REPRODUCTIVE AND NUTRITIONAL CYCLES OF THE PORTUNUS* PELAGICUS (LINNAEUS) (: BRACHYURA) OF THE MADRAS COAST BY A. ABDtm RAHAMAN (Department of Zoology, Madurai University,~ Madurai,-2, India)

Received December 28, 1966

(Communicated by Prof S. Krishnaswamy, l~.A.sc.)

ABSTRACT The gonadal and hepatic indices were deterrmned. Even though the crab Portunus pelagicus is a continuous breeder, there appears to be three maximal periods of development of the gonad and hepatopancreas. The gonad index is high in the months of November-January and June and the hepatic index shows the greatest development in the months of November-January and August. There appears to be a direct relationship between gonadal and hepatopancreatic development. These results have been discussed in the light of previous work.

INTRODUCTION

THE reproductive cycle of invertebrates and their sexual periodicities have been extensively studied by many workers (Bennett and Giese, I955; Farmanfarmaian et al., 1958; Giese, 1959 a, 1959 b; Giese et al., 1964; Raha- man, 1965). Of these mention may be made of the studies on the periodic changes in the reproductive cycle of several species of of tem- perate regions by Boolootian et al. (1959) and Giese (1959). Except for the work on the Indian prawn Penaeus indieus (Subrahmanyam, 1963) similar work on tropical arthropods has been very few. Prasad and Tampi (1953) studied the biology of the blue swimming crab, Portunus pelagieus (Neptunus pelagieus) which forms an important fishery along the east coast of India. Delsman and De Man (1925) found berried of this species throughout the year in Batavia. Prasad and Tampi (loc. eit.) working on the same species and basing their observations on the commercial landings as well as

* Genus name Neptunus has been changed to Portunus. International Commission of Zoological Nomenclature (1959) cited by Stephenson and Campbell (1959). ;, Formerly Department of ZoolosY, University of Madras. Madurai Centre, Madurai-2, 76 Reproductive and Nutritional Cycles of Crab P. pelagicus 77 on the occurrence of larval forms in the plankton observed that" the maximum breeding activity is during September to March ". From this it is clear that an elaborate study based on the gonadal and hepatic indices, would throw light on the reproductive and nutritional cycles of Portunus pelagicus. The present paper deals with these aspects.

MATERIAL AND METHOD The crabs of the species Portunus pelagicus Linnaeus were collected in nets from the offshore region of Tondi, on the east coast of India, Madras State, 70 miles from Madurai. They were in a live condition when brought to the shore. Random sampling was made. Initially twenty were sampled, but the data were no more informative than data on a sample of ten animals collected monthly as was also found by Giese (1959). So ten animals were taken for analysis every month;, larger sampling being done whenever feasible. Soon after being brought to shore, the selected animals were transported to the laboratory which is about a mile away from the shore, in an earthen vessel containing sufficient sea-water for aeration. Sufficient time was given (about 1 to 2 hours) for the animals to acclimatize to the laboratory conditions before being sacrificed. Specimens that were not in a healthy condition (diseased or inactive) as well as those that had just moulted were not used for analysis. After separation of sexes, the adhering water on the surface including the appen- dages was completely wiped off using a towel. The length of the carapace was measured accurately to within a millimetre from one tip to the other of the spinous lateral extension of the carapace. The animals were weighed to the nearest gram. The length of the carapace varied between 80ram. and 150 ram. in the animals chosen, and it was observed that the weight of the crab shows a linear relationship with that of the length of the carapace. The animals were dissected, by cutting open the carapace. However, in the male, the carapace was slit open and separated carefully from the adhering tissue lining the inside of the carapace as only then the testes and other accessory reproductive organs could be completely seen and removed without damage. Care was also taken to exclude the hepatopancreas attached to the testes, as the latter was of a different colour. The gonads were taken out and were weighed accurately in a balance up to the milligram. Similarly, the hepato- pancreas was dissected out carefully, the body fluid surrounding it removed with the help of a pipette and weighed accurately. A microscopic examina- tion of the gonads was made to identify the state of maturity of the animals. 78 A. ABDULRAHAMAN The hepatic and gonad indices were calculated according to the formula given by Farmanfarmaian et aL 0958) whereby the wet weight of the hepato- pancreas or gonad is divided by the wet weight of the and multiplied by 100.

RESULTS A perusal of Table I shows that there is no definite peak with regard to the gonad index. There appears to be three maximal periods, Le., November (3.51 mean), January (3.00 mean) and June (2-26 mean). How- ever, there appears to be a greater breeding activity in November-January periods. There is a possible second maximal breeding period about the month of June. Further, the data would indicate that breeding in these forms is more or less continuous, the spawning season alternating with periods of sexual maturity.

TABLE I

Gonad Hepatic Gonad Hepatic Gonad Hepatic Month index index index index index index (mean) (mean) (mean) (mean) (mean) (mean) ~ ~ ~ ~+~ ~+~

1964 September..... 1.04 3.21 2.35 2.05 1.31 2.98 October ..... 0.45 2.26 2.89 1-67 1.91 1.91 November .... 1.05 4.01 5.96 2.71 3.51 3-36 December .... 0.67 2.23 0.52 1-56 0.56 2.03 1965 January, .... 0.18 2.56 5-26 4-14 3.00 3.44 February ...... 0.52 2.73 2.26 2.88 1.39 2.80 March ...... 0-47 1-78 1.97 1.54 1.22 1-65 April ...... 0-47 2- 66 0- 26 2- 83 0- 36 2- 75 May - .. 0.39 1.65 3-51 2.38 1.95 2.02 June .... 0.48 2.47 4.04 3.39 2-26 2-93 July .. ;. 0.37 2.27 1.40 3.92 0.82 3.10 August ...... 0.38 2.98 3.32 3.95 1.72 3 "42

The seasonal changes in the hepatic index also exhibits similar pattern. The maximal hepatic indices are found in the months of November (3.36 mean), January (3-44 mean) and August (3.42 mean). The first two peaks coincide with the maximal gonadal activity. Even though the third peak appears in August, the hepatic index for the month of June is also high (2.93 Reproductive and Nutritional cycles of. Crab P. pelagicus 79 mean) and may also be correlated with the higher gonadal activity in June (2.26 mean). A comparison of the gonadal and hepatic indices (vide Figs. 1 and 2) shows that with an increase in the gonadal activity there is also an increase in the hepatic index. This is of interest since in several invertebrates an inverse relationship appears to exist [e.g., Pisaster ochraceus and P. brevi- spinus (Farmanfarmaianet al., 1958), Asterias rubens (Delaunay, 1928), Oreaster hedemanni Rahaman, 1965)]. However, the pattern of the reproductive and nutritional cycles of this form corresponds to the results obtained in the antarctic starfish Odontaster validus (Pearse, 1965).

7

"

~, i !',,,

• , ,. , , : ..--, , o " .,, ,." :/ X ",. :r" \',,/ . 4" ~ I "" ~ t / ~Iflf .,"

e

,~ Hor, IT~

FIG. 1. Showing the gonad index in the male and female Portunus pelagicus during different months of the year.

.... ~d

5 4 tI~

.2 I I I f , ! I I ! I • . J , . fo,, o ~ • ~s~ , HONTH5 , ,~ /,

FIG. 2. Showing the hapatic index in the male and female Portunus pelagicus during different months of the year. 80 A. ABDUL RAHAMAN

DISCUSSION It has been shown by Stephep_son(1934) that species inhabiting the tropi- cal waters may exhibit several types of breeding cycles, i.e., continuous breed- ing around the year, discontinuous breeding in relation to lunar phases during greater or shorter period in a year, two spawning periods and lastly one single breeding season. Such different types of breeding cycles have been observed in the Adyar estuary (Panikkar and Aiyar, 1939) and in sessile fauna of the Madras harbour (Paul, 1942). The breeding season of crabs seem to vary very much. In the temperate regions the crabs Hemigrapsus nudus, Pachygrapsus crassipes and Emerita analoga seem to have a single breeding cycle (Boolootian et al., 1959). Stead (1898) regarded the spawning season of Neptunus in Australian waters to be about August-November. However, Thomson (1951) found the egg-bearing season to be from September-April. Based on the commercial catches and availability of berried females it has been reported that Portunus sanguinolentus (Neptunus sanguinolentus) breeds in February-March on the west cost of India (Menon, 1952). Petrolisthes cinctipes and Pugettia pro- ducta occuring along the west coast of United States (Boolootian et al., 1959) and Portunus pelagicus (Neptunus pelagicus) occurring in Batavia breed throughout the year (Delsman and De Man, 1925). The same species occurring at Tondi, on the east coast of India, appears to exhibit a similar trend. Delsman and De Man (1925) observed that the berried crabs of Portunus pelagicus (Neptunus pelagicus) occur throughout the year. The data obtained during the year 1964--65 also show that the mature males and females occur during all months of the year. However, three definite peaks in the gonadal and hepatic indices occurring in the months of November, January and in the period of June--August suggest an intense breeding activity at least during those seasons. As sampling had to be necessarily done in a random fashion in any one sample animals in different reproductive conditions were represented. Thus the population sampled was "inhomogeneous '" (Giese et aL, 1958), consisting of immature, mature animals, spawners and spent ones. It is presumed that the reproductive activity of an individual crab may be rather protracted, though the majority appear to have definite breeding periods. However, the reproductive rhythm of an individual animal of a species may not always coincide which results in asynchronous spawning (Panikkar and Aiyar, 1939). Unlike several other invertebrates [Pisaster ochraceus and P. brevispinus, Farmanfarmaian et al., 1958), Asterias rubens (Delaunay, 1928), Oreaster Reproductive and Nutritional Cycles of Crab P. pelagicus 81 hedemanni (Rahaman, 1965)], where the gonadal and hepatic indices show an inverse relationship the gonad and hepatopancreas show the same maximal development in the months of November and January as well as in the period of June-August. The cause of a similar pattern in the antarctic starfish Odontaster validus (Pearse, 1965) was suggested to be the availability of food during the period of gonadal development. However, such an explanation may not be tenable in tropical waters where food may abound throughout the year. The exact relationship between the gonad and hepatopancreas as well as the availability of food needs further investigation.

ACKNOWLEDGEMENTS

The author expresses his deep sense of gratitude to Prof. S. Krishnaswamy, Professor of Zoology, Madurai University, Madurai, for suggesting the problem, help and guidance and to Dr. R. Theodore Srinivasagam for offering helpful suggestions in the preparation of this paper.

REFERENCES

Bennet, J. and Giese, A.C. .. "The annual reproductive and nutritional cycles in two western sea urchins," Biol. Bull., 1955, 109, 226-37. Boolootian, R. A., Giese, A. C. "Reproductive cycles of five west coast crabs," Physiol. ZooL, Farmanfarmaian, A. and 1959, 32, 213-20. Tucker, J. Delsman, H. C. and De Man, "On the 'Radjungans' of the Bay of Batavia," Treubia, J.C. 1925, 6, 308-23. *Delaunay, H. .. "Sur l'excretion azotee des asteries," C.R. Soc. Biol., Paris, 1926, 94. Farmanfarmaian, A., Giese, A.C. "Annual reproductive cycles in four species of West Coas Boolootian, R. A. and Starfishes," J. Exp. Zool., 1958, 138, 355-67. Bennett, J. Giese, A. C. "Reproductive cycles of some West Coast Invertebrates," Internat. Symp. Photoperiodicity, Gatlingburg, 1957, Washington, D.C., A.A.A.S., 1959a. "Annual reproductive cycles of marine invertebrates," Ann. Rev. Physiol, 1959 b, 21, 547-76. • . , Greenfield, L., Huang, H., "Organic productivity in the reproductive cycle of the purple Farmanfarmaian, A., sea urchin," Biol. Bull., 1958, 116, 49-58. Boolootian, R. A. and Lascar, R. ----, Krishnaswamy, S., Vasu, "Reproductive and biochemical studies on a sea urchin, B. S. and Lawrence, J. Stomopneustes variolaris from Madras harbour," Comp. Biochem. Physiol., 1964, 13, 369-80. $2 A. ABDUL RAHAMAN

Menon, I~ishna, M. .. "A note on the bionomics and fishery of the swimming crab Neptunus sanguinolentus (Herbst) on the Malabar Coast," •Jr. ZooL Soc. India., 1952, 4, 177-84. Panikkar, N. K. and Aiyar, "'Observations on breeding in brackish-water animals of R.G. Madras," Proc. Indian Acad. Sci., 1939, 9, 343-64. Paul, M. D. .. "Studies on the growth and breeding of certain sedentary organism in the Madras harbour," Ibid., 1942, 15, 1-42. Prasad, R. R. and Tampi, "A contribution to the biology of the blue swimming crab P. R. S. Neptunus pelagicus (Linnaeus) with a note on the zoea of Thalamita crenata Latreille," J. Bombay Nat. Hist. $oc., 1953, 51, 674-89. Pearse, J. S. .. Personal communication, 1965. Rahaman, A. Abdul .. "Annual changes in the gonad and hepatic indices of the starfish Oreaster hedemanni of the Madras Coast," 1965 (In press). *Stead, D. G. .. "Contributions to knowledge of the Australian fauna. I. Observations on the genus Neptunus,'" Proc. Linn. Soc., New South Wales., 1898, 23, 746-58. *Stephenson, A. .. "The breeding of reef animals, II. Invertebrates other than coral. Great Barrier Reef Expedition, 1928-29," ScL Rept., 1934, 3, 247-72. *Stephenson, W. and Campbell, "The Australian Portunids (Crustacea: ). III. B. The genus Portunus," Aust. J. Mar. Freshw. Res., 1959, I0, 84-124. Subrahmanyam, C. B. .. "A note on the annual reproductive cycle of the prawn Penaeu~ indicus (M-F~W.) of Madras Coast," Curr. Sei., 1963, 32, 165-66. *Thomson, J.M. .. "Catch composition of the Sand crab, fishery in Moreton Bay." Aust. J. Mar. Freshw. Res., 1951, 2, 237-44. * Not referred to in original.

44-67. Printed at The Baagalore Press, Mysore Road, Bangalore 18, and Published by B. S. Venkatachar, Editor, "Proceedings of the Indian Academy of Sciences." Bangalore