-management approach in the two countries. However, there are some challenges such as the financial support provision and regular community engagement which need to be thoroughly researched and addressed to achieve the sustainability of the positive impacts of the co-management in the MTBR.

Saline-tolerant striped catfish

Dao Minh H, Duong Thuy Y, Pham Thanh L, Bui Minh T, Vo Nam S, Do Thi Thanh H, Bui Thi Bich H, Nguyen Thi Ngoc T, Dang Quang H, Kestemont P, Nguyen Thanh P, Farnir F. 2022. Selective breeding of saline-tolerant striped catfish (Pangasianodon hypophthalmus) for sustainable catfish farming in climate vulnerable Mekong Delta, Vietnam. Aquaculture Reports 25:101263. DOI: 10.1016/j.aqrep.2022.101263.

Striped catfish (Pangasianodon hypophthalmus), a freshwater species cultured mainly in the Mekong Delta region in Southern Vietnam, is facing a significant challenge due to salinity intrusion as a result of climatic changes. Given these evolving environmental conditions, selecting new strains with a higher salinity tolerance could make production of striped catfish economically feasible in brackish environments. In this study, a selection program aimed at developing a striped catfish strain able to survive and grow fast in a saline environment. The results from this study demonstrate that a selective breeding for increased saline tolerance of striped catfish can already be effective after one generation of selection under saline environment. The improved salinity tolerance of striped catfish developed in the present study is of practical significance in the context of Mekong Delta aquaculture, where the striped catfish breeding activities are projected to be greatly affected by salinity intrusion due to climate change. The selected animals originating from this study also constitute a valuable genetic resource for subsequent studies targeting a better understanding of the physiology and genomic characteristics of this improved strain as well as the mechanisms of osmoregulatory adaptation to salinity in striped catfish.

Salinity affects intestinal microbiota & gene expression

Hieu DQ, Hang BTB, Lokesh J, Garigliany M-M, Huong DTT, Yen DT, Liem PT, Tam BM, Hai DM, Son VN, Phuong NT, Farnir F, Kestemont P. 2022. Salinity significantly affects intestinal microbiota and gene expression in striped catfish juveniles. Applied Microbiology and Biotechnology. DOI: 10.1007/s00253-022-11895-1.

Inland aquaculture with striped catfish (Pangasianodon hypophthalmus) is important in Southeast Asia, particularly in Mekong Delta in Vietnam. Currently, it faces climatic challenges, especially extensive salinity intrusion. Saline water is observed up to 40 km far from the river mouth and increased salinity levels in striped catfish farms rise up to 9 psu (practical salinity units). In teleost fish, the gut is important to regulate water balance in marine environments but less so in freshwater fish. Here, juvenile striped catfish, have been chronically exposed to a salinity gradient from freshwater to 20 psu and were sampled at the beginning (D20) and the end (D34) of exposure. Results revealed that the intestinal microbial profile of striped catfish reared in freshwater conditions were dominated by the phyla Bacteroidetes, Firmicutes, Proteobacteria, and Verrucomicrobia. Alpha diversity decreased as salinity increased. Furthermore, the beta diversity between groups was significantly different. It is likely that the fish intestine contributed to osmoregulation by modifying the expression of osmoregulatory genes. In conclusion, the fish intestinal microbiota was significantly disrupted in salinities higher than 10 psu and these effects were proportional to the exposure time. The modifications of intestinal gene expression related to ion exchange and stressful responses may help the fish to adapt hyperosmotic environment.


Contamination of Water, Sediment and Fish

Douny C, Zoumenou YMBG, Aïna M, Toko II, Igout A, Guedegba L, Chabi SK, Kestemont P, Scippo M-L. 2021. Contamination of Water, Sediment and Fish with Residues of Pesticides Used in Cotton Production in Northern Benin. Archives of Environmental Contamination and Toxicology. DOI: 10.1007/s00244-021-00888-2. shareable link

In Northern Benin, insecticides are used for cotton production. These insecticides can be easily transferred to water ponds close to cotton fields. To monitor insecticides levels in water, sediments and fish samples from water ponds, a GC–MS analytical method was developed to detect residues of endosulfan, DDT and its parent compounds, isomers of HCH, pyrethroids and chlorpyrifos. In addition, the influence of storage conditions of water sample on pesticides determination performance has been studied. Concentrations of insecticide residues in sediment for all water ponds ranged from non-detected to 101 µg/kg and from non-detected to 36 µg/kg in fish. Preliminary risk assessment for consumers of the North of Benin showed that the Estimated Daily Intakes were lower than the Acceptable Daily Intakes and Acute Reference Doses for all consumers. However, as one fish can be contaminated by five pesticide residues at the same time, it is not possible to exclude a risk for the consumer due to his exposure to mixtures of pesticides.

Clay-based refractory materials in Tunisia

Grine O, Moussi B, Hajjaji W, Pilate P, Yans J, Jamoussi F. 2021. Low-cost northern Tunisian kaolinitic clay-based refractory materials and effect of a rich alumina clay addition. Arabian Journal of Geosciences 14:1595. DOI: 10.1007/s12517-021-08099-8. shareable link

The addition of various quantities of raw materials could be used in order to improve the physical and pyroscopic performances of silica-alumina refractories manufacturing. This work deals with the valorisation of the Sidi Bader (area of Tabarka, North West Tunisia) kaolinitic clay in refractory silica alumina bricks. The chemical and mineralogical composition of the investigated raw materials shows alumina content between 20 and 35% and silica content less than 65%, while the mineralogical composition consists mainly of kaolinite associated with illite, quartz, and anatase. Commercial alumina-rich clay (AS) is added to the Sidi Bader clay. The characterization and optimization results of the chamotte grog provide a less dense and more porous chamotte, but mineralogically stable by sintering the Sidi Bader clay for 6 h at 1500 °C. The obtained results are highly encouraging, but further investigation is necessary to refine this potential valorisation. Adding more than 20% of alumina-rich clay will possibly yield better results.


Numidian clay for ceramic tiles

Moussi B, Hajjaji W, Hachani M, Hatira N, Labrincha JA, Yans J, Jamoussi F. 2020. Numidian clay deposits as raw material for ceramics tile manufacturing. Journal of African Earth Sciences 164:103775. DOI: 10.1016/j.jafrearsci.2020.103775.

Tunisia has a growing industry of ceramic tiles. Several clays collected in the Numidian Flysch Formation (Upper Oligocene) at Tabarka, and Sejnane (Northern part of Tunisia) were tested for their potential use in ceramic manufacturing to provide a database that could be used by investors. The mineralogy composition of raw clays is dominated by kaolinite and illite and shows relatively high quartz content for the two sites of Tabarka and Sejnane. Chemical analyses highlight a significant richness in SiO2 which can be explained by the presence of clays and silica sand. Technological tests confirm the aptitude of these clays to be used in the manufacture of ceramic tiles on an industrial scale.

Fish production in Benin

Pèlèbè ROE, Imorou Toko I, Ouattara IN, Attakpa EY, Montchowui EH, Kestemont P. 2019. Fish production in cages and pens in the northern Benin water reservoirs. Livestock Research for Rural Development 31. http://www.lrrd.org/lrrd31/9/peleb31148.html

This study aims at assessing the production of Clarias gariepinus and Oreochromis niloticus reared for 120 days in cages and pens installed in the Batran water reservoir in the cotton basin and Songhaï water reservoir outside the cotton basin in northern Benin. For C. gariepinus, the final biomass and the production values are significantly higher in Batran-caged fish while the lowest values are obtained with the same infrastructure in Songhaï. Differences are significant between the two infrastructures only in Batran. With regard to O. niloticus, values obtained for these two parameters are about twice as high in Songhaï compared to Batran in both cages and pens. They are similar between the two infrastructures in each water reservoir. However, cages that do not promote fish contact with aquatic sediment would be more appropriate to avoid the health risks associated with agricultural pesticides in the water reservoir located at the cotton basin.

Deadly effect of insecticides on fish

Guedegba NL, Toko II, Agbohessi PT, Zoumenou B, Douny C, Mandiki SNM, Schiffers B, Scippo M-L, Kestemont P. 2019. Comparative acute toxicity of two phytosanitary molecules, lambda-cyhalothrin and acetamiprid, on Nile Tilapia (Oreochromis Niloticus) juveniles. Journal of Environmental Science and Health, Part B 54:580–589. DOI: 10.1080/03601234.2019.1616986.

This study compares the toxicity of two active ingredients for fish, a pyrethroid and a neonicotinoid, that are components of a commercial insecticide (Acer 35 EC) used in cotton crop in many West African countries. For 96 hours, the juveniles of Nile Tilapia (Oreochromis niloticus) were exposed to increasing concentrations of active ingredients or a mixture similar to Acer 35 EC. During the experiments, the behavioural responses (loss of balance, colour change, hyperactivity, etc.) that usually precede death were observed in the exposed fish. Fish mortality and lethal concentrations of each chemical were determined. All insecticides had profound impacts on Nile tilapia behaviour which confirm the neurotoxicity of each single active compound as well as of their mixture.

Reproductive biology of fish

Osombause JS, Mandiki SNM, Ulyel J-P, Micha J-C, Kestemont P. 2019. Ovarian activity and plasma sex steroid levels of Distichodus antonii in relation to environmental conditions in the upper basin of the Congo River. African Journal of Aquatic Science 0:1–10. DOI: 10.2989/16085914.2018.1555511.

 Distichodus antonii is an endemic fish species of the Congo River basin. Its wild populations are threatened due to overfishing. Understanding its reproductive biology helps in conservation and management efforts for the species. Ovarian activity and levels of steroid profiles in wild populations were investigated with respect to temperature and rainfall. These were synchronised in two annual reproductive seasons that correspond to the long (September and October) and short (May) rainy season.

Pesticides & Mekong aquaculture

Nguyen QT, Douny C, Tran MP, Brose F, Nguyen PT, Huong DTT, Kestemont P, Scippo M-L. 2019. Screening of quinalphos, trifluralin and dichlorvos residues in fresh water of aquaculture systems in Mekong Delta, Vietnam. Aquaculture Research 50:247–255. DOI: 10.1111/are.13890.

Pesticides are often used in rice farms in Vietnam, which risk to impact on integrated and alternative productions (rice in combination with shrimp or fish). This study developed and validated a method using gas chromatography & mass spectrometry to determine pesticide residues in water samples. One pesticide could be detected in rice field systems. Its concentration could be high in fish. The other two pesticides tested are banned and could not be found in the samples.

Insecticide & Cotton in Benin

Zoumenou BGYM, Aïna MP, Imorou Toko I, Igout A, Douny C, Brose F, Schiffers B, Gouda I, Chabi Sika K, Kestemont P, Scippo M-L. 2018. Occurrence of Acetamiprid Residues in Water Reservoirs in the Cotton Basin of Northern Benin. Bulletin of Environmental Contamination and Toxicology 102:7–12. DOI: 10.1007/s00128-018-2476-4.

Insecticides, such as Acetamiprid, a neonicotinoid, are frequently used in Benin to protect cotton crops. It is therefore expected that water reservoirs close to cotton fields are contaminated with acetamiprid residues via drift, runoff, leaching or drainage. The authors developed an Ultra performance liquid chromatography (UPLC)–UV method to determine acetamiprid residues in water samples. The levels found do not represent a risk for human consumption of this water nor for aquatic species. However, acetamiprid is often used in combination with other pesticides which could be more harmful.


Euphorbia as natural antioxidant

Bach LT, Dung LT, Tuan NT, Phuong NT, Kestemont P, Quetin-Leclercq J, Hue BTB. 2018. Antioxidant activity against hydrogen peroxide-induced cytotoxicity of Euphorbia hirta L. AIP Conference Proceedings 2049:030018. DOI: 10.1063/1.5082519.

Euphorbia hirta is an important plant in traditional medicine in tropical regions, especially used to treat asthma and diarrhoea. This study aimed to investigate the antioxidant capacities of plant extractions and some isolated compounds from E. hirta. Results showed that the plant can serve as natural antioxidative. Its further pharmacological potential should be tested to treat oxidative stress which may be related to neurodegenerative diseases.

Pesticides & Benin cotton fields

Gouda A-I, Imorou Toko I, Salami S-D, Richert M, Scippo M-L, Kestemont P, Schiffers B. 2018. Plant protection practices and pesticide exposure levels of Northern Benin cotton producers. Cahiers Agricultures 27. DOI: 10.1051/cagri/2018038.

The level to which cotton producers are exposed to pesticides is alarming. Since the majority never received any education nor instructions of use, 75% apply higher amounts than recommended and 80% do not protect themselves during mixing, loading and spraying. Empty pesticide containers are often left in cotton fields or even worse, used for domestic purposes.

Pikeperch production in the Caspian Sea

Falahatkar, B, Efatpanah, I, & Kestemont, P 2018, ‘Pikeperch Sander lucioperca production in the south part of the Caspian Sea: technical notes’, Aquaculture International, vol. 26, no.1, pp. 391–401, DOI: 10.1007/s10499-017-0222-2

Pikeperch (Sander lucioperca) is a popular food fish in the Caspian Sea basin. However, due to over-fishing in the early 20th century and destruction of natural spawning areas, wild populations have completely collapsed. From 1989, Iranian Fisheries Organization developed the artificial propagation and rearing activities for the rehabilitation of natural populations. This publication summarizes the developments concerning reproduction, stock rehabilitation, on-growing etc. in Iran.

Richelle, L, Visser, M, Bock, L, Walpole, P, Mialhe, F, Colinet, G & Dendoncker, N 2018, 'Looking for a dialogue between farmers and scientific soil knowledge: Learnings from an ethno-geomorphopedological study in a Philippine’s upland village' Agroecology and Sustainable Food Systems, vol 42, no. 1, pp. 2-27. DOI: 10.1080/21683565.2017.1322661

Thinh NQ, Phu TM, Douny C, Phuong NT, Huong DTT, Kestemont P, Scippo M-L. 2018. Bioconcentration and half-life of quinalphos pesticide in rice-fish integration system in the Mekong Delta, Vietnam. Journal of Environmental Science and Health, Part B 53:35–41. DOI: 10.1080/03601234.2017.1371551.


Pezzulo, C, Hornby, GM, Sorichetta, A, Gaughan, AE, Linard, C, Bird, TJ, Kerr, D, Lloyd, CT & Tatem, AJ 2017, 'Sub-national mapping of population pyramids and dependency ratios in Africa and Asia' Scientific Data, vol 4, 170089. DOI: 10.1038/sdata.2017.89

Schmitz, M, Baekelandt, S, Tran Thi, LK, Mandiki, R, Douxfils, J, Nguyen, TQ, Do Thi Thanh, H & Kestemont, P 2017, 'Osmoregulatory and immunological status of the pond-raised striped catfish (Pangasianodon hypophthalmus S.) as affected by seasonal runoff and salinity changes in the Mekong Delta, Vietnam' Fish Physiology and Biochemistry, vol 43, no. 1, pp. 39-49. DOI: 10.1007/s10695-016-0266-7

Schmitz, M, Ziv, T, Admon, A, Baekelandt, S, Mandiki, SNM, L'Hoir, M & Kestemont, P 2017, 'Salinity stress, enhancing basal and induced immune responses in striped catfish Pangasianodon hypophthalmus (Sauvage)' Journal of Proteomics, vol 167, pp. 12-24. DOI: 10.1016/j.jprot.2017.08.005


Bich Hang, BT, Nguyen, PT & Kestemont, P 2016, 'Oral administration of Escherichia coli lipopolysaccharide enhances the immune system of striped catfish, Pangasianodon hypophthalmus (Sauvage)' Aquaculture Research, vol 47, no. 4, pp. 1299-1308. DOI: 10.1111/are.12589