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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