Uwajima Fisheries High school

An ovigerous female of Argulus matuii Sikama, 1938 was collected from the body surface of a yellowfin seabream Acanthopagrus latus (Houttuyn, 1782) in a cove facing the Bungo Channel off Ehime Prefecture, western Japan. This represents a new host record for A. matuii, and the female collected is herein described. This female, which was fixed and preserved in 70% ethanol, showed a prominent body coloration, i.e., six streaks of yellow fringed with dark brown pigments, on the dorsal surface of the carapace even on 279th day (ca. nine months) after fixation, but the yellow streaks disappeared and the dark brown fringes were fading on 1675th day (ca. four years and seven months) after fixation. Thus, this paper reports on the usefulness of those yellow streaks in identification of A. matuii for a certain period after fixation but also emphasizes the importance of a detailed examination of morphological features in identification of long-term ethanol-preserved argulid specimens. The species is distinguished from the five marine congeners from Japan by its possession of numerous supporting rods in the marginal membranes of the first maxillae.

Seasonal changes in population structure of a trophically transmitted parasite Heliconema anguillae (Nematoda: Physalopteridae) were examined in Japanese eels Anguilla japonica caught from a small cove in Ehime Prefecture, western Japan. Demographic classification of the samples from May 2008 to March 2009 showed that the nematode infrapopulations in host individuals continuously involved newly recruited worms besides adults. Considering the complex life cycle of H. anguillae infecting the eel definitive hosts via their feeding on littoral crabs as the source of infection, this finding suggests that the eels in the cove constantly consume those intermediate hosts regardless of season. However, temperate eel species, including Japanese eels, are generally thought to lose their feeding activities during winter, and indeed, the winter water temperature at low tide in the sampling locality falls below the optimal thermal range for feeding. We thus suggest that the estuarine Japanese eels have a specific overwintering response to keep their feeding activity, unlike freshwater individuals, and require further studies to compare winter activities between various habitats within a river-estuarine system in different climatic zones along with the eel’s geographical distribution.

We study deformations of plane curves in the similarity geometry. It is known that continuous deformations of smooth curves are described by the Burgers hierarchy. In this paper, we formulate the discrete deformation of discrete plane curves described by the discrete Burgers hierarchy as isogonal deformations. We also construct explicit formulas for the curve deformations by using the solution of linear diffusion differential/difference equations.

Reduction and glycosylation of benzophenone, which is an endocrine disrupting chemical, were investigated using immobilized marine microalga and plant cells from the viewpoint of bioremediation of benzophenone. Immobilized marine microalga of Chrysocampanulla spinifera reduced benzophenone to diphenylmethanol. Immobilized marine microalga of Amphidinium crassum glucosylated diphenylmethanol to the corresponding glucoside. The sequential biotransformation with C. spinifera and A. crassum effectively converted benzophenone into diphenylmethyl glucoside. On the other hand, immobilized plant cells of Catharanthus roseus transformed benzophenone to diphenylmethanol, diphenylmethyl glucoside, and diphenylmethyl primeveroside, which was a new compound, by one-step biotransformation.

A total of 263 adult and preadult Chinese temperate bass Lateolabrax sp. caught at 20 locations in the coastal waters of western Japan from October 1999 to September 2008 were used for age, growth and maturity examinations. Examination of marginal increments of transverse sections of otoliths showed that rings (opaque zones) were formed once a year from spring to summer. According to the number of rings and the sampling month, ages were assigned to individuals. For males, we obtained the following von Bertalanffy growth equation: L(t) = 618{1 − e−0.420 (t + 0.273)}. Females attain sizes over 600 mm SL mainly after 5 years of age and attain sizes of 850–1,000 mm SL at 8–10 years and over 1,100 mm SL about 15 years. Based on histological examinations of gonads and seasonal changes in gonadosomatic indices, potential spawning period was confirmed during mid-October to late January. In males, the minimum size and age at first maturity were estimated as 380 mm SL and 2 years old, respectively, though most males reach sexual maturity at 3–4 years old. Furthermore, female specimens at the mature or developing stages were over 470 mm SL and 4 years old.