著者

松本 清二 岩田 勝哉

出版者

The Ichthyological Society of Japan

雑誌

魚類学雑誌 (ISSN:00215090)

巻号頁・発行日

vol.44, no.1, pp.35-41, 1997-05-26 (Released:2010-06-28)

参考文献数

13

被引用文献数

1

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Paternal egg guarding and mouthbrooding of larvae and juveniles were observed in the swamp-eel, Monopterus albus. In aquaria, the male guarded and cared for eggs in the bubble nest floating inside a plastic tube (5 cm in dia-meter, 50 cm in length). It was suggested that spawning and fertilization occurred outside the nest tube, and that the male carried the fertilized eggs (ca. 4 mm in diameter) in his mouth and inserted them into the bubble mass. Until the hatching of larvae (7-8 days after spawning), the male frequently added fresh bubbles into the bubble mass. As soon as the larvae (18-21 mm in TL) hatched and emerged from the bubble nest, the male sucked them into his mouth. Fifty juveniles (32-37 mm in TL) and two yolk-sac larvae (22 mm in TL) were released from the mouth of a male collected from a natural habitat. Those juveniles were retrieved by the male, some of them voluntarily returning to the male's mouth. The mouthbrooding male frequently performed pumping behavior (i.e., inflating and deflating the buccopharyngeal cavity), thereby acquiring to take fresh air. Eggs removed from the bubble nest successfully hatched only when directly exposed to aeration. In addition, only about 40% of the hatched larvae survived more than 10 days when they were kept in well-aerated water without the male parent. These suggest that both the bubble nest and mouthbrooding are indispensable for successful development and survival of eggs and larvae in this species, which inhabits swamps and paddy fields.

著者

岩田 勝哉

出版者

日本海水学会

雑誌

日本海水学会誌 (ISSN:03694550)

巻号頁・発行日

vol.60, no.5, pp.324-334, 2006 (Released:2013-02-19)

参考文献数

63

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TMAO (trimethylamine oxide) and urea are stable end products and cannot be metabolized further to provide skeletons for biosynthesis. These substances are widely utilized in various marine fishes. Particularly, in cartilaginous fishes, a large amount of urea and methylamines including TMAO are accumulated as osmolytes in their tissues. In marine teleostean fishes, a considerable amount of TMAO also maintain in their bodies, although the levels are far less than those of cartilaginous fishes. However, urea levels in teleostean tissues are generally low, and only a few species utilize urea as a device for ammonia detoxification. In this paper multiple functions of TMAO and urea on marine fishes are discussed.

著者

岩田 勝哉

出版者

日本比較生理生化学会

雑誌

比較生理生化学 (ISSN:09163786)

巻号頁・発行日

vol.15, no.3, pp.184-192, 1998-09-30 (Released:2011-03-14)

参考文献数

57

被引用文献数

2

著者

岩田 勝哉 高村 典子 李 家楽 朱 学宝 三浦 泰蔵

出版者

日本陸水学会

雑誌

陸水学雑誌 (ISSN:00215104)

巻号頁・発行日

vol.53, no.4, pp.341-354, 1992-10-29 (Released:2009-06-12)

参考文献数

18

被引用文献数

1

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上海郊外の淀山湖湖畔にある中国綜合養魚系では,ソウギョ(Ctenopharyngodon idella)と食性の異なる他の数種のコイ科の魚を水草を主な飼料として混養し,非常に高い生産をあげている。このシステムでは,養魚池中に多量に排出されるソウギョの糞が直接,間接的に他の魚の餌として重要な役割を果たしていることが推察される。事実,この池から取り上げたフナ(Cayassius auratus)やコクレン(Aristichthys nobilis)の消化管内容物中にはソウギョの糞に由来する水草の断片が多数発見されている。本研究ではソウギョの糞が池の食物連鎖網の中でどのような役割を果たしているかを知るために,セキショウモ属の水草(中国名:苦草,Vallisneria spiralis)の砕片からなるソウギョの糞を養魚池から集め,それを実験室内で分解した。16日間の分解期間の問,糞中の炭素はほぼ一定の速度で減少し,元の含有率の約1/2にまで減少したが,窒素は分解8日後までほとんど減少しなかった。分解過程のソウギョの糞の単位乾燥重量あたりの窒素やアミノ酸含有率は分解8日後までは時間経過に伴って増加し,上限に達した。その後の含有率は分解時間の進行に関わらずほぼ一定値を示した。培養液中に加えた15NH4や3H-チミジンは速やかに分解過程の糞に取り込まれた。分解過程のソウギョの糞は細菌が繁殖するための基質として役立ち,また,付着細菌を含む分解過程の糞全体は池に共存する無脊椎動物や魚の新たな食物資源として重要な役割を果たすことが示唆された。

著者

岩田 勝哉

出版者

日本陸水学会

雑誌

陸水学雑誌 (ISSN:00215104)

巻号頁・発行日

vol.38, no.1, pp.19-32, 1977-01-30 (Released:2009-10-21)

参考文献数

26

被引用文献数

4 7

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By using unialgal culture of the two species of green algae (Closterium moniliferum : 300μ in length and Selenastrum sp. 10μ) which were labeled with 14C, the assimilation efficiency in terms of carbon of three cyprinids, Kawachibuna (Carassius auratus cuvieri), Nigorobuna (C. auratus grandoculis) and Silver carp (Hypophthalmichthys molitrix) was studied at the various life stages. In addition, radioactivities of different fractions (oligo-and poly-saccharides, organic acids, lipides, protein and residue) of the both species of 14C-algae and of the fecal algae egested by Kawachibuna and Silver carp were measured.In Kawachibuna and Nigorobuna, the assimilation efficiency for Closterium increased with their growth until they attained to 20 mm in total length (B. L. 14-15 mm), and reached the maximum level of more than 20 mm length (57-63%) at the successive stage. In Silver carp of 20 mm total length, the assimilation efficiency for Closterium was lower than for Kawachibuna and Nigorobuna of the same length. In Silver carp of more than 33 mm total length (B. L. 26-27 mm), 54-64% of carbon was assimilated.Kawachibuna and Silver carp are already known to change their food items from zooplankton to phytoplankton when they grow up more than 15 and 24 mm in body length respectively. The body length at which the maximum values of assimilation efficiency were obtained coincides approximately with the body length at which the change in diet occurs. It is suggested that the increase in the assimilation efficiency for Closterium with the growth of the fishes is not directly correlated with the increase in the length of their intestines but with a functional differentiation of their digestive systems.The three cyprinids assimilated 12-16% of carbon of Selenastrum and the rate was fairly stable throughout their lives, in contrast with those for Closterium. No difference was found in photosynthetic activity between fecal algae of Selenastrum egested by young Kawachibuna and fresh ones, while the activity of fecal algae of Closterium was approximately one-fifth of the fresh ones. The difference in assimilation efficiency may be related partly to the physiology of digestion of the cyprinids and partly to differences in chemical nature and cell structure of the two species of algae.

著者

松本 清二 岩田 勝哉

出版者

The Ichthyological Society of Japan

雑誌

魚類學雜誌 (ISSN:00215090)

巻号頁・発行日

vol.44, no.1, pp.35-41, 1997-05-26

被引用文献数

1

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Paternal egg guarding and mouthbrooding of larvae and juveniles were observed in the swamp-eel, <I>Monopterus albus</I>. In aquaria, the male guarded and cared for eggs in the bubble nest floating inside a plastic tube (5 cm in dia-meter, 50 cm in length). It was suggested that spawning and fertilization occurred outside the nest tube, and that the male carried the fertilized eggs (ca. 4 mm in diameter) in his mouth and inserted them into the bubble mass. Until the hatching of larvae (7-8 days after spawning), the male frequently added fresh bubbles into the bubble mass. As soon as the larvae (18-21 mm in TL) hatched and emerged from the bubble nest, the male sucked them into his mouth. Fifty juveniles (32-37 mm in TL) and two yolk-sac larvae (22 mm in TL) were released from the mouth of a male collected from a natural habitat. Those juveniles were retrieved by the male, some of them voluntarily returning to the male's mouth. The mouthbrooding male frequently performed pumping behavior (i.e., inflating and deflating the buccopharyngeal cavity), thereby acquiring to take fresh air. Eggs removed from the bubble nest successfully hatched only when directly exposed to aeration. In addition, only about 40% of the hatched larvae survived more than 10 days when they were kept in well-aerated water without the male parent. These suggest that both the bubble nest and mouthbrooding are indispensable for successful development and survival of eggs and larvae in this species, which inhabits swamps and paddy fields.