Chemical analyses have been made for chlorinity, sulfate, total carbon dioxide, hydrogen sulfide, ammonia and phosphate in brackish lake waters and sediment pore waters from Lake Hamana. Also dissolved calcium in pore waters and sulfide-sulfur in sediments have been determined. In summer, the bottom water is strongly reducing with hydrogen sulfide due to the stagnation and the development of chemocline. The fact of the decreasing in chlorinity with depth in the pore water column suggests that chloride in the bottom water diffuses from the bottom surface into the deeper layer of the sediment core, where the low salinity lake water has been buried before. The biophile elements are remineralized through microbial sulfate reduction by degradation of utilizable organic matter to release carbon dioxide, ammonia and phosphate into pore waters. A steady state diagenetic model applied to the vertical profiles of total carbon dioxide, ammonia and phosphate in pore waters can be used to estimate the stoichiometric elemental ratio of the metabolized organic matter, and the following ratio is obtained; C : N : P ≈ 106 : 16 : 0.83 which almost agrees with the Redfield ratio.

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Seasonal variation in the estuarine circulation (vertical circulation) in Ise Bay was estimated by a box model analysis using the salinity and river discharge data from 1982 to 1991. The estuarine mixing type of Ise Bay is classified by using the stratification-circulation diagram. Ise Bay is classified into the stratified estuary throughout the year. More than 99% of the total upestuaryward salt flux is caused by the vertical circulation (advection) throughout the year except for January. The vertical diffusion is inert during the strongly stratified period (April - October) and intense during the weakly stratified period (November - March). The maximum and minimum of the vertical circulation occur in February and June, respectively. The corresponding maximum and minimum values of the vertical circulation, upwelling velocity, horizontal velocity in the upper layer and horizontal divergence in the upper layer of the northern division are 8290 m³ s^-1, 1.5 m day^-1, 4.6 cm s^-1 and 2.5×10^-6s^-1 in February and 2300 m³ s^-1, 0.4 m day^-1, 1.6 cm s^-1 and 0.7×10^-6 s^-1 in June, respectively. It is suggested that the intense vertical circulation in winters is driven by the northwesterly monsoon wind.

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Japanese spiny lobster (Panulirus japonicus) is a nocturnal animal. We observed the diurnal variation of the spiny lobster activity in an experimental tank under a diel L/D cycle of 12:12. Under a standard condition with 3.3×10² lx daytime brightness and 0 lx nighttime brightness, the spiny lobsters exhibit clear diurnal variation pattern almost in phase with the brightness change. The pattern, however, is changed or collapsed under several conditions as follows: (1) When the nighttime brightness was higher than a threshold value of about 1.8×10^-4 lx, the nighttime activity is considerably suppressed. (2) Under continuous darkness, the phase of the diurnal variaton pattern is shifted and its period becomes 23 hours rather than 24 hours. By using this nature, the minimum recognizable daylight brightness to the spiny lobsters was estimated to be about 2.3×10^-5 lx. (3) When a spiny lobster was put in a new circumstance, the activity of the spiny lobster is generally increased considerably for the first several days. This type of activity increase occurs both for the nighttime and in daytime in parallel. (4) A collapse of the activity pattern would occur not only due to external conditions but also due to internal conditions of the spiny lobsters. The nature of the spiny lobster activity at the time of molting is discussed as an example.

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