Fig. 4.

Maturity scores (a) and ovary stages (b) of Euphausia superba in 400, 1000, 1500, 2000 and 4000 μatm pCO₂ seawater. Maturity scores are the average scores (mean ± SE) of krill in each treatment for weeks 39, 41, 43 and 46 combined (n = 5 for the 400–2000 μatm pCO₂ treatments and n = 3 for the 4000 μatm pCO₂ treatment). Ovary stages are the average ovary stages (mean ± SE) of female krill in week 46 only. The physical ovary stages relating to each stage number are also provided (2 = oogenesis, 3 = previtellogenesis (cell size < 200 µm), 4 = previtellogenesis (cell size > 200 µm), 5 = early vitellogenesis). Higher maturity scores and ovary stages indicate a more advanced reproductive stage. For 400 – 2000 μatm pCO₂ treatments n = 8, and for the 4000 μatm pCO₂ treatment n = 2