Very slow embryonic and larval development in the Antarctic limpet Nacella polaris

Cold polar marine species have very slow embryonic and larval development rates. Antarctic echinoids, bivalve molluscs and brooding gastropods develop up to 12 times slower than temperate and tropical species, departing from Arrhenius relationships and outside the normal Q 10 of 2–3 associated with 10 °C reductions in biochemical reaction rates. The slowing of development at temperatures around 0 °C has been reported previously to be much greater than for other parts of the global marine temperature range. Here we spawned and reared embryos and larvae of the Antarctic limpet Nacella polaris at 0.6 °C to the post-torsional veliger stage. Spawned eggs were 221 µm in diameter. Development rates were three times slower than any previously reported for patellogastropod limpets, with first division at 2.5 h post-fertilisation, the gastrula stage being reached after 55 h, hatching occurring after 70–75 h and the trochophore stage being reached after around 100 h. The marked slowing of development around 0 °C matches that previously reported for other polar taxa. This supports the hypothesis that there is a cold marine physiological transition to markedly slower physiological rates at temperatures near 0 °C. The transition is especially apparent here for development, but has also been reported for growth, both of which involve significant protein synthesis.