Presence of postlarval alvinocaridid shrimps over south-west Indian Ocean hydrothermal vents, with comparisons of the pelagic biomass at different vent sites

Abstract

Two types of alvinocaridid shrimp postlarvae were taken at plume depth over the Kairei and Edmond hydrothermal vent fields in the south-west Indian Ocean. These postlarvae were superficially indistinguishable from similar postlarvae taken previously over hydrothermal vents in the Atlantic. The micronekton invertebrate taxa in the water column over the Kairei and Edmond sites were similar to those in the Atlantic. The most frequently taken deep-water fish at Kairei was an unidentified cyemid snipe eel, whereas in the Atlantic its place was taken by Gonostoma bathyphilum and species of the melamphaeid Scopeloberyx. Previous sampling over East Pacific Rise hydrothermal sites at 13°N failed to take any alvinocaridid postlarvae, but the ostracod Gigantocypris agassizi was a major component of the micronekton.