Bulletin of the Society of Sea Water Science, Japan

The International Geosphere-Biosphere Prograrn-IGBP

Haruhiko OHYA

1995 Volume 49 Issue 3 Pages 117-121
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.117

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Environment and Biological Production of Lake Hamana

Hisashi KUROKURA

1995 Volume 49 Issue 3 Pages 122-128
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.122

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Outline of geography, environment, biological production and fisheries in Lake Hamana is reported and the relations among these characters are discussed. Geographic characters cause anoxic water in the lake basin during summer season. The circulation of inorganic and organic nutrients are highly influenced by the existence of the anoxic water. Biological production and fisheries in the lake are directly and/or indirectly affected by the distribution of these materials. In conclusion, the relations between the changes in geographic characters and development of the fisheries industry are clearly observed in the history of Lake Hamana after 1951.

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Eutrophication Control by Utilizing the Characteristics of Brackish Ecosystems

Masumi YAMAMURO

1995 Volume 49 Issue 3 Pages 129-135
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.129

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Species Diversity of Aquatic Macrophytes in Brackish Waters

Hidenobu KUNII

1995 Volume 49 Issue 3 Pages 136-139
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.136

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In contrast to their dominance on land, few angiosperms occur in the aquatic environment, and even fewer have adapted to living in the marine and brackish environment. In this paper, species richness in fresh, brackish and marine habitats is reviewed briefly, and the results of comparison of species richness between 3 brackish lakes and their inlet rivers are described. In Japan, there exist 15 seagrass species and only 7 species are recognized as brackish inhabitants.

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Distribution Patterns of Polychaetous Annelids in an Estuary

Hitoshi HONDA, Toshihiro CHIBA, Kinuko ITO, Satoshi KATAYAMA, Yoshio C ...

1995 Volume 49 Issue 3 Pages 140-147
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.140

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Polychaetous annelids are the most dominant macrobenthos in an estuary, Hiroura lagoon, Miyagi Prefecture, Japan. The most abundant species in a polychaete assemblage of Hiroura consists of Notomastus sp. Okuda,Neanthes japonica(Izuka), and Prionospio japonicaOkuda. A dense population of polychaete worms provides large food resollrces for fish inhabiting Hiroura. However, field studies revealed that the abundance of the various species showed spatial and temporal fluctuations. Combined biological and environmental factors affect the seasonal changes in abundance of polychaetes. Polychaete life history traits including reproductive patterns are main factors influencing species' population dynamics.

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Salinity Tolerance and Osmoregulation in Freshwater and Brackish Water Mytilids

Taeko KIMURA, Izuru KAKUTA, Hisashi KUROKURA

1995 Volume 49 Issue 3 Pages 148-152
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.148

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Salinity tolerance and osmotic regulation were studied using two mytilid bivalves:Limnoperna fortunei fortunei, a freshwater species, and L. fortunei kikuchii, a brackish water species.L. fortunei fortunei tolerated rather lower salinity levels, 0-3%, while L. fortunei kikuchii, euryhaline species, survived in 0-30%. In media with concentrations of >3%, hemolymph osmolalities of L. fortunei kikuchii increased; at lower salinities, this species was a hyperosmotic regulator. The concentrations of Na, Mg, Ca, K, NPN and ammonia in hemolymph were also increased at lower salinity levels. These results suggest that L. fortunei kikuchii has osmoregulative ability.

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Changes in Functions of Superficial Mucous Cells in Tridentiger obscurus obscurus Exposed to Seawater

Izuru KAKUTA, Toshiharu SENGOKU, Hiroshi SASANO, Shiro MURACHI

1995 Volume 49 Issue 3 Pages 153-160
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.153

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Tridentiger obscurus obscurus from the mouth of Kyu-Kitakami river in Miyagi prefecture were transferred directly from freshwater to seawater. The numbers of mucous cells in the epidermis of the body and biological components of the mucus covering the fish body were estimated in fish in freshwater and in seawater.
Within 72 hours after the transfer, the fish showed a loss of body weight, a decrease in muscle water content, and increases in ammonia, non-protein nitrogen (NPN), sodium, calcium, and magnesium in muscle. After 240 hours, most parameters, except ammonia and calcium, in muscle returned to nearly the same levels as those in freshwater. No remarkable change was observed in the potassium concentration in muscle. After 72 hours of exposure to seawater, the ammonia excretion rate of Tridentiger decreased to about half of the control.
Within 48 hours after the transfer, the numbers of mucous cells in the epidermis of the body decreased compared to those of the control. After 72 and 168 hours, they increased to about 2 times those of the control. After 240 hours, they returned to the same levels as those of the control.
The weight of mucus secreted on the body epidermis of T. obscurus increased remarkably from 24 to 168 hours after the exposure to seawater. The mucus contained protein, ammonia, sialic acid, sulfur, chloride, potassium, calcium, iron, zinc, bromine, and strontium. The components of the mucus seem to be altered to some degree by environmental changes.

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The Japan Sea Water Upstreaming to Lake Shinji through a Man-made Canal, the Sada River

Katsumi TAKAYASU, Tomohiro AIDA

1995 Volume 49 Issue 3 Pages 161-170
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.161

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The Sada River is a canal, 8.3km in length, built about 200 years ago which connects the Sea of Japan with Lake Shinji directly. Observation was carried out using a automatic water quality and current meter to investigate the movement of invading sea water through the River. The results indicated that, though the movement of the river water is basically controlled by the tidal fluctuation of the Sea of Japan, the sea water can scarcely reach Lake Shiniji because of the long distance of the canal and small tide range of the sea. The acceleration of sea water upstreaming mainly depends on the pushing effect of a strong west wind and sea water swelling due to the low atmospheric pressure in the Sea of Japan. The moment the upstreaming of oxygen-rich sea water into the lake depends on the atmospheric conditions which is inconsistent. If it is possible to control artificially the inflow of sea water into the lake, it will greatly enhance the self-purification of the lake water and bottom sediment which in turn will increase the benthic biological activity.

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Aquatic Organisms and the Salt

1. Rotifer

Fumio TAKASHIMA

1995 Volume 49 Issue 3 Pages 171-173
Published: 1995
Released on J-STAGE: February 19, 2013

DOIhttps://doi.org/10.11457/swsj1965.49.171

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