A combination of surveys and experiments were used to assess the reproductive patterns of Siphonaria diemenensis in 2 zones on the rocky shore at Griffith Point, San Remo, Victoria. One zone was in the high intertidal (Zone 2) and one was in the low intertidal area on the shore. There were 3 sites in Zone 1 and 2 sites in Zone 2 (see parent record for more details).
The breeding season of S. diemenensis was between August and May and spawning correlated with the phases of the moon. The numbers of egg masses at each site were recorded from regular searches during the breeding seasons in 1980-81 and 1981-82. The reproduction rates were highly variable between seasons in Zone 1 and less variable in Zone 2. It was suggested that the variation in reproductive rates between the different zones was correlated with changes in food availability.
An experiment was conducted to determine the reproductive effort of different sized individuals and to examine how responsive reproductive patterns are to changes in environmental conditions. On 18 August 1980, limpets were collected and placed within steel mesh enclosures (10x10cm). The enclosures were assigned to 8 different treatments groups (n=3). Details of the treatments are outlined in the attached resource. Egg masses were collected from the enclosures at regular intervals and at the completion of the experiment on 4 April 1981, 5 limpets were collected per enclosure. The shell length and dry weight was recorded for each limpet.
