Distribution and depuration of the potentially carcinogenic malachite green in tissues of three freshwater farmed Chinese fish with different food habits

The use of malachite green (MG) in fish farming is prohibited in China due to its potentially toxicological and carcinogenic nature, but it is still illegally used in some places. Uptake, accumulation and deputation of MG in various tissues were studied under laboratory conditions in three common freshwater fish, Parabramis pekinensis (plant-eating fish), Carassius auratus (omnivorous fish) and Ophiocephalus argus (carnivorous fish). The concentrations of MG and its primary metabolite, the reduced and colorless leucomalachite green (LMG), were analyzed by liquid chromatography-mass spectrometry (LC-MS2). Absorption of MG occurred during the waterborne exposure and the MG concentrations in gills of the three fish species all showed a maximum at 0 h after an acute water exposure (6 mg l(-1) MG for 20 min). Afterwards, both MG and LMG declined very rapidly in the blood of the fish. Levels of MG and LMG were still above 0.002 mu g g(-1) in fresh weight muscle at 240 h and may persist for as long as 10 days. Most MG was converted rapidly to LMG in the fish and deputation of LMG was very slow in fat tissue. skin and gonads of the fish. Distribution of LMG was strongly dependent on the fat content in the tissues of the fish, but not related to their different feeding habits. Therefore, it appears that fat tissue, skin and gonads of the fish contaminated by MG and LMG pose the greatest risk for human consumption. (C) 2008 Published by Elsevier B.V.

Food habits of two-year-old Chinese mitten crab (Eriocheir sinensis) stocked in Lake Bao'an, China

Gastric mills of 362 specimens of two-year-old Chinese mitten crab (Eriocheir sinensis), which contained recognizable food items, from Lake Bao'an, China were examined. The food items were macrophytes, algae, arthropods, oligochaetes, fish, protozoa, rotifers, gastropods, and detritus, and the percent frequencies of occurrence (FO) for these items were 87.3%, 82.0%, 48.2%, 28.2%, 28.7%, 0.3%, 0.6%, 0.3% and 88.7%, respectively. Unidentified animal tissue was often observed and had a FO of 46.1%. In total, FO of plants (macrophytes + algae) was 87.7% and of animals was 89.8%. However, 5.8% of the gastric mills contained only animals, 5.3% had only macrophytes, and 0.3% contained only algae. There was no significant difference (p>0.05) in food habits between male and female crabs. The ratio of cell number of macrophytes to algae was about 156:1.

Food habits and feeding rhythm of the early juvenile Chinese mitten crab (Eriocheir sinensis) in experimental tanks

Gastric mills were examined from 98 early juvenile Chinese mitten crabs (Eriocheir sinensis) from experimental tanks. Recognizable food items were macrophytes, algae, oligochaetes, and detritus; their percent frequencies of occurrence were 94.6%, 86.5%, 10.7%, and 18.3%, respectively. The crabs had a diet feeding rhythm.

Food utilization of adult flatfishes co-occurring in the Bohai Sea of China

Stomach contents were examined of 4527 adult individuals of 12 flatfish species collected during the 1982 - 1983 Bohai Sea Fisheries Resources Investigation. Their food habits, diet diversity, similarity of prey taxa, trophic niche breadth and diet overlap were systematically analysed. Ninety-seven prey species belonging to the Coelenterata, Nemertinea, Polychaeta, Mollusca, Crustacea, Echinodermata, Hemichordata and fish were found and five of them were considered to be principal prey for flatfishes: Alpheus japonicus, Oratosquilla oratoria, Alpheus distinguendus, Loligo japonicus and Crangon affinis. Among the flatfishes, Paralichthys olivaceus was piscivorous, whereas Pseodopleuronectes yokohamae and Pseudopleuronectes herzensteini both had polychaetes and molluscs as their main prey groups. Pleuronichthys cornutus was classified as a polychaete-mollusc eater, with a strong preference for crustaceans. Verasper variegatus, Cynoglossus semilaevis, Eopsetta grigorjewi and Cleisthenes herzensteini ate crustaceans. Kareius bicoloratus was classified as a mollusc-crustacean eater: Cynoglossus abbreviatus, Cynoglossus joyneri and Zebrias zebra were grouped as crustacean-fish eaters. However, Z. zebra also took polychaetes and C. abbreviatus and C. joyneri preyed on some molluscs. Trophic relationships among the flatfishes were complicated, but they occupied distinctive microhabitats in different seasons and selected their specific prey items, which was favourable to the stability of the flatfish community in the Bohai Sea.

Effect of dietary carbohydrate sources on growth performance and utilization for gibel carp (Carassius auratus gibelio) and Chinese longsnout catfish (Leiocassis longirostris Gunther)

The nutritional function of monosaccharides, disaccharides and polysaccharides for omnivorous gibel carp and carnivorous Chinese longsnout catfish were investigated and the ability of these two species to utilize carbohydrates was compared. For each species, triplicate groups of fish were assigned to each of five groups of isoenergetic and isonitrogenous experimental diets with different carbohydrate sources: glucose, sucrose, dextrin, soluble starch (acid-modified starch) and alpha-cellulose. The carbohydrates were included at 60 g kg(-1) in Chinese longsnout catfish diets and at 200 g kg(-1) in gibel carp diets. A growth trial was carried out in a recirculation system at 27.8 +/- 1.9 degrees C for 8 weeks. The results showed that fish with different food habits showed difference in the utilization of carbohydrate sources. For gibel carp, better specific growth rate (SGR) and feed efficiency (FE) were observed in fish fed diets containing soluble starch and cellulose, but for Chinese longsnout catfish, better SGR and FE were observed in fish fed diets containing dextrin and sucrose. Apparent digestibility coefficient of dry matter (ADC(d)) and apparent digestibility coefficient of energy (ADC(e)) were significantly affected by dietary carbohydrate sources in gibel carp. ADC(d) and ADC(e) significantly decreased as dietary carbohydrate complexity increased in Chinese longsnout catfish except that glucose diet had medium ADC(d) and ADC(e). In both species, no significant difference of apparent digestibility coefficient of protein was observed between different carbohydrate sources. Dietary carbohydrate sources significantly affected body composition, and liver phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK), glucose 6-phosphate dehydrogenase (G6PD) and malic enzyme (ME) activities also varied according to dietary carbohydrate complexity. Fish with different food habits showed different abilities to synthesize liver glycogen, and the liver glycogen content in gibel carp was significantly higher than in Chinese longsnout catfish. The influence of carbohydrate source on gluconeogenesis and lipogenesis was also different in the two fish species.

DRAMATIC CONSEQUENCES OF FOOD HANDOUTS TO MACACA-THIBETANA AT MOUNT-EMEI, CHINA

Food handouts to Macaca thibetana at Mt. Emei have had dramatic consequences for both man and monkey as tourism has increased over the last decade. Food handouts and human submissive behaviour facilitate beg-robbing by the monkeys. which can be regarded as a mixed conditioning chain. Because of their lack of understanding of primate behaviour and resulting inappropriate responses, many visitors have lost possessions and have been severely frightened or even injured; in fact there have been 1 0 deaths as an indirect result over that past 8 years. The appropriate human response proved to be the display of dominance to maintain a distance from a beg-robbing monkey. Road-ranging macaques have also been injured or killed by visitors to obtain meat or bones or merely for amusement. Attempts should be made to eliminate the negative effects of food handouts by increasing visitors' awareness of behavioural and ecological aspects and through aversive conditioning of the macaques.

Feeding habits of Calanus sinicus (Crustacea : Copepoda) during spring and autumn in the Bohai Sea studied with the herbivore index

Pigment ingestion rate (PIR) and egg production rate (EPR) of the dominant copepod Calanus sinicus, as well as chlorophyll-a concentration and phytoplankton assemblages were measured in the Bohai Sea, North China in June 1997, October 1998 and May 1999. A herbivore index (H) was also calculated as the carbon specific ratio of PIR and EPR, in order to investigate its feeding habits in the spring and autumn phytoplankton bloom respectively. On average, chlorophyll-a concentration was relatively similar (1-1.34 mg m(-3)) in the three cruises, but PIR was quite different. It was 3.24 mu g C female(-1) d(-1) in October, equivalent to one half of the PIR for June and one third of the PIR for May. Average EPR was highest in May, and quite similar during the other two months. According to H values, herbivorous feeding contributed 100% of the egg production of C. sinicus in June, 82.5% in May, but only 47.8% in October. It is possible that omnivorous feeding of C. sinicus in October was induced by a prevalence of large-sized diatoms and sufficient non-phytoplankton food resources during the autumn bloom period.