BULLETIN OF MARINE SCIENCE, 67(2): 845–856, 2000 PAPER

REPRODUCTIVE CYCLES OF DIADEMA SETOSUM AND MATHAEI (ECHINOIDEA: ECHINODERMATA) FROM KUWAIT (NORTHERN ARABIAN GULF)

Adel H. Alsaffar and Khalid P. Lone

ABSTRACT A study was undertaken on the seasonal variations in the reproductive biology of Diadema setosum and Echinometra mathaei from the coral reefs of Kuwait. Sixteen monthly samples were taken for both and gonads were processed for histological studies. Both species had peak spawning in summer months when maximum seawater temperature was between 24.2 and 28.8ºC. Peak spawning was seen for Diadema in April- May (24–28ºC), while this point for Echinometra was achieved in June (28.8ºC). The spawning peak was much broader for Diadema. The breeding season in both species coincided well with increasing seawater temperature and day-length. The gonad color was not related to sex and there was no difference in drained weight of male and female of both the species. Both spermatogenesis and oogenesis were histologically similar to other echinoid species described by other authorities.

The Indo-Pacific echinoids Diadema setosum and Echinometra mathaei are distrib- uted from Japan to southern Australia and from Mexico to the Gulf of Suez (Khamala, 1971). Throughout their distribution, their ecology, biology and reproduction have been studied (Pearse, 1968, 1969; Kobayashi, 1969; Lessios, 1981; Illiffe and Pearse, 1982; Drummond, 1995). Reproduction in previously studied populations was either continu- ous or restricted to certain part of the year (Pearse and Cameron, 1991). Reproduction of these species has not been studied on the coral reefs of Kuwait. Despite the extreme difference in seawater temperatures (minimum 10.6ºC in January; maximum 32.8ºC in August with air temperature reaching beyond 50ºC), the populations of both species are well established at the coral reef, with E. mathaei being more prevalent than D. setosum. The population density of D. setosum has been reported to range from 3 to 15 urchins m−2 while that of E. mathaei exceeds 100 urchins m−2 (Downing and El-Zahr, 1987; Downing, 1992; Downing and Roberts, 1993; Carpenter et al., 1997; Harrison et al., 1997). Here we report the reproductive periodicity of these species and compare it with studies on these species elsewhere.

MATERIALS AND METHODS

Urchins were collected from Kuwait’s Kubbar Island reef (29º 04.25'N, 48º 29.50'E) from the sampling positions shown in Figure 1. Diadema setosum were taken from the reef edge at a depth ranging from 3 to 5 m, at a bearing of 140o magnetic to the light tower on the Island. E. mathaei were taken from the reef flat at a position 70 m from the reef edge along the previous bearing at a depth ranging from 1–2 m. The urchins were collected in early morning in the middle of the lunar month (at full moon), or as soon as possible thereafter. Each month, 20 to 30 individual urchin of each species were collected by divers in mesh bags, transported to the laboratory and immediately laid on a table with the oral opening facing down to allow the excess of water to drain. The sampling was done for 16 mo starting from the month of November 1985 through February 1987.

845 846 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 2, 2000

Figure 1. Map showing the location of Kuwait’s main coral reefs and the sampling sites at the island of Kubbar. The expanded view of the island and the reef shows the island in solid line with its light tower while the reef surrounding the islands is shown in dotted line. The numbers one and two correspond to the sampling sites for Diadema setosum and Echinometra mathaei respectively. The position two was 70 m from the bigger reef edge. The solid arrow represents 140º magnetic from sampling site 1 to the light tower.

Each urchin was weighed to the nearest 10 mg and then carefully cut in half and the color, sex and the state of maturity of the gonad were estimated. The gonads were removed and weighed to the nearest mg. The drained weights for Diadema ranged from 27.91–105.13 g (n = 346) while the weights for Echinometra were 23.61–66.32 g (n = 329). After weighing, the gonad was fixed in 10% buffered formalin and embedded in paraffin. Sections were cut at 6–8 μ and stained with haematoxylin-eosin and examined for male and female gametogenic cycle. The gonad index (GI) was computed according to the formula (Lamare and Stewart, 1998; Meidel and Scheibling, 1998; Walker and Lesser, 1998) given below: ALSAFFAR AND LONE: REPRODUCTION OF DIADEMA SETOSUM AND ECHINOMETRA MATHAEI 847

Weight of the gonad (g)× 100 GI = Drained weight of the urchin (g)

The GI data were evaluated using a single-factor (fixed effect of time) ANOVA at a significance level of 5%. Where significant effects were found, the Student-Newman-Keuls (SNK) multiple comparison test was applied to identify differences among sampling times (Sokal and Rohlf, 1981). The relationship between the drained body weight, gonad weight (GW) and GI was also analyzed using linear regression.

RESULTS AND DISCUSSION

Minimum water temperature was observed in January (range 10.6º–17.6ºC mean mini- mum = 16.0ºC) while the maximum was in August (range 28.3º–32.8ºC; mean maximum = 30.3ºC). The day-length ranged from 10 h 20 min in December to 14 h in June; Fig. 2). Salinity ranged from 42–44 ‰ while the pH of the seawater was 8.2–8.4. There was a slight increase in the gonad weight with the increase in the drained body weight in both species, but this relationship was not significant statistically. Similarly, the relationship between drained body weight and GI was also not significant. The regression equations for the two species are given below:

Diadema GW = −0.8126 + 0.0462 × drained body weight (r2 = 0.2857; n = 346) GI = 1.6436 + 0.0251 × drained body weight (r2 = 0.0297; n = 346)

Echinometra GW = −0.4475 + 0.0378 × drained body weight (r2 = 0.2178; n = 329) GI = 1.6928 + 0.0231 × drained body weight (r2 = 0.0205; n = 329)

The relationship between the gonad weight, gonad index and test diameter was recently studied in green urchin (Strongylocentrotus droebachiensis) and a diadematoid urchin (Centrostephanus rodgersii). Both studies found that there was no significant relation- ship between the gonad output, gonad index and the test diameter (Byrne et al., 1998; Meidel and Scheibling, 1998). This relationship indicates a decreasing investment in re- production beyond a given size. A decrease in reproductive effort beyond a given maxi- mal size is common in many particularly, the echinoids (Lawrence and Lane, 1982; Guillou and Lumingas, 1999). This can also be due to a decrease in feeding activity and metabolism with age. The GI of E. mathaei was low and remained more or less constant during the months of November (2.64 ± 0.16; mean ± S.E.) through April (2.49 ± 0.24) when water tempera- ture averaged less than 25ºC (Fig. 2). The gonads start maturing rapidly from April and peaked in the month of June. The maximum GI (6.62 ± 0.52) was also encountered in June. The spawning activity of this species peaks during June and July, as in July the GI dropped to values comparable to May values. This spawning occurred between the June full moon and the new moon of July. GI values gradually decreased until the minimum was reached in January. The GI at this time was 1.22 ± 0.16 (Fig. 2). The ANOVA (F15, 314 = 20.99, P = 0.000) showed significant differences among the GI values of different months 848 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 2, 2000

Figure 2. Minimum and maximum water temperature, day-length and mean gonad index (percentage of drained body weight, ± SE) of Echinometra mathaei and Diadema setosum between November 1985 and February 1987. Means are based on, at least, 20 sea urchins each every month.

(Fig. 2). Post-hoc comparisons showed that May, June and July GI values were signifi- cantly (P < 0.05) higher than those were for the other months (Table 1). January 1987 values were also lower than the November 1985 and April, August 1986 GI values (P < 0.05). The GI for D. setosum was unlike that for E. mathaei, and started increasing slowly from November (2.18 ± 0.27) and reaching an initial maximum in January (3.78 ± 0.32). There was a slight decrease in the GI in February (3.13 ± 0.38), but after this time the values continued increasing until the peak values were observed in April (5.52 ± 0.34). The values remained constant in May (5.53 ± 0.25) and then declined. Diadema, starts spawning from mid April when seawater temperature was 22–28ºC. The spawning activ- ity of Diadema was more prolonged than that of Echinometra and continued until the end ALSAFFAR AND LONE: REPRODUCTION OF DIADEMA SETOSUM AND ECHINOMETRA MATHAEI 849

Table 1. Results of single factor ANOVA on the effects of date (time) on the gonad index of Echinometra mathaei and post-hoc Student-Newman-Keuls (SNK) test according to Sokal and Rohlf (1981).

ASNOVA SfdSMFP Source of variation B5etween groups 3587.2 12295.8 200.9 0.0 W1ithin groups 3487.4 331 1.2

SNK test MPonth N7ov. 85 MPay, June, July, Oct. 86, Jan. 8 < 0.05 D.ec. 85 M7ay, June, July 86, Jan 8P< 0.05 J.an. 86 M7ay, June, July 86, Jan 8P< 0.05 F.eb. 86 M7ay, June, July 86, Jan 8P< 0.05 M.ar. 86 M7ay, June, July 86, Jan 8P< 0.05 A.pr. 86 M7ay, June, July 86, Jan 8P< 0.05 Mtay 86 APll months significan < 0.05 Jtun. 86 APll months significan < 0.05 Jtul. 86 APll months significan < 0.05 A.ug. 86 M7ay, June, July 86, Jan 8P< 0.05 S,ep. 86 MPay, June, July 86 < 0.05 O6ct. 86 NPov. 85, May, June, July 8 < 0.05 N,ov. 86 MPay, June, July 86 < 0.05 D6ec. 86 MPay, June, July 8 < 0.05 J6an. 87 NPov. 85 to Aug. 86, Dec. 8 < 0.05 F,eb. 87 MPay, June, July 86 < 0.05 All other comparisons, except the ones reported above, were non-significant.

of July, when the GI reached 3.03 ± 0.23 and the water temperature reached 30ºC. There is some overlap between the spawning of the two species. After July, the GI remained more or less constant until October after which time it decreased to its minimum (1.11 ± 0.16) in January. The low GI stage coincides with minimum water temperatures and short day-length. Fujisawa and Shigei (1990) while working with eight species of urchins in Japanese waters described similar temperature optima for the spawning of D. setosum (24–30ºC) and E. mathaei (22–30ºC). When the monthly GI of D. setosum were com- pared by ANOVA, the month was found to be highly significant (F15, 331 = 28.22, P = 0.000). Detailed post-hoc test (SNK) showed that April, May and June values were sig- nificantly different (Table 2) from rest of the months (Fig. 2). The successive phases of gametogenesis in echinoids follow an orderly time course in an individual or within a population (Pearse and Cameron, 1991). At the population level, most species of echinoids undergo discrete annual rhythms of active gametogenesis and spawning and this has been seen for many species and localities (Table 3). Species living near the equator spawn for a longer period of time than the temperate species (Fujisawa and Shigei, 1990; Lessios, 1985; King et al., 1994; Guillou and Michel, 1994; Guillou and Lumingas, 1998, 1999; Byrne et al., 1998; Meidel and Scheibling, 1998). These studies clearly show that environmental conditions have far reaching effects on the repro- duction of these echinoderms. Of the environmental factors studied, temperature, photo- period, food and salinity are more important than are the other factors. 850 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 2, 2000

Table 2. Results of single factor ANOVA on the effects of date (time) on the gonad index of Diadema setosum and post-hoc Student- Newman-Keuls (SNK) test according to Sokal and Rohlf (1981).

ASNOVA SfdSMFP Source of variation B6etween groups 5588.2 12329.2 208.2 0.0 W6ithin groups 4159.7 393 1.3

SNK test MPonth N.ov. 85 Jan. 86, Apr −SPep. 86, Jan. 87 < 0.05 D.ec. 85 Jan. 86, Apr −JPun. 86, Jan. 87 < 0.05 J6an. 86 APll months significant except Jun. 8 < 0.05 F.eb. 86 Jan. 86, Apr −JPun. 86, Jan. 87 < 0.05 M.ar. 86 Apr −JPune, Dec. 86, Jan.87 < 0.05 Atpr. 86 APll months significan < 0.05 Mtay 86 APll months significan < 0.05 Jtun. 86 APll months significan < 0.05 J7ul. 86 NPov. 85, Jan. Apr. Dec. 86, Jan. 8 < 0.05 Nov. 85, Jan. Apr.−Jun. Dec. 86, Aug. 86 JPan.87 < 0.05 Nov. 85, Jan. Apr.−Jun. Dec. 86, Sep. 86 JPan.87 < 0.05 O.ct. 86 Jan., Apr −JPun. 86, Jan. 87 < 0.05 N.ov. 86 Jan. Apr −JPun. 86, Jan. 87 < 0.05 D.ec. 86 Jan. Mar −SPep. 86, < 0.05 J5an. 87 Nov. 8 −NPov. 86, Feb. 87 < 0.05 F.eb. 87 Jan. Apr −JPun. 86, Jan. 87 < 0.05 All other comparisons, except the ones reported above, were non-significant. Seasonally changing seawater temperatures are often believed responsible for seasonal patterns of reproduction. Populations of D. setosum near the equator are reproductively active throughout the year (Pearse, 1968; Tuason and Gomez, 1979; Hori et al., 1987), while those in more seasonal subtropical areas have summer spawning periods. Pearse (1974) was of the opinion that breeding in this species proceeds only when seawater temperature is above 25ºC (in areas farther than 20º north and south of the equator). Similarly, E. mathaei appears to have a much greater temperature range for reproduction (Pearse, 1974). In some other species like Strongylocentrotus purpuratus gametogenesis stopped when temperature reached 17ºC (Cochran and Engelmann, 1975). On the other hand, there are studies which show that temperature can induce gametogenesis out of season in echinoids which inhabit areas where seawater temperature fluctuations are quite marked (Yamamoto et al., 1988; Sakairi et al., 1989; Horii, 1997). In the present study, we observed that GI of the Echinometra was low from October until March. These are the months when the water temperatures are low (generally below 25ºC) and day-length is less than 12 h (see below also). As seawater temperature rose above 25ºC in May (28ºC), the GI increased sharply and peaked in June when the seawater temperature was 28.8ºC and the photoperiod was also maximum (summer solstice). Diadema’s GI increased more gradually, and active spermatogenesis and oogenesis were seen from the month of Febru- ary onward. The seawater temperature during February ranged from 11.4–16.5ºC. The ALSAFFAR AND LONE: REPRODUCTION OF DIADEMA SETOSUM AND ECHINOMETRA MATHAEI 851

Table 3. Spawning times of Diadema and Echinometra spp. in various parts of the World.

Species Leocation Sepawning Tim Referenc Diadema antillarum Blermuda Apri −N2ovember Iliffe and Pearse, 198 Byarbados Januar −A6pril Lewis, 196 Cçoura ahMarc −D4ecember Randall et al., 196 Pdanama (Caribbean) Y1ear roun Lessios, 198 Vdirgin Islands Y4ear roun Randall et al., 196 Diadema mexicanum Pranama (Pacific) Septembe −N1ovember Lessios, 198 Diadema savignyi Srouth Africa (east coast) Decembe −J5anuary Drummond, 199 Diadema setosum Ayustralia Januar −M4arch and Stephenson, 193 November−December Eegypt Jun −A9ugust Pearse, 196 Heonshu, Japan Jun −A2ugust Yoshida, 195 Pdhilippines Y9ear roun Tuason and Gomez, 197 Sdingapore Y7ear roun Hori et al., 198 Kluwait Apri −M)ay (Present Study Echinometra lucunter Brarbados (quiet area) Novembe −J4anuary Lewis and Storey, 198 and July−August Byarbados (wave swept) Jul −S4eptember Lewis and Storey, 198 August−O7ctober Harvey, 194 Bdermuda Y5ear roun Lessios, 198 Ptanama Augus −S6eptember Cameron, 198 Peuerto Rico Jun −A9ugust McPherson, 196 South Florida Echinometra mathaei Adustralia Y8ear roun Pearse and Phillips, 196 Edgypt (Red Sea) Y9ear roun Pearse, 196 Eygypt (Suez) Jul −S9eptember Pearse, 196 Hdawaii Y1ear roun Pearse and Cameron, 199 Heonshu, Japan Jun −A9ugust Kobayashi, 196 Keuwait Jun −J)uly (Present Study Echinometra vanbrunti Pranama (Pacific) Septembe −O1ctober Lessios, 198 Echinometra viridis Planama Apri −D5ecember Lessios, 198 Pruerto Rico Septembe −O6ctober Cameron, 198 Seouth Florida Jun −A9ugust Mcpherson, 196 peak GI was observed in April–May in this species and the water temperature ranged from 19–28ºC. This means that the temperature optima for Diadema were slightly lower than those for Echinometra. These results are similar to the results of Fujisawa and Shigei (1990), who showed that the optimal temperature for early development and spawning in Japan were slightly lower (22–29ºC) for D. setosum than for E. mathaei (22–33ºC). Photoperiod has also been implicated in the echinoid reproduction. For many echino- derms living in shallow waters, initiation of gametogenesis is correlated with autumn photoperiod (decreasing days and increasing nights) and that out of season maturity can be achieved by controlling the day-length (Pearse and Walker, 1986; Pearse et al., 1986a,b; McClintock and Watts, 1990; Walker et al., 1998). In the present study, it appears that decreasing day-length and seawater temperature are the cues for the initiation of the ga- metogenesis while increasing day-length and seawater temperature are the cues for the final maturation of the gonads for spawning. 852 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 2, 2000

Lunar cycles also affect the gametogenesis in echinoid and apart from annual or semi- annual rhythms, monthly or semi-monthly rhythms of spawning are also known. Such rhythms are more pronounced in diadematoid populations. D. setosum and Diadema mexicanum gonads were full of gametes near the time of full moon (Lessios, 1981, 1984). While Diadema antillarum and Centrostephanus coronatus had mature gonads at the time of new moon (Iliffe and Pearse, 1982; Lessios, 1984) while some populations of D. setosum and D. antillarum did not show any lunar rhythm and some authors are of the view that lunar rhythm may also be depending on other factors like water temperature and moon light (Pearse, 1968; Hori et al., 1987). In the present study, we collected urchins at or around full moon. Since our sampling was done monthly, we cannot precisely predict for the presence or absence of lunar cycle. However, it appears that the spawned between the full moon and the next new moon as the GI were reduced in both species when the next sample was collected at full moon in their respective spawning season. However, further work is needed in this direction. The color of the gonads ranged from light yellow to dark brown. There was no relation- ship between color and sex, however. It was observed that the females generally had lighter gonadal coloration (different shades of yellow) than the males that exhibited dark colored gonads. However, there was some overlap present, as far as the gonad color is concerned. Also, it was observed that the mature and spawning individuals had lighter colors and this was particularly noticeable for females. These observations are similar to the one described by Hori et al. (1987) for D. setosum from Singapore. These authors reported gonad color from pale cream to brown, with no relation to sex. Kobayashi (1994) reported that gonads from D. setosum in Thailand became increasingly lighter in color (from dark brownish yellow to light yellow or transparent) as the maturity stage increased. Also, we found that the resting and immature gonads looked firmer than the mature go- nads. An observation also reported by Hori et al. (1987) and Kobayashi (1994). The color and texture of the gonads has an obvious commercial importance in the development of urchin fishery (King et al., 1994; Walker and Lesser, 1998; Walker et al., 1998). The sex ratio of the two species was determined from the histological slides. In D. setosum, the sex ratio of male to female was 1:1, whereas this ratio for the E. mathaei was one female to 3 males. Lessios (1981) described that in his studies on D. mexicanum, D. antillarum, Echinometra vanbrunti, Echinometra lacunter and Echinometra viridis, the sex ratios in Echinometra spp. and Diadema spp. were opposite to each other. The fe- males were higher in Diadema while males predominated in samples of Echinometra. Our results are in line with the results of Lessios (1981) as far as the Echinometra sp. is concerned but differ for the Diadema sp. Hori et al. (1987) described that the sex ratio in D. setosum from the Singapore was more skewed towards the male side in a sample of around 459 animals. Sex ratios deviating from 1:1 are also known for the same species originating from different localities. Pearse (1968, 1969) and Pearse and Phillips (1968) showed this quite clearly for E. mathaei. This means that environmental conditions might have some effect on the sex ratios and further studies in this direction (sex ratios in same species from different localities and environmental regimes) may also help in understand- ing of the sex determination mechanisms in echinoids. The histology of the gonads of both species was correlated with the gonadal index. The process of gametogenesis was similar in the two species studied and was similar to that of other urchins (Pearse, 1968, 1969, 1974, 1975; Holland, 1967; Lessios, 1981; Hori et al., 1987; Drummond, 1991, 1995; Byrne et al., 1998; Meidel and Scheibling, 1998; Guillou ALSAFFAR AND LONE: REPRODUCTION OF DIADEMA SETOSUM AND ECHINOMETRA MATHAEI 853

and Lumingas, 1999). Five stages of gametogenesis can easily be defined both in male and female urchins of the two species studied. These stages were (1) recovering, (2) grow- ing, (3) premature, (4) mature and (5) spent. These stages were similar to the histological picture described by Fuji (1960) and recently described in detail by King et al. (1994), Walker and Lesser (1998), Walker et al. (1998), Byrne et al. (1998) and Meidel and Scheibling (1998). Gametogenesis was synchronous in both sexes of the species studied. From November until January, we found the Echinometra gonads (both sexes) to be ‘re- covering’, with very little nutritive phagocytic cells present and the lumen of the testis empty. In this species we found one odd individual in late January with advanced stages of spermatogenesis. In Diadema, the gonads were more or less in the same stages as that of Echinometra. In the latter part of the February, the lumen of the gonads was filled with nutritive phagocytes, and there were clear signs of active gametogenesis. This gametoge- nesis was at a more advanced stage in Diadema than Echinometra. In March samples of Diadema, the spermatogenic and oogenic activity was at an advanced stage while that of Echinometra lagged behind. In May, we found terminal mature samples, spawning samples and some post-spawned individuals in both species. The percentage of post-spawned samples was more prevalent in Diadema as compared with Echinometra. This means that both spermatogenesis and oogenesis proceeds quite faster, being completed in few weeks. The peak-spawning season was achieved earlier in Diadema (April–May) than the Echinometra (June). The maturity in the population seems to be synchronous although individuals could be found in two or three different maturity stages during spawning season. This observation was more consistent for Diadema and probably is the reason for the long spawning season for this species. The late spawners were, however, very re- stricted in numbers. Our histological studies combined with the GI data clearly show one peak-spawning season in both the species studied. The reason for this may be the sharp differences be- tween the minimum and maximum seawater temperatures (average difference of 22.2ºC) in Kuwaiti waters (Fig. 2). The general synchrony of reproduction in both the species suggests that in addition to temperature and photoperiod, food is also an important factor. As reported above, during the spawning period individual sea urchins were encountered in two-three gametogenic stages at one time. Such variations, which have been reported for other urchin species (Byrne, 1990; King et al., 1994; Meidel and Scheibling, 1998), are probably related to individual differences in the acquisition and allocation of energy resources for gametogenesis. Also, it has been documented very recently that food avail- ability and provision of quality food can affect the gametogenic cycle in echinoids (Guillou and Michel, 1994; Guillou and Lumingas, 1999; Walker and Lesser, 1998). The spawning temperature optima, and, thus the spawning season of sea urchins, has also been linked to their embryonic temperature sensitivity. This factor is also correlated with the distribu- tion of a specific (Fujisawa and Shigei, 1990). There was not any significant difference between the body weights of male and female individuals. The average minimum and maximum body weight for D. setosum male was observed in November (35.55 ± 1.72 g) and January (79.19 ± 17.79 g), respectfully. These values for females were 35.41 ± 1.85 g in December and 76.60 ± 29.76 g in January. For E. mathaei, the corresponding minimum values for males were 28.92 ± 3.21 in February and 29.18 ± 4.31 g (March) in females. The maximum values for male and female of this species were encountered in December (58.72 ± 6.04 and 63.02 ± 7.84 g, respectively). The average weight of D. setosum was always slightly higher than that of E. mathaei. 854 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 2, 2000

These are the first observations on the reproduction of urchins from Kuwait and detailed studies are needed to describe the role of these species in the biology of Kuwait’s coral reefs.

ACKNOWLEDGMENTS

The authors are thankful to N. Downing and C. R. El-Zahr for their vital help in collection of the urchins and in the laboratory work. S. Alhazeem helped us in drawing the map given in Figure 1. We are thankful to four anonymous referees and the editorial board who were kind enough to suggest improvements in the manuscript.

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DATE SUBMITTED: September 30, 1999. DATE ACCEPTED: April 5, 2000.

ADDRESS: (A.H.A., K.P.L.) Mariculture and Fisheries Department, Kuwait Institute for Scientific Research, P.O. Box 1638, Salmiya, Kuwait 22017. Tel. (965) 5711295 Ext. 275; Fax = 5711293. Corresponding Author: (A.H.A.) E-mail: .