The reproductive ecology of deep-sea ophiuroids around the Crozet plateau, Southern Indian ocean, under contrasting productivity regimes

The reproductive characteristics of six ophiuroid species, Ophiura irrorata loveni, Ophiura lienosa, Amphioplus daleus, Ophiacantha cosmica, Ophiernus quadrispinus and Ophioplexa condita, were studied at two localities in the vicinity of the Crozet Islands in the Southern Indian Ocean. The two localities were notable in having almost identical environmental characteristics other than major differences in surface-water primary productivity and organic matter flux. The two localities were only 460 km apart. Three species were sufficiently abundant at the two sites to compare their reproductive biology under different productivity regimes. Ophiura irrorata loveni showed significant differences in oocyte size distributions and population size distributions between the two sites. The differences appeared to be related to the characteristics of organic matter flux at the two localities. Ophiacantha cosmica and Ophioplexa condita showed differences in abundance between the two sites. This appeared to be related to the availability of suitable substrata.