Lethal Limits of High Temperature for Two Crayfishes, the Native Species Cambaroides Japonicus and the Alien Species Pacifastacu

FISHERIES SCIENCE 2002; 68: 763–767

Lethal limits of high temperature for two crayﬁshes, the native species Cambaroides japonicus and the alien species Pacifastacus leniusculus in Japan

Kazuyoshi NAKATA,1,*,a Tatsuo HAMANO,1 Ken-Ichi HAYASHI1 AND Tadashi KAWAI2

1Department of Applied Aquabiology, National Fisheries University, Shimonoseki, Yamaguchi 759-6595 and 2Hokkaido Nuclear Energy Environmental Research Center, Kyowa, Hokkaido 045-0123, Japan

ABSTRACT: Lethal limits of high temperature were studied to clarify the effects on the survival of the endangered Japanese crayﬁsh species Cambaroides japonicus and the alien species Pacifas- tacus leniusculus. After the acclimation period for 2 weeks at 16¡C, the temperature was raised at a rate of 1¡C per week. As a result, the ultimate upper lethal temperatures of C. japonicus and P.leniusculus were 27.0 and 31.1¡C, respectively, and the lethal temperature for P.leniusculus was signiﬁ- cantly higher than for C. japonicus. The natural distributions of these two species are discussed in terms of the temperature tolerance.

KEY WORDS: Cambaroides japonicus, crayﬁsh, distribution, lethal temperature, Pacifasta- cus leniusculus, tolerance.

INTRODUCTION north-western USA and south-western Canada.4 It occupies a fairly wide range of habitats and is Three crayfish species are distributed in Japan. The found in large rivers, swift to sluggish streams, and Japanese crayfish Cambaroides japonicus (de Haan lakes, and usually occurs under large rocks and 1841) is the only native representative and the decaying vegetation.2 This species was first intro- others, Pacifastacus leniusculus (Dana, 1852) and duced into Japan for use as food in 1928. At first, Procambarus clarkii (Girard, 1852), are alien it had been distributed only in Lake Mashu in species introduced from North America during Hokkaido; however, the range of their distribution a period from 1926 to 1930.1 Miyake described has drastically increased, especially in eastern two species of Pacifastacus naturalized in Japan, Hokkaido.5 In Obihiro City in Hokkaido, the distri- P.leniusculus and Pacifastacus trowbridgii.1 bution of P.leniusculus was newly recorded in a However, we have accepted the theory that they are river within the city in 2000.6 At Lake Shikaribetsu the same species, the latter being an intraspecific in Hokkaido, P.leniusculus is now established variation of the former.2,3 and has drastically increased in number while C. The Japanese crayfish lives in cold, clear brooks japonicus has disappeared.7 and lakes in northern Japan, including Hokkaido, In general, temperature is a major limiting Aomori, Akita, and Iwate Prefectures.1 Natural factor for aquatic poikilothermic animals. Tem- populations of C. japonicus have drastically perature influences the geographic and local dis- declined, prompting the Japanese authorities tribution, growth, metabolism, reproduction and (Fisheries Agency in 1998 and Environment life histories, and has indirect effects through its Agency in 2000) to designate it as an endangered influence on water chemistry.8 Cambaroides species. japonicus and P.leniusculus survive in low water The signal crayfish P.leniusculus is native to per- temperature at near-freezing point.6,7 Further- manent water bodies in cool temperate regions of more, the range of the water temperature of habitats of C. japonicus is relatively narrow, up to only about 20°C in summer.9 Thus, knowledge of the ultimate upper lethal temperature (UULT) is *Corresponding author: Fax: 81-138-40-5548. Email: nakata@fish.hokudai.ac.jp important for the survival of C. japonicus in rela- aLaboratory of Marine Biodiversity, Graduate School of Fish- tion to restocking areas that have been depopu- eries Science, Hokkaido University, Hakodate 041-8611, Japan. lated and affecting the possible distribution range Received 22 June 2001. Accepted 22 December 2001. of C. japonicus and P.leniusculus in Japan. 764 FISHERIES SCIENCE K Nakata et al.

MATERIALS AND METHODS After the acclimation period, the temperature of the aquaria was raised by 1°C over a 24-h period Experiments on the UULT, which is the highest and this temperature was maintained for the fol- temperature that can be tolerated for a long period lowing 6 days (i.e. an increase of 1°C per week) by of time, obtained by gradually raising the acclima- controlling the biotron temperature system. tion temperature,10 of C. japonicus and P.leniuscu- The photoperiod was 12 h light : 12 h dark. lus were carried out at the laboratory in the Observations were made four times a day, twice National Fisheries University. each during the day and night. During the day, white fluorescent lamps were used with a low light intensity of 100–200 lx on the water surface, Size measurements because C. japonicus normally live in shaded areas.13 Night-time observations were made under In the present study, the total length (TL) from the a red light, which has been shown to minimally apex of the rostrum to the caudo-mesial margin influence the behavioral pattern for a freshwater of the telson and carapace length (CL) from the shrimp Macrobrachium sp.14 The water tempera- posterior margin of the orbit to the mid-dorsal ture was measured at every observation. All posterior margin of the carapace were used for size individuals were fed with an artificial diet measurements. (Hayashikane Sangyo Co., Ltd, Shimonoseki, Japan) once a day. Cambaroides japonicus normally moulted and grew with the diet (Nakata Samples et al., unpubl. data, 2001). One-third of the rearing water was changed every 5 days. Crayfish were obtained during seasons when The thermal tolerance test was continued until actual temperatures approximated the desired all of the animals were dead. The criterion of acclimation level. For C. japonicus, 20 individuals death in the present study was the cessation of (nine males and 11 females; 10.6–27.8 mm CL) the beating of the scaphognathites according to were collected from Hokkaido on 14 May 2000. Gladwell et al.15 From the present experiment, Details of the sampling station are omitted here the relationship between the test temperatures because of conservation measures for this popula- and percent survival (%) can be determined. Based tion. For P.leniusculus, 20 individuals (12 males on the method of Tsuchida and Setoguma,16 the and eight females; 14.7–37.8 mm CL) were col- UULT value was determined graphically at 50% lected on 30 September 2000 at the Kikanko River mortality. The present experiments were con- in Obihiro City, Hokkaido, where C. japonicus is no ducted during the period from 22 May 2000 to 5 longer observed.6 The water temperatures in the February 2001. sampling stations were 15.6°C for C. japonicus and 16.3°C for P.leniusculus. Observations on behavior

Temperature tolerance test We observed the behavior of the crayfish during the experimental period based on stress responses Prior to the experiment, the test animals were to high temperature in fish.17 As temperature placed individually in aquaria that were prepared increases within the upper critical range, the stress in a biotron and were acclimated for 2 weeks. The response in fish was classified into three progres- acclimation temperature was 16°C as C. japonicus sive phases.17 The first external indications of grows well and has been shown to actively forage abnormal behavior are a reluctance to feed, at 14–18°C in natural conditions.9 Pacifastacus sudden bursts of activity with frequent collisions leniusculus can live in the wild at these water tem- with the side walls of the tank, rolling and pitching peratures.6,7,11 Each aquarium was provided with and rapid ventilatory movements. In the second gentle aeration, and an artificial burrow made of a phase, the fish becomes quiescent with short gray-colored straight PVC pipe with suitable sizes bursts of weak swimming, often floating on its side was placed in each aquarium. The sizes of artificial or back and may rapidly change color and increase burrows were determined based on a study on its ventilatory movements. In the third phase, burrows of C. japonicus12 and similarly propor- movements are restricted to the opercula, pectoral tioned artificial burrows were used for P.leniuscu- fins and eyes, and cease with the death of the fish.17 lus. Thus, the internal diameters of the burrows Further, in some crayfish species, sluggish move- were selected from 13 mm, 20 mm, 30 mm, 40 mm ments were observed when prodded, a phenom- and 50 mm, with lengths of TL ¥ 3. enon that has been used as evidence of high Temperature tolerance of crayfish FISHERIES SCIENCE 765

temperature stress.18,19 These stress responses were 33°C, the remaining two crayﬁsh died (Table 1). discerned in the present study. The lethal temperature of P.leniusculus was signiﬁcantly higher than that of C. japonicus (Jonckheere’s test, P < 0.001) (Fig. 2). The UULT RESULTS of P.leniusculus was estimated at 31.1°C. Six individuals moulted at 18–27°C. Lethal limit of high temperature for C. japonicus

At 21°C after 46 days from the start of the experi- DISCUSSION ment, the first individual died from an abnormal moult, in which a part of the new carapace did not For C. japonicus, two individuals died with abnor- regenerate (Fig. 1). At 25°C after 70 days, some indi- mal moults at 21 and 26°C (Fig. 1). We previously viduals moved sluggishly on prodding. Above 26°C, observed more than 100 moults of C. japonicus at the number of dead individuals increased to three, 16°C under the same rearing conditions as in the six, six and three at 26, 27, 28 and 29°C, respectively. present study; however, no crayfish died with such An individual died from an abnormal moult at abnormal moults (Nakata et al., unpubl. data, 26°C. At 30°C, the last individual died (Table 1). The 2001). In a previous thermal study of P.leniusculus percent survival (%) drastically reduced above 26°C in the USA, four test animals died due to abnormal (Fig. 2). The UULT was estimated to be 27.0°C. moulting by abrupt transfer to high temperature During the experiment, seven and four individuals of 29–31°C.20 It was concluded that they were moulted at 16–19°C and 20–25°C, respectively. unable to tolerate the stress of moulting imposed Food intake remained unchanged up to the day the by the stress of severe thermal shock.20 The dead animals died. C. japonicus with abnormal moulting may have been affected by thermal shock. As the maximum water temperatures in summer Lethal limit of high temperature for in the natural habitats of C. japonicus are about P.leniusculus 20°C,9 the distribution of P.leniusculus can extend to the habitat of C. japonicus regarding tempera- The behavior of animals did not change up to 104 ture, judging from the present study. Recently, P. days at the temperature of 29°C. At 30°C, some leniusculus has been extending its range, especially individuals moved sluggishly on prodding and the in eastern Hokkaido.5 In Lake Shikaribetsu, food intake decreased. At this temperature five Hokkaido, where the maximum water temperature individuals died. The numbers of dead individuals were four and nine at 31 and 32°C, respectively. At

Fig. 1 Cambaroides japonicus male, which died during an abnormal moulting at 21°C. Upper, the moulted Fig. 2 Percent survival of the two crayﬁshes, exuvia of the crayﬁsh (10.9 mm in carapace length); Cambaroides japonicus and Pacifastacus leniusculus at lower, the body from the moult. A part of the new cara- 16–33°C after acclimation to 16°C for 2 weeks. The test pace did not regenerate. temperatures were raised at a rate of 1°C per week. 766 FISHERIES SCIENCE K Nakata et al.

Table 1 Upper lethal temperature of two crayﬁsh species, Cambaroides japonicus and Pacifastacus leniusculus Cambaroides japonicus Pacifastacus leniusculus Lethal temperature Carapace length* Lethal temperature Carapace length* (°C) (mm) Sex (°C) (mm) Sex 21 10.9† 30 28.0 26 16.5 30 30.6 26 20.2† 30 31.8 26 21.6 30 35.5 27 18.6 30 38.6 27 18.7 31 16.9 27 19.1 31 26.7 27 20.4 31 30.8 27 20.6 31 37.8 27 23.5 32 16.7 28 15.9 32 17.6 28 19.0 32 18.2 28 20.3 32 19.2 28 20.7 32 21.8 28 21.4 32 24.6 28 21.5 32 27.4 29 12.1 32 30.3 29 14.3 32 32.5 29 23.0 33 23.6 30 27.8 33 26.1

* Carapace length was measured after the crayﬁsh had died. † These crayﬁsh died during moulting.

is about 20°C, P.leniusculus is now established on natural distribution and suitability of aquacul- while C. japonicus has disappeared.7 Both C. tural environments. japonicus and P.leniusculus often hide under and/or between rocks and in burrows,21,22 and feed on similar detrital materials.23,24 Thus, the funda- ACKNOWLEDGMENTS mental niche of these two species may overlap. Pacifastacus leniusculus grows faster and is more We sincerely wish to thank Dr S. Goshima of fecund than C. japonicus;13,25,26 therefore, the popu- Hokkaido University for his valuable suggestions lations of P.leniusculus will dominate compared and critical comments of the manuscript. We with C. japonicus when P.leniusculus invades to a are grateful to Messrs M. Hirata, K. Aono, Y. local population of C. japonicus. Kobayashi and the members of the Otofuke River In other experiments using a different experi- Groundwork Group, who contributed to this study. mental method, the incipient lethal temperature We also acknowledge Drs K. Yamamoto and (ILT) of P.leniusculus, which was measured by A. Araki, National Fisheries University, and Mr maintaining at an acclimation temperature and T. Kikkawa, Marine Ecology Research Institute who then an abrupt transfer to a higher temperature,17,27 gave us valuable comments and Dr B. Wood for was reported to be approximately 32–33°C.11,20 The correcting the English. We thank two anonymous critical thermal maximum (CTM) of P.leniusculus, referees for their valuable comments on the which was determined by raising the temperature manuscript. from the ambient acclimation level at a constant rate so that there was no significant time lag between the water temperature and the internal REFERENCES temperature of the animal17,27 was near 31°C after an acclimation at 20°C.18 These values are similar 1. Miyake S. Japanese Crustacean Decapods and. Stomatopods in Color I. Hoikusya, Osaka. 1982. to the UULT value of 31.1°C in the present study. As 2. Riegel JA. The systematics and distribution of crayfishes in gradual changes in temperature in the present California. Calif. Fish Game 1959; 45: 29–50. study are a more natural phenomenon than rapid 3. Hamano T, Hayashi K, Kawai T, Hayashi H. Crayfish (Crus- changes of several degrees, the UULT provides a tacea, Decapoda) in Lake Mashu Hokkaido. Res. Crustac. useful criterion for the thermal tolerance in studies 1992; 21: 73–87. Temperature tolerance of crayfish FISHERIES SCIENCE 767

4. Henttonen P, Huner JV. The introduction of alien species of their effects on excitable tissue during heat death. J. Therm. crayfish in Europe: A historical introduction. In: Gherardi F, Biol. 1975; 1: 79–94. Holdich DM (eds). Crayfish in Europe as Alien Species. A. A. 16. Tsuchida S, Setoguma T. Temperature responses of young Balkema, Rotterdam. 1999; 3–9. Schlegel’s black rockfish Sebastes schlegeli. Nippon Suisan 5. Hiruta S. The present status of crayfish in eastern Hokkaido Gakkaishi 1997; 63: 317–325. and Britain. J. Environ. Educ. 1998; 1: 181–195. 17. Elliott JM. Some aspects of thermal stress on freshwater 6. Nakata K, Hamano T, Kawai T, Hirata M, Takakura Y, Kagami teleosts. In: Pickering AD (ed). Stress and Fish. Academic H, Tsutsumi K, the Otofuke River Groundwork Group. Dis- Press, London. 1981; 209–246. tributions of crayfish in the Tokachi region of Hokkaido, 18. Firkins I, Holdich DM. Thermal studies with three species of Japan, with notes on temporal changes in density. Report freshwater crayfish. Freshwater Crayfish 1993; 9: 241–248. Obihiro Centennial City Museum 2001; 19: 79–88. 19. Mirenda RJ, Dimock RV Jr. Temperature tolerance of the 7. Nakata K, Tanaka A, Hamano T, Kawai T. Distribution of the crayfish Cambarus acuminatus, 1844 (Decapoda, signal crayfish Pacifastacus leniusculus in Lake Shikari- Astacidea). Crustaceana 1985; 48: 249–259. betsu. Hokkaido, Japan. Bull. Higashi Taisetsu Mus. Nat. 20. Becker CD, Genoway JG, Merrill JA. Resistance of a Hist., 2002; 24: 27–34. northwestern crayfish, Pacifastacus leniusculus (Dana) to 8. Lee DO’C, Wickins JF. Crustacean Farming. Blackwell, elevated temperatures. Trans. Am. Fish. Soc. 1975; 104: London. 1992. 374–387. 9. Kawai T, Hamano T, Matsuura S. Molting season and 21. Kawai T. Burrow of a Japanese crayfish Cambaroides reproductive cycle of the Japanese crayfish, Cambaroides japonicus (de Haan, 1841). Res. Crustac. 1992; 21: 65–71. japonicus in a stream and a small lake in Hokkaido. 22. Guan R. Burrowing behaviour of signal crayfish, Pacifasta- Suisanzoshoku 1994; 42: 465–470. cus leniusculus (Dana), in the River Great Ouse, England. 10. Fry FEJ, Hart JS, Walker KF. Lethal temperature relations for Freshwater Forum 1994; 4: 155–168. a sample of young speckled trout, Salvelinus fontinalis. 23. Kawai T, Hamano T, Matsuura S. Food habits of the Japan- Univ. Toronto Stud. Biol. Ser. 1946; 54: 1–35. ese crayfish Cambaroides japonicus (Decapoda, Astacoidea) 11. Becker CD, Genoway JG. Resistance of crayfish to acute in a stream in Hokkaido, Japan. Fish. Sci. 1995; 61: 720–721. thermal shock; preliminary studies. In: Gibbons JW, Sharitz 24. Guan R. Feeding ecology of the signal crayfish Pacifastacus RR (eds). Thermal Ecology. National Technical Information leniusculus in a British lowland river. Aquaculture 1998; 169: Service, Springfield, VA. 1974; 146–150. 177–193. 12. Nakata K, Hamano T, Hayashi K, Kawai T, Goshima S. 25. Ackefors H. The positive effects of established crayfish Artificial burrow preference by the Japanese crayfish introductions in Europe. In: Gherardi F, Holdich DM (eds). Cambaroides japonicus. Fish. Sci. 2001; 67: 449–455. Crayfish in Europe as Alien Species. A. A. Balkema, Rotter- 13. Kawai T, Miyake S, Hamano T. Individual density and repro- dam. 1999; 49–61. duction of Cambaroides japonicus (de Haan, 1841) in the 26. Skurdal J, Taugbøl T, Burba A, Edsman L, Söderbäck B, southernmost habitat. Res. Crustac. 1990; 19: 55–61. Styrrishave B, Tuusti J, Westman K. Crayfish introductions 14. Bernadi N. Temperature influence upon food ingestion in the Nordic and Baltic countries. In: Gherardi, F, Holdich, and spontaneous locomotion of the freshwater prawn DM (eds). Crayfish in Europe as Alien Species. A. A. Balkema, Macrobrachium acanthurus (Wiegmann, 1836) (Crustacea, Rotterdam. 1999; 193–219. Decapoda, Palaemonidae). J. Therm. Biol. 1990; 15: 33– 27. Wedemeyer GA, McLeay DJ. Methods for determining the 36. tolerance of fishes to environmental stressors. In: Pickering 15. Gladwell RT, Bowler K, Duncan CJ. Heat death in the cray- AD (ed). Stress and Fish. Academic Press, London. 1981; fish Austropotamobium pallipes—I. On movements and 247–276.