Parental size and environmental conditions affect egg capsule production by Nassarius reticulatus (Linnaeus 1758) (Gastropoda: Nassariidae)

In shallow coastal habitats scavenging netted whelks Nassarius reticulatus attached egg capsules to the stipes of red algae Chondrus crispus and occasionally on Furcellaria lumbricalis and Plumaria plumose. In the laboratory egg capsules were laid on aquaria sides and lids by individuals ≥21 mm shell length. Larger size classes produced more egg capsules and spawned over a longer period and in doing so partitioned less energy into shell growth. Large netted whelks (25–28.9 mm) produced larger capsules which contained significantly more and larger eggs than those produced by smaller individuals (21–24.9 mm). Egg capsule production continued throughout the year by regularly fed N. reticulatus held at ambient seawater temperatures. Egg production increased in the spring and summer with peak production during June (15 °C), decreased between August and October and resumed again during the winter (November to February at ~7 °C). During the summer (15–16 °C) egg capsules were smaller and contained smaller eggs than those deposited during the winter (7–10 °C), although the number of eggs·capsule⁻¹ was similar. Enforced food limitation reduced the number and size of the egg capsules, the number and size of eggs produced·female⁻¹ and the duration of the breeding period. Hatching success of N. reticulatus egg capsules was high (95%) even at winter seawater temperatures (11–8.5 °C) and the duration of embryonic development was fastest between 15 and 17.5 °C.