Histological assessment of selected tissues in tigerfish (Hydrocynus vittatus Castelnau, 1861) from the Sanyati Basin,Lake Kariba,Zimbabwe: a DDT-sprayed area

A pilot investigation was conducted in 2014 in the Sanyati Basin of Lake Kariba to ascertain whether long-term DDT spraying in the Kariba catchment had a negative effect on fish health. The aim was to assess the health of tigerfish, Hydrocynus vittatus, by means of histological analysis and to analyse water, sediment and tissue samples for bioaccumulated levels of chlorinated pesticides, including DDT. Eighteen tigerfish were collected by seine netting along the north-eastern shoreline of the Sanyati Basin in April 2014 and samples of their gill, liver, kidney, muscle and brain tissue were processed for histology and assessed using light microscopy. No detectable levels of DDT and/or its metabolites were found in the water or sediment samples and only a low concentration of p,p′-DDE in fish tissues. No major histological alterations were observed in the fish tissues. Consequently, there seems to be no risk of DDT exposure following the consumption of tigerfish from the Sanyati Basin of Lake Kariba. These results were unexpected, given the historical use of DDT within the current study area. It is recommended that these findings be compared with those from other regions of Lake Kariba.     

THE BIRDS OF LIVINGSTONE TOWNSHIP,NORTHERN RHODESIA, 1942–1950

Summary

Clark, R. A. 1979. DDT contamination of the Sacred Ibis. Ostrich 50:134-138.

Samples of fat and brain from Sacred Ibises Threskiornis aethiopicus in Pretoria, Transvaal, were analyzed for organochlorine insecticides. Except for traces of p,p'-DDT only p,p'-DDE was found to occur (means of 28,35 mg/kg wet fat and 0,22 mg/kg wet brain). There was a significant correlation between the concentrations of DDE in the fat and brain of birds (r = 0,53; p ? 0,01). In the period when Sacred Ibises mobilized their fat reserves there was no significant correlation between the level of body fat and the concentration of DDE in either the brain or the remaining body fat.     

The geographic variation and potential risk of DDT in the blood of Pied Kingfishers from northern KwaZulu-Natal,South Africa

Evans, S.W. & Bouwman, H. 2000. The geographic variation and potential risk of DDT in the blood of Pied Kingfishers from northern KwaZulu-Natal, South Africa. Ostrich 71 (1 & 2): 351–354.

DDT has, since 1946 been used in the intradomicilliary control of malaria in northern KwaZulu-Natal. The Pied Kingfisher was selected as representative for organisms in relatively high trophic levels. Blood was obtained from Pied Kingfishers at Kosi Bay (n = 5), Pongolo Floodplain (n = 13), Mkuzi Nature Reserve (n = 4), Ndumu Nature Reserve (n = 4) and St Lucia (n = 3), extracted and analysed [SWEl] via gas chromatography. The highest blood DDE and σDDT concentrations were obtained for the birds from the Pongolo Floodplain (means of 95.92 μg 1^?1/107.01 μg μg 1^?1) and Kosi Bay Nature Reserve (means of 189.09 μg 1^?l/241.8 μg 1^?1). DDT was detected in the blood of Pied Kingfishers from Kosi Bay (mean 47.14 μg 1^?1) and Pongolo Floodplain (mean 44.34 pg 1^?1) only. This indicated their proximity to DDT application and the greater influx of DDT and its metabolites into the water component of these systems. The EDDT plasma concentrations in the Pied Kingfisher blood were calculated by multiplying the blood values of σDDT by 1.8. Using the regression, log₁₀Y = 0.7785 + 0.8593 (log₁₀X), relating the σDDT in eggs to σDDT in plasma of American Kestrel Falco sparverius it was possible to calculate the mean Pied Kingfisher egg σDDT concentration. The approximate mean Pied Kingfisher egg concentration of σDDT was calculated at 2.26 mg kg^?1 for Kosi Bay and 1.24 mg kg^?1 for the Pongolo Floodplain. Using the highest calculated plasma value of σDDT for Kosi Bay and the Pongolo Floodplain indicated that egg σDDT concentrations could be as high as 4.01 mg kg^?1 and 4.17 mg kg^?1 respectively. These calculated levels may be significant when compared to levels of DDE, known to have a detrimental effect, in the eggs of the Brown Pelican Pelecanus occidentalis, where a concentration of 2.5 to 3 mg kg^?1 was associated with substantially impaired reproductive success. The highest calculated egg concentration was nearing this level and it is therefore possible that the Pied Kingfisher population may be at risk.     

ON THE RACE OF CARDINAL WOODPECKER Dendropicos fuscescens (Vieillot) OCCURRING IN THE EASTERN TRANSVAAL

Summary

Hustler, K. &; Marshall, B.E. 1996. The abundance and food consumption of piscivorous birds on Lake Kariba, Zimbabwe-Zambia. Ostrich 67:23-32.

About 40 species of piscivorous birds have been recorded on Lake Kariba (Zimbabwe-Zambia) but only 26 were observed during this study, carried out in 1986–87. The Reed Cormorant Phalacrocorax africanus was the most numerous and made up 51.4% of all the birds seen, followed by the Whitewinged Black Tern Chlidonias leucoptera (26.7%), and the Darter Anhinga melanogaster (10.8%). Several species roosted or bred in the drowned trees which project above the lake surface but gently sloping shores were the most important feeding grounds. Relatively few birds were seen on steeply sloping shores or in open water. There was a distinct pattern of seasonal abundance, with birds being most numerous in the rainy season (November-April). The relative abundance of some fish species also was greatest during this period. There was a positive relationship between the numbers of some bird species and the relative abundance of these fish. The mean density of piscivores (0.05 ha^?1) was low compared to some other African waters. This is attributed to the fact that Lake Kariba is relatively deep and its shoreline is mostly steep. The mean population of 25 000 birds consumed less than 1000 t of fish per annum, compared to almost 40000 t taken by the commercial fisheries. A considerable portion of the birds' diet was fish that were not taken commercially.     

PRODUCTION OF THE AFRICAN CATFISH (CLARIAS GARIEPINUS) I. GROWTH,MORTALITY AND YIELD SOUTH OF THE ZAMBEZI

SUMMARY

Clarias gariepinus were sampled from eight water bodies in southern Africa between 1973 and 1975. Aging results indicate a similar growth pattern for most areas with a near linear age-length relationship. Between year growth compensation was found to be present in Lakes Kyle and Mcllwaine in Zimbabwe, and to a lesser extent in Hardap Dam, South West Africa, but not present in Lake Kariba, Zimbabwe.

The fishable biomass of catfish from Lake Kyle is estimated between 0,61 to 1,14 kg ha^?1. Fishable biomass for all species is in the range 12,1 to 22,7 kg ha^?1.

The instantaneous growth rate was found to be between 0,20 and 0,25 for fully recruited age groups. The fishing mortality appears to be in the range of 0,4 for Lakes Kyle and Kariba and 0,5 for Lake McIlwaine. All of these levels are above the yield per recruit F₀, 1 levels of 0,27, 0,28 and 0,24 respectively which would normally indicate that each of these stocks is being overexploited. However, this does not appear to be the case in these tropical impoundments.     

Organochlorine pesticides in Cyprinus carpio from Sidi Salem Dam,north-western Tunisia

Cyprinus carpio (Linnaeus, 1758) caught in Sidi Salem Dam in 2011 were analysed for the levels of organochlorine pesticides (OCPs), including hexachlorobenzene (HCB), aldrin, heptachlor, lindane, dieldrin, endrin, and pp′-DDT and its two main metabolites pp′-DDD and pp′-DDE, in order to evaluate the extent of contamination of the dam. Fish were sampled monthly within the dam during 2011. Muscle, liver and gill tissues were analysed by gas chromatography for the determination of OCPs. Samples had variable concentrations of OCPs, ranging from 2.26 to 17.93 ng g?1, 0.59 to 42.67 ng g?1 and 3.30 to 84.27 ng g?1, which were isolated from gills, muscle and liver, respectively. The organochlorine pesticide levels found posed no threat to human health. The highest OCP levels were found in the liver tissues. The pp′-DDE concentrations and their ratios to ΣDDTs indicate aged DDT pollution and suggests that there has been no recent input of technical DDT from the agricultural areas into Sidi Salem Dam.     

Effects of DDT on the Fish Eagle Haliaeetus vocifer population of Lake Kariba in Zimbabwe

Twenty clutches were collected from nests of Fish Eagles Haliaeetus vocifer at Lake Kariba, Zimbabwe, and a small dam nearby in 1989-90. Unaltered DDT, and metabolites DDD and DDE, were found in every egg. Mean levels of σDDT(= DDT + DDD + DDE) generally varied from 14 to 49 mg/kg dry weight per clutch, but 113–223 mg/kg dry weight were found in clutches from the eastern end of the lake and the mouth of the Sengwa River. SDDT and DDE levels were significantly correlated with the Ratcliffe Index of eggshell thickness. Comparison with museum specimens showed that the Ratcliffe Index has declined by 11% since 1936-41 due to a significant fall in shell weight. Eggshell thinning exceeded 20% at the eastern end of the lake.
Aerial surveys in 1987 and 1990 found that hatching success along the southern lakeshore exceeded 72%, but chicks were seen in fewer than half the nests at the eastern end. However, the density of breeding pairs was greatest here.
Residue levels have increased by about 8% since 1980, rising more steeply in areas recently sprayed for tsetse fly control and falling in others. The threat from DDT may now be receding as regional use has declined and will end, for tsetse fly control, by 1995. None was used for this purpose in 1991. Mercury levels in adult birds were very high and may pose a significant risk.
The breeding population may be limited by availability of safe nest sites. Chicks are sometimes eaten by people. Settlement along the lakeshore is increasing and safe sites are becoming scarcer as dead trees in the lake collapse and large trees onshore are destroyed by elephants.     

Mercury and chlorinated hydrocarbons in the food chain of Lake Päijänne, Finland

The sediments and various organisms in Lake Päijänne were examined for contaminants. The average mercury content of water plants was 9, of plankton 14, of sediment 114, of zoobenthic predators 83, of fish 332–1510 and of birds 240–13685 μg kg⁻¹ (wet weight). The average PCB content of plants was 3, of plankton 21, of the zoobenthos 44, of fish 36-117 and of birds 219–13490 μg kg⁻¹. The average ΔDDT content of plants was 0.5, of plankton 6, of the zoobenthos 14, of fish 7–42 and of birds 144-8262 μg kg⁻¹. Regional differences in mercury content were most pronounced in sediment and fish. PCB concentration was highest near a town. ΔDDT was quite evenly distributed. Water plant species did not differ from each other, nor did the plankton fractions. The zoobenthic predators contained more chlorinated hydrocarbons than did the herbivores. There were clear differences between most species of fish and the chlorinated hydrocarbon content was highest in vendace. In adult birds levels of all residues were significantly higher than in juveniles.
In most cases PCB content was positively correlated with ΔDDT and in birds PCB, ΔDDT and mercury levels were correlated. DDT residues occurred mostly as DDE, but in vendace the proportion of DDT was high. At most trophic levels, ΔDDT/PCB was 0.15-0.40 but in birds it reached 1–2.     

Tissue Residue Guideline for ∑DDT for Protection of Aquatic Birds in China

DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is a chlorinated hydrocarbon insecticide that has been used worldwide. While the use of DDT has been phased out in many countries, it is still produced in some parts of the world for use to control vectors of malaria. DDE (1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene) and DDD (1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) are primary metabolites of DDT and have similar chemical and physical properties. DDT and its metabolites (DDE and DDD) are collectively referred to as ∑DDT. The lipophilic nature and persistence of the ∑DDT result in biomagnification in wildlife that feed at higher trophic levels in the food chain. Wildlife in aquatic ecosystems depend on aquatic biota as their primary source of food, which provide the main route of exposure to ∑DDT. Studies about effects of ∑DDT on birds were reviewed. The tissue residue guidelines for DDT (TRGs) for protection of birds in China were derived using species sensitivity distribution (SSD) and toxicity percentile rank method (TPRM) based on the available toxicity data. Risks of ∑DDT to birds were assessed by comparing the TRGs and ∑DDT concentrations in fishes from China. The tissue residue guideline for protection of birds in China is recommended to be 12.0 ng ∑DDT/g food.     

Effects of sex and sampling site on the relative proportion of pesticides in uropygial gland secretions of European Blackbirds (Turdus merula)

Dichlorodiphenyltrichloroethane (DDT) is a pesticide that was commonly used for decades worldwide. The use of DDT was banned in the 1970s and 1980s in Europe because of its high toxicity and persistence in the environment, bioaccumulation in living organisms and biomagnification through food webs. However, monitoring using both invasive and non-invasive methods has routinely reported the occurrence of DDT metabolites such as dichlorodiphenyldichloroethylene (DDE) in wild birds, providing valuable information about the exposure to pesticides and potential differences between species and over time. Here, we analysed the relative proportion of DDE in the uropygial gland secretions of European Blackbirds Turdus merula from two localities in southern Spain. Given the negative effects of this pollutant on animal immunity, we also tested for associations between the prevalence of haemosporidians and the relative proportion of DDE in their secretions. Relative proportions of DDE varied between sampling sites and were higher in females than in males, regardless of their age. In spite of the potential immunosuppressive effect of DDE, haemosporidian infection was not associated with DDE presence.     

Health and chemical burdens of fish species from polluted and hyper-eutrophic freshwater ecosystems in South Africa

Three aquatic ecosystems in South Africa, the Hartbeespoort, Klipvoor and Bospoort Dams, are classified as hyper-eutrophic, because of high nutrient loads and chemical pollution. Water and two fish species, Clarias gariepinus and Cyprinus carpio, were collected from these dams to assess the impact of eutrophication and chemical pollutants on their health status. Water and muscle samples were analysed for organic and inorganic chemicals. Condition factor was determined and a necropsy performed to note any macroscopic abnormalities. A histology-based fish health assessment was done on the liver, kidney, gills and gonads. A number of fish from the three dams exhibited livers with fatty change and focal discoloration, skin lesions and parasites within the visceral cavity. The prevalence and severity of histopathology in the liver resulted in higher liver index values than the index values for kidneys and gills. Aluminium, silicon and chromium were detected in the water and muscle tissue. The DDT metabolite p,p’-DDE was present in both species, as well as in fish from the reference site, Marico-Bosveld Dam. Only C. gariepinus from Hartbeespoort Dam had p,p’-DDD levels higher than 5 µg g^?1 per edible portion. Water from hyper-eutrophic dams adversely affects the health of freshwater fish.     

Elevated Concentrations of Pesticides and PCBs in Soils at the Southern Caspian Sea (Iran) are Related to Land Use

Soil contamination by organochlorine pesticides or PCBs is almost undocumented for Iran. Here we report a soil survey in Mazandaran and Guilan provinces that hold >30% of the agricultural areas of Iran where pesticide use is widespread. Concentration of DDTs, HCHs, cyclodienes, and PCBs were measured in 45 soil samples from different agricultural land uses and forest land. The average concentrations of ∑DDT (37 μg kg^?1) and ∑HCH (21 μg kg^?1) in agricultural soils are among the largest ever reported and exceed international soil screening standards. All residues were larger in agricultural than in forest soil. Within agricultural land, ∑DDT were largest for tea gardens, lindane was largest in rice fields, and cyclodiens largest in citrus orchards. The ratio of (DDD + DDE)/DDT is an index of the extent of DDT degradation in soil and was lower in tea gardens than in other soils (0.7 versus 2–5), indicating either ongoing DDT input or lower degradation rate in the tea gardens that are more acid than the other soils (pH 4.5 versus 6.5–7.0). The o,p′–DDT/p,p′–DDT ratio was about 3 in forest soils, suggesting that DDT is derived from dicofol application and not from technical DDT as in agricultural soils. The PCB 28, 180, and 138 showed the highest mean concentration compared with other PCB congeners in all land uses. This survey is the first of this kind for Iran and illustrates that concentrations of organochlorine pesticide in soil are relatively large.     

Inhibition of photosynthetic electron transport by DDT and DDE

The effect of DDT and DDE (a metabolite of DDT) on chloroplast electron transport was investigated. Photosynthetic electron transport in isolated spinach and barley chloroplasts as well as chloroplasts isolated from macroscopic green algae,Cdium fragile andChaetomorpha aerea, was inhibited by both compounds. Photoreduction and photophosphorylation measured in the presence of ferricyanide showed 50% inhibition at 2×10^–5 M DDT and DDE. P/2e ratios were 1·2–1·5, and remained constant in the presence of both inhibitors. The addition of uncouplers such as ammonium ion and carbonyl cyanide,m-chlorophenylhydrazone did not overcome the inhibition of the chlorinated hydrocarbons. Inhibition of phenazine methosulfate-catalyzed cyclic photophosphorylation by DDT and DDE was observed at low light intensities but was not seen at 2·5×10⁵ erg cm^–2sec^–1 and above. In the presence of DDT, a slow rise in measuring beam fluorescence was observed. The actinic beam fluorescence was slightly less than that in the control. Inhibition by DDT and DDE appears to be similar to that of DCMU. Brief sonication of the chloroplasts increases the sensitivity to DDT. The lack of penetration of DDT to terrestrial plant chloroplasts may be the reason why these are protected from this insecticide.     

Influence of Visceral Obesity and Liver Fat on Vascular Structure and Function in Obese Subjects

Endothelial dysfunction and increased intima–media thickness (IMT) have been found in obese patients. Both regional fat distribution and liver steatosis may influence these markers of subclinical atherosclerosis. We sought to determine the interrelationships of endothelial function, carotid IMT, visceral and subcutaneous adipose tissue accumulation, and liver steatosis in severely obese subjects. In 64 severely obese patients (BMI 42.3 ± 4.3 kg/m²), we determined (i) endothelial function as flow‐mediated dilation (FMD) of the brachial artery, (ii) carotid IMT, (iii) visceral fat diameter, and (iv) degree of liver steatosis using ultrasound. FMD was associated inversely with visceral fat diameter and degree of steatosis (r = ?0.577, P < 0.0001 and r = ?0.523, P < 0.0001, respectively). Carotid IMT correlated with visceral fat mass (r = 0.343, P = 0.007) but not with liver steatosis. After adjustment for conventional cardiovascular risk factors, FMD was predicted independently by the visceral fat diameter, age, and sex (r² = 0.48, P < 0.0001), but not by the degree of liver steatosis or plasma adiponectin levels. In contrast, age and sex were the only predictors of IMT (r² = 0.33, P < 0.001). In obese patients, visceral fat diameter is a major determinant of endothelial dysfunction, independent of traditional risk factors or the degree of liver steatosis and plasma adiponectin. Measurement of visceral fat diameter by ultrasound is a novel and simple method to identify subjects with an increased risk for atherosclerosis within an obese population.     

Organic contaminant exposure in the Lake St. Clair food web

Chemical concentrations and distributions in an aquatic food web were studied to quantify the relative importance of chemical properties versus food web processes in determining exposure dynamics of organic contaminants in aquatic ecosystems. Five organochlorines were measured (Pentachlorobenzene QCB, Hexachlorobenzene HCB, Octachlorostyrene OCS, Dichlorodiphenyldichloroethylene DDE and Polychlorinated Biphenyls PCBs) in the food web of Lake St. Clair. Levels of QCB in aquatic organisms ranged from 1.0 to 25 µg kg^–1 lipid, and levels of HCB ranged from 10 to 410 µg kg^–1 lipid. More elevated concentrations of OCS (13 to 392 µg kg^–1 lipid), DDE (162 to 11 986 µg kg^–1 lipid) and PCB (650 to 64 900 µg kg^–1 lipid) were observed. Organism — water equilibrium ratios were calculated for all species sampled to quantify the importance of food web processes in regulating contaminant exposure dynamics. Correlations of organism — water equilibrium ratios with body size were not significant for QCB, HCB and OCS (P>0.1), but were found to be significant for DDE and PCB (P<0.01).Results support the conclusion that both chemical properties and food web dynamics regulate the distribution and concentration of organochlorines in aquatic ecosystems. Food web processes are important, however, for chemicals, that are not metabolized and have octanol — water partition coefficients (log K _ow) greater than 5.5.     

Mercury in the marine food chain in the Southern Ocean at Macquarie Island: an analysis of a top predator,Patagonian toothfish (<Emphasis Type="Italic">Dissostichus eleginoides</Emphasis>) and a mid-trophic species,the warty squid (<Emphasis Type="Italic">Moroteuthis ingens</Emphasis>)

The characteristics and habitat of the Patagonian toothfish (Dissostichus eleginoides) are typical of fish that accumulate high concentrations of mercury. In this study, mercury determinations were made on samples of muscle tissue from Macquarie Island toothfish and the Southern Ocean deepwater warty squid (Moroteuthis ingens). The analysis of mercury in the biological tissues was made by cold vapour-atomic absorption spectrometry following acid digestion. Performance of the analytical procedure was assessed by analysis of certified reference material (DORM-2, dogfish muscle). Mercury concentrations of 16 Macquarie Island toothfish ranged from 0.12 mg kg^–1 (550 g, 381 mm TL) to 0.59 mg kg^–1 (6,100 g, 823 mm TL), with a mean concentration of 0.33±0.12 mg kg^–1. A significant correlation was found between mercury and either toothfish weight or total length. The fish analysed were juveniles, which suggests that larger individuals would have higher mercury concentrations well exceeding food standard code limits for mercury in fish (typically 0.5 mg kg^–1). Warty squid, also from around Macquarie Island, had a low mean mercury concentration of 0.086 mg kg^–1 in mantle tissue; no significant correlation existed between mercury concentration and either squid mantle length or total weight. It is postulated that the squid have a mechanism, possibly involving the digestive gland, that prevents bioaccumulation of mercury in the mantle, and presumably other body tissues.     

Visceral fat is an independent predictor of all-cause mortality in men

Objective: To examine the independent associations of abdominal fat (visceral and subcutaneous) and liver fat with all‐cause mortality. Research Methods and Procedures: Participants included 291 men [97 decedents and 194 controls; mean age, 56.4 ± 12.0 (SD) years] who received a computed tomography (CT) examination at the preventive medicine clinic in Dallas, TX, between 1995 and 1999, with a mean mortality follow‐up of 2.2 ± 1.3 years. Abdominal fat was determined using contiguous CT images from the L3‐L4 to L4‐L5 intervertebral space. Liver fat was assessed using the CT‐determined liver attenuation value, which is inversely related to liver fat. Logistic regression was used to determine the independent association between the fat depots and all‐cause mortality. Results: During the study, there were 97 deaths. Visceral fat [odds ratio (OR) per SD: 1.83; 95% CI: 1.23 to 2.73], abdominal subcutaneous fat (1.44; 1.02 to 2.03), liver fat (0.64; 0.46 to 0.87), and waist circumference (1.41; 1.01 to 1.98) were significant individual predictors of mortality after controlling for age and length of follow‐up. In a model including all three fat measures (subcutaneous, visceral, and liver fat), age, and length of follow‐up, only visceral fat (1.93; 1.15 to 3.23) was a significant predictor of mortality. Discussion: Visceral fat is a strong, independent predictor of all‐cause mortality in men.     

CHANGES IN THE ABUNDANCE AND MORTALITY RATE OF TIGERFISH IN THE EASTERN BASIN OF LAKE KARIBA

SUMMARY

Tigerfish populations increased in the eastern basin of Lake Kariba following the successful invasion of the pelagic clupeid Limmothrissa miodon. Strong year-classes persisted for several years but the number of young tigerfish declined, a phenomenon which cannot be accounted for. The influence of these year classes on different fisheries was demonstrated. The mortality rate of the younger fish was related to the rate at which their numbers were changing with mortality rates being highest when numbers were declining most rapidly. Concern about the future of this fish was expressed because of increased fishing in its main breeding area.     

Impact of Obstructive Sleep Apnea on Liver Fat Accumulation According to Sex and Visceral Obesity

Rationale

Associations between obstructive sleep apnea (OSA) and liver fat accumulation have been frequently investigated because both morbidities are common. Visceral fat was reported to be closely related to OSA and liver fat accumulation. Recently, sex differences in the association between OSA and mortality have gained much attention.

Objectives

To investigate the associations among OSA, liver fat accumulation as determined by computed tomography, and visceral fat area and their sex differences.

Methods

Studied were 188 males and 62 females who consecutively underwent polysomnography and computed tomography.

Results

Although the apnea-hypopnea index was positively correlated with liver fat accumulation in the total males, none of the OSA-related factors was independently associated with liver fat accumulation in either the total male or female participants in the multivariate analyses. When performing subanalyses using a specific definition for Japanese of obesity or visceral obesity (body mass index (BMI) ≥25 kg/m² or visceral fat area ≥100 cm²), in only males without visceral obesity, percent sleep time with oxygen saturation <90%, in addition to BMI, insulin resistance, and serum triglyceride values, was independently correlated with liver fat accumulation (R² = 15.1%, P<0.001). In males, percent sleep time of oxygen saturation <90% was also a determining factor for alanine aminotransferase values regardless of visceral fat area. In contrast, OSA was not associated with liver fat accumulation or alanine aminotransferase values in females whether or not visceral obesity was absent.

Conclusions

Sex differences in the visceral fat-dependent impact of OSA on liver fat accumulation existed. Although the mechanisms are not known and ethnic differences may exist in addition to the specific criteria of visceral obesity in Japan, the treatment of male patients with OSA might be favorable from the viewpoint of preventing liver fat accumulation and liver dysfunction even in patients without obvious visceral fat accumulation.     

Population dynamics of two small cichlid fish species in a tropical man-made lake (Lake Kariba)

The population dynamics of two small cichlid fishes (Pharyngochromis darlingi andPseudocrenilabrus philander) were studied in Lake Kariba, a very large African man-made lake. They are of no economic importance but make up about 14% and 7% respectively of the inshore fish population and are the major components of the diet of fish-eating birds on the lake.P. darlingi isthe larger species (L = 156.5 mm) and is found on both shelving and steep, eroding shores. Its mortality rate differs in each habitat (Z = 0.44 and 0.72 month^–1 respectively), only 0.79% survive for 12 months and its % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaiaac+% cadaqdaaqaaiaadkeaaaaaaa!384D!\[P/\overline B \] ratio is 5.45 (on shelving shores).Ps. philander is smaller (L = 83.9 mm) and is restricted to shelving areas with abundant vegetation. Its monthly mortality rate was high (Z = 7.69), only 0.05% survive to 12 months whilst its % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaiaac+% cadaqdaaqaaiaadkeaaaaaaa!384D!\[P/\overline B \] ratio was very high (7.69). The estimates of growth obtained forP. darlingi differ considerably from those given in an earlier study in Lake Kariba and some possible reasons for this are discussed. In suitable habitats, the combined production of both species could be 40 kg ha^–1 yr^–1 which indicates their potential importance to the ecology of the lake.