In spite of the world-wide distribution and common occurrence of Aurelia aurita, the details of its reproductive ground have little been given. A series of work to make the reproductive ground of this medusa clear was carried out in Urazoko Bay, a small inlet, situated in the eastern part of Wakasa Bay on the Japan Sea coast, in the period from November 1970 through April 1973.
The occurrence patterns of early liberated ephyrae, metephyrae and young medusae at their maximum season were respectively checked by examining the samples collected by means of vertical hauls of a plankton-net (45cm in mouth diameter and 0.33mm in mesh szie) at each of the stations settled in the bay (Fig. 1). The settlements of planulae and early polyps were examined by monthly observations throughout the breeding season from late November 1970 through July 1971, using the collectors made of five upper shells of Pecten albicans and hung at the depth of 0, 2, 5 and 10 meters (Fig. 3) from the rafts which were set at each of the stations in the bay (Fig. 2). The results obtained are summarized as follows:
1) Early ephyrae were mainly distributed in the inner part of the inlet or the coastal shallow areas of the waters (Figs. 4 and 5).
2) Planulae and early polyps were found on the collectors in the inner part of the bay from January to June, most abundantly between the surface and 5 meter layer (Fig. 6).
3) According to these results and the distribution patterns of marine plants in the bay, it will be concluded that the reproductive ground of this medusa in the bay is the areas that are covered with marine plants such as Sargassum and Zostera (Figs. 8 and 9).

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The experimental area was located on Tokawa-cho, Choshi City, Chiba, in which the acrylic panels were fixed to the shore rocks and exposed to the barnacles settlement for a given time. In experimental tanks, barnacles settled on the panels were consumed by the limpets which are commonly seen at this shore. The limpets used could be categorized into four groups; L₁ (4∼5mm), L₂ (8∼9mm), L₃ (12∼13mm) and L₄ (22∼23mm). The groups L₂ and L₄ respectively consumed 24 barnacles larvae for 18 hours, and the group L₃ 8 larvae, but the group L₁ could not consume barnacles of any size.
The limpets of 1.79∼3.16cm shell length damaged the barnacles larvae which had grown up to 1.2mm in about 14∼15 days after their settlement. The other predious shell, Thais claviger, is emphasised as one of the grazers in this shores, and it might consume more barnacles larvae than limpets, though details are unknown.
According to the above observation, the influence of limpets on the formation of barnacles' life zone could be discussed, especially on the critical period of barnacles just after their settlement.

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Seasonal changes of attaching diatom flora were observed by means of the slide glasses immersed at intervals of about one month during the period from August 1978 to to August 1979 at 7 stations in Shonai Estuary, the Bay of Hamana-ko, Shizuoka Prefecture. At the same time, the measurements of water temperature, chlorinity, DO, chlorophyll-a and COD were made.
Shonai Estuary was found to be divided into four areas; one was mainly influenced by river water (Type I), another weakly by river water (Type II), another by coastal sea water (Type IV) and another was the middle area between Type II and IV (Type III).
The species compositions of attaching diatoms on slide glasses changed gradually from Type I to Type IV, and in each area several dominant species were observed which represent the environmental conditions of it. The combination of dominant species in each area was as follows; Nitzschia sp.-A-Navicula sp.-C, D-Fragiralia sp.-B in Type I, Nitzschia sp.-A-Nitzschia closterium-Navicula sp.-C, D in Type II, Nitzschia sp.-A-Nitzschia closterium-Navicula sp.-A, D in Type III and Navicula sp.-A-Nitzschia sp.-B-Cocconeis scutellum in Type IV.

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Observations were made on the effect on the attachment of organisms of anti-fouling paints on the 50 ton FRP (Fiberglass Reinforced Plastics) research vessel, “Takamaru”. The ship-bottom was divided into three parts and each painted with six kinds of anti-fouling paints in the same order.
After shipping for six months, July 1978 to February 1979, the attached organisms were observed on each part of the bottom. Two conclusions were reached. It was proved that No. 5 paint containing organic tin and cuprous oxide is more effective than the other paints. A different biomass was found on different areas of the ship-bottom treated with the same paint.

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Grazing activity of sea urchins, Strongylocentrotus nudus and St. intermedius, which were fed marine fouling organisms, was obserbed. Mussel, Mytilus edulis galloprovincialis, and barnacles, Balanus tintinnabulum, B. rostratus and B. trigonus, were eaten by sea urchins. A linear relation was found between the maximum diameter of the mouth of sea urchins (d mm) and the the maximum shell length of the mussels (l mm). The mussels were eaten completely in the case of l≤d. The maximum number of mussels eaten was 15/day/sea urchin. The mussels were eaten partially in the case of d<1≤1.75d, but they were not eaten at all in the case of l>1.75d. Averege number of barnacles scraped was 3.3/day/sea urchin. B. tintinnabulum of thin shell was eaten better than B. trigonus and B. rostratus of thick shell. When a sea urchin was introduced into the netting cage of cultured scallop, Patinopecten yessoensis, the sea urchin fed on encrusting bryozoans and compound ascidians as well as slime fouled on the shell surface of the scallop. Thus, the grazing activity of the sea urchins is applicable to controlling fouling organisms on cultured scallop.

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The reproductive cycles and fertilities of seven species of barnacles (Balanus improvisus DARWIN, Balanus amphitrite DARWIN, Balanus eburneus GOULD, Balanus albicostatus PILSBRY, Balanus kondakovi TARASOV & ZEVINA, Balanus reticulatus UTINOMI and Chthamalus challengeri HOEK) have been determined by periodic sampling from the raft or intertidal piles and by examination of their gonads and retained embryos.
The breeding of the first three species was characteristically seen as extreme or rather strong eurythermy. However the last four species could breed only at a limited range of temperature. The number of broods per year of each species was estimated as follows; B. improvisus is 32 times, B. amphitrite 21∼26, B. eburneus 20, B. albicostatus 22, B. kondakovi 15∼22, B. reticulatus 13 and C. challengeri 2∼3.
The above-mentioned results and other breeding habits of these species were compared with those of different species of barnacles studied by previous workers.

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As a part of studies on the effect of the warm water effluent from nuclear power plant on marine organisms, the distribution of acorn barnacles which are representative fouling organisms in Uchiura Bay in relation to the effluent from Takahama Nuclear Power Plant was investigated during the one-year period beginning with late May 1978.
The experiments were carried out at three fixed stations in the bay: black celluloid plates (25×18.5cm) and poly vininyl chloride plates of the same colour and size were suspended at 1, 3 and 7 meters depth for 1 or 2 months (Fig. 1), and the species and number of barnacles settled on each plate were checked every month, together with hydrographic observations. As the results, more than five species of barnacles were identified. The most dominant species at each station was Balanus trigonus, followed by B. eburneus and B. improvisus. The latter two were regarded as recent invaders into this locality from foreign countries by cargo boats.
The three species cited above were often most abundant at station 1 located about 500 meters apart from the end of the discharge canal (Figs. 6-11). The water temperature at the station was usually 3°C or more higher than under the natural condition, especially in the layers less than 5 meters in depth (Figs. 2 and 3).
Therefore, it may be suggested from the results that the warm water effluent offers suitable condition for the settlement and breeding of these dominant barnacles.

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