Nakao s (4 Ergebnisse)

SC. Zustand: Gut. Obr., [WES1].// Deu 400g.

The effects of imposex and parasite infection on the reproductive cycle of Neptunea arthritica as well as sexual maturity size were examined from April 2003 to August 2004 in Saroma Lagoon, Hokkaido, Japan. Samples were sexed and divided into two groups (normal and abnormal), based on the degree of imposex and parasite infection. In normal whelks, males reached sexual maturity at a smaller size (60 mm in shell length) than females (75 mm). Normal whelks copulated from March to August, with a peak between May and July, and spawned from May to August, with a peak in JuneJuly. In all groups, the female ovary and pallial oviduct, and the male seminal vesicle developed synchronously, and inverse to the male testis. Abnormal whelks follow a normal reproductive cycle. However, significantly lower reproductive organ index values, modifications in the number of individuals and periods extension in each developmental stage were observed. Gonads of individuals with severe imposex (stage 3) and parasite infection were reduced to a thin layer of tissue or eliminated. Imposex (stage 3) and parasite infection had serious effects on the population reproductive cycle of N. arthritica, but infection by parasites seemed to be the more disruptive phenomenon according to its proportion (25%). 10 pp., 8 figs, 4.…

The age and growth of the whelk, Neptunea arthritica, was estimated based on growth striae on the operculum. Individual whelks were sexed and divided into normal and abnormal groups, based on the presence of imposex and parasite infection. The monthly marginal growth was used to determine the annual growth mark formation on the operculum. The whelk's sex (male and female), condition (normal and abnormal) and size (mature and immature) were evaluated as factors that can affect the marginal growth. Only in normal females did size affect the marginal growth, suggesting that parasite infection and imposex were not a biasing factor in the age estimation. Significant differences between low and high monthly marginal growth in normal males were found. Between operculum length and shell length and total body weight a positive relationship was found, while the same trend was observed in all female groups as well as abnormal males, but differences were not significant. The same relationship was observed between the number of stria with shell length and total body weight in all groups. The results suggest that opercula striae could be used to age N. arthritica. The Gompertz equation was the best curve that fitted the data for growth in normal groups, based on Akaike's information criteria, and it was used for all groups. The age at first sexual maturity was estimated for normal males and females to be 4.6 and 6.1 years, respectively. 12 pp., 8 figs, 4.…

Zustand: New. Analytic Extension is a property of analytic functions. This title contains papers gathered from various fields in analysis such as integral transforms, reproducing kernels, operator inequalities, Cauchy transform, partial differential equations, inverse problems, Riemann surfaces, Euler-Maclaurin summation formulas, and several complex variables. Editor(s): Saitoh, Saburou; Hayashi, Nakao; Yamamoto, Masahiro. Series: International Society for Analysis, Applications and Computation. Num Pages: 288 pages, biography. BIC Classification: PBKD. Category: (P) Professional & Vocational; (UP) Postgraduate, Research & Scholarly; (UU) Undergraduate. Dimension: 235 x 155 x 17. Weight in Grams: 597. . 2001. 2001st Edition. hardcover. . . . . Books ship from the US and Ireland. …