Sparidae: L III B10

Pachymetopon grande Günther, 1859.

Bronze bream

Egg diameter in µm	Number of oil globules	Diameter of oil globule in µm	Yolk texture	Perivitelline space	Position of oil globule at hatch	Gut length   at eye- pigment stage	Myomeres
910-985	1	190-200	clear	narrow	stern	41% of NL	24

Egg: The “Gestalt” of this egg is well presented in Plate A. There is a pair of yellow blotches behind the eyes, a cluster at the anus and another mid-tail. Sometimes there are a few spots on the nose. Black, stringy, linked pigment runs the length of the embryo dorsally. The oil globule is pale to bright amber, and the egg has a yellow hue when fresh. Incubation is about 40 hours. The eggs were sometimes seen in a late blastula stage, suggesting both morning and evening spawning. Mature eggs tend to sink.

Larva: The three yellow pigment patches of the early larva (B & C), are similar to Pagellus (LIIIC5), but the larger size of the egg and larva separates them.  The yellow mid-tail patch persists to at least day 4 (E). Although a series was reared, flexion was not recorded.  B: NH, C: 1 day, D: 3 days, E: 4 days, F: 10 days, G: 28 days, H: 39 days, I: 59 days (22-23°C).

This species proved quite difficult to rear, but a small group was taken through to 50+ days in 2001. Thirtyone larval barcode sequences are currently available, 17 of which match the sequences of 5 adult P. grande collected from KZN waters for this study (BOLD). Three have matched Pachymetopon aeneum (LIIIC1B), and 7 have matched Polyamblyodon germanum. One of the larvae, hatched from an egg collected in August 2008, matches the barcode of adult Petrus rupestris and 2 match Cymatoceps nasutus. Two eggs, collected in February 2008, erroneously identified under this code, have barcoded as the scombrid Euthynnus affinis (LIIIA11A); surprising since these two are usually easily separated.

This was a fairly common egg off Park Rynie (Table 3: Introductory Notes). Winter was the main spawning season (blue graph). The egg was seen on 3 occasions in the DHM samples (green graph). Annual abundance of the eggs in Park Rynie plankton samples has remained

Linked samples	Offshore	Inshore
Eggs	914	1541
Hits	112	207

fairly steady (white graph). The Park Rynie linked samples found the majority of eggs inshore (63%), indicating most spawning inside the 20m depth contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.

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