PENELOPE A. LUCKENS

紀要類（bulletin）departmental bulletin pape

PENELOPE, A. LUCKENS

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

THE BREEDING AND SETTLEMENT OF OHTHAMALUSCHALLENGERI HOEK AT ASAMUSHI DURING 1968著者 PENELOPE A. LUCKENSjournal orpublication titleThe bulletin of the Marine Biological Stationof Asamushi, Tohoku Universityvolume 13number 4page range 251-254year 1969-03-25URL http://hdl.handle.net/10097/00131344BULLETIN OF THE MABINE BIOLOGIOAL STATION OF ASAMUSHI, VOL. Xlli, NO. 4. 1969, THE BREEDING AND SETTLEMENT OF OHTHAMALUS OHALLENGERI HOEK AT ASAMUSHI DURING 19681 > By PENELOPE A. LucKENS Biological Institute, T~hoku University, Senilai, Japan!Jl The previous paper (Luckeus 1968) summarised the distribution and ecology of Ohthamahts challengl'ffi Hoek the dominant barnacle of the intertidal zone at Asamushi, and gave the results of breeding samples taken at two levels during 1967. Further samples were taken from the same areas during 1968 and the results were compared for the two years. Samples of similar sizes and ages of barnacles were taken from the same two areas in the manner designated in the previous paper. BREEDING Although the first mature larvae were found more than a month earlier in 1968 the general pattern of breeding over the two seasons was remarkably similar. As in 1967 there were two distinct breeding periods at the upper level, and a longer continuous one at the lower level (Fig. 1). In 1967 the few specimens which settled in June and July were not dense enough to form' breeding populations in the same season at Hadakajima. Con-sequently, the 1961 settlement class first bred in the spring and early summer of 1968 at low levels. However the dense early settlements of 0. challengeri on Mytilus at low levels in June 1968 grew rapidly and bred in the late summer and autunm ofthe same year. In a sample taken in early September (4-X-68) 58% of the barnacles contained developing embryos while another 20% contained eggs. The remaining 22% had only slightly developed ovaries. 85% of the previous two seasons settlements at the same level contained embryos, while the other 15% contained eggs. SETTLEMENT In spite of similarities in the pattern of breeding shown from the samples collected in the two years, settlement differed markedly at Hadakajima. Hoshiai (pers. com.) thought that there were two settlement periods in each season. These 1) Contributions from the Marine Biological Station of Asamushi, Aomori Ken, No. 375 2) Present adress: New Zealand Oceanograpic Institute, Wellington, New Zealand. 251 252 P.A.LUCKENS BREEDING OF h· CHALLENGE Rl HADAKAJIMA 1968 50°/o I I UPPER LEVEL II LOW ER LEVEL MATURE EMBRYOS EYED EMBRYOS IMMATURE EMBRYOS EGGSIN OVARY OVARY CLEAR OR GRANULAR EGGS ABSENT 0 °/0 1--LL....,..JC:Ll::!.CL1::1,LLJ::L.t:.L....,Id...U...U--Q.LLW.li,Ll..llL--+J_j__l____l,,J_ _ ___J FEB MAR APR MAY JUN JU L AUG SEP 100 °/o r--.-__.__,lllr1_rw'._.. ___________ .....,..._.._,.--. ....... .----__._---, _ __. ___ --1 50 °/0 II :~: I Fig. l. Samples of 0. challengeri from the two sampled levels at Hadakajima during 1968 showing the percentage at each breeding stage. are generally in May-June and August-September at Asamushi. In any year either one or both of these periods may be marked by dense settlements while in another year settlements may be barely noticeable. At any place the breeding samples may show a normal two-peaked pattern, but settlement may occur during or after only one of the two peaks. Since there is a period of several weeks between the release of the nauplii and the settlement of the cyprids, it is unlikely that cyprids will settle in the same area as their parents. Consequently settlement at any one place is not directly related to breeding performance there although in an area where similar conditions prevail similar breeding times might be expected. BREEDING AND SETTLEMENT OF OH'l'HAMALUS OHALENGERI 253 During 1961 settlement at Hadakajima was light and sporadic until August and September when heavy settlements occurred. In 1968 a very slight settlement in May was followed by several heavy settlements in June and July, and scattered newly-settled specimens mainly at low levels in August and September. In the second half of July 1968 a survey of shores in Hokkaido showed that heavy settlements had taken place only at Akkeshi. On all the shores visited along the south and west coasts of Hokkaido, from Akkeshi to Kutsugata on the west coast of Rishiri Isiand, 0. challengeri was the dominant shore barnacle. Over this same range Akkeshi was the only shore visited where the sea froze over during the winter. Ice abrasion on the even rock surfaces had removed many of the barnacles leaving clear rock available for settlement. The heavy settlement here was probably related to the extensive available clear rock surface adjacent to adult barnacles in crevices. Such animals are probably removed every winter by ice action, unless in protected crevices, and can contribute little to the breeding population. In colder areas on the north-east of Hokkaido and on coasts north of Japan where the shores freeze over every winter 0. challengeri is replaced by 0 . dalli. At Akkeshi, where 0. dalli has also been recorded, and where 0. chctllengeri is very close to its northern temperature limits, it may well be that the local population is maintained by influx of larvae from a winter ice-free area. The ability of barnacles to colonise bare rock areas can be important where changes in the shoreline result in fresh surfaces becoming available. At Asamushi during 1967 the building of a breakwater along the site of the bypass meant that a large area of newly-immersed rock surface free from other organisms was available for barnacle settlement. During 1967 dense settlements occurred on these rocks, but in 1968 with little rock surface available there settlement was slight. Low level large Mytilus at Hadakajima were heavily settled in June 1968, although not unt il August 1967. Since at all stages of the tide a current flows north between Asamushi and Yunoshima this carries larvae past the breakwater before reaching Hadakajima. In 1961 with the availability of large areas of settlement surface on the breakwater most of the larvae settled there in the early breeding period leaving very few larvae to settle at Hadakajima. During the second settlement period in August there was little free space on the breakwater and larvae were available and gave rise to heavy settlements at Hadakajima. With most of the breakwater rocks still covered in barnacles in 1968 there was a return to the more usual situation, and heavy settlements were recorded on both bare rock and Mytilus at Hadakajima in June. Besides variations in the area available for settlement from year to year-affected particularly by large-scale reclaimation schemes-there is the less easily 254 P.A. LUCKENS measured variation in larva.l output and planktonic sm·vival, both of which are easily affected by numerous chance factors. Where current systems within bays, and the mixing of bay and ocean waters have been insufficiently investigated, there can be little except speculation on the place of origin of larvae settling in any area, unless the adult distribution is very restricted. An absence of settlement, or a very light settlement may have many causes, but when a heavy settlement is recorded on an extensive new area, while areas only slightly downstream have received little, then it is likely that the available areas upstream have absorbed almost all the larvae from that body of water. The presence of a large area of newly-immersed rock should affect the settlement of downstream areas for only a short period after it becomes available for settlement. The help so willingly given in innumerable ways by Professor l\'Iutsuo. Kato of the Biological Institute, Tohoku University, and by Professor Eturo. Hirai and the staff of the Asamushi Marine Biological Station throughout the work is gratefully acknowledged. The work was completed during the tenure of a Mombusho Scholarship. SUMMARY 1. The pattern of breeding of C. challengeri was similar in 1967 and 1968, but commenced earlier in 1968. 2. Settlement varied at Hadakajima in the two seasons. 3. With the presence of a large area of fresh rock surface in 1967 few larvae were available for settlement immediately downstream, but the situation appeared to have returned to normal in 1968. 4. Settlement season and density varies in different parts of the geographic range of the species. LITERATURE CITED HosmAI, T., 1965. Synecological study on intertidal communities VI. A synecological study on the intertidal zonation of the Asamushi coastal area with special reference to its reformation. Bull . Mar. Bioi. Stat. Asamushi, 12: 93-126. LuCKENS, P.A., 1968. The breeding and settlement of Chtltamalus clwllengeri Hoek at Asamushi during 1961. Ibid., 13 : 75-82. 

THE BREEDING AND SETTLEMENT OF OHTHAMALUS CHALLENGERI HOEK AT ASAMUSHI DURING 1968

Institutional Repositories DataBase (IRDB)

https://tohoku.repo.nii.ac.jp/?action=repository_action_common_download&item_id=133954&item_no=1&attribute_id=18&file_no=1

THE BREEDING AND SETTLEMENT OF OHTHAMALUS CHALLENGERI HOEK AT ASAMUSHI DURING 1968

Abstract

Similar works

Full text

Available Versions

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

Institutional Repositories DataBase (IRDB)