1990. Dynamics of filter feeding in Corbiculafluminea (Bivalvia: Corbiculidae). Can J. Zool. 68: 115-120. Filtration rates of Corbiculafluminea were measured using 2-pm microspheres from three riverine habitats which differed in ambient suspended particle concentration; rates were measured at particle concentrations spanning the range for the three habitats. Filtration rates were significantly different across the three habitats, and were inversely correlated with the mean ambient suspended particle concentrations: 66.4 mL/h for 1 1 mg/L, 100.2 mL/h for 7 mg/L, and 144.9 mL/h for 4 mg/L for the Tombigbee, Ouachita and Tangipahoa rivers, respectively. However, the weight of particles filtered by clams from the three rivers was not significantly different. These results indicate that C.fluminea can make physiological adjustments to its filtration rate to achieve some "optimal" rate of particle removal. Within each habitat, particle concentration had a significant effect on filtration rates for the Tombigbee River and Tangipahoa River populations; maximal filtration rates were observed in the range of ambient particle concentrations for each habitat. The effects of particle size and type on filtration rates were examined for clams from the Tombigbee River. Filtration rates were measured with microspheres of various sizes, natural suspended particles, and Chlorella. Filtration rates were highest with natural suspended particles; these particles were also the smallest in size (3 X 5 pm). Rates were also highest when measured with particles representative of the size range encountered in the field. There was no significant difference in filtration rates measured with similar-sized microspheres and Chlorella. Pseudofeces were produced by all sizes of clams from each population at particle concentrations greater than 12 mg/L. For the Tombigbee River population, pseudofeces were produced by all sizes of clams at particle sizes greater than or equal to 16 pm. These data indicate that there are potential morphological constraints on the clam gill that limit the range of particle concentrations and sizes that can be processed. Laboratory observations also demonstrated the capacity for deposit feeding in C.fluminea. Our data indicate that filter feeding in C.flumineu is a complex phenomenon, requiring an understanding of how the physiological process of feeding is influenced by morphological constraints imposed upon gill functioning and by the temporal effects of environmental variables. In addition, the plasticity in the filter-feeding response and the capacity for alternative feeding modes contribute to the success of C.fluminea as an invasive species. WAY, C. M., HORNBACH, D. J., MILLER-WAY, C. A., PAYNE, B. S., et MILLER, A. C. 1990. Dynamics of filter feeding in Corbiculafluminea (Bivalvia: Corbiculidae). Can J. Zool. 68 : 1 15-120. Les taux de filtration ont t t t mesurts au moyen de microsphkres de 2 pm chez des Corbiculafluminea provenant de trois cours d'eau a concentrations difftrentes de particules en suspension; l...

Mussels were acclimated to each of four experimental temperatures (20, 24, 28, and 32 °C) for 30 days. Mussels averaged 10.29 mg tissue dry weight. Oxygen consumption rates at 32 °C were 3.65 times larger than consumption rates at 20 °C (p < 0.01). Ammonia excretion rates at 32 °C were 4.9 times greater than those at 20 °C (p < 0.01). O:N ratios were >60 at 20 and 24 °C but declined (p < 0.01) at 28 and 32 °C to <40. Filtration rates, an estimate of feeding rates, were not significantly different at 20 and 24 °C (p > 0.50) but declined at 28 and 32 °C (p < 0.01). Filtration rates at 32 °C were only 27% of the rates at 20 °C. These results indicate that (i) the metabolic expenditure of Dreissena polymorpha rose 265% as the temperature rose from 20 to 32 °C, (ii) metabolism relied more heavily on lipids and carbohydrates at 20 and 24 °C while protein catabolism increased at 28 and 32 °C, and (iii) the potential feeding rates of D. polymorpha declined by 73% as temperature rose from 20 to 32 °C. Above 28 °C D. polymorpha was unable to match energy expenditures with concurrent food intake and forced to rely on stored fuels.

designed morphology. By using the same method, we have also successfully synthesized PbS hollow spheres of submicrometer scale. Compared with previous methods of preparing hollow spheres, the route presented here is simpler and more effective. It may stimulate technological interest and prospect many applications in materials related fields. ExperimentalIn a two-step procedure for the preparation of NiS hollow spheres, 4 mL MMA monomer was first added to 6 mL absolute ethanol, which was irradiated in the field of 2.59 10 15 Bq of a 60Co c-ray source with a dose of 0.8 kGy. After irradiation, transparent PMMA gel was obtained. This PMMA gel was then divided into pieces, which were put into a mixture consisting of 50 mL ethanol containing 0.664 g NiSO 4´6 H 2 O, 1.66 g CS 2 , and 20 mL distilled water. While the gel was reaching its swelling equilibrium, 20 mL of isopropanol was added, which should scavenge the formed oxidative radicals ( . OH). Then the gel was also irradiated with the same c-ray source as above with a dose of 48.8 kGy. The samples were heated for 3 h at 125 C in air, forming films, which were washed with distilled water and ethanol solution several times till the final products had high purity.EDX spectra were obtained using a JEOL-2010 transmission electron microscope. AFM was carried on a Seiko SPI 3800N high-vacuum scanning probe microscope system. FESEM was performed on a JEOL JSM-6700 field-emission scanning electron microanalyzer. TEM images were obtained on a Hitachi H-800 transmission electron microscope with an accelerating voltage of 200 kV. HRTEM was obtained on a JEOL-2010 transmission electron microscope. The UV-vis absorption was recorded on a UV-vis spectrophotometer Specord 200 (Analytik Jena AG) absorption diode array spectrometer using 1 cm quartz cuvettes. Fluorescence was detected by a Hitachi 850 fluorescence spectrometer with a Xe lamp at 25 C (k ex = 277 nm).

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