Mycotoxins' Prevalence in Food Industry By-Products: A Systematic Review.

The recovery of biomolecules from food industry by-products is of major relevance for a circular economy strategy. However, by-products' contamination with mycotoxins represents a drawback for their reliable valorization for food and feed, hampering their application range, especially as food ingredients. Mycotoxin contamination occurs even in dried matrices. There is a need for the implantation of monitoring programs, even for by-products used as animal feed, since very high levels can be reached. This systematic review aims to identify the food by-products that have been studied from 2000 until 2022 (22 years) concerning mycotoxins' contamination, distribution, and prevalence in those by-products. PRISMA ("Preferred Reporting Items for Systematic Reviews and MetaAnalyses") protocol was performed via two databases (PubMed and SCOPUS) to summarize the research findings. After the screening and selection process, the full texts of eligible articles (32 studies) were evaluated, and data from 16 studies were considered. A total of 6 by-products were assessed concerning mycotoxin content; these include distiller dried grain with solubles, brewer's spent grain, brewer's spent yeast, cocoa shell, grape pomace, and sugar beet pulp. Frequent mycotoxins in these by-products are AFB1, OTA, FBs, DON, and ZEA. The high prevalence of contaminated samples, which surpasses the limits established for human consumption, thus limiting their valorization as ingredients in the food industry. Co-contamination is frequent, which can cause synergistic interactions and amplify their toxicity.

In vitro gastric bioaccessibility of avocado peel extract in beef and soy-based burgers and its impact on Helicobacter pylori risk factors.

The objective of the present study was to investigate the impact of phenolic-rich avocado peel extract (APE) as an ingredient in beef and soy-based burgers to increase their antioxidant activity, reduce lipid and protein oxidation during gastric digestion, and inhibit urease and anhydrase carbonic activity, which are considered as key factors in the main steps of Helicobacter pylori adhesion in the stomach. The gastric bioaccessible fraction of soy and beef burgers with added 0.5% APE obtained by in vitro digestion exhibited a higher content of phenolic compounds, including monomeric and oligomeric (epi)catechin forms and quercetin, and reduced levels of thiobarbituric acid-reactive substances (TBARS) and carbonyls (49% to 73% and 57% to 60%, respectively) when compared with control burgers. Moreover, the burgers with APE inhibited urease and carbonic anhydrase activity. Results generally showed that including APE reduces the primary risk factors associated with H. pylori infection.

Explore Gastric Lipolysis and Lipid Oxidation of Conventional versus Pasture-Based Milk by a Semi-dynamic In Vitro Digestion Model.

Research on gastric lipolysis of commercial cow's milk with different fatty acid (FA) compositions is scarce. Gastric lipase exhibits specificity for the sn-3 chain position of triacylglycerols, whose structure is influenced by milk FA composition. Therefore, during gastric digestion of conventional (C) vs pasture-based (P) milk, differences may occur on lipolysis, which has impact on free FA available, influencing their absorption/metabolism rate and physiological hormonal responses. Those two milk types were subjected to the INFOGEST semi-dynamic digestion model. Five gastric emptying points were analyzed for oxidative degradation of polyunsaturated fatty acids (PUFA) and individual free FA. The relative release of medium-chain FA (C8:0-C12:0) was higher than that of longer-chain FA (C14:0-C18:0), and a linear increase in markers of PUFA oxidative degradation occurred along gastric digestion. Quantitatively, C8:0, C18:2n-6, C18:3n-3, and CLAc9t11 were higher (P < 0.001) in P milk when compared with C milk.

Incorporation of avocado peel extract to reduce cooking-induced hazards in beef and soy burgers: A clean label ingredient.

In this study, the benefits of using avocado peel extract (APE), rich in phenolic compounds, to reduce the oxidation and formation of harmful compounds resulting from cooking, were investigated. Beef and soy-based burgers with the addition of APE (0.5% and 1%) were studied after pan frying concerning proximate and physicochemical characteristics, inhibition of protein and lipid oxidation products (thiobarbituric acid reactive substances [TBARS], hexanal, and carbonyls), heterocyclic aromatic amines (HAs) and acrylamide formation. Sensory analysis was additionally performed. APE-affected proximate composition, protein, fat, and ash contents (%) were found to be markedly higher in APE-incorporated burgers (~28.32 ± 0.29, ~14.00 ± 0.01, and ~1.57 ± 0.05, respectively), compared with the controls (~26.55 ± 0.51, ~12.77 ± 0.32, and ~1.48 ± 0.16, respectively). Lower concentrations of TBARS, hexanal, and carbonyls were observed in APE-treated burgers on Days 1 and 10, post-cooking, compared to controls. Overall, it was found that APE had a greater protective effect than the positive control (sodium ascorbate incorporated) in beef burgers. In soy burgers, the positive control demonstrated pro-oxidant activity. The addition of 0.5% APE was found to inhibit HAs and acrylamide formation in beef and soy burgers. Although the addition of APE affected the color of both meat and soy burgers, it did not impact consumer preference. It was therefore concluded that APE extract might be a suitable clean-label alternative to synthetic antioxidants, and that it can protect and increase the nutritional value of meat and meat-free burgers.

Western Dietary Pattern Antioxidant Intakes and Oxidative Stress: Importance During the SARS-CoV-2/COVID-19 Pandemic.

The importance of balanced dietary habits, which include appropriate amounts of antioxidants to maintain the immune system, has become increasingly relevant during the current SARS-CoV-2/COVID-19 pandemic, because viral infections are characterized by high oxidative stress. Furthermore, the measures taken by governments to control the pandemic have led to increased anxiety, stress, and depression, which affect physical and mental health, all of which are influenced by nutritional status, diet, and lifestyle. The Mediterranean diet (MD), Atlantic diet (AD), and the Dietary Guidelines for Americans all provide the essential vitamins, minerals, and phenolic compounds needed to activate enzymatic and nonenzymatic antioxidant responses. However, viral pandemics such as the current COVID-19 crisis entail high oxidative damage caused by both the infection and the resultant social stresses within populations, which increases the probability and severity of infection. Balanced dietary patterns such as the MD and the AD are characterized by the consumption of fruit, vegetables, legumes, olive oil, and whole grains with low intakes of processed foods and red meat. For a healthy lifestyle in young adults, the MD in particular provides the required amount of antioxidants per day for vitamins D (0.3-3.8 µg), E (17.0 mg), C (137.2-269.8 mg), A (1273.3 µg), B-12 (1.5-2.0 µg), and folate (455.1-561.3 µg), the minerals Se (120.0 µg), Zn (11.0 mg), Fe (15.0-18.8 mg), and Mn (5.2-12.5 mg), and polyphenols (1171.00 mg) needed to maintain an active immune response. However, all of these diets are deficient in the recommended amount of vitamin D (20 µg/d). Therefore, vulnerable populations such as elders and obese individuals could benefit from antioxidant supplementation to improve their antioxidant response. Although evidence remains scarce, there is some indication that a healthy diet, along with supplemental antioxidant intake, is beneficial to COVID-19 patients.

Sustainability indicators for municipal solid waste management: A case study of the Recife Metropolitan Region, Brazil.

Municipal solid waste (MSW) management in Brazil faces major challenges in order to meet the requirements proposed by the National Solid Waste Policy, which has been in force since 2010 and complicates decision-making, especially in small municipalities. In this context, sustainability indicators are important support tools that help in setting out performance actions for municipal sustainable development. The main objective of this article is to evaluate the four sustainability dimensions (social, environmental, economic, and legal/institutional) using sustainability indicators for MSW management in the Recife Metropolitan Region (RMR) in Northeast Brazil. To do this, the progress of the region was evaluated against the principal goals and guidelines proposed by solid waste plans and by the United Nations Sustainable Development Goals. It was found that some progress has been achieved in recent years, such as the closure of dumps, a reduction of the per capita MSW mass collected, and an increase in the coverage rate for solid household waste collection. However, selective collection and financial autonomy still fall well short of the region's goals. According to the results of this study, municipalities in the RMR require more environmental education and joint actions involving government, the private sector, and the general population.

Influence of culinary practices on protein and lipid oxidation of chicken meat burgers during cooking and in vitro gastrointestinal digestion.

The impact of six culinary practices - oven/microwave combined with/without seasoning with oregano/beer - on lipid and protein oxidation of chicken burgers after cooking and after in vitro digestion was assessed. Five oxidation markers - malondialdehyde (MDA), 4-hydroxy-2-nonenal (HNE), hexanal (HEX), carbonyls, and Schiff bases - as well as free amino acids and total fatty acids content were measured. Oregano prevented MDA, HEX, and HNE formation during cooking, while beer seems not to influence their formation. After in vitro digestion, MDA, carbonyls, and Schiff bases increased, regardless of the culinary practice, while HNE and HEX values were reduced. Globally, cooking with oregano exhibited the lowest losses of PUFAs and formation of all oxidation markers, thus it should be used as a mitigation strategy to avoid the formation of oxidation products during cooking, as well as to prevent their formation during in vitro digestion.

Stability of antibacterial and coccidiostat drugs on chicken meat burgers upon cooking and in vitro digestion.

The impact of culinary practices - oven or microwave cooking combined with herbs and/or beer - on antibacterial and coccidiostat drugs stability and bioaccessibility in chicken meat was evaluated. Fourteen compounds from 6 classes (ß-lactams, tetracyclines, sulfonamides, fluoroquinolones, macrolides, and coccidiostats) were monitored after cooking and in vitro digestion (INFOGEST protocol) at two fortification levels. Depending on their reduction, the presence of transformation products derived from cooking or digestion was investigated. In general, compounds were stable during cooking except amoxicillin, chlortetracycline and tylosin (reductions > 50%). Molecular rearrangement and dechlorination reactions are the most probable transformations derived from cooking. Adding herbs/beer does not benefit their reductions. During in vitro digestion, maximum bioaccessibilities of 60% were observed for all quantified compounds. As drugs and bile salts interact, increasing the absorption of lipophilic drugs, their bioaccessibility predictions must not be based only on the determination of their free form using LC-MS/MS.

Transport of mycotoxins across human gastric NCI-N87 and intestinal Caco-2 cell models.

Aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisin B1 (FB1), and ochratoxin A (OTA) are prevalent mycotoxins co-occurring in food, and their oral intake is conceivable to occur in the gastrointestinal epithelium. The intestinal absorption of some mycotoxins has been studied but only considering their isolated intake, while their gastric absorption in humans has not been explored. This study evaluated the bidirectional in vitro transport of four mycotoxins, isolated and in mixture, across gastric NCI-N87 and intestinal Caco-2 monolayers. AFB1 and DON were bidirectionally transported, more rapidly for AFB1; whereas OTA and FB1 were only transported in the absorptive direction, the first in both monolayers, and the second only in the gastric epithelium. The mixture of four mycotoxins exhibited some differences in cell uptake/excretion ratios. AFB1 presented the highest fraction absorbed (>96%) isolated and in mixture, followed by DON (72.8 and 82.9%); and OTA (11 and 66%) when transported isolated and in mixture, respectively. Different absorptive patterns on both epithelia were found when mycotoxins are transported isolated or in mixture. Further investigation on combined ingestion of toxins and their mixed transport should be considered for the proper evaluation of human absorption and toxicity of those mycotoxins considering their frequent co-occurrence and consequent co-exposure.

Influence of oven and microwave cooking with the addition of herbs on the exposure to multi-mycotoxins from chicken breast muscle.

Mycotoxins can contaminate poultry production via fungal infection of feeds. The impact of different cooking methods on mycotoxins stability and bioaccessibility is scarcely studied. Recent cooking practices such as the use of roasting bags along with some seasonings to cook chicken have become a trend to maintain the tenderness of the meat. This study evaluated the impact of oven roasting and microwaving of chicken breast muscles, with/without roasting bags and/or herbs addition on the stability and bioaccessibility of the 10 prevalent mycotoxins. Cooking itself reduced mycotoxins content, while using bags did not confer any advantage; adding herbs reduced mycotoxins content by up to 60%, but also appeared to increase their bioaccessibility. Thus, strategies to reduce their increased bioaccessibility should be the subject of future research. Notwithstanding, adding herbs prior to cooking could be used as a mitigation strategy to reduce mycotoxins in meat.

Exploring sub-individual variability: role of ontogeny, abiotic environment and seed-dispersing birds.

Within-individual trait variation - otherwise known as sub-individual variation - is an important component of phenotypic variation, with both a genetic and epigenetic basis. We explore its adaptive value and the effects of ontogeny and the environment on sub-individual variability. We conducted a field study to analyse the effects of tree age, soil pH, soil water content and soil nutrients on sub-individual variability in fruit size of hawthorn (Crataegus monogyna) in three sites in northwest Spain. Additionally, we examined how bird-mediated selection influences average and sub-individual variation in fruit size. Results show that average and sub-individual variations in fruit size were related to fitness affecting seed dispersal. Older trees produced larger fruits, but tree age did not affect sub-individual variation in fruit size. Abiotic environmental factors differently affected sub-individual variation and average fruit size. Seed-dispersing birds exerted correlated selection on average and variation in fruit size, favouring trees with larger and less variable fruit size at one site. Our work suggests that the fruit size variation within individual trees, the sub-individual variation, is modified by abiotic environmental factors and, additionally, is an adaptive trait that responds to natural selection.

Clinical Evolution of Patients Using Ventricular Assist Devices as a Bridge for Transplantation.

OBJECTIVE: To evaluate the clinical evolution of patients with implantation of ventricular assist device (VAD) and identify the intervening factors for death. METHODS: This analytical, retrospective study was carried out in a public reference hospital in cardiopulmonary diseases located in northeastern Brazil. The study population encompassed the medical records of 16 patients who underwent VAD implantation. Data collection took place from January to August 2016, through the consultation of medical records. Descriptive analysis, odds ratio, and the Fisher's Exact, Wilcoxon, Friedman and t-tests were used to analyze the data. RESULTS: All patients experienced complications during the use of the device, with bleeding being the main cause (11 [68.8%]). There was a significant decrease in noradrenaline (P = .025), milrinone (Primacor; P = .007), and dobutamine (P = .046) flow rates with the clinical evolution of patients. Regarding hematologic parameters, the use of VAD promoted a significant improvement in hemoglobin (P < .001), hematocrit (P = .003), activated partial thromboplastin time (P = .013), and fibrinogen (P = .049) values at the 3 time points analyzed. Regarding the clinical outcome of the patients, the majority (10 [62.5%]) underwent cardiac transplantation. CONCLUSIONS: This study allowed for better knowledge of the clinical evolution of patients with VAD implantation, highlighting the benefits of this type of device as a bridge for heart transplantation.

Toxicological interactions between mycotoxins from ubiquitous fungi: Impact on hepatic and intestinal human epithelial cells.

Aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisin B1 (FB1) and ochratoxin A (OTA) are toxic fungal metabolites co-occurring naturally in the environment. This study aimed to evaluate the toxicological interactions of these mycotoxins concerning additive, antagonistic and synergistic toxicity towards human cells. The theoretical biology-based Combination index-isobologram method was used to evaluate the individual and binary effect of these toxins and determine the type of the interaction using as models Caco-2 (intestinal) and HepG2 (hepatic) cells. Cytotoxicity was assessed using the MTT test at the concentrations of 0.625-20 µM for all the compounds. DON exerted the highest toxicity toward both cells, OTA and AFB1 also showed a dose-effect response, whereas no toxicity was verified for FB1. Synergism or antagonism effects occurred when exposing AFB1-DON and AFB1-OTA on Caco-2 cells at higher or lower concentrations, respectively; while DON-OTA showed synergism throughout all inhibition levels. Concerning HepG2, AFB1-DON exerted a strong synergism, regardless of the level; whereas AFB1-OTA had slight synergism/nearly additive effect; and, OTA-DON had a moderate antagonism/nearly additive effect. Synergistic strengths as high as a dose reduction index of 10 for AFB1-DON were observed in hepatic cells. Taken together our findings indicate that the toxicological effects differ regarding the type of mycotoxins used for combinations and the stronger synergistic effect was observed for mixtures containing DON in both cells. Therefore, even though DON has not been classified as to its carcinogenicity to humans, this mycotoxin may present a serious threat to health, mainly when co-occurring in the environment.

Domestic Cooking of Muscle Foods: Impact on Composition of Nutrients and Contaminants.

Meat and fish are muscle foods rich in valuable nutrients, such as high-quality proteins, vitamins, and minerals, and, in the case of fish, also unsaturated fatty acids. The escalation of meat and fish production has increased the occurrence of pesticide and antibiotic residues, as result of pest control on feed crops, and antibiotics used to fight infections in animals. Meat and fish are usually cooked to enrich taste, soften texture, increase safety, and improve nutrient digestibility. However, the impact of cooking on nutritional properties and formation of deleterious compounds must be understood. This review summarizes studies, published in the last decade, that have focused on how domestic cooking affects: (i) composition of nutrients (protein, fatty acids, vitamins, and minerals); (ii) antibiotic and pesticide residue contents; and (iii) the formation of cooking-induced contaminants (heterocyclic aromatic amines, polycyclic aromatic hydrocarbons, and thermal degradation products of antibiotics and pesticides). Cooking affects the nutritional composition of meat and fish; frying is the cooking method that causes the greatest impact. Cooking may reduce the pesticide and antibiotic residues present in contaminated raw meat and fish; however, it may result in the formation of degradation products of unknown identity and toxicity. Control of cooking time and temperature, use of antioxidant-rich marinades, and avoiding the dripping of fat during charcoal grilling can reduce the formation of cooking-induced contaminants.

Clinical features and factors associated with non-carious cervical lesions and dentin hypersensitivity.

Determining the factors associated with NCCLs and DH in populations could guide the implementation of specific preventive measures. This study evaluated the clinical features and factors associated with non-carious cervical lesions (NCCLs) and dentin hypersensitivity (DH) in a Brazilian population. The participants were 118 patients at the Dentistry Clinic of our dental school. They completed an interview to obtain personal information and determine the possible factors associated with NCCLs and DH. Clinical examination was undertaken to record the NCCLs, shape of the lesion and certain occlusal factors. DH was diagnosed by air and probe tests. Data were analysed with the multilevel Poisson regression and prevalence ratios, and the respective 95% confidence intervals were calculated. The prevalence of NCCLs and DH among patients was 67·8% and 51·7%, respectively. Of a total number of 2902 teeth examined, 9·65% had NCCLs and 5·82% were sensitive to air. The most affected teeth for both conditions were the premolars. Most of the NCCLs were wedge-shaped and located in the maxilla. The factors associated with NCCLs and DH were age and presence of premature occlusal contacts. NCCLs were also significantly associated with consumption of wine and alcoholic beverages, and DH with consumption of acidic fruits and juices. NCCLs were a common finding, with higher frequency in more advanced age groups, the maxilla and premolars. A significant association occurred between NCCLs, premature contacts and consumption of wine and alcoholic beverages. DH was associated with NCCLs, premature contacts and with the consumption of acidic fruits and juices.

Powdered coconut water as a storage medium to preserve the viability of periodontal ligament cells: a laboratory study.

AIM: To investigate the ability of newly developed powdered coconut water formulas (ACP) with different osmolarities to maintain the viability of periodontal ligament (PDL) cells over time compared with other solutions. METHODOLOGY: Dogs teeth were extracted and stored for two periods, 3 h or 24 h, in the following media: long-shelf life CW (CW), pH-adjusted long-shelf life CW (pH-CW) and powdered CW that was pH and osmolality adjusted (ACP-404-I, 250 mOsm kg-1 H2 O; pH 7.0; ACP-404-II, 372 mOsm kg-1 H2 O; pH 7.0; ACP-404-III, 300 mOsm kg-1 H2 O; pH 7.4). The positive control group (Pc) corresponded to immediate measurement after tooth extraction, and two negative controls (Nc) corresponded to 3 h and 24 h of dry time. PDL cells were extracted, and cell viability analysed by Trypan blue exclusion. Data were analysed statistically using two-way anova followed by the Tukey test and one-way anova followed by the Dunnett test (P < 0.05). RESULTS: At 3 h and 24 h, ACP-404-I had a performance similar to those of ACP-404-II and pH-CW, with significantly higher (P = 0.004) percentages of viable cells than ACP-404-III and CW. The positive control group had a significantly higher (P = 0.002) percentage of viable cells than the negative control groups, CW and ACP-404-III, irrespective of the period evaluated. CONCLUSION: Powdered coconut water formulas, ACP-404-I and ACP-404-II, preserved viability for up to 24 h.

Seed predators exert selection on the subindividual variation of seed size.

Subindividual variation among repeated organs in plants constitutes an overlooked level of variation in phenotypic selection studies, despite being a major component of phenotypic variation. Animals that interact with plants could be selective agents on subindividual variation. This study examines selective pressures exerted during post-dispersal seed predation and germination on the subindividual variation of seed size in hawthorn (Crataegus monogyna). With a seed offering experiment and a germination test, we estimated phenotypic selection differentials for average and subindividual variation of seed size due to seed predation and germination. Seed size affects germination, growth rate and the probability of an individual seed of escaping predation. Longer seeds showed higher germination rates, but this did not result in significant selection on phenotypes of the maternal trees. On the other hand, seed predators avoided wider seeds, and by doing so exerted phenotypic selection on adult average and subindividual variation of seed size. The detected selection on subindividual variation suggests that the levels of phenotypic variation within individual plants may be, at least partly, the adaptive consequence of animal-mediated selection.

Proteins differentially expressed by Shiga toxin-producing Escherichia coli strain M03 due to the biliar salt sodium deoxycholate.

Shiga toxin-producing Escherichia coli (STEC) can cause conditions ranging from diarrhea to potentially fatal hemolytic uremic syndrome. Enteropathogen adaptation to the intestinal environment is necessary for the development of infection, and response to bile is an essential characteristic. We evaluated the response of STEC strain M03 to the bile salt sodium deoxycholate through proteomic analysis. Cell extracts of strain M03 grown with and without sodium deoxycholate were analyzed by two-dimensional electrophoresis; the differentially expressed proteins were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Three proteins were found to be differentially expressed due to sodium deoxycholate. Glycerol dehydrogenase and phosphate acetyltransferase, which are involved in carbon metabolism and have been associated with virulence in some bacteria, were downregulated. The elongation factor Tu (TufA) was upregulated. This protein participates in the translation process and also has chaperone activities. These findings help us understand strategies for bacterial survival under these conditions.

Study of the radio-opacity of base and liner dental materials using a digital radiography system.

OBJECTIVES: This study investigated the radio-opacity of commercially available glass ionomer cements (GICs), flowable resin composites (FRCs) and calcium hydroxide cements (CHCs) and compared this with the radio-opacity of enamel, dentine and aluminium stepwedge. 16 GICs, 8 FRCs and 4 CHCs were analysed. METHODS: Three sets of three samples were prepared: 1 mm, 2 mm and 3 mm thickness for GIC and FRC and 1 mm thickness for CHC. Specimens of enamel and dentine with the same thicknesses were obtained. As a control, an aluminium stepwedge was used. Radiographs were taken with a digital Kodak RVG 5000 (0.32 s, 30 cm). The images were analysed using the Image Tool(®) program (v. 2.00; The University of Texas Health Science Center, San Antonio, TV) to obtain the mean grey values. RESULTS: Analysis of variance was used to investigate the significance of differences among the groups. For pairwise comparisons, the Tukey test was applied (p < 0.05). The GICs Ionomaster (Wilcos, Petrópolis, Brazil), Maxxion (FGM, Joinville, Brazil), Bioglass R (Biodinâmica, Ibiporã, Brazil), Bioglass F (Biodinâmica), Vidrion R (SS White, Rio de Janerio, Brazil) and Vidrion F (SS White), presented radio-opacity lower than that of dentine. All FRCs and CHCs studied showed radio-opacity higher than that of dentine. Vitro Fil (DFL, Rio de Janeiro, Brazil), Magic Glass (Vigodent, Rio de Janeiro, Brazil), Vitrebond (3M, Sumaré SP, Brazil), Riva Self Cure (SDI, Victoria, Australia), Riva Light Cure (SDI), Fill Magic (Vigodent), Opallis (FGM, Joinville, Brazil), Surefil SDR (Dentsply, Milford, DE), Tetric N (Ivoclar Vivadent, Schaan, Lichtenstein), Tetric (Ivoclar Vivadent), Hydro C (Dentsply, Petrópolis, Brazil), Hydcal (Technew, Madalena, Portugal) and Liner (Vigodent) showed radio-opacity similar to or greater than that of enamel for all thicknesses. CONCLUSIONS: The increased thickness of the materials studied increases their radio-opacity. Some commercially available GICs used as a base and liner for restorations have a very low radio-opacity (Ionomaster, Maxxion, Bioglass R, Bioglass F, Vidrion R and Vidrion F).

Re-oligotrophication as a challenge for tropical reservoir management with reference to Itaparica Reservoir, São Francisco, Brazil.

The process of reservoir eutrophication has been recognised as a central problem in tropical reservoir environmental quality. Effects of eutrophication are complex interactions involving a decrease in water quality, especially loss of aquatic biodiversity, occurrence of undesired species such as cyanobacteria with its cyanotoxins, mass development of macrophytes such as Egeria densa with its mechanical impact on turbines, and an increase in greenhouse gas emissions, mainly of methane. The eutrophication process can be described by the OECD critical load concept or related models. The phosphorus use efficiency is given by the Chl a-P - relationship, indicating eutrophic conditions by only 10 µg L(-1) P in Itaparica Reservoir, Brazil. Eutrophication of the reservoir is quantified for internal phosphorus sources (inflow, mineralisation of inundated soils and vegetation, net cage aquaculture) and external ones (agriculture, emissions of natural caatinga vegetation and rural communities) The actual internal P load is calculated to be 0.40 g m(-2) a(-1), and the critical P load is given with 1.20 g m(-2) a(-1). The external P load amounts about 1.16 g m(-2) a(-1) and thus exceeds the critical export rate of 7.1 kg km(-2) a(-1) by 50%, thus a bundling of measurements has to be considered when attempting to promote re-oligotrophication.