Aquaculture Sci. 57（3），371－382（2009）

Larval Appearance of the Sea Urchin Loxechinus albus in Chiloé Island,

1 Sohei KINO

Abstract: To obtain basic information about propagation for the Chilean sea urchin, Loxechinus albus, distribution of echinopluteus larvae of this species was investigated from 1986 to 1989 in the eastern coastal waters of Chiloé Island, Chile. Echinopluteus larvae of three sea urchins: L. albus, Pseudechinus magellanicus and Arbacia dufresnei were observed in the waters. The larva of L. albus was distinguished from the other two species mainly by the difference in skeletal rod structure. The larvae of this species were observed for almost a year, and the 4-armed larvae appeared mainly from November to January. The metamorphic larvae were observed only once in October 1988 in Hueihue in the investigation period. The number of larval appearance in the southern waters was larger than that in the northern waters.

Key words: Loxechinus albus; Sea urchin; Echinopluteus larva; Metamorphic larva

Sea farming is currently the main counter- not observed in the investigational waters. measure for the propagation of sea urchins. In Though there are many reports of the spawn- Chile, the sea urchin, Loxechinus albus is one ing season in L. albus (Gutiérrez and Otsu 1975; of the most important fisheries resources, and Bückle et al. 1978; Bay-Schmith et al. 1981; due to the need for propagation, artificial seed Guisado and Castilla 1987; Zamora and Stotz production of this species was studied (Zamora 1992; Oyarzún et al. 1999; Kino and Agatsuma and Stotz 1994; Cárcamo 2004). To succeed 2007), there are few reports for the larval and in propagation of the target species, it is very juvenile periods in natural waters. As for the important to clarify the reproduction system, natural larva of L. albus, the qualitative appear- and to investigate the ecology from spawning ance in the spawning season in Chiloé Island through to juvenile via the larval period. and Guaitecas was reported (Bay-Schmith et al. According to Larraín (1975), four species of 1981), and the annual appearance of 4-armed sea urchin, L. albus, Pseudechinus magellanicus, larvae in Chiloé Island was also reported (Kino Arbacia dufresnei and Tetrapygus niger are dis- and Agatsuma 2007). However, no complete tributed in the investigational waters. Under report of the 4-armed stage through to the artificial rearing conditions, the larval morphol- metamorphic stage was found. McEdward and ogy of L. albus (Arrau 1958; Bückle et al. 1976; Miner (2007) reviewed echinoid larval ecology, Guisado and Castilla 1987) and A. dufresnei but there are many unknowns regarding natu- (Bernasconi 1942) have been reported, while ral L. albus larva, and the recruitment system those of P. magellanicus and T. niger were not of this resource is not clear. In this study, the reported. Therefore, identification of sea urchin period and quantity of larval appearance were larvae appearing in the waters was tried except investigated in eastern coastal waters of Chiloé for the larva of T. niger, of which adults were Island.

Received January 27, 2009: Accepted April 27, 2009. 1 INTEM Consulting, Inc., Tokyo 160-0023, Japan. E-mail: [email protected] 372 S. Kino

focused on the Gulf of and the Gulf of Materials and Methods Corcovado, respectively. During Period-III, it was carried out only at the Hueihue-A, Queilen Larval appearance was surveyed at 14 locali- and Quellón sites. ties (26 sites) from June 1986 to March 1989 Planktonic larvae were collected at inter- (Fig. 1). Among these localities, in Hueihue, vals of 3–4 days at least, except for the three seven sites (D-J) at an interval of 1.5 km months during July–September 1988. Larvae to 10.5 km offshore were also studied from were collected two or three times per investi- December 1986 to March 1987. Numbers and gation by vertical hauls of a Kitahara-Plankton durations surveyed are shown in Fig. 2. The net (xx13, 25 cm diameter) from a depth of 20 durations were different among the localities m to the surface at each site. The filtering rate and sites, mainly divided into the three periods: was assumed to be 100%. The larvae collected June 1986–June 1987 (Period-I), July 1987–June were fixed immediately with 5% neutral forma- 1988 (Period-II) and October 1988–March 1989 lin seawater. The number of L. albus larvae by (Period-III). During periods I and II, the surveys each developmental stage was counted using a

Hueihue 10.5 km offshore 1 Hueihue Hueihue 2 Linao

1.5 km A A B D C 。 B 110

1 km Linao

3

1 Quemchi 2 3 4

4 B A 5

6

7 5 Teupa

A

Guaitecas

Channel Moraleda B

Republic of CHILE 6 7 Queilen Quellon' Chadmo Yaldad Cailin

Tranqui I. Cailin I. Paula

Centinela Coldita I. Laitec I. Chaullin I. Chaullin Laitec 3 km 3 km

Fig. 1. Localities and sites (●) for Loxechinus albus larvae collection in eastern coastal waters of Chiloé Island, Chile. Larval Appearance of Loxechinus albus 373

Number surveyed Duration surveyed by month Locality Site by period 1986 1987 1988 1989 III III J J A S OND J FMAMJ J A S OND J FMAMJ J A S OND J FM

Period-I Period-II Period-III Hueihue A 64 48 25 B 34 C 8 D 46 E-J 59 Linao A 13 B 8 Quemchi 9 Dalcahue A 13 B 9 Teupa A729 B524 Queilen 54 83 50 Quellon' 56 82 44 Chadmo 18 Centinela 16 Chaullin 16 Paula 23 Cailin 19 Laitec 21 Yaldad 9 68

Fig. 2. Number and duration surveillance, of Loxechinus albus larvae at each locality and site in eastern coastal waters of Chiloé Island, Chile. projector (Nikon V12), a biological microscope oral rods of L. albus and P. magellanicus were and/or a dissecting microscope. The number fenestrated, while those of A. dufresnei were of larvae was calculated as the mean number non-fenestrated. The body rods of L. albus and per vertical haul. To differentiate the three A. dufresnei were jointed at the end of body, species of larvae, L. albus, P. magellanicus and while those of P. magellanicus were straight. A. dufresnei in the waters, complete 4-armed Recurrent rods were found in L. albus and A. larvae were obtained in a laboratory by artificial dufresnei. In the 6-armed stage, L. albus and fertilization, and taxonomic identification was P. magellanicus added one pair of postero- performed using the structure of the skeletal dorsal arms with fenestrated rods. However, A. rods of these larvae in the 4-armed stage. As for dufresnei larvae did not have a 6-armed stage, the larvae after the 6-armed stage, they were but did have an 8-armed stage having one pair mainly differentiated by characteristic skeletal of postero-dorsal and postero-lateral arms. In rods (the body rod, the post-oral rod and the the 8-armed stage of L. albus, two anterior cili- ventral transverse rod), formation of ciliated ated bands between the right post-oral arm and bands, and the existence of pedicellaria, besides left one, and other two ciliated bands between the characteristic 4-armed stage. Former stud- the right postero-dorsal arm and left one were ies about the morphology of L. albus larvae found. In P. magellanicus, four anterior ciliated (Arrau 1958; Guisado and Castilla 1987) were bands developed around each base of the two also checked. post-oral arms and two postero-dorsal arms. A. dufresnei larvae developed into the 10-armed Results stage with one pair of pre-oral arms. The cili- ated bands of A. dufresnei did not develop as in Identification of L. albus larvae the other two species. In the metamorphic stage Morphological characteristics of L. albus, P. of L. albus, five primary spines were lined circu- magellanicus and A. dufresnei at each develop- larly without pedicellaria at the end of the body. mental stage (except the 6-armed stage) are In P. magellanicus, the posterior transverse rods shown in Fig. 3. In the 4-armed stage, post- developed like a pectin-skeleton. In A. dufresnei, 374 S. Kino

(a)(b)(c) (d)(e) 2 1 4 7 7 6 12 6 A Not observed 3 12

10 9 9 8 13 13 8 14

4 1 2 R 6 7 11 6 7 3 B 12 12 14 8 10 8 11 14 R 13 13 14 15

1

2 6 4 R 6 7 7 C 3 14 9 8 8 10 16 5 9 10-armed 15 Fig. 3. Morphological characteristics of the larvae of Loxechinus albus (A), Pseudechinus magellanicus (B) and Arbacia dufresnei (C) by developmental stage in random scale; (a) 4-armed stage, (b) skeletal rod side view of the 4-armed stage, (c) 8-armed stage, (d) metamorphic stage, and (e) metamorphosing larvae. 1: post-oral arm, 2: antero-lateral arm, 3: postero-dorsal arm, 4: pre-oral arm, 5: postero-lateral arm, 6: post-oral rod, 7: antero-lateral rod, 8: body rod, 9: recurrent rod, 10: ventral transverse rod, 11: posterior transvers rod, 12: anterior ciliated band, 13: posterior ciliated band, 14: spine, 15: pedicellaria, 16: tube foot, R: arm rod the postero-lateral arms elongated to approxi- December, respectively. In Queilen, the number mately 2.5 mm, while the post-oral arms elon- of 6-armed larvae reached a peak of 8.0 individu- gated to approximately 4 mm. Metamorphosing als in December. In Hueihue-A, B and D, Teupa-A larvae of P. magellanicus and A. dufresnei were and B and Yaldad fewer 4, 6 and 8-armed (－＜ 3.7 observed to have posterior transverse rods (P. individuals) larvae appeared in December than m.) and a characteristic flat spine (A. d.), while in Queilen and Quellón. Meanwhile, 4.5 and 6.0 no metamorphosing larva of L. albus appeared. six-armed larvae appeared in October at Hueihue-A and D, respectively. No metamor- Larval appearance of L. albus phic larvae were found at any sites. The numbers of larvae appearing at the During the period-II (Table 2), larval appear- investigation sites are shown in Tables 1-3. As ance was poor and sporadic from July to May no larvae of L. albus were found at Hueihue-C, compared with period-I. Two peaks were Linao-A and B, Qeumchi and Dalcahue-A, these found in October and February in Queilen and sites were omitted from the Table. Quellón. In Queilen, 23.3 and 22.0 four-armed During the period-I (Table 1), the larvae larvae appeared in October and February, respec- appeared from October to April, and peaked in tively. In Quellón, 6.7 and 26.7 four-armed larvae December. In Queilen and Quellón, the larvae appeared in October and February, respectively. appeared more abundantly from November to Few 6 and 8-armed larvae were observed. No January than those at the other sites, reaching a metamorphic larvae were found at any sites. peak of 32.3 and 72.0 four-armed larvae in During the period-III (Table 3), the larvae Larval Appearance of Loxechinus albus 375

Table 1. Mean number of Loxechinus albus larvae in the 4, 6 and 8-armed stages (4, 6 and 8) appeared per vertical haul from a depth of 20 m to the surface at each site in eastern coastal waters of Chiloé Island, Chile (Period-I) Hueihue A Teupa A Larval stage Larval stage Year Month Day Day 468Hueihue D 468 1986 Jun. 11 17 Larval stage 20 Day 24 468 1 Jul. 9 11 15 22 22 44 Aug. 10 10 17 17 20 24 Dalcahue B Yaldad Sep. 88 15 Larval stage 16 Larval stage Day Day 29 29 468 468 Oct. 661.0 8 13 4.5 Hueihue B 13 6.0 15 Teupa B Queilen QuellÓn 20Larval stage 20 Larval stage Larval stage Larval stage 24 Day Day Day Day 27 468 27 468 4 68 4 68 Nov. 33 40.3 449.3 3 15.7 777 7 1.3 6 2.0 10 10 10 12 11 11 11 0.3 10 0.3 17 17 17 18 18 15 1.5 1.3 13 0.7 18 0.3 17 1.0 21 21 21 21 20 1.3 24 24 24 25 25 25 26 28 28 28 29 0.3 27 Dec. 111 22327.7 1 555 5 32.3 0.7 4 0.3 9 0.3 0.7 9 3.7 2.7 9 0.7 2.0 9 12 0.7 12 1.0 12 1.0 10 0.3 12 0.7 0.7 11 15 15 0.7 15 16 3.3 1.0 3.3 16 1.7 16 28.7 0.7 0.7 15 72.0 19 19 2.7 0.3 19 0.3 1.0 20 4.3 18 36.7 0.7 22 1.0 3.0 1.0 22 1.3 1.7 0.3 22 2.7 2.7 0.7 23 3.3 8.0 22 1.7 2.0 0.3 23 2.7 3.3 0.3 26 11.3 2.3 25 0.3 0.3 0.7 29 29 29 30 30 30 29.3 3.0 29 1.0 1987 Jan. 222 2 7.0 6.3 1.3 555 76663.0 3.0 1.3 5 0.3 0.3 999 9 0.3 0.7 8 0.3 12 12 12 13 13 13 0.3 0.3 12 16 16 16 16 15 19 19 19 20 20 20 19 23 0.6 23 23 23 0.3 22 0.3 21 0.3 1.7 26 26 26 27 27 27 26 0.3 30 30 30 30 29 222 4333 2 Feb. 666 65 999 1010119 13 13 13 13 0.3 12 16 16 16 0.3 17 17 17 0.3 16 20 20 20 0.3 21 19 18 23 23 24 24 24 23 27 0.3 27 27 28 26 Mar. 22 40.3 330.3 32 6 0.7 5 999 1010100.3 9 0.3 13 12 16 16 16 17 17 1.0 17 16 20 0.3 19 18 23 23 23 24 0.3 24 0.7 24 23 27 27 27 26 30 30 30 31 0.3 0.7 31 0.3 30 30 Apr. 1 0.3 2 9 6 0.3 13 13 0.7 14 0.3 14 20 21 21 22 28 28 28 7866 May 14 15 15 12 12 19 19 19 28 26 26 29 4522 Jun. 12 12 10 9 16 17 23 22 23 24 30 Numbers of larvae appearing are highlighted and blank cells with a date indicate 0 individuals. appeared from October to February, reach- March 1987. Defined larval appearance was ing a peak from November to December. In observed in October, December and February. Queilen, 390.0 four-armed larvae appeared in The larvae appeared most abundantly on December, the highest number in this investiga- December 19 when 4 and 6-armed larvae were tion. In Quellón, the number reached a peak of found at all sites. The most 4-armed and 6-armed 49.7 individuals in November. The larvae were larvae were 29.0 individuals at H (7.5 km offing) more abundant than those during periods-I and 4.7 individuals at F (4.5 km offing), respec- and II. No metamorphic larvae were found in tively. On October 13, the number of 6-armed Queilen or Quellón either. On the other hand, in larvae was the most abundant, and the maxi- Hueihue-A, the larvae appeared only in October mum number was 12.0 individuals at G (6.0 km and metamorphic larvae of 1.3 individuals offing). Only 0.3 and 0.7 eight-armed larvae appeared for the first time in this investigation. appeared at E (3.0 km offing) on November 28 Table 4 shows the larval appearance offshore and at J (10.5 km offing) on December 19. No (site D–J) in Hueihue from October 1986 to metamorphic larvae were observed. 376 S. Kino

Table 2. Mean number of Loxechinus albus larvae in the 4, 6 and 8-armed stages (4, 6 and 8) appearing per vertical haul from a depth of 20 m to the surface at each site in eastern coastal waters of Chiloé Island, Chile (Period-II) Teupa A Teupa B Queilen QuellÓn Chadmo Centinela Paula Day Larval stage Day Larval stage Day Larval stage Day Larval stage Day Larval stage Day Larval stage Day Larval stage Year Month 468 468 4 68 4 68 468 468 468 1 1987 Jul. 878 9 14 14 14 14 16

21 21 22

28 28 28 29 0.3

Aug. 44 11 12 18 18 19 1.3 0.3 19 1.0 25 9.7 0.7 25 0.3 Chaullin Larval stage Day 31 2.7 468 1 0.3 Sep. 3 0.3 3

7 8 990.3 10 10 14 15 15 21 17 24 24 24 24 24 24 28 29 11 Oct. 56 78 12 13 6.7 15 0.3 15 3.3 19 4.3 20 0.7 22 23.3 22 4.0 26 7.0 27 2.0 30 0.7 2.0 29 Nov. 2 1.3 3 5 0.3 5 9 0.3 10 10 10 10 10 13 12 16 17 17 17 17 16 19 19 5.7 20 20 23 24 24 6.0 24 1.0 24 0.3 23 2.0 26 7.0

30 1.7 0.3 30 1.0 1.3 1 1110.3 1 0.3 0.3 Dec. 3 0.3 3 0.7 7 8 10 10 10 9 10 10 0.3 15 17 15 0.3 16 17 17 17 17 21 22 22 22 28 24 30 31 30 30 30 29 1988 Jan. 4 1.0 5 5555 7 11 14 14 18 19 20 20 20 20 21 21 26 25 26 28 28 12 2 2 Feb. 4426.7 99 9 0.7 0.3 11 11 2.0 0.3 15 0.7 15 18 22.0 18 0.3 22 5.7 22 25 25 24 26 26 25 29 1 Mar. 3 3 3333 77 10 10 9 14 14 15 15 15 15 18 17 21 21 2.7 23 23 25 25 28 28 31 45 4 Apr. 77 11 11 15 14 18 18 22 22 25 25 26 29 28 22 May 6 5 666 99 12 13 16 11.7 16 19 1.3 20 23 24 27 26 31 Jun. 881 Numbers of larvae appearing are highlighted and blank cells with a date indicate 0 individuals. Larval Appearance of Loxechinus albus 377

Table 3. Mean number of Loxechinus albus larvae in the 4, 6, 8-armed and metamorphic stages (4, 6, 8 and M) Table 2. continued appeared per a vertical haul from a depth of 20 m to the Cailin Laitec Yaldad surface at each site in eastern coastal waters of Chiloé Day Larval stage Day Larval stage Day Larval stage Year Month 468 4 68 468 Island, Chile (Period-III) 1987 Jul. Hueihue A Queilen QuellÓn 14 Larval stage Larval stage Larval stage 15 Day Day Day 16 Year Month 468M 4 68M 4 68M 17 3 1.3 3 0.7 20 1988 Oct. 6 21 22 10 0.7 10 0.3 10 23 13 13 25 17 17 27 20 20 28 28 28 24 24 24 29 27 27 0.3 30 31 31 1 3 Aug. 3 Nov. 78 7 11 10 10 14 14 14 14.0 14 18 18 116.0 17 19 21 22 6.0 21 26 25 4.3 24 49.7 28 28 29 2.3 0.7 28 6.0 31 Dec. 1 3.3 0.3 1 0.7 Sep. 55390.0 5 4.0 0.3 3 9 15.0 9 4 5 12 13 27.3 0.3 12 0.3 7 18 5.7 15 8 19 20 4.7 2.3 20 0.3 10 24 22 0.3 0.3 15 15 0.3 15 26 27 1.0 27 16 29 24 24 28 1989 Jan. 221.3 0.7 30 6 3.0 9 32.7 9 2.0 Oct. 12 1.0 16 17 0.3 16 19 19 15 0.7 23 23 23 19 26 26 20 30 30 30 32 Feb. 66 6 9 0.3 9 Nov. 2 13 13 13 3 16 16 20 22 20 10 10 25 23 27 27 27 4 16 16 0.3 17 Mar. 66 6 19 99 20 13 13 13 21 17 16 23 1.3 23 1.0 23 20 20 20 26 24 23 28 27 28 27 30 30 30 Dec. 1 0.3 11 Numbers of larvae appearing are highlighted and blank cells 2 999 with a date indicate 0 individuals. 12 14 15 16 16 16 17 18 21 Table 5 shows a comparison of larval appear- 22 1.3 30 30 31 ance in the (northern localities 555 1988 Jan. 6 7 from Dalcahue: Fig. 1, 1-4) and the Gulf of 8 11 12 Corcovado (southern localities from Teupa: 20 20 20 22 Fig. 1, 5-7). Considering overall larval distribu- 221 Feb. 3 tion in the waters, L. albus larvae were more

11 highly distributed in the

24 24 than in the Gulf of Ancud and the difference in appearance number per investigation was Mar. 33 99 approximately four times. Comparing the larval 15 15

23 3.3 23 appearance by larval stage, the 4-armed larvae of the Gulf of Corcovado were 10 times more 44 Apr. numerous than that at the Gulf of Ancud. As for the 6-armed stage, the larval appearance in 26 May the Gulf of Ancud was somewhat higher than that of the Gulf of Corcovado in period-I, but no larvae appeared in periods-II and III. Six Jun. 9 time more 8-armed larvae appeared in the Gulf of Corcovado than in the Gulf of Ancud, while metamorphic larvae appeared only in the Gulf of Ancud (period-III). 378 S. Kino

Table 4. Mean number of Loxechinus albus larvae by developmental stage (4, 6 and 8-armed) collected per vertical haul from a depth of 20 m to the sea surface at intervals of 1.5 km to 10.5 km offshore in Hueihue, Chiloé Island Larval Site and distance from coast Date stage D-1.5km E-3.0km F-4.5km G-6.0km H-7.5km I-9.0km J-10.5km Oct. 13, 1986 4-armed 1.0 -- 6-armed 6.0 3.0 2.0 12.0 5.0 -- 8-armed -- Nov. 7 4-armed -- 6-armed -- 8-armed -- 28 4-armed --- 6-armed --- 8-armed 0.3 --- Dec. 5 4-armed 1.0 6-armed 8-armed 19 4-armed 0.3 1.3 17.7 18.7 29.0 12.7 13.3 6-armed 1.0 1.3 4.7 2.3 0.7 0.7 1.0 8-armed 0.7 Jan. 2, 1987 4-armed 6-armed 8-armed 23 4-armed 6-armed 8-armed Feb. 6 4-armed 6-armed 8-armed 20 4-armed 0.3 0.3 0.3 0.7 6-armed 0.7 0.7 1.0 8-armed Mar. 9 4-armed 6-armed 8-armed 23 4-armed 6-armed 8-armed Blank cells and horizontal bars (-) indicate no larvae and no data, respectively.

Table 5. Comparison of larval appearance of Loxechinus albus in the Gulf of Ancud (northern regions from Dalcahue) and the Gulf of Corcovado (southern regions from Teupa) June1986– July 1987– July 1988– Total June1987 (I) June 1988 (II) March 1989 (III) Gulf of Gulf of Gulf of Gulf of Gulf of Gulf of Gulf of Gulf of Ancud Corcovado Ancud Corcovado Ancud Corcovado Ancud Corcovado 4-armed larvae (indiv.*) 108.3 309.5 0.0 174.8 0.7 678.2 109.0 1162.5 6-armed larvae (indiv.*) 56.8 42.8 0.0 9.4 0.0 16.0 56.8 68.2 8-armed larvae (indiv.*) 3.0 13.1 0.0 1.2 0.0 4.2 3.0 18.5 Metamorphic larvae (indiv.*) 0.0 0.0 0.0 0.0 1.3 0.0 1.3 0.0 Total larvae (indiv.*) 168.1 365.4 0.0 185.4 2.0 698.4 170.1 1249.2 Number surveyed 263 171 48 359 25 94 336 624 Larval number per a survey 0.6 2.1 0.0 0.5 0.1 7.4 0.5 2.0 *the total sum of the mean number of larvae in each survey by vertical haul from a depth of 20 m to the surface

Strongylocentrotus nudus and S. intermedius, Discussion appear at the same time (Kawamura 1970). Since 3 species of echinopluteus larvae appeared Identification of L. albus larvae in the investigational waters, identification of There is a high possibility that sea urchin target species in the larval stage is essential to larvae from several species appear simulta- clarify their ecology. Although the larval develop- neously in the same waters. In Hokkaido, ment of L. albus (Arrau 1958; Bückle et al. 1976; Japan, larvae of two regular sea urchins, Guisado and Castilla 1987) and primary stage of Larval Appearance of Loxechinus albus 379

A. dufresnei (Bernasconi 1942) were reported, larvae were found. Although the appearance of L. albus was morphologically identified from the 8-armed larvae was relatively high in Queilen other two species by characteristics such as arm and Quellón, no metamorphic larvae were rods, a specific body skeleton and a ciliated band. observed. Moreover, metamorphic larvae (1.3 Larvae of Anthocidaris crassispina and individuals) appeared only once in October Pseudocentrotus depressus possess complex body 1988 in Hueihue. Therefore, no relationship rod structure and a recurrent rod (Komatsu between the appearance period of 4-armed and Noguchi 1997). Four-armed larvae of L. larvae and metamorphic larvae was observed in albus are similar to them, but L. albus was dif- this study. The occasional appearance of meta- ferentiated from these two species due to the morphic larvae suggests that stock recruitment absence of the pedicellaria after the 8-armed of L. albus in the natural environment is not stage. As for the pedicellaria of L. albus, there periodic every year. are two reports; the larva does not possess The metamorphic larvae of S. intermedius it, but has one–five spines at the end of the appear at a rate of more than one individual body (Arrau 1958), or the larva possesses it per collection in a 30 cm diameter ×9 m deep (Guisado and Castilla 1987). In this study, the column of the seawater in the sea urchin fish- absence of the pedicellaria coincided with the ing grounds where natural seed collection is former report. Larvae of S. intermedius and developed for this species (Kawamura 1984). Hemicentrotus pulcherrimus possess simple This larval density corresponds to approximately body rod structure without a recurrent rod 1.5 individuals per collection in this study. If the (Komatsu and Noguchi 1997). Four-armed same criterion was applied for L. albus, it could larvae of P. magellanicus are similar to them, be said that the appearance of 1.3 individuals of but P. magellanicus was differentiated from metamorphic larvae per collection in Hueihue these two species as it had the posterior trans- was not necessarily too small to realize some verse rod and pedicellaria after the 8-armed countermeasures for propagation of this species. stage. Larvae of A. dufresnei were distinguished In this study, the larval appearance number from other species by special arms, a pair of per collection in the Gulf of Corcovado was 4 postero-lateral arms, except in the 4-armed times higher than that of the Gulf of Ancud stage. Though the ciliated band of A. dufresnei (Table 5). In 1986–1989, the Gulf of Corcovado did not develop like other species, four lingui- (south of Dalcahue) was the main fishing form structures in the center of the body may ground of L. albus, while there were few fishing be ciliated bands. banks in the Gulf of Ancud, and the number of the fishing banks decreased by 2001. However, Larval appearance of L. albus some of them were still functioning as fishing Though Bay-Schmith et al. (1981) reported banks (Barahona et al. 2003). This suggests that the larvae of L. albus appear in December that there were abundant resources of L. albus in Chiloé and Guaitecas, the results of this as spawners in the Gulf of Corcovado compared study showed that the appearance period was to the Gulf of Ancud and there were differences longer still, namely 4-armed larvae of L. albus in in larval appearance, too. the waters were observed from July to May of On the other hand, it was found that the the following year and the peak was November larval appearance number in period-III was –January, suggesting the existence of some higher than that in periods-I and II in Queilen spawning groups. Consequently, metamorphic and Quellón. Kino and Agatsuma (2007) men- larvae appear with a high probability after tioned that they found some places without the peak of 4-armed larvae appearance. The synchronized spawning with other places in maximum number of 4-armed larvae (390.0 the Gulf of Corcovado, indicating an unclear individuals) was observed in December 1988 spawning season. Consequently, the phenom- in Queilen, but after this no metamorphic enon mentioned above suggests high spawning 380 S. Kino synchronicity in period-III in the same waters. the Gulf of Ancud (closed sea) such as the In S. intermedius, 8-armed larvae appear seawater current allow the hatched blastula to approximately one month later than 4-armed disperse widely in the gulf over a short time larvae in the natural environment, and after and larvae spend the 4-armed stage through another month metamorphic larvae appear the metamorphic stage there until returning to (Kawamura 1984). In L. albus, the period from the coast again. Larval transport is influenced hatching to the 8-armed stage and that from by hydrodynamics of the waters and duration the 8-armed to the metamorphic stage are of the larval planktonic period (McEdward almost the same under artificial rearing condi- and Miner 2007). In fact, the difference in tidal tions (Arrau 1958). Artificial seed production level is up to approximately 7m in the Gulf of of S. intermedius (Kawamura et al. 1983), P. Ancud, data at , X region (Servicio depressus and H. pulcherrimus (Kakuda 1978) Hidrográfico y Oceanográfico de la Armada show much the same growth pattern. The larval de Chile 2007) and movement of seawater due floating period of L. albus up to metamorpho- to this tidal current is involved in the disper- sis lasts 24 days at 17–19℃ in a mass culture sion of sea urchin larvae. As the water mass with sufficient food organisms (Zamora and in the Moraleda Channel (fjord in XI region) Stotz 1994). Approximately 2 weeks passed to moves 2.0–3.5 km daily and 109–195 km over appear the large number of 8-armed stage, 2.3 2 months (Fierro et al. 2000), considering the individuals after the mass appearance of the larval floating period of L. albus, the movement 4-armed stage, 390.0 individuals in December of seawater is involved in larval transport in the in Queilen (Table 3). As the seawater tempera- investigational waters. Further investigation ture in the main larval period is low at 12–14℃ into larval distribution and movement is neces- (Kino and Agatsuma 2007), the larval floating sary to clarify the ecology. period is much longer than that of artificially cultured larvae, and lasts approximately 1–2 From this study, the tendency of larval months in this period in the natural environ- appearance of L. albus in Chiloé Island was ment, depending on the abundance of food for clarified; however, the small number of meta- the larvae. Appearance of metamorphic larvae morphic larvae also indicates the difficulties in October in Hueihue suggests that 4-armed in recruitment of resources of this species. In larvae appeared quite a bit earlier, and the float- S. intermedius, larval mortality is high during ing period must be longer than in November the floating period (Kawamura 1984). The –December because of the low seawater tem- small number of post larvae of L. albus com- perature. pared with the 4-armed stage also suggests Four-armed larvae of S. intermedius move high mortality in this study (Table 5). As larval and disperse from the coast to offshore mortality is not determined by larval stage, (approximately 5 km) due to seawater cur- but the abundance of food organisms after the rents in the open sea, and spend the 6-armed 4-armed stage in Evechinus chloroticus (Lamare and 8-armed stages there, then the larvae and Barker 1999), the appearance of a small gather and settle down in a shallow water zone number of L. albus 6-armed and 8-armed larvae going with the current from offshore to the in Chiloé Island suggests a lack of food possi- coast (Kawamura 1984). In the sampling site of bility due to blooming of diatom in the waters. Hueihue offshore (1.5–10.5 km distance from It could be said that the appearance of meta- the coast), L. albus larvae were widely distrib- morphic larvae depends on spawning, food and uted irrespective of developmental stage. The hydrographic conditions each year. Moreover, appearance number of 4-armed larvae in the the most important fact is that the metamorphic offing was higher than that at the coast. Larval larvae appeared only once in October 1988. In distribution in S. intermedius was not observed. this region, though the main spawning season This suggests the environmental features of of L. albus is between November and January Larval Appearance of Loxechinus albus 381

(Kino and Agatsuma 2007) and the closed fish- Investigación, Subsecretaría de Pesca-Unversidad de ing season is October–March (Stotz 2004), Concepción, 68 pp. Bernasconi, I. (1942) Primeros estados larvales de Arbacia there is contradiction between the spawning dufresnei (Blv.). Physis. (Revista de La Sociedad season and appearance of metamorphic larvae. Argentina de Ciencias Naturales), 19(53), 305-317. This suggests early spawning that is more Bückle, F., C. Guisado, E. Tarifeño, A. Zuleta, L. Córdoba, directly involved in resource stocking than the C. Serrano and R. Maldona (1976) Estudios biológicos del erizo Loxechinus albus (Molina) (Echinoidea actual main spawning season and the need for Echinodermata). I. Investigaciones preliminares en a review of the closed fishing season. As the cultivos masivos de larvas de erizo. Biol. Pesq. Chile, larvae disperse widely in their floating period, 8, 31-64. further investigation into larval ecology over Bückle, F., Ch. Guisado, E. Tarifeño, A. Zuleta, L. Córdova and C. Serrano (1978) Biological studies on the Chilean a wide area to obtain useful information about sea urchin Loxechinus albus (Molina) (Echinodermata: the propagation of this species is needed. On Echinoidea). IV. Maturation cycle and seasonal changes the other hand, as larval appearance in Queilen in the gonad. Ciencias Marinas, 5, 1-18. or Quellón is superior to other sites in Chiloé Cárcamo, P. (2004) Massive production of larvae and seeds of the sea urchin Loxechinus albus. In“ Sea urchins. Island, changes in larval appearance could be Fisheries and ecology” (eds. By J. M. Lawrence and O. used as a monitoring factor for the reproduction Guzmán). DEStech publ., Lancaster. pp. 299-306. capacity of L. albus resources around Chiloé Fierro, J., M. Bravo and M. Castillo (2000) Characterization Island. of the tidal regime and current along the channel Moraleda (43°54’S－45°17’S). Cienc. Tecnol. Mar., 23, 3-14. Acknowledgements Guisado, C. and J. C. Castilla (1987) Historia de vida, reproducción y avances en el cultivo del erizo comes- This study is a part of an international tech- tible chileno Loxechinus albus (Molina 1782) (Echinoidea, Echinidae). In“ Manejo y Desarrollo Pesquero” (ed. By P. nical cooperation of the Overseas Fishery Arana), pp. 59-68. Cooperation Foundation between Japan and Gutiérrez, J. and I. Otsu (1975) Periodicidad en las the Republic of Chile. I sincerely thank Dr. Y. variaciones biométricas de Loxechinus albus Molina. Agatsuma of Tohoku University and Dr. H. Rev. Biol. Marina. Valparaíso, 15, 179-199. Kakuda, N. (1978) Study for seed production of sea urchin-III Nakagawa of Hiroshima University for their (as for mass rearing of larvae). Suisanzoshoku, 25(4), kind comments and suggestions for the prepa- 121-127 (in Japanese). ration of this manuscript. I am also grateful to Kawamura, K. (1970) On the development of the plank- Dr. K. Kawamura for his guidance and encour- tonic larvae of Japanese sea urchins, Strongylocentrotus intermedius and S. nudus. Hokusuishi-hou, 12, 25-32 agement, to Mr. Ricardo Troncoso T. for sup- (in Japanese). porting the study, and to the staff members Kawamura, K., Y. Nishihama, K. Yamashita, T. Sawazaki, of the Instituto de Fomento Pesquero, Austral K. Kawamata and A. Obara (1983) Experiment for tech- University and the Salmones Aucar for collec- nical development of Strongylocentrotus intermedius mass seed production. Bulletin of Hokkaido Marine tion of plankton samples. Aquaculture Center, pp. 71-103 (in Japanese) . Kawamura, K. (1984) Natural seed capturing, intermediate References culture and release of Japanese sea urchin Strongylocentrotus intermedius. Hokusuishi-geppo, 41, 270-315 (in Japanese). Arrau, L. U. (1958) Desarrollo del erizo comestible de Kino, S. and Y. Agatsuma (2007) Reproduction of the sea Chile Loxechinus albus Mol. Rev. Biol. Mar., 7(2, 3), urchin Loxechinus albus in Chiloé Island, Chile. Fish. 39-67. Sci., 73(6), 1265-1273. Barahona, N., J. M. Orenzans, A. Parma, G. Jerez, C. Komatsu, M. and M. Noguchi (1997) Class Echinoidea. In: Romero, H. Miranda, A. Zuleta, V. Catasti and P. M. Chihara & M. Nomura editors. In“ An Illustrated Galvez (2003) Bases biológicas para rotación de áreas Guide to Marine Plankton in Japan”, Tokai University en el recurso erizo. Informe final, Fondo Investigación Press, pp.1319-1345 (in Japanese). Pesquera PIN No.2000-18, Instituto de Fomento Lamare, M. D. and M. F. Barker (1999) In situ estimates of Pesquero, Investigación y Fomento Pesquero, 378 pp. larval development and mortality in the New Zealand Bay-Schmith, E., C. Werlinger and J. Silva (1981) Ciclo sea urchin Evechinus chloroticus (Echinoermata: anual de reproducción del recurso Loxechinus albus Echioidea). Mar. Ecol. Prog. Ser., 180, 197-211. entre X y XII Región. Informe Final Proyecto de Larraín, A. P. (1975) Los equinoídeos regulares fósiles y 382 S. Kino

recientes de Chile. Gayana, Zoología, 35, 1-189. Stotz, W. (2004) Sea-urchin fisheries: a Chilean perspec- McEdward, L. R. and B. G. Miner (2007) Echinoid larval tive. In“ Sea urchins. Fisheries and ecology” (ed. By J. ecology (Chapter 5). In“ Edible sea urchins. Biology M. Lawrence and O. Guzmán). DEStech publ., Lancaster. and ecology, second edition” (ed. By J. M. Lawrence), pp. 3-17. Elsevier Science B. V., pp. 71-93. Zamora, S. and W. Stotz (1992) Ciclo reproductivo de Oyarzún, S. T., S. L. Marín, C. Valladares and J. L. Iriarte Loxechinus albus (Molina 1782) (Echinodermata: (1999) Reproductive cycle of Loxechinus albus Echinoidea) en Punta Lagunillas, IV Región, Coquimbo, (Echinodermata: Echinoidea) in two areas of the Chile. Revista Chilena de Historia Natural. 65, 121-133. Magellan region (53°S, 70-72°W), Chile. Scientia Zamora, S. and W. Stotz (1994) Cultivo masivo en laborato- Marina, 63, 439-449. rio de juveniles de erizo Loxechinus albus (Molina, Servicio Hidrográfico y Oceanográfico de la Armada de 1782), (Echinodermata: Echinoidea). Invest. Pesq., Chile (2007) Tablas de marea de la costa de Chile. (Chile). 38, 37-54. SHOA pub. No. 3009, 218 pp.

チリ共和国チロエ島におけるウニ Loxechinus albus 幼生の出現

城野草平

チリウニの増殖の基礎資料を得るために1986～89年にかけてチリ共和国チロエ島東部沿岸におい て本種の浮遊幼生分布を調査した。調査海域ではチリウニ Loxechinus albus のほか，Pseudechinus magellanicus，Arbacia dufresnei の 2 種のウニ類幼生が観察された。チリウニの幼生は主に体の骨格で 他種と判別された。その幼生はほぼ周年観察され，4 腕期幼生はおもに11月から 1 月にかけて出現し た。変態期幼生は全調査期間をとおして1988年10月の Hueihue においてのみ観察された。幼生の出 現数はチロエ島の南部が北部よりも多かった。