Developing optimal methods for the culture of host sea anemones

A project undertaken at the National Marine Science Centre, Coffs Harbour NSW, and supervised by Southern Cross University researchers Dr Anna Scott and Associate Professor Peter Harrison

Background

Over 1,000 species of sea anemone have been described worldwide, of these only ten are known to provide essential habitat for symbiotic anemonefish. Owing to this unique and fascinating interaction, these anemones are highly prized for the aquarium trade. Individuals are sourced entirely from the wild as very little is known about their sexual reproductive biology, precluding their culture in aquaria. This has resulted in wide-scale and unregulated exploitation, which is severely depleting local populations and threatening their existence in some areas of the Indo-Pacific.

Host sea anemones are particularly susceptible to overexploitation as they are thought to have a long life span, slow growth rates, and sporadic recruitment. Ease of collection, in combination with high demand and high income generated from collection, further increases susceptibility to exploitation. Poor survival in captivity leads to added pressure on populations as more anemones are collected to compensate for the high mortality rates. Ensuring the survival of host sea anemone populations is important not only for the anemones, but also for their anemonefish, which cannot survive in the wild without their hosts.

Research by Scott and Harrison provides the first scientific description of the sexual reproduction, larval development, settlement and metamorphosis of two species of host sea anemone, Entacmaea quadricolor and Heteractis crispa in the Solitary Islands Marine Park, northern NSW, Australia. Predictable annual spawning periods were observed for both species during a three year period. Gametes were collected, reared and settled on terracotta settlement plates. These juveniles are now over four years old.

Objectives

Prior to this research, conservation efforts for these species were constrained by the lack of information on key life history characteristics. The opportunity is now available to establish reliable culture techniques that produce large numbers of juvenile anemones. However, in order to ensure the efficient cultivation and grow out of juvenile anemones further research is needed to determine the:

  • sperm concentrations that optimise fertilisation success of spawned anemone eggs
  • stocking densities that maximise settlement and survival of juvenile anemones
  • feeding rates that optimise juvenile anemone growth

Determining these key requirements has important implications for the success of mass culture ventures that plan to supply the aquarium trade or re-seed reefs.

 

 

Figure 1.

Figure 2. Development of a juvenile H. crispa anemone