FURUYA Noboru

INAMORI Yuhei

KURIHARA Yasushi

INAMORI, Yuhei

FURUYA, Noboru

KURIHARA, Yasushi

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STUDIES ON THE EFFECTS OF SOME ENVIRONMENTAL FACTORS ON SURVIVAL AND GROWTH OF THE POLYCHAETE, PERINEREIS NUNTIA VAR. VALLATA

紀要類（bulletin）departmental bulletin pape

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

STUDIES ON THE EFFECTS OF SOME ENVIRONMENTALFACTORS ON SURVIVAL AND GROWTH OF THEPOLYCHAETE, PERINEREIS NUNTIA VAR. VALLATA著者 INAMORI Yuhei, FURUYA Noboru, KURIHARA Yasushijournal orpublication titleThe bulletin of the Marine Biological Stationof Asamushi, Tohoku Universityvolume 16number 3page range 133-141year 1979-03-29URL http://hdl.handle.net/10097/00131431BULL· J\UR, BroL. ST. AsAMUsm, ToaoKu Umv., VoL. 16, No. 3, 133-141, 1979 STUDIES ON THE EFFECTS OF SOME ENVIRONMENTAL FACTORS ON SURVIVAL AND GROWTH OF THE POLYCHAETE, PERINEREIS NUNTIA VAR. VALLATA Yil:HEr INAMORI*, NoBORU FURUYA** and YAsusm KURIHARA1l Biological Institute, F'aculty of Science, TOhoku University, Sendai 980, Japan and **Department of Water Treatment Engineering, Meidensha Electric Mfg. Co., Ltd. T6kyo, 141, Japon The effects of environmental factors on growth of polychaete Perinereis nuntia var. vallata which usually inhabit the pebbly shore were studied. The young worms reared for 4 months after artificial fertilization at 20°0 were placed under different experimental conditions. The worms fed on the sludge actively at tem-perature ranging from 20 to 36°C, but hardly below 10°0 and above 40°0. They survivad for a long period at below 40°0 and chlorinities of 10.4-19.31rx!. Weight gain and food conversion efficiency in a high population density (33 worms/100 em') were less than those in a low population density (9 worms/100 cm2), indicat-ing that the growth correlated negatively with the population density. The food intake and the weight gain in the sand-gravel substratum were more conspicuous as compared with those either in gravels or in sand, indicating suitability of the mixture of sand and gravel for the living of the worms. INTRODUCTION It is known that the polychaetous annelid Perinereis nuntia var. vallata inhabit the coastal area with specific gravities ranging from 10.00 to 24.00 (CI 7.81-17.94%.) (ISHIKAWA 1938). FuKUSHIMA and ISHIDA (1966) observed them on gravels of tidelands in a bay facing the open sea. YosHIDA (1970) reported that they inhabited substratum of sandy mud, mud or gravels which was periodically exposed by ebb tide. These facts indicate that P. nuntia var. vallata usually inhabits gravel lands that is under a relatively little influence of river water. It is probable that the environmental factors such as chlorinity, water temperature and substratum, are subjected to seasonal fluctuations and the changes of these factors influence the growth of individuals. The present paper reports on the results of the experiments conducted to clarify the effects of environmental factors such as chiorinity, temperature and substratum on the growth and survival of adults P. nuntia var. vallata. 1) lllllll: fil;-'1'-, ;!;lil. :¥f., !1\Jl{ !It * Present address; Department of Water Treatment Engineering, Meidensha Electric Mfg. Co., Ltd. T6ky6, Japan 133 134 Y.INAMOR!, N. FURUYA AND Y. KURIHARA METHODS The worms used for these experiments were obtained through artificial insemination and reared in the vessels with the sea water whose chlorinity (hereafter described as Cl) was maintained at 19.3%o for about 4 months. The rearing vessels used here were acrylic resin containers of 0.5 l in volume. The rearing experiment was carried out according to the sand filtration method, by covering the bottoms of the containers with glass wool, filling them with a mixture of the sea sand and gmvels of in diameter 4-6 mm to make the surface area 58 em• and the depth 8 em each, which were then introduced with a continuous flow of the sea water diluted with demineralized water that flowed out from the bottom (Fig. 1). The inflow of water for each container was 12.4 lfday. The diet used was activated sludge composed mainly of bacteria and protozoa obtained by aerat-ing the domestic sewage that was mainly composed of organic matters and inorganic salts. It was carefully placed on the surface of the mixture of sand and gravels in which the worms were kept. The decrease in the amount of the sludge was taken to be the food intake. The difference in the individual body weight between the beginning and the end of each experiment divided by the number of days of experimental period was taken to be the body weight gain per day, and the body weight gain divided by the food intake as the food conversion efficiency. The diet was supplied as much as worms conld consume. In calculating the food convers-ion efficiency, the diet and the body weight gain were estimated in terms of dry weight in all cases. In the analysis of Cl was determined with MoHR's method (JAPAN SEWAGE WoRKS AssociATION 1967). As a rule, the experiment was conducted 7 times on each experimental group, and the estimation was made based on the average value. The experiment was conducted at a room temperature of 18-21°0, and aeration was done so as to maintain the dissolved exygen concentra-tion (hereafter called as DO) of the surface water at 5-6 mgfl. Fig. 1 Experimental apparatus. A: Air; I: Inflow; G: Gravel; S: Sand; W: Glass wool; 0: Out flow GROWTH OF PEBINEBEIS 135 RESULTS 1. Effect of ooncentration of the sea water To study the effect of concentration of the sea water on growth, the sea water diluted with demineralized water to a chlorinity of 2.0, 3.4, 5.7, 10.4, 15.6 or 19.3%o was passed, and as much activated sludge as the worms could consume was placed as diet in each container. The worms of about 0.2 g wet weight were reared at a density of 5, 10 and f9 individuals per 58 cm2 (9, 17 and 33 individuals per 100 cm2) for 20 days. The food intake, weight gain, food conversion efficiency and survival at the respective chlorinities of the culture water are shown in Fig. 2. At any chlorinity of the sea water the effect on survival was hardly recognized, whereas the food intake and the weight gain varied greatly depending on chlorinity: in the group of 33 individuals/100 cm2, the food intake was 200.4, 322.2 and 267.4 400 100 o·~ <> .. ·o .... ·· ····o ,.. • ~·. 'C 80 .. e- 300 ,• ...... -:.:" ··· ... 0 ~ 0 I .' e, ~ 0 ' ,, 0 60 .;;, ' '• - ' • I!' 200 #·····'; > ~ ~ 40 • jj-o , ~"' .: 'C 100 20 0 J: ' 00 5 10 15 20 00 5 10 15 20 Cl %o C I 0/oo 8 ,.. 0 15 • 7 ~. :;;; 'C ..... , ' g ~ 6 ' ' :0 .. ' I ' ~ .: I \ ·;; '" 5 I • ~ 10 E , R 4 : ·. c ·. .~ c 0 'ii 3 I '<> ~ "' I ~ I ~ 5 .c • 0 ,.../j .'!! 2 0 ~ 'C s:: ·* 0 1 0 1.1. 00 5 10 15 20 00 5 10 15 20 Cl o/oo Cl 0/oo Fig. 2 Effect of concentration of the sea water (indicated by chlorinity). 0: 9 individuals/ 100 omt, e: 17 individuals/100 om2, 0: 33 individuals/100 cmt, 1.36 Y. INAMORI, N; FURUYA AND Y. KURIHARA mg/100 cm2/day and the weight gain was 1.0, 4.7 and 2.8 mg/individualfday at 10.4%, Cl, 15.6 and 19.3%, respectively. The growth was positive at chlorinities of over 10.4%,. At 5.7 and 3.4%, Ci, however, the weight gain was zero though the corresponding food intake was 181.4, and 95.5 mg/100 cm2fday. Thls shows that the growth lowers at low chlorinities, though food intake is active. Addition-ally, the tendency that the body weight gain increased with a decrease in popula-tion density could be recognized. The average value of the food conversion efficiency obtained at the respective densities was 2.7, 7.7, 10.9 and 9.1% at CI 5.7, 10.4, 15.6 and 19.3%, respectively. These data indicate that the assimilation ratio of the taken food is hlgher with increasing chlorinity. 2. Effect of water temperature To investigate the effect of water temperature on the growth of P. nuntia var. vallata, experimental containers were placed in water baths maintained at 10, 20, 30, 34, 38 and 47'0 (with a variation of ±3'0), and supplied with the sea water (Cl 19.3 %,) and sludge. . The individuals, each about 0.2 g in wet weight, were placed in the 58 cm2 containers to give the population density of 29 wormsflOO cm2• The period of experiment was 17 days. The worms were weighed both in the beginning and at the end of the experiment. The results are shown in Fig. 3. The adult worms were able to survive adequately under temperatures ranging as widely as 10 to 38'0. However, at 10'0 the food intake decreased extremely without weight gain, and at 34 '0 the weight gain was zero. Tills shows that the worms do not grow both at low and hlgh temperatures. The food intake, weight gain, and food conversion efficiency were 267.4 mg/100 cm2Jday, 2.8 mg/individualfday and 7.2% at 20'0 and 222.4 mg, 1.9 mg and 5.1% at 30'0 respectively. Both the food intake and ·weight gain increased largely as compared with those at 10'0 and 34°0. Thus the optimum water temperature for the growth of the worm falls somewhere between 10'0 and 34 '0, probably in the vicinity of 20'0. Under hlgh temperature of 46-47'0 the worms died about 2 hours after thermal exposure. 3. Effect of population density To study the effect of population density on the growth of the worm, three groups of worms of 0.2-0.3 g wet weight placed in experimental containers of 58 cm2 at the density of 9, 17, and 33 per 100 cm2, and two groups of worms of about 0.5 g wet weight placed in containers of !50 cm2 at the density of 7 and 13 per 100 cm2 were reared. They were reared for 17 days, at 20'0, 0119.3%,. The results in the groups of 0.2--0.3 g initial wet weight are shown in Fig. 4: the food intake per 100 cm2 and per individual were 127.3, 211.0, and 267.4 mg/100 cm2/ day, and 14.8, 12.3, and 8.3 mg/individualfday at the density of 9, 17 and 33 individuals/100 cm2, respectively. The food intake per unit area increased as the GROWTH OF PERINEREIS 100 80 ~ • 60 • > -~ 40 , "' 20 0o 10 20 30 40 50 Temp. °C 3 ,. • "0 "'? :c 2 c -"' E c • "' 1 ~ "' "' ~ 00 10 20 30 40 50 Temp. •c ,. 300 • ~ NE 0 0 0 ~200 E ~ • ~c 100 "0 & ~10 • ,. 0 c 8 m ·;; ::: 6 m c 0 '§ m 4 > c 0 0 "0 2 0 0 u.. 00 10 Temp. °C 20 30 40 Temp •. 'c Fig. 3 Effect of water temperature. 137 50 population density increased, but the food intake per individual increased with a decrease in population density. The weight gain and the food conversion efficiency were 2.8 mg/individualfday and 7.2% at a high density (33 individuals/ . 100 em'), and 7.2 mg/individualfday and 11.2% at a low density (9 individuals/ 100 em'). These values differed conspicuously depending on the population density. Thls indicates that the individual growth increases as the population density decreases. A similar tendency was observed in worms of 0.5 g initial wet weight (Table 1). These facts indicate that the population density is effective even on the growth. 4. Effects of substrata It is known from studies on benthos found in tidal flat that the substratum or the particle size is as important as other environmental factors for their survival (TsucHIYA and KURIHARA, 1976). In order to study the effects of substrata on 138 Y. INAMORI, N. FURUYA AND Y. KURIHARA 100 80 ~60 0 <i .~ ~ 40 , (/) 20 0)'--'--'~-0 10 203040 lndiv.J10o crJ 10 8 > • .,:.-:,; .: 6 --"' Ec 4 •• "' ~""' "' ·; 2 ::: 00 10 20 30 40 lndiv.f1oocm2 300 ~ ., "e u 0 S!200 --"' E.ll • .~100 " 0 & 20 ;:; 15 ., ~ ., ·= 0;-E· 10 5 \ 0, ........ ~~- 0o 10 203040 lndiv.f100c..J 0 10 20 3040 lndiv.f1ooc~ 15 ~ 0 >-~ u c !!?_10 u ;;: ~ • c 0 -~ • 5 > c. 0 u ., 0 0 u.. 0 10 20 30 40 0 lndiv.f1oOcm2 Fig. 4 Effect of population density on the growth of the small sized-worms. Table 1. Effect of population density on the growth of the large sized-worms Population density wormsf100om2 Survival (%) Food intake mg/100cm'/ day I mgfindividualf day Weight gain mg/individual/ day Food conversion efficienc,r.: (%) 7 13 100 I 98 145.3 168.3 I 21.8 I 12.8 13.0 6.1 13.3 10.8 GROWTH OF PERINEREIS 139 the growth of the worm, a series of experiments were conducted using substrata of three classes, i.e., fine sea sand (0.1 mm in diameter or less), gravels (4-6 mm in diameter) and a uniform mixture of the two. The survival, food intake, weight gain, and food conversion efficiency in these substrata were compared. In this experiment the population density was 29 individuals per 100 cm2 and the experimental period was 17 days. The results are shown in Table 2. The effects of the kind of substratum. on the worm's survival were not observed, but variations were detected in the food intake, weight gain, and food conversion efficiency; the food intake was 267.4 mg/100 cm2/day in the sand-gravel group. The value drop-ped to 57"/o in the sand group and 62"/o in the gravel group as compared to that of the sand-gravel group. The weight gain of the sand-gravel group was obviously greater than that of the sand. Regarding the food conversion efficiency, the sand-gravel group indicated a value of 7 .2"/o, while the gravel group attained a value of 9.2"/o. Thus, it seems that gravels are more appropriate for growth than sand alone. Table 2. Effects of substrata Population Food intake Weight gain Food Substrata density Survival mg/ mg/ mg/ conversion worms{ IOOcm'/ individual/ individual/ efficiency 100cm11 (%) day day day (%) Sea sand 29 90.0 152.3 4.9 1.5 5.6 Sea sand + 29 88.6 267.4 8.3 2.8 7.2 Gravel Gravel 29 89.2 166.2 5.4 2.5 9.2 DISCUSSION The polychaete P. nuntia var. vallata will be unable to survive in an environ-ment of constantly low chlorinity. Although they were able to survive for a short period of time even at Cl 2.0-5.0%., their growth was zero. Therefore low chlorinity is not desirable for their survival and a chlorinity of 10.0%o or more is required for their growth, differing from N eanthes japonica which can survive and grow positively at a low chlorinity range such as 0.5-4.5%. {INAMORI and KURIHARA 1979). This may be supported by the observation that the lower survival limit of of the specific gravity of the natural habitat is 10.00 (CI 7.81%o). In planarians organic matter is known to be lost in the form of mucus or other forms (TEAL 1957). The present polychaete excreted a large amount of mucus in low chlorine medium, forming a protective coat on the body surface. The mucus secretion may affect largely the growth, lowering growth at low chlorinity. Since P. nuntia var. vallata were observed to be inactive in ingestion at 10°0, 140 Y. INAMORI, N. FURUYA AND Y. KURIHARA this species is not able to grow at low water temperatures. At the water tem-perature of 30°C, P. nuntia var. vallata was observed to have adequately grown up though not exceeding the case at 20°C, and to ingest vigorously. At 34°C, the weight gain was not observed, but feeding behavior was observed as sufficiently as the body weight was maintained. Although at 47°C, the present worms died in about 2 hours they were able to survive long enough at 40-45°C. Mter being placed at a temperature of 45°C for several hours, they were able to survive by forming burrows with falling water temperature to about 30°C. Therefore, it can be said that the tolerance of P. nuntia var. vallata against high temperatures is extremely high. On the other hand, N. japonica died in 2 hours at 43°C, and became inactive in ingestion at 3.5°C. But at 6°C it began to ingest, and at 9.5°C the weight gain was more than that at 30°C (INAMORI and KuRIHARA 1979). This indicates that, in contrast to P. nuntia var. vallata, tolerance against low tem-perature is rather high in N. japonica, although the optimum water temperature for both species is in the vicinity of 20°C. INAMORI and KuRIHARA (1979) reported that the weight gain of an individual of N. japonica decreased as population density increased. As in the case of N. japonica, the present species also showed a tendency that the higher the population density, the less the food intake, and the lower the density, the more the weight gain per individual. For explaining the effect of the population density various factors can be considered. At a high density the shape of burrows becomes unsuitable for living (INAMORI and KuRIHARA 1979), and the frequency of contact with other individuals during feeding increase, resulting in shortening of feeding time (YosHIDA, 1976). In natural field P. nuntia var. vallata inhabits substrata containing gravels, while N. japonica inhabits muddy-sand of tidal fiats formed in estuaries. It was found in the present experiment that the growth of P. nuntia var. vallata was retarded in a substratum of sand alone as compared with that in a substratum containing gravels. Thus, the particle size of substratum seems to be importance for the growth of worm from the standpoint of food intake, growth and food conversion efficiency. The authors wish to express thanks to Dr. M. TsuomYA for his help and to Dr. K. 0SANAI for his helpful comments. Thanks are also extended to Mr. E. FUJDIOTO for his encouragement. This study was partly supported by a grand in aid for Environmental Science research fund from the Ministry of Education, Japan. REFERENCES FuKUSHIMA, M. and A. IsHIDA 1966 Isogokai no shiiku to sono seikatsushi. (Rearing and life history of the nereid worm Perinereis brevicirris (GRUDE). The Aquiculture, 14: 51-56. (In Japanese) IMAJIMA, M. 1972 Review of annelid worms of the family nereidae of Japan, with description of five new species or subspecies. Bull. Nation. Sci. Mus.15: 37-153 lNAM:ORI, Y. and Y. KURIHARA 1979 Analysis of the environmental factors affecting the life of the brackish polychaete, Ncanthes japonica (IzuKA). I. The effects of the GROWTH OF PERINEREIS 141 environmental factors on survival and growth. Bull. Mar. Biol. St. Asamushi, Tohoku Univ., 16: 87-100. IsHIKAWA, H. 1938 Tsuri, esamushi riyO no kenkyU. (Research on the utilization of fishing bait.) Tsuri, JiryO Kenkyll Kai, Fukuoka (In Japanese) JAPAN SEWAGE WORKS AssoCIATION. 1967 Standard methods for the examination of sewage. JSWA, Tokyo 489 pp. (In Japanese) TEAL, J. M. 1957 Community metabolism in a temperate cold spring. Ecol. Monogr. 27: 283-302. TsuomYA, M. and Y. KURIHARA 1976 Studies on the distribution of the macrobenthos with special reference to the movement of the fine particles at GarnO Lago~n, Miyagi Prefecture. Physiol. Ecol. Japan, 17: 145-151. (In Japanese w1th English summary) . YosmDA, S. 1970 Isogokai no yOshoku ni kansuru kenkyU. I. ChikuyO no hOhO ni tsuite. (Research on the culture of the nereid worm Perinereis nuntia var. vallata. I.) The Aquiculture, 18: 1-7. (In Japanese) YosHIDA, S. 1976 The effects of worm density and amount of food for the culture of nereid worm Perinereis nuntia var. vallata. Bull. Jap. Soc. Sci. Fish., 42: 1193-1198. (In Japanese with English summary) 

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STUDIES ON THE EFFECTS OF SOME ENVIRONMENTAL FACTORS ON SURVIVAL AND GROWTH OF THE POLYCHAETE, PERINEREIS NUNTIA VAR. VALLATA

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