Effects of food and topography on ranging behavior of black crested gibbon (Nomascus concolor jingdongensis) in Wuliang mountain, Yunnan, China

We studied the ranging behavior of a habituated group of black crested gibbons (Nomascus concolor jingdongensis) in a high, seasonal habitat on Mt. Wuliang, central Yunnan, China, between March 2005 and April 2006. Our results indicated that the total home range size for the study group was 129 ha, or 151 ha if the lacunae within the borders in which gibbons were not observed were included. This is a much bigger range size than that of other gibbon species. However, 69.7% of their activities occurred within 29 ha. The intensity of quadrant use was significantly correlated with the distribution of important food patches. The mean yearly daily path length was 1,391 m. Gibbons traveled farther when they spent more time feeding on fruit. To avoid often passing through ridges with little food, gibbons usually stayed in the same valley for successive days, and then moved on to another valley for another several days, which resulted in a concentrated ranging pattern.

Effects of live food and formulated diets on survival, growth and protein content of first-feeding larvae of Plelteobagrus fulvidraco

In recent years, much progress has been made in the rearing of fish larvae fed only artificial diets. A preliminary study was made in an attempt to evaluate the effects of live food and formulated diets on survival, growth and body protein content of first-feeding larvae of Plelteobagrus fulvidraco. Three test diets varying in protein level were formulated: Feed 1 containing 45% protein, Feed 2 with 50% protein and Feed 3 with 55% protein. Larvae fed live food (newly hatched Artemia, unenriched) were the control. The experiment started 3 days post-hatch and lasted for 23 days. At the end of the 23-day trial, survival was best in the control group (65.6%) whereby the final body weight and specific growth rate (SGR) were significantly lower than those in the test feed groups. At the same time, coefficients of variation for SGR and final body weight in the test groups were significantly higher than those in the control. Whole body protein content in all treatments showed a similar tendency during development: significantly higher 3 days post-hatch, then decreasing significantly, and then increasing unstatistically 10 days post-hatch. All results suggest that live food is still better for first-feeding larvae of P. fulvidraco, since live food leads to healthier larvae growth.

Effect of food and temperature on the growth and development of Moina irrasa (Cladocera : Moinidae)

Body length, instar duration, fecundity, and survival rate of Moina irrasa from a subtropical Chinese lake were studied at three food concentrations (4, 8, and 40 mg/L, wet weight) and six temperatures (10, 15, 20, 25, 30, and 35degreesC) in the laboratory. Body length tended to decrease with increase of temperature, while the trend was reversed as food concentration rose. M. irrasa had three juvenile instars, except there were four at 10degreesC, and the number of adult instars showed great variation (3-15). Water temperature and food concentration both affected the duration time of adult instars. The largest broods were from the third to sixth adult instars, depending on food and temperature, and the mean highest number of offspring per brood was 56 at 25degreesC. A significant relationship between body length and brood size appeared at high (40 mg/L) and medium (8 mg/L) food concentrations, while there was no significant relationship at low food concentration except at 25 degreesC. The intrinsic rate of population increase ranged between 0.104 and 1.825 ind./day.

Effect of available food and temperature on the growth and reproduction of Daphnia rosea

Population parameters of Daphnia rosea were studied at various concentrations of Chlorella sp. (0.25, 0.75 and 3.0 mg C l(-1)) at several temperatures (20, 25, 28, and 30 degrees C) in the laboratory. Although there were some differences in the degrees of the effects of the various temperature-food combinations, both food and temperature exerted influences on almost all of the main population parameters of D. rosea. At a water temperature of 28 degrees C, growth and reproduction were reduced, and at the lowest food level (0.25 mgC l(-1)), reproduction failed. D, rosea did not survive at 30 degrees C in spite of abundant food supply, indicating that 30 degrees C is a physiological limit. A positive relationship between body length and brood size was recognized at high and medium food levels. The slope of the regression was the highest at the highest food level and at the lowest temperature (20 degrees C). The low food level exerted a negative influence on the net reproductive rate by lowering the size of egg-bearing females, by decreasing the brood size of each size class, by decreasing the brood number per female, and by increasing the period of empty brood chamber. High water temperature (28 degrees C) also exerted a negative influence on the net reproductive rate in a similar way. For the better understanding of the key factors driving the midsummer dynamics of daphnids in the field, it may be of crucial importance to compare the population parameters of the field populations with experimentally derived values under controlled conditions of food concentration and temperature.

Grazing on toxic and non-toxic Microcystis aeruginosa PCC7820 by Unio douglasiae and Corbicula fluminea

To explore the potential grazing effects of mussels on Microcystis aeruginosa, a common bloom-forming phytoplankton, Unio douglasiae and Corbicula fluminea were fed with Scenedesmus obliquus, toxic and non-toxic strains of Microcystis aeruginosa as single food and as mixtures in the laboratory. When fed with single foods, U. douglasiae has similar clearance rates on the three algae populations, while C. fluminea has significantly lower clearance rate on toxic M. aeruginosa than those on the other two algae populations. When fed with mixture foods, both the mussels show significantly higher clearance rates than on single foods. The clearance rates of U. douglasiae on the different food mixtures are not significantly different, and C. fluminea has a significantly lower clearance rate on the toxic food mixtures than that on non-toxic food mixtures. Although the relative lower clearance rates of C. fluminea on toxic food, we may still deduce that both the mussels can exert grazing pressure on phytoplankton. The deduction is supported by the composition of the excretion products. The excretion products (faeces and pseudofaeces) of both mussels contained mainly S. obliquus. In both mixed-food treatments, the ratios of S. obliquus to M. aeruginosa in the excrete products are significantly higher than those in the foods. Therefore, it can be concluded that both mussels prefer M. aeruginosa to S. obliquus, and can cause grazing pressure on M. aeruginosa.

Diet overlap between the endemic fish Anablariflus grahami(Cyprinidae) and the exotic noodlefish Neosalanx taihuensis (Salangidae) in lake Fuxian, China

We studied diet composition and overlap of the exotic noodlefish (Neosalanx taihuensis) and the endemic fish Anaborilius grahami in a deep, oligotrophic lake in the Yunnan Plateau. A. grahami dominated the fish community in Lake Fuxian before the invasion of N. taihuensis in 1982, but it is now in the process of extinction, corresponding with an explosive increase in N. taihuensis population. Schoener's index (alpha=0.773) indicate that N. taihuensis and A. grahami have significant diet overlap, with both fish feeding mainly on zooplankton. An increased proportion of littoral prey, such as Procladius spp., Coleoptera, and epiphytes, in the diet of A. grahami indicated that this endemic fish shifted its main habitat from the off-shore zone in the late 1980s to the littoral zone at the present. A difference in reproduction between the two fishes, along with the overfishing, may have exacerbated the occupation of A. grahami's pelagic niche by N. taihuensis. The endemic species has shown large competitive disadvantage for food and space in the presence of N. taihuensis.

An enzyme-linked immunosorbent assay for rare minnow (Gobiocypris rarus) vitellogenin and comparison of vitellogenin responses in rare minnow and zebrafish (Danio rerio)

A competitive enzyme-linked immunosorbent assay (ELISA) was developed to determine vitellogenin (Vtg) in rare minnow (Gobiocypris rarus) based on the separation and purification of rare minnow Vtg (r-Vtg) as well as the production of polyclonal antibody against r-Vtg in rabbits. Three different ELISAs for measuring r-Vtg were then compared: (1) indirect ELISA with the antibody against carp (Cyprinus carpio) Vtg (c-Vtg) (IC-ELISA); (2) competitive ELISA with the antibody against c-Vtg, and using r-Vtg for coating the plates and preparing standard curve (CC-ELISA); (3) competitive ELISA with the antibody against r-Vtg, and using r-Vtg for coating the plates and preparing standard curve (CR-ELISA). The result showed that the homologous CR-ELISA was the most sensitive among the three assays for quantifying r-Vtg. The sensitivities to 17 alpha-ethinylestradiol (EE2) Of rare minnow and zebrafish (Danio rerio) were compared upon the establishment of homologous competitive ELISA. The lowest observed effect concentrations (LOECs) to induce Vtg were found to be 0.8 ng EE2 l(-1) for rare minnow and 4 ng EE2 l(-1) for zebrafish respectively. Afterwards, CR-ELISA was applied to measure Vtg concentration in whole body homogenate (WBH) of juvenile rare minnow fed by three diets (tubifex from wastewater treatment plant, Artemia nauplii and commercial pellet food), and the agreements between bioassay and GC-MS analysis demonstrated that rare minnow was a sensitive fish model for assessing estrogenic effects of endocrine disrupting compounds in aquatic environment. (c) 2006 Elsevier B.V. All rights reserved.