Delayed arm regeneration in the Antarctic brittle star Ophionotus victoriae

We describe the levels of natural arm damage in the Antarctic brittle star Ophionotus victoriae and the rate of arm regeneration over the period of 1 yr, as measured in our aquarium facil- ities at Rothera Point, West Antarctic Peninsula. The natural incidence of arm damage in O. victoriae is high (97% of individuals examined). The rate of regeneration was 0.44 mm wk -1 , which is slow, but within the range of data from temperate brittle stars and also in line with data from the literature showing a general trend of decreasing arm regeneration rate with temperature. The Q10 for arm regeneration rate of 2.6 across brittle stars is within the expected biological range. However, O. victo- riae arm regeneration experiences a lag phase of up to 5 mo before reproducible amounts of new tissue are produced. Such a long lag phase has not been documented for any other brittle star species and produces a range of Q10 values from 3.6 (when compared to the slowest documented lag phase for a temperate brittle star) to exceptionally high Q10 values of 14.9 and 15.4 (when either fastest or average regeneration times are considered for temperate brittle stars and this Antarctic species). This indicates that the initial process of arm regeneration in O. victoriae is either different to that of other brittle stars or it is dependent on factors other than the effects of temperature on enzyme-mediated biochemical reactions, such as gonadal cycles and seasonality.

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