Reproductive effort in four species of intertidal limpets

Reproductive effort was measured in 4 species of intertidal limpets: Cellana tramoserica (Sowerby) Notoacmea petterdi (Tenison Woods), Patella peroni Blainville and Patelloida alticostata (Angas) from south-eastern Australia. Field studies between 1971 and 1975 enabled indices of reproductive effort to be obtained using both gonad to body weight ratios and energy budgets. The ratio of annual gonad production to somatic tissue energy content is highest for Patella peroni (2.19). The ratios for C. tramoserica and Patelloida alticostata are lower but similar (1.02), and N. petterdi has the lowest ratio (0.78). The percentage of assimilated energy allocated to reproduction is also highest in Patella peroni (26.6%), but this index of reproductive effort is similar for the other three species (10.3 to 12.9%). Consequently, these 4 species are ranked in different orders with respect to reproductive effort, depending upon which index is used. However, the difference between both indices is small, and is less than has usually been anticipated. The difference is interpreted as being the result of the low metabolic rate of N. petterdi rather than as evidence for the inadequacy of one of the indices of reproductive effort.