Distribution, size‐frequency, and growth‐ring analyses of Tawera mawsoni (Bivalvia: Veneridae) at Macquarie Island

Abstract

Tawera mawsoni (Hedley, 1916), the most southerly occurring of all the Tawera species in the Australasian region, lives on sandy substrates from 12 to 450 m depth around Macquarie Island, on Macquarie Ridge, and on Caroline Ridge. Most shells sampled are homogeneous in shape, sculpture, colouring, and shell thickness, except that some from south of Macquarie Island have thinner valves. Tawera mawsoni appears to produce annual growth rings. Shell shape does not appreciably alter with growth. Recruitment rate is low and variable from year to year. Predation appears to be an important cause of mortality, the chief predators being naticids (Falsilunatia pisum) and muricids (Trophon macquariensis and T. mawsoni). No size class of Tawera mawsoni is excluded from predation.

Keywords:

• Tawera mawsoni
• Bivalvia
• Veneridae
• cockle
• distribution
• size‐frequency
• growth rate
• gastropod predation
• Macquarie Island