Egg-laying behaviour and intracapsular development of Argobuccinum pustulosum (Gastropoda: Ranellidae) in temperate waters at the South coast of Chile

Abstract

Egg-laying behaviour, egg masses and intracapsular development of the ranellid snail Argobuccinum pustulosum are described here. Snails were collected by diving, at Corral Bay (39°53′S; 73°25′W) in the south of Chile, and adult individuals were reared in tanks with circulating seawater at ambient temperature to obtain their egg masses. The spawn produced is an irregular flat mass, taking between 3 and 9 days for the females to complete the egg deposition. Peduncleless tube-shaped capsules of 9–12 mm in length, amounted to 47–149 per mass (average = 100; n=9 masses). Eggs measured 168 µm in mean diameter. Number of eggs/embryos per capsule varied between 2500 and 5400. At mean temperatures of about 11.2–11.7°C, the intracapsular development lasted approximately 54–56 days, with the hatching of numerous planktotrophic veliger larvae of about 260 µm in shell length. Maximum production of larvae by a female is estimated at over 650,000 per spawn, and under multiple spawns it could exceed a million per breeding season. Capsule wall (100 µm thickness) consists of six laminae with protein fibres whose laminar arrangement permits a high light transmittance, accounting for the marked transparency of these capsules. Attributes of the development and of their hatching larvae, suggest a long period of planktonic larval dispersal for this snail. This would promote connectivity among geographically separated populations, thus in turn explaining the wide geographic distribution showed by this species in Southern oceans.

Keywords:

• Argobuccinum pustulosum
• intracapsular development
• egg laying
• egg masses
• Ranellidae

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

This research was supported by Dirección de Investigación y Desarrollo, Universidad Austral de Chile, grant DID-UACh 2007-57 to C.S. Gallardo. Specially the supplementary support obtained from this Agency after the fire of December 2007, is greatly appreciated and acknowledged. Collaborative work with the colleague J.I. Cañete was partially financed by Dirección de Investigación y Postgrado from Universidad de Magallanes (PR-F2-03-RN-05 and PR-F2-01-CNR-10). We are also grateful for the use of facilities at the Coastal Laboratory of Aquatic Resources in Calfuco. Thanks are also due to anonymous reviewers for critical revision and additional references provided, as well as to Dr Kirsten Benkendorff for improving the English.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark