著者

梶原 武

出版者

長崎大学水産学部

雑誌

長崎大学水産学部研究報告 (ISSN:05471427)

巻号頁・発行日

vol.11, pp.49-63, 1961-08-31

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Investigations of attaching materials and animal fouling organisms on the test nets were carried out at the Stations in Sakibe Inlet of Sasebo Bay from 1958 to 1960. During this period, a series of test nets were installed monthly and replaced the exposed nets for one month, two and three. A test net was constructed by the seven pieces of cremona nets (20s/9, mesh length 50mm, 10×10 mesh) spread over the frame which eight bamboos (dia. 2cm, length 60cm) were joined with two hemp-palm ropes (dia. 5mm) at intervals of one meter. It was suspended from the surface to seven meter depth below, weighted with stones. The fouling animals on the nets were counted and weighted. About bamboos and ropes, the areas occupied with animals were measured. 1. The rich fouling fauna were found in early summer and autumn, i.e., Hydroides norvegica, Styela plicata, Bugula califoarnica, B. neritina, Costazia costazii, Mytilus edulis, Balanus amphitrite albicostatus, B. trigonus and Amphipoda were abundant from spring to summer and H. norvegica, Serpula vermicularis, S. plicata, B. neritina, B. amphitrite communis in autumn. But peaks of several species of compound ascidians and Ciona intestinalis occurred in cold season. There can be recognized an active and a resting period of fauna in a year, the former begins in May and continues to November, and the latter seems to extend from December to April. 2. Generally the beginning of settlement of fouling animals were found earlier on long exposed nets than fresh nets. This phenomena may be explained that the fine attaching materials which were formed on old nets provide suitaple conditions for settling. 3. The characters of suspended solids in the sea water appeared to play a major role in determining the variability of the fouling populations. Also the interrelationships among various species of fouling community give deep influences to the population density and attaching constructions. Therefore grouping member of community through by ecological factors as sessile form and food habit etc., may offer the positive view points to the fouling faunas. 4. Fouling animals of sessile type, as Balanus, we called the primary fouling animals, and the moving fouler on attachment surface, as Amphipoda, the secondary fouling animals. The former consists of groups which feed on the suspended matters by filter, but the latter mainly on the detritus.佐世保湾崎辺浦で1958年以降,試験網の浸漬による付着物の研究をおこなってきた.この資料に基いて,網竹綱の三つの基盤に付着した付着生物の季節消長の概要をのべた. 1 付着生物の付着と生育の旺盛な時期は5~7月,9~11月の年2回みられ,冬期は付着種類は少なくなる.夏期8~9月は付着種類はやや減少するが生育はかなり盛んである.2各季の主な種類は,5~7月ではカサネカンザシ,ナギサコケムシ,フサコケムシ,コブコケムシ,ムラサキイガイ,タテジマフジッボ,サンカクフジツボ,Amphipoda,シロボヤであり,秋期におおいのは,カサネカンサジ,シロボヤ,ヒトエカンザシ,サラサフジツボ,フサコケムシであった.また12~4月におおいのは,Amphipoda,群体ボヤ,ユウレイボヤである. 3 本水域の優占種は,カサネカンザシーシロボヤである.またここでの付着生物群集の性格は,カサネカンザシ(フサコケムシ)―シロボヤ(ムラサキイガイ)―サラサフジツボ(タテジマ)―Tube-buildingAmphipodsにより代表されるものと考える. 4 おおくの種類は,浸漬期間の長い基盤に新らしい基盤よりも早い時期から付着がはじまる.これは古い基盤の付着ヌタが生物の付着や生育に好条件となることによるのではないかと推測される.5 付着の状態や摂餌方法により,付着生物を第1次付着生物(固着,懸濁物を餌料とする),第2次付着生物(基盤上を動き,付着ヌタを餌料とする)の二に分けた. 6 付着生物の生態学的研究で,環境調査では餌となる懸濁物の性質の調査も必要である.また付着生物群集の性格を明らかにするために,各生物種を付着の仕方,形態,摂餌方法,死後の状態等で整理することが必要であると考える.