Vertical and horizontal distribution of sessile animals on intertidal substrata in eutrophicated inner Tokyo Bay was observed. Sessile animal assemblage at most of the observation sites consisted mainly of two species. The barnacle Chthamalus challengeri made a belt in the upper and middle intertidal levels, and the mussel Mytilus edulis galloprovincialis made another in the lower level.
In some estuarine sites, the lower part of the Chthamalus belt was replaced by another barnacle Balanus amphitrite, and the upper part of the Mytilus belt by another mussel Limnoperna fortunei kikuchii. This suggests that salinity condition is an important factor on the horizontal faunal change, and competition for space may influence the vertical distribution of the intertidal sessile animals.

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A leaflike shrimp Nebalia sp., which belongs to the most primitive genus of Malacostraca, has been found abundantly at the base of Bryopsis sp. growing in an outdoor concrete tank used for Homarus culture at Sanriku. The species is considered to be desirable as a living food organism for larval rearing because of its suitable size and tolerance to deterioration of the bottom condition.
Sampling was done in the pond from July to December of 1983. Water temperature ranged from 22.3°C in summer to 4.5°C in winter. The animals were found throughout the season with the highest occurrence of egg-bearing females in October. The larvae were reared successfully at water temperature between 15°C to 25°C in combination with the salinity between 20‰ to 33‰ under the continuous darkness. The larvae showed the best growth at 25°C in combination with 33‰. The most effective food for the larval rearing in the laboratory was the fine particles of the dried food as shrimp pellet and krill.
The larvae hatched out as adult form. Number of segments in the flagellum branches of the first antenna and the second antenna increased from 3:3, expressed as segmentation formula, at I stage to 4:3, 5:4, 6:5, 7:6 and 8:7 at II, III, IV, V and VI stages, respectively. After VII stage, the increase became irregular.

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In order to obtain the fundamental data to control the formation of marine microbiofouling by bacteriophages, titanium and aluminum alloy plates were immersed at Okunouchi Bay in Seto Inland Sea, and the marine fouling bacteria attached were isolated and characterized. Then the bacteriophages lysing the marine fouling bacteria were located and characterized. The results obtained were as follows;
(1) Nineteen strains of fouling bacteria were isolated from the surface of the test plates. As the result of their characterization, they belonged to the following genera; Pseudomonas (8 strains), Vibrio (5 strains), Flavobacterium (4 strains) and Moraxella-Acinetobacter (one strain). It was found that motile bacterial strains were dominant on the surface of the titanium plate, while non-motile bacterial strains were dominant on the surface of the aluminum alloy plate.
(2) The bacteriophages lysing the marine fouling bacteria were isolated from seawater of Aki-Nada, Hiroshima Bay and other places. Thirteen of the 19 strains of the fouling bacteria were susceptible to the bacteriophage-lysates enriched from the seawater. All of the bacteriophage strains had hexagonal heads and their diameter were 54-58nm.

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The response of Bugula neritina in the colonial growth of the early stage to the water temperature was examined by culturing colonies in one-liter beakers at various water temperatures of 5, 10, 13, 15, 19, 22, 25, 28, 30 and 32°C. Colonies consisting of one zooid attached to slide glasses were placed in the beaker with 800ml of food plankton suspension adjusted at the density of 10, 000cells/ml. Food suspension was made by diluting the dense stock suspension with the filtered sea water. We renewed food suspension every day, and counted the zooid number of each colony every few days to estimate the intrinsic rate of the increase of zooids number which numbered between 3-200.
Although the colonies cultured at lower than 10°C did not increase their zooid number, they were able to stay alive for more than one week. They grew in the laboratory as fast as in the natural sea where the water temperature was between 13°C and 22°C, but the growth speed in the laboratory was low at greater than 25°C compared with that in the natural sea. At 30 and 32°C, they could grow well for only a few days from the start of the culture. If the culture continued without the food suspension becoming highly contaminated by bacteria, they might be able to grow well even at 32°C.

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The summer breeding serpulid polychaetes Hydroides fusicola and Pomatoleios kraussii were collected in winter and reared in the laboratory in order to induce winter breeding and to elucidate the effects of environmental factors on gametogenesis.
In both species winter breeding could be induced by exposing individuals to a raised water temperature of 23°C and feeding on an algal food Chaetoceros calcitrans. A number of healthy nectochaetal larvae were obtained by artificial fertilization and the settlement of the larvae on substrata was observed.
The gonial multiplication and growth of oocytes including vitellogenesis were accelerated at the raised water temperature.
Not only the growth of oocytes but also the gonial multiplication at a low temperature of 13°C was accelerated by feeding.
It was assumed that the full maturity in winter was attained about a month after the beginning of the rearing using the algal food at 23°C.

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