Showing papers by "University of Zambia published in 2002"
TL;DR: A 3-day course of nitazoxanide significantly improved the resolution of diarrhoea, parasitological eradication, and mortality in HIV-seronegative, but not HIV-Seropositive, children.
367 citations
TL;DR: In this article, a sequence space using Orlicz functions is defined, and certain properties and inclusion relations between known sequence spaces and new sequence spaces are given, where the inclusion relation between known sequences and new sequences is discussed.
Abstract: In this paper we define a sequence space using Orlicz functions. We give certain properties and inclusion relations between known sequence spaces and new sequence space.
117 citations
TL;DR: In this paper, the authors investigated the impact of land tenure and use on the recovery of miombo woodlands in central and southern Africa and concluded that regulation of land use is more important than change in land tenure to the proper management of the miombo forests.
Abstract: Aim Population pressure and communal land ownership are often perceived as serious threats to forest conservation in savanna woodlands of central and southern Africa. I aimed at testing the hypothesis that the rate of miombo woodland recovery after clearing and re-growth structure are determined by land tenure and use.
Location Miombo woodland under customary, leasehold, forest reserve and national park on ten permanent and temporary sites was studied in central Zambia. Two sites were in mature woodland and eight sites were in re-growth miombo ranging in age from 1 to 30 years.
Methods I enumerated and measured girth at breast height (1.3 m above ground) of trees/stems in sixty-four 20 × 10 m plots in 1982, 1986 and 2000 at six sites and annually from 1990 to 2001 at four sites to determine stem density and status (live, dead or cut) and wood biomass. A total of 239 trees were cut, wood biomass measured and the data used to develop equations for estimating wood biomass on study plots. Distance between each study site and the nearest human settlement was estimated during each sampling period using aerial photographs, topographical maps and the global positioning system.
Results Land tenure was responsible for significant differences in stem density, wood biomass and rate of biomass accumulation in re-growth following clearing of mature miombo woodland. Although stem density was highest on customary land, wood biomass and accumulation rate were lowest. The highest biomass was on plots in forest reserves, with intermediate values for leasehold and national park. Fire was responsible for tree mortality at all the study sites and its impact was highest at a site in a national park. Sites close to human settlements had the highest density of cut stems but this activity did not significantly reduce wood biomass. Rate of woodland recovery was higher on sites cleared in the 1970s than on sites cleared in the 1990s, irrespective of age of re-growth. The development of the first, second and third re-growths following successive woodland clearing in 1972, 1981 and 1990, respectively, was not significantly different, except for stem density which was highest in the second re-growth. Analysis of interactions between five land tenure and use factors (independent variables) and re-growth structure revealed that 52% (P=0.0000) of the variation in stem density was because of re-growth age and decade in which the woodland was cleared while distance to human settlements and age of re-growth explained 42% (P=0.0000) of the variation in wood biomass. Individually, distance to human settlements explained 25% (P=0.0000) of the variation in wood biomass accumulation rate.
Conclusion The results supported the hypothesis that rate of miombo woodland recovery and structure were influenced by land tenure and use. However, analysis of interactions between factors revealed that use related factors (i.e. decade in which woodland was cleared and distance to human settlements) and re-growth related factors (age and type of re-growth) were more important than land tenure per se in explaining variation in miombo recovery. The conclusion from these results is that regulation of land use is more important than change in land tenure to the proper management of miombo woodland.
117 citations
TL;DR: The current study suggests the presence of human tapeworm carriers and a high risk of human cysticercosis in the surveyed areas as well as in urban centres where pigs from rural areas are increasingly sold, slaughtered and consumed.
96 citations
TL;DR: The proportion of cysts expected to be found at the surfaces exposed by visual examination or incision at meat inspection was calculated using an indirect method, which incorporated the area revealed by incision and visual inspection of an organ and the proportion of Cysticerci located in the particular organ.
81 citations
TL;DR: Women who discover their HIV status during the course of their pregnancy are more liable to develop major depressive illness and somatic disorders, according to a study of pregnant HIV-infected women in Zambia.
Abstract: The diagnosis of HIV in a pregnant women or pregnancy in an HIV-positive woman can be associated with an affective disorder, caring for which can present a major challenge for physicians and health care workers. The associated somatic symptoms can cause serious morbidity. This study aims to explore the mental health of pregnant HIV-infected women. The study took place at the University Teaching Hospital in Lusaka, Zambia and at satellite clinics. Study participants were either pregnant women who were diagnosed with HIV during the course of their pregnancy, or women who knew their HIV-positive status prior to becoming pregnant. A questionnaire was used to assess the psychological state of the women. The majority of women (85%) showed major depressive episodes and had significant suicidal thoughts. About 60% of the women whose HIV was diagnosed during their pregnancy showed signs of somatic illness. Those who knew their HIV status before becoming pregnant did not show severe depressive episodes, but showed anxiety about the HIV status of their babies. This suggests that women who discover their HIV status during the course of their pregnancy are more liable to develop major depressive illness and somatic disorders. Physicians dealing with these women need to be cognisant of the strain HIV can add to pregnancy and of the psychological and psychiatric support they may require.
75 citations
TL;DR: The Traditional Ecological Knowledge of the Bisa people of northern Zambia on species, life cycles and host plants of the caterpillars they exploit for food and for household income generation, and the traditional control of caterpillar harvesting, were investigated through a household survey.
Abstract: The Traditional Ecological Knowledge (TEK) of the Bisa people of northern Zambia on species, life cycles and host plants of the caterpillars they exploit for food and for household income generation, and the traditional control of caterpillar harvesting, were investigated through a household survey. The accessed indigenous knowledge on caterpillar biology was validated through a forest survey, caterpillar collections and identifications. Eight species of caterpillars were harvested from the surrounding miombo woodlands. Their life systems and host plants were well understood by members of local communities and this knoweldge was communicated amongst them orally. Popular commercial species were Gynanisa maya Strand and Gonimbrasia zambesina Walker. Over 20 miombo tree species hosted the two species but the mean numbers of the caterpillars on Julbernadia paniculata Troupin were significantly larger than those on other host plants (p < 0.05), indicating that J. paniculata was probably the main host plant of the two species. Traditional regulation of caterpillar harvesting involved: (i) monitoring for edible caterpillar development and abundance and for changes in caterpillar habitats, (ii) protection of host plants and moth eggs against late bush fires, through use of traditional fire technology, and (iii) temporal restriction of edible caterpillar harvesting. The possibility of the Zambian Government promoting caterpillar harvesting as an economic incentive to the Bisa people to conserve both this renewable edible caterpillar natural resource and their environment is discussed.
73 citations
TL;DR: It is confirmed that the simultaneous occurrence of type I/type II cytokines in the early stage of infection in susceptible BALB/c mice, reflected by the presence of macrophages exhibiting a mixed classical/alternative activation phenotype, is associated with uncontrolled parasite growth and early death.
Abstract: The contribution of cytokines and chemokines to resistance and susceptibility to African trypanosomiasis remains controversial. In the present study, the levels of type I and type II cytokines and of the MCP-1 chemokine were compared during the early and late stages of Trypanosoma congolense infection in susceptible BALB/c and resistant C57BL/6 mice. Moreover, the status of macrophage activation was compared in these animals by analyzing the inducible nitric oxide synthase-arginase balance, tumor necrosis factor secretion, and expression of the FIZZ1 and YM genes. Data show that changing from a predominant type I cytokine environment in the early stage of infection to a predominant type II cytokine environment and an enhanced MCP-1 secretion in the late stage of infection correlates with resistance to T. congolense. Concomitantly, macrophage activation evolves from a classical to a predominant alternative phenotype. We further confirmed that the simultaneous occurrence of type I/type II cytokines in the early stage of infection in susceptible BALB/c mice, reflected by the presence of macrophages exhibiting a mixed classical/alternative activation phenotype, is associated with uncontrolled parasite growth and early death. Interleukin-4 (IL-4) and IL-13 signaling did not influence the susceptibility of BALB/c mice to T. congolense infection and interestingly were not the main trigger to alternative macrophage activation. In T. congolense-resistant C57BL/6 mice, our results corroborated the induction of FIZZ1 and YM gene expressions with the alternative pathway of macrophage activation. In susceptible BALB/c mice, however, YM but not FIZZ1 induction reflected the emergence of alternatively activated macrophages. Hence, the FIZZ1 and YM genes may be useful markers to discriminate between distinct populations of alternatively activated macrophages.
71 citations
TL;DR: The alignment of incentives (to promote access and quality for those intended to be covered by the public budget) and the effective decentralisation of control over key resources--seem to us the key tools to address the stubborn problems of hospitals.
48 citations
TL;DR: The human immunodeficiency virus pandemic has contributed to a marked increase in patients infected with tuberculosis in parts of SubSaharan Africa and in patients with osteoarticular tuberculosis who are positive for the virus, the prognosis will depend on the stage that the human immunosuppressive virus infection has reached by the time of presentation.
Abstract: The human immunodeficiency virus pandemic has contributed to a marked increase in patients infected with tuberculosis. In parts of SubSaharan Africa, osteoarticular tuberculosis has increased fourfold in the past decade and approximately 60% of the patients are infected with the human immunodeficien
41 citations
TL;DR: Morbidity in HIV seropositive adults was dominated by tuberculosis, other respiratory infections or persistent diarrhoea, and affected individuals had a wide range of CD4 counts, including those with asymptomatic HIV infection.
TL;DR: It is suggested that the continuous man to animal contact and the use of casual workers in feedlots may be factors that are conductive to T. saginata transmission.
TL;DR: Mycoplasma contamination of the licensed anthrax vaccine administered to military personnel has been suggested as a possible cause of Persian Gulf illness, but vaccine samples tested by nonmilitary laboratories were negative for viable myCoplasma and mycoplasm DNA and did not support its survival.
Abstract: Mycoplasma contamination of the licensed anthrax vaccine administered to military personnel has been suggested as a possible cause of Persian Gulf illness. Vaccine samples tested by nonmilitary laboratories were negative for viable mycoplasma and mycoplasma DNA and did not support its survival. Mycoplasma contamination of anthrax vaccine should not be considered a possible cause of illness.
TL;DR: Albendazole reduces diarrhoea in African AIDS patients, but it is unclear if the clinical response to treatment reflects pathogen eradication and/or mucosal recovery.
Abstract: Background:
Albendazole reduces diarrhoea in African AIDS patients, but it is unclear if the clinical response to treatment reflects pathogen eradication and/or mucosal recovery.
Methods:
Adults with HIV-related persistent diarrhoea were treated with albendazole 800 mg twice daily for 14 days. Clearance of parasites was evaluated at 3 and 6 weeks by stool microscopy. At baseline and at 6 weeks duodenal biopsies were taken for electron microscopy (EM) and morphometry.
Results:
Ten (7%) of 153 patients had cryptosporidiosis, 54 (37%) had isosporiasis and 23 (16%) had microsporidiosis. By 3 weeks, these protozoa were cleared in 27 (46%) of 59 patients initially positive. By 6 weeks, 34 (39%) of 87 patients experienced complete clinical response, 18 (21%) partial response and 35 (40%) no response. Crypt depth increased by 15% over 6 weeks (P < 0.001), but villous height increased only in patients with complete response (median + 50 μm, interquartile range (IQR) 2–90, compared to patients with partial (+ 4 μm, IQR – 15,41) or no response (− 13 μm, IQR − 62,12; P=0.008)). Fifteen patients died: body mass index < 17.5 kg/m2 and crypt depth < 180 μm independently predicted death.
Conclusions:
Albendazole therapy reduced the burden of protozoal infection and promoted mucosal recovery in patients with a complete clinical response.
TL;DR: A survey on customary land and an adjacent forest reserve was conducted in the Kopa area of northern Zambia in November 2000 as discussed by the authors, where the objectives of the survey were to describe habitats of edible caterpillars and assess temporal and spatial variations in caterpillar abundance.
Abstract: A survey on customary land and an adjacent forest reserve was conducted in the Kopa area of northern Zambia in November 2000. The objectives of the survey were to describe habitats of edible caterpillars and assess temporal and spatial variations in caterpillar abundance, the impact of tree cutting during caterpillar harvesting and the potential of edible caterpillars as sources of income for rural households. The results showed that edible caterpillars have the potential, even in years of moderate abundance, to generate incomes of over US$60 per household that are comparable to, or even higher than, incomes from the sale of agricultural crops. The most favourable habitats for the production of the two most popular edible caterpillars, Gynanisa maja Strand and Gonimbrasia zambesina Walker, were in young re-growth Brachystegia-Julbernardia (miombo) woodland regenerating after abandonment of chitemene shifting cultivation, probably because of the increase in abundance of their main host tree, Julbe...
TL;DR: Reduced snail-parasite compatibility might be at least partially responsible for the decrease observed, over the last three decades, in the prevalence of urinary schistosomiasis on the shores of Lake Kariba, Zambia.
Abstract: Reduced snail-parasite compatibility might be at least partially responsible for the decrease observed, over the last three decades, in the prevalence of urinary schistosomiasis on the shores of Lake Kariba, Zambia. To explore this possibility, the prevalences of urinary schistosomiasis in schoolchildren were investigated in three disparate areas of Zambia (Lake Kariba, Lake Bangweulu and Lusaka), and attempts were made to infect the snails that developed from the eggs of snails collected from each of these sites with Schistosoma haematobium from each of the sites. The prevalence of S. haematobium infection in schoolchildren ranged from 0% around Lake Bangweulu to 76% around Lake Kariba. The F1 progeny of Siavonga (Lake Kariba) snails showed good compatibility with the local parasite but were also susceptible to all of the geographical strains of S. haematobium tested. The interaction between the S. haematobium and S. mansoni found along the shores of Lake Kariba may favour S. mansoni, since preva...
TL;DR: In this article, a project that is investigating weed management strategies which involve use of cleaner production (CP) approach and the utilization of the weed for economic purposes is reported, and the ecological implications of these methods are being assessed.
Abstract: The aquatic weed situation in the Kafue River in Zambia continues to be a major challenge to the sustainable utilization of the water resources of the river. The general methods for managing the weeds, especially the water hyacinth, include use of bio-agents, chemicals, mechanical and physical approaches. These have had very little impact. This paper reports on a project that is investigating weed management strategies which involve use of cleaner production (CP) approach and the utilization of the weed for economic purposes. In addition, the ecological implications of these methods are being assessed. Effluent assessments indicated that apart from nitrates and phosphates, other effluent parameters met the Environmental Council of Zambia standards. Results further show that all the 24 areas surveyed for CP have uncontrolled socio-economic activities which generate both point and non-point sources of pollution that enter the water bodies. To minimize pollution, efforts include devising policy and technical strategies with the involvement of the affected riparian community. Production of mushroom by the communities using the water hyacinth substrate has been demonstrated. Up to 2.1 kg of mushroom was harvested from a single flush over a period of 4–5 weeks. Vegetables grown on soils treated with water hyacinth manure performed better than those grown using commercial fertiliser. The economics of the production are however, yet to be confirmed. If weed usage is proven economically and ecologically viable, the riverine community is envisaged to play a big role in aquatic weed management. High numbers of invertebrates known to be sensitive to pollution have been recorded in the weed-infested Kafue River implying that the water is of “good” quality for these aquatic invertebrates. This observed quality of water may be due to water hyacinth playing a role by sieving pollutants from the river.
TL;DR: The suggested intrauterine antigenic stimulation may be important not only for generating immune responses to natural early infections, but also for enhancing the immunogenicity and efficacy of vaccines administered to newborns.
Abstract: The present work investigated the transplacental passage of circulating anodic schistosome antigens (CAA) and the production of foetal antibodies in response to antigenic stimulation in Schistosoma mattheei infected cows. Three groups were available: six calves born to non-infected cows received colostrum from a pool from non-infected cows (group 1), six calves born to non-infected cows (group 2) and six calves born to infected cows (group 3) received colostrum from a pool from infected cows. Schistosoma-specific IgG (1) antibody and CAA levels were measured in the colostrum pools, the sera collected from the cows, and the sera collected from the calves at birth, after intake of colostrum and at day 30. The specific IgG (1) antibody levels were significantly higher in the sera from cows of group 3. In four cows of group 3 high CAA levels were detected. The specific IgG (1) antibody levels were 0.646 and 0.176 OD for the infected and non-infected colostrum pool, respectively, and the CAA levels were 5667 and 2557 pg CAA/mL, respectively. At birth high levels of specific IgG (1) antibody and CAA were detected in 4 calves of group 3; levels in the other two calves were negligible. After intake of colostrum, specific IgG (1) antibody levels of group 1 increased slightly at day 1 to become again insignificant at day 30. In group 2 specific IgG (1) antibody levels increased significantly between days 0 and 1, to decrease, although not significantly, at day 30. Finally, in group 3 the delta OD values increased at day 1 and remained high until day 30. After intake of colostrum the CAA level increased very slightly for groups 1 and 2 to become again undetectable at day 30. In group 3 a nonsignificant decrease in CAA levels was observed at day 1 followed by a further significant decrease to reach low levels at day 30. The suggested intrauterine antigenic stimulation may be important not only for generating immune responses to natural early infections, but also for enhancing the immunogenicity and efficacy of vaccines administered to newborns.
TL;DR: It can be concluded that there is no difference in the transportation of either fertilised or unfertilized ova in the reproductive tract of pigs.
TL;DR: Assessing the degree of competition for hospital services in two hospital markets in Zambia found substantial differences among different hospital types in prices, costs and quality, suggesting that the hospital service market is a segmented market.
Abstract: Hospital reforms involving the introduction of measures to increase competition in hospital markets are being implemented in a range of low and middle-income countries. However, little is understood about the operation of hospital markets outside the USA and the UK. This paper assesses the degree of competition for hospital services in two hospital markets in Zambia (Copperbelt and Midlands), and the implications for prices, quality and efficiency. We found substantial differences among different hospital types in prices, costs and quality, suggesting that the hospital service market is a segmented market. The two markets differ significantly in their degree of competition, with the high cost inpatient services market in Copperbelt relatively more competitive than that in the Midlands market. The implications of these differences are discussed in terms of the potential for competition to improve hospital performance, the impact of market structure on equity of access, and how the government should address the problem of the mine hospitals. Copyright © 2002 John Wiley & Sons, Ltd.
TL;DR: The seasonal selling pattern of the animals suggests that most farmers prefer selling the heaviest animals in the flock, with RMs being the most affected class and followed by RFs, RFs and castrated males (CMs; 19%).
TL;DR: The continuing need for integrating indigenous technical knowledge (ITK) into IPM technology could ensure household food security and enhance sustainable livelihoods of rural smallholder farmers is demonstrated.
Abstract: A study was conducted in Muswishi area, Zambia, with the objective of assessing indigenous technical knowledge (ITK) and relating this knowledge to integrated pest management (IPM) in maize production. The methods used included surveys, participatory rural appraisal (PRA), transect walks and semi-structured interviews (SSI). It was found that ITK does exist among some Muswishi smallholder farmers. Eighty-nine percent of respondent farmers never used any chemical pesticides. However, 22% used natural products to manage insect pests. The most widely used natural plant products were Swartzia madascariensis Desv, Tephrosia vogelli Hook.f, Euphorbia tirucalli L, wood ash and cow dung. Farmer’s own assessment indicated that the integration of ITK into IPM technology led to increased maize yields (> 37.5%). This study demonstrated the continuing need for integrating ITK into IPM technology. Such an approach could ensure household food security and enhance sustainable livelihoods of rural smallholder farmers.
Journal Article•
TL;DR: Judging by the results obtained in this study, pollution from the mining activity around the Kafue River drainage area in the Copperbelt region has not led to any accumulation of elements in tissues of the hippopotami in the Kafu National Park.
Abstract: Hepatic and renal concentrations of the elements arsenic, cadmium, cobalt, copper, lead, manganese, mercury, molybdenum, selenium and zinc were studied in samples collected from hippopotami from the Kafue River in the Kafue National Park and the Luangwa River in the Southern Luangwa National Park in Zambia. There were no significant differences between trace element concentrations in the tissues of the hippopotami taken in the Kafue River and the Luangwa River. The concentrations of copper and other essential elements were similar to those reported in normal domestic and wild ruminants. Judging by the results obtained in this study, pollution from the mining activity around the Kafue River drainage area in the Copperbelt region has not led to any accumulation of elements in tissues of the hippopotami in the Kafue National Park. The trace element concentrations observed may serve as reference for similar future studies on hippopotami.
01 Jan 2002
TL;DR: Subclinical mastitis, as defined by raised milk sodium/potassium (Na/K) ratio (>0.6), is common among several populations and is associated with poor infant growth and, in HIV-infected women with high milk HIV viral load, a risk factor for mother to child transmission.
Abstract: Subclinical mastitis, as defined by raised milk sodium/potassium (Na/K) ratio (>0.6), is common among several populations and is associated with poor infant growth (Filteau et al. in press) and, in HIV-infected women with high milk HIV viral load, a risk factor for mother to child transmission.1, 2
06 Jul 2002-Journal of The South African Veterinary Association-tydskrif Van Die Suid-afrikaanse Veterinere Vereniging
TL;DR: The incidence of trypanosomosis was determined using the haematocrit centrifuge technique (HCT) as well as polymerase chain reaction (PCR) on 120 goat blood spots on filter paper, implying that factors such as age, healthy appearance and small sample size notwithstanding, trypanOSomosis does not seem to pose a serious threat to goat health in the districts from where the animals originated.
Abstract: The incidence of trypanosomosis was determined using the haematocrit centrifuge technique (HCT) as well as polymerase chain reaction (PCR) on 120 goat blood spots on filter paper. Both techniques failed to detect a positive reaction, implying that factors such as age, healthy appearance and small sample size notwithstanding, trypanosomosis does not seem to pose a serious threat to goat health in the districts from where the animals originated.
TL;DR: Two untypable strains of P.dagmatis and P.hemolytica were isolated from cases of pneumonic pasteurellosis in Lusaka, Zambia and belonged to capsular types A, D, and somatic types 3 and 4.
Abstract: Keywords: Pneumonic pasteurellosis, Pasteurella hemolytica, Pasteurella multocida.
P.hemolytica (6 strains) and P.multocida (12 strains) were isolated from cases of pneumonic pasteurellosis in Lusaka, Zambia. All P. hemolytica strains were of biotype A, while P. multocida strains belonged to capsular types A, D, and somatic types 3 and 4. Two untypable strains of P.dagmatis were also isolated.
Trop. Vet. Vol. 20(3) 2002: 130-131
TL;DR: The article looks at the scope and challenges in research and teaching in computational physics in Africa and the establishment of a “resource centre” at an international organization along with regional centres, with international contributions is suggested.
TL;DR: There was a significant impact of colostrum on the parasitological and serological course of early S. mattheei infections, and calves of group 2 showed significant reductions of 42, 28 and 42% in total worm counts, female worm counts and tissue egg counts, respectively, and a reduction of 25% in cumulative faecal egg counts.
Abstract: The study investigated whether the susceptibility of calves to an early Schistosoma mattheei infection may be modified by intake of colostrum from infected cows. Twelve calves born to non-infected mothers were randomly divided into 2 groups of 6. The animals from group 1 were fed colostrum originating from a pool collected from non-infected cows, the calves from group 2 received colostrum from a pool collected from cows infected with S. mattheei. One month after birth all calves were infected by exposure to 1000 cercariae of a local strain of S. mattheei, and perfused 12 weeks later to determine the worm- and tissue egg counts. IgG H+L , IgG 1 , IgG 2 and IgA levels against soluble adult worm antigen preparation of S. bovis (SWAP bovis) were analysed in both colostrum pools and in the serum from the calves collected during the study before and after receiving colostrum, then on days 7, 30, 73 and 122. Faecal egg counts were determined from day 73 onwards. The IgG H+L , IgG 1 and IgA levels of the positive colostrum pool were higher than those of the negative pool. Calves of group 2 showed significantly higher levels of IgG H+L and IgG 1 until day 73, to reach equal levels at necropsy. Calves of group 2 showed significant reductions of 42, 28 and 42% in total worm counts, female worm counts, and tissue egg counts, respectively, and a reduction of 25% in cumulative faecal egg counts. These findings indicate that there was a significant impact of colostrum on the parasitological and serological course of early S. mattheei infections.
TL;DR: The first Jesuits arrived in Northern Rhodesia (Zambia today) in 1891 and were the sole Catholics in the territory as mentioned in this paper until the arrival of the first Jesuit priests in 1905, which led them into ongoing contact with the British South Africa Company (B.S.A.C.).
Abstract: The Catholic Church as represented by the White Fathers (today known as Missionaries of Africa) arrived in Northern Rhodesia (Zambia today1) in 1891. Until the arrival of the first Jesuits in 1905, they were the sole Catholics in the territory. As part of their method of evangeli zation, both the White Fathers and the Jesuits started basic schools almost from the beginning. Within a short time, this led them into ongoing contact with the secular government, which until 1924 was the British South Africa Company (B.S.A.C.) and the colonial government from 1924 to 1964.
TL;DR: Several soil nutrients, pH, organic carbon, and total soluble salts from the upper 10 cm of soil samples from 72 shrimp ponds in Texas were analyzed and no measurable negative effect on shrimp production by the increase of elemental concentrations was measured.
Abstract: Several soil nutrients, pH, organic carbon, and total soluble salts from the upper 10 cm of soil samples from 72 shrimp ponds in Texas were analyzed. Large increases in sediment concentrations of C, N, Mg, K, Na, Fe, Mn, Zn, Cu, B, nitrate, and water-soluble salts was observed after one production cycle, followed by an asymptotic increase in older ponds. An approximately linear increase in soil concentration of S and P with pond age was observed. The pH showed a marked decrease in ponds that had been used for one production cycle, but stabilized in older ponds. No correlation between Ca and growing cycle was observed. Calculated recovery rates for elements supplied in feed were less than 10% in several cases and 15% for P. No measurable negative effect on shrimp production by the increase of elemental concentrations was measured.