Haliotis midae: Peters, H.

Growth rates of a number of Haliotis midae populations around the South African coast were studied by means of tagging. These populations ranged from the cool waters of the western coast to the more temperate environment of the eastern Cape. Standard von Bertalanffy growth curves were fitted and growth parameters derived. These ranged from 0.19 to 0.25 for K, the average rate at which L∞ is approached, and from 156 to 173 for L∞, the average theoretical maximum length. These indicate far higher growth rates than were previously published for this commercially fished species, and the reasons for this difference are discussed. The expectation that growth rates would be fastest in the warmer eastern Cape waters was not realized, there being no significant difference in growth between the Bird Island population on the eastern coast and the Robben Island population on the western coast. These new growth parameters indicate that H. midae in the commercial fishery grounds is attaining sexual maturity some four years earlier, and the minimum legal size some five years earlier, than previously considered. This has considerable significance for modelling studies presently underway. Movement of a small population of adult H. midae was studied over a three-year period, after which 47% of the original abalone were still present on the study site. Of these, 81.5% still occupied exactly the same position on the rocks. This indicates that H. midae that have located an optimum habitat, and that are not disturbed, tend not to move.

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Two new species ofSyllis(Polychaeta: Syllidae) from South Africa, one of them viviparous, with remarks on larval development and vivipary

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315413001926 ◽

2014 ◽

Vol 94 (4) ◽

pp. 729-746 ◽

Cited By ~ 6

Author(s):

Carol Simon ◽

Guillermo San Martín ◽

Georgina Robinson

Keyword(s):

South Africa ◽

New Species ◽

South African ◽

The Other ◽

Coralline Algae ◽

Colour Pattern ◽

The Family ◽

Two New Species ◽

Haliotis Midae ◽

Characteristic Colour

Two new species of South African Syllidae of the genusSyllisLamarck, 1818 are described.Syllis unzimasp. nov. is characterized by having unidentate compound chaetae with long spines on margin, a characteristic colour pattern and its reproduction by vivipary. Vivipary is not common among the polychaetes, but most representatives occur in the family Syllidae Grube, 1850 (in five otherSyllisspecies, two species ofDentatisyllisPerkins, 1981 and two species ofParexogoneMesnil & Caullery, 1818).Syllis unzimasp. nov. differs from the other viviparous species in having large broods (>44 juveniles) which develop synchronously. Development of the juveniles is similar to that of free-spawningSyllisspecies, but the appearance of the first pair of eyespots and the differentiation of the pharynx and proventricle occur later inS. unzima.Syllis amicarmillarissp. nov., is characterized by having an elongated body with relatively short, fusiform dorsal cirri and the presence of one or two pseudosimple chaeta on midbody parapodia by loss of blade and enlargement of shaft.Syllis unzimasp. nov. was found in high densities on culturedHolothuria scabraJaeger, 1833 with single specimens found on a culturedCrassostrea gigasThunberg, 1793 and on coralline algae, respectively, whileS. amicarmillariswas found mainly in sediment outside an abalone farm and less frequently on culturedHaliotis midaeLinnaeus, 1758. We discuss the possible benefits of the association withH. scabratoS. unzimasp. nov.

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