On the structure of a population of Oliva oliva (L., 1758) in Papua New Guinea (Studies on Olividae. 22)
Tursch, B.; Ouin, J.M.; Bouillon, J. (1995). On the structure of a population of Oliva oliva (L., 1758) in Papua New Guinea (Studies on Olividae. 22). Apex (Brux.) 10(2-3): 29-38
In: Apex (Bruxelles). Société Belge de Malacologie: Bruxelles. ISSN 0773-5251, meer
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Population characteristics > Population structure
Gastropoda [WoRMS]; Mollusca [WoRMS]; Oliva oliva (Linnaeus, 1758) [WoRMS]; Olividae Latreille, 1825 [WoRMS]
ISEW, Papua New Guinea [Marine Regions]
Marien/Kust |
| Author keywords |
Mollusca, Gastropoda, Olividae, Oliva oliva, size, colour |
| Auteurs | | Top |
- Tursch, B.
- Ouin, J.M.
- Bouillon, J., meer
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| Abstract |
Monthly samplings of the population of O. oliva on the black sand beach of Sisimangum (Hansa Bay, Papua New Guinea) were effected during 8 months. The very sharp size frequency distribution did not vary appreciably and suggests a high mortality at about half of the maximum size. No significant change was observed in the distribution of shell colour classes. Predation pressure is high: counts of the presence of scars on the shell show that most of the specimens have survived an unsuccesful attack. The distribution of scars suggests that the responsible predator(s) form a "search image" adjusted to the most abundant class of prey (16-20 mm black shells). Such apostatic selection could stabilise the balanced colour polymorphism observed in the population. Abrupt changes in shell colour were experimentally induced by maintaining black specimens on white sand. These induced colour shifts allow an estimation of the growth rate, which averages 4.0 mm/year (for shells in the 13-22 mm range). |
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