An experimental study of the effects of smallmouth bass on the behavior, growth and survival of prey fish

ABSTRACT The effects of smallmouth bass on the behavior, growth and survival of the prey fish (goldfish, ayu and Japanese dace) were examined experimentally in artificial ponds. In most cases, goldfish aggregated both when smallmouth bass were present and absent. Ayu and Japanese dace aggregated more frequently in the presence of smallmouth bass. All prey fish fed predominantly on benthic algae or aquatic insects and their dietary composition was not affected by smallmouth bass. In goldfish and Japanese dace, the total number of feeding acts exhibited by each individual was significantly less in the presence of smallmouth bass than in the absence and, in goldfish, the growth rate was less when smallmouth bass were present. In contrast, the presence of smallmouth bass did not affect either the total number of feeding acts or the growth rate of ayu. However, ayu were preyed on by smallmouth bass most frequently among the three prey species. Smallmouth bass tended to prey on smaller individuals, but ayu were not smaller than goldfish or Japanese dace.     

Reproductive cycle and human chorionic gonadotropin-induced ovulation in hatchery reared Japanese catfish Silurus asotus

ABSTRACT:   The annual reproductive cycle, including the first maturity of ovarian development and plasma levels of testosterone (T) and estradiol-17β (E2), was examined in female Japanese catfish Silurus asotus reared under natural conditions. In addition, the possible period that final oocyte maturation and ovulation can be induced by human chorionic gonadotropin (hCG) injection were investigated. Results showed that female Japanese catfish matured 1 year after hatching under reared conditions. The beginning of vitellogenesis was in March and ovarian development and plasma T and E2 levels peaked in June. Thereafter, the gonadosomatic index gradually decreased to October and regression of oocytes at the tertiary yolk globule stage was observed. Female Japanese catfish could be induced to final oocyte maturation and ovulation by hCG treatment during the period from June to September. In addition, the fertilization rates were relatively high and stable during this period. These results suggest that yearling female Japanese catfish can be used as brood stock for seed production. This is the first study to investigate the annual reproductive cycle in Japanese catfish. These data will provide useful information regarding brood stock management and seed production.     

The change of a satoyama landscape and its causality in Kamiseya,Kyoto Prefecture,Japan between 1970 and 1995

We focused on patterns of land use in a particular satoyama landscape (Japanese traditional rural landscape, comprised of an integral social and ecological network of a village and its surroundings, such as agricultural lands, open forestlands and forests), and the effects of human activities upon them during Japan’s economic growth of the last few decades. Changes of landscape patterns and their probable causes were traced since the beginning of the 1900s to the present, and clarified. Societal, economic and technological changes, especially those that occurred after 1970, were considered the focal points from which major landscape changes developed. We compared the spatial features, patterns of land use and landscape diversities of each land unit, defined in terms of both their natural and man-made conditions for the year 1970, to those of 1995. We found land-use diversity to be strongly related to changes in the patterns of land use, with a decrease in diversity for all land units after 1970. Diversity of forest-age distribution on the other hand, increased. These changes, with the complex, changing patterns of each land unit, could be explained by differences in accessibility from the village and variations in the topography, as well as land ownership of the land units. We selected those land units found to have responded to these factors between 1970 and 1995, and classified them into four types of pattern changes, determined mainly by accessibility and topography.This revised version was published online in May 2005 with corrections to the Cover Date.     

拐枣果浸渍液对机体乙醇代谢的影响

为探明拐枣解酒机理，以拐枣果浸渍（HP）为试样，对致醉小白鼠进行试验，并对人酒后进行临床应用．测定其对机体乙醇代谢的影响．结果表明，HP可显著降低机体组织乙醇含量（相对降低率50．05％）及乙醇代谢排出量（相对降低率52．73％）．