This document summarizes research on the genus Monostroma found in Uranouchi Inlet and Ukibuchi in Tosa Bay, Japan. Monostroma was found to have different life cycles including dimorphic sexual alternation of generations with a microscopic sporophyte and macroscopic gametophyte, similar to M. nitidum. Thallus length varied seasonally between sites. An unknown species of Monostroma was observed to have female gametes that can directly develop into thalli without a sporophyte stage through a unique parthenogenesis process. Further research is needed to better understand zoospore development and release and characterize genetic changes during the life cycle.

1. Occurrence, basic cultural characteristics, sex ratio and morphogenetics of Monostroma in Uranouchi Inlet and Ukibuchi of Tosa Bay, Pacific ocean. Felix bast , Usa Marine Biological Institute, 781-1161, Japan April-August 2006

2. Introduction to the habitat and life cycle

13. Cultural characteristics

14. Study area, Usa Latitude = 33.436384 Longitude = 133.440371

16. Temperature variation

17. Salinity Variation

18. 24 Hrs change in ambient water temperature and salinity at sites on 07-28

19. Tidal graph showing sampling times 曇り 気温（℃） 31 – 26 降水 確率 30 ％） 天気

22. Thalli collection

23. Seasonal changes in Thalli length: S1 and S2

24. Seasonal changes in Thalli length: S4 and S5

25. Study Area: Ukibuchi Lat 33.035678 , Long: 133.034445

26. Seasonal changes in Thalli length: Ukibuchi

27. Sex ratio at 4 sites

28. Salinity tolerance S1 S4

29. Standardization A1 A2 5 4 3 45 µmolphotons/m 2 /s Light Intensity S1 Thallus PES (S1) Media

30. Salinity tolerance S1 samples were found to be more tolerant to the salinity.

31. Morphogenetic observations in unidentified Monostroma islolated from Usa, Tosa.

34. Zygote development illustration

36. Plano zygotes 10 µm

37. Zygote development illustration

38. Zygote settlement and development 10µm 10µm In 48 hrs planozygotes lose flagella and settle down the substratum.

39. Zygote settlement and development 10µm 10µm Distal end swollen to form a new cell, in 7 days by taking various shapes.

40. Zygote settlement and development 10µm 10µm 10µm Pyrinoid In 1 month most are elliptical and starts forming cysts.

41. Sporophyte 10µm 10µm Complete maturation of sporophyte takes very long time, 6-8 months.

42. Sporophyte maturation 10µm 10µm S hape of sporophyte slightly elongate. Upon acquiring motility, zoospores swim away.

43. Zoospore release Have 4 flagella of same length. Does not have eye spots. 10 µm 10 µm

44. Zoospore development illustration

45. Settled zoospore and germination In about 10 Days, first transverse cell division happens. 10 µm 10 µm

46. Development of zoospore, 4 cell stage 15 days old culture. Thalli appears to have 3D structure 10µm 10µm

47. Zoospore development illustration

48. Development of zoospore, 8 cell stage 20 days old (after zoozpore release from sporophyte) culture 10µm 10µm

49. Zoospore development illustration

50. Further development of zoospore 3 dimensional erect filament. 30 days old culture 10 µm 10 µm

51. Formation of microscopic thalli Basal tissue (arrow head) develops into rhizoid. 60 days old culture. 100µm 10 µm

55. Prospective research

58. Thank you!