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MARINE ECOLOGY PROGRESS SERIES Vol. 156: 175-181, 1997 Published September 25 Mar Ecol Prog Ser , Timing of spawning and fecundity of a tropical and subtropical anemonefish (Pomacentridae: Amphiprion) on a high latitude reef on the east coast of Australia Darren L. Richardson*, Peter L. Harrison, Vicki J. Harriott Centre for Coastal Management, Southern Cross University, PO Box 157, Lismore, New South Wales 2480, Australia ABSTRACT The timing of spawning and fecundity of the anemonefishes Amphiprion latezonatus Waite and A. akindynos Allen were monitored over a 1 yr period at Julian Rocks, a subtropical rocky reef located on the east coast of Australia. The tropical species A. akindynos had a shorter spawning season than the subtropical endemic species A. latezonatus, although peak spawning activity in both species occurred during the warmest time of the year. Despite having a shorter spawning season than tropical congeners, both species had the highest fecundity of anemonefishes studied to date. Both species displayed weak lunar spawning periodicity; A. akindynos had slightly more spa~vningsin the lunar quarters before and after the full moon than the quarters before and after the new moon, whereas A. latezonatus had significantly fewer spawnings in the lunar quarter before the full moon than during the other 3 lunar quarters. The spawning patterns of A, ahndynos and A. latezonatus were more similar to A. clarlui in temperate Japan than to congeners in tropical regions, suggesting that environmental fac- tors associated with high latitude environments may modify the reproductive biology of anemonefishes. KEY WORDS: Lunar and seasonal spawning patterns . Anemonefish . Reproduction INTRODUCTION have a short intense summer breeding season (Bell 1976, Ochi 1985). Despite the short breeding season, The timing of spawning and fecundity of Amphi- temperate A. clarkii assemblages have the highest prion anemonefishes has been investigated at several fecundity of anemonefish studied to date (Bell 1976, tropical localities (Allen 1975, Ross 1978, Fricke in Ochi 1985). Tropical anemonefishes appear to have a Thresher 1984) and in the warm temperate seas of strong lunar, or semi-lunar, periodicity in the timing of Japan (Bell 1976, Ochi 1985). These studies indicate spawnings (Allen 1975, Ross 1978, Fricke in Thresher that anemonefish assemblages in temperate regions of 1984). By contrast, temperate A. clarkii assemblages Japan have spawning periods and fecundity that are display weak lunar spawning patterns that are incon- substantially different from congeners in tropical sistent between years and localities (Bell 1976, Ochi waters (Moyer 1980). Anemonefishes in tropical 1985). regions typically have a year-round non-seasonal It has been speculated that the short spawning sea- spawning pattern (Allen 1975, Ross 1978), whereas son, weak lunar spawning rhythms and high fecundity temperate Japanese populations of Amphiprion clarkii of temperate Japanese Anlphipnon clarkii assemblages are local adaptations to highly seasonal and severe winter water temperatures (Bell 1976, Moyer 'Present address: WBM Oceanics, PO Box 203, Spring Hill, Queensland 4004, Australia. 1980).If local environmental controls caused these pat- E-mail: [email protected] terns, then other high latitude anemonefish assem- O Inter-Research 1997 Resale of full article not permitted 176 Mar Ecol Prog Ser 156: 175-181, 1997 blages should display spawning patterns that are more all egg clutches to be examined at least once during consistent with congeners in temperate Japan than their development. those in tropical localities. The study aims to describe The age of eggs was estimated by examining the the timing of spawning and fecundity of a tropical and colour and morphology of eggs (Ross 1978) relative to a subtropical species of anemonefish at a high latitude ambient water temperature. Since the deposition area locality on the east coast of Australia, to determine of egg clutches was roughly circular, the maximum whether: (1) spawnings follow seasonal patterns,, and minimum diameters of egg clutches were mea- (2) spawnings are synchronised to lunar phases, and sured with a plastic ruler and the deposition area cal- (3) fecundity of temperate species is higher than that of culated using rrr2 (Robertson et al. 1988). Gaps in the tropical congeners. deposition area were measured in the same way and subtracted from the total deposition area. The total number of eggs per clutch was estimated by counting MATERIALS AND METHODS all eggs within 4 replicate 0.25 cm2 quadrats, and then multiplying the egg density per cm2 by the deposition Reproduction of anemonefish was studied from area. Total counts were conducted on clutches that had November 1993 to February 1995 at Julian Rocks sparse or low numbers of eggs. Since some egg mortal- (28" 36'S, 153" 37' E), located on the southeast coast of ity may have occurred by the time eggs were ob- Australia (Fig. 1). Julian Rocks consists of a group of 4 served, fecundity estimates may in some cases under- islets located 2 km off the northern New South Wales estimate the total number of eggs produced. coastline (Richardson et al. 1997). Two species of To determine whether anemonefishes followed lunar anemonefishes cooccur at this locality: the widely dis- or semi-lunar spawning patterns, the frequency of tributed tropical Anlphiprion akindynos, and a species spawning within each quarter of the lunar cycle was endemic to the eastern Australian subtropics, A, late- compared using X', to test the null hypothesis that the zonatus. frequency of spawning did not vary significantly All anemonefishes were mapped within a 15000 m2 among lunar phases. area located on the west side of Julian Rocks, and all adult pairs were examined for the presence of eggs over time. The timing of egg surveys was based on RESULTS the positive linear relationship between embryo development time and water temperature (Bell 1976, Breeding seasons D Richardson unpubl.). Since the incubation time of eggs at water temperatures <22"C was 10 to 12 d, sur- The length of the spawning season varied between veys were conducted every 8 to 10 d at these water anemonefish species and among breeding pairs of fish. temperatures (June to November 1994). During Egg clutches of Amphiprion latezonatus were re- summer (temperatures -22"C), incubation times of corded in every lunar month, although the total num- embryos were around 6 to 9 d (D. Richardson ber of clutches declined in the cooler months (Fig. 2). unpubl.), thus surveys were conducted every 6 d from The length of the breeding season varied among A. November to June. The regularity of surveys allowed latezonatuspairs from 2 to 11 lunar months (n = 5 pairs, mean = 5.2 mo + 1.22 SE) (Fig. 3).A. akindynos had a shorter spawning season, extending from November to May-Ju1.y (Figs. 2 & 3).Water temperatures during this period ranged from 19 to 26°C. The length of breeding 0I 200 400 *-.- l..., ,l) season was hlghly variable among A. akindynos pairs Kilometres (Fig. 3), ranging from 1 to 7 lunar months (n = 14 to l!/ scale I:IO 000 000 2500's i 15 pairs, mean = 3.1 mo + 0.53 SE). '7 l BRISBANE 8-,, I Lunar spawning cycles Jul~anRocks Byron Bay 1'' The total number of spawnings of Amphiprion late- II zonatus within each quarter of the lunar month is South Pacific Ocean shown in Table 1A. The total number of spawnings i 30'00's t was approximately equal for the first, second and fourth quarters, while there were very few in the third Fig. 1. Julian Rocks locality map quarter (the quarter following the full moon). The dis- Richardson et al.: Spawning and fecundity of anemonefish 177 26 2 7 mated at 10300 to 33 140 eggs per female, Arnphiprion latezonatus 244 n 26 with a mean of 18083 (k4386.1 SE) eggs per 22 Arnphiprion ak~ndynos female. The number of eggs per clutch 20 = --...-O........Mean monthly water temperature ranged from 1496 to 2508 eggs (mean 1865 18 + 258.5 SE) (Table 2). Total A. latezonatus 16 egg production peaked during January and 14 February, although the mean monthly clutch 12 size of A. latezonatus showed no consistent 10 seasonal trends (Fig. 4). 8 Amphiprion akindynos pairs produced an 6 estimated 814 to 2463 eggs per clutch 4 (mean 1598 * 131.87 SE) and between 2 to 15 clutches (mean 6.7 k 1.00 SE) annually 2 (Table 3). Annual egg production of A. akin- 0 dynos ranged from 2160 to 26890 eggs per female (mean = 11370 t 2117.7 SE) (Table 3). Although mean annual egg pro- Lunar month (date of full moon) duction of A. akindynos pairs was almost half that of A, latezonatus, an unpaired t-test de- Fig. 2. Mean monthly water temperature (error bars show +SE) and the tected no significant difference In the mean total number of Amphiprion latezonatus and A. akindynos egg clutches annual product,on of eggs between A,ak,n- observed over 13 lunar months at Julian Rocks. The number of breeding dynOS and A. latezonatus pairs (df = 18; = pairs observed with eggs ranged from 0 to 15 in A. akindynos and 1 to 5 in A. latezonatus -1.514; p = 0.147), reflecting the high vari- ability in clutch sizes among pairs. Consistent with A. latezonatus, the total number of eggs tribution of the total number of spawnings in quarters produced by A, akindynos per lunar month declined in of the lunar month was significantly different from an cooler months, although the size of deposition areas did equal distribution (df = 3, x2 = 8.933, p c 0.05).Females spawned 0 to 3 times within a lunar month, at approximately semi-monthly intervals in summer months 1993 1994 1995 N DJ FMA MJ J AS 0 N DJ F (December to April) and at monthly and bi-monthly intervals in cooler months (May to November; Table 1A).

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