Biological Sciences

Aquaculture of Marine Invertebrates

(Joanna Murray, Dr Watson, Dr Bentley and Dr Giangrande)

Reducing the impact of the marine aquarium trade: propagation of fan worms by regeneration

This work is funded by the Leverhulme Trust: www.leverhulme.org.uk

Worldwide, over 2 million people own marine aquariums and at least 10 million invertebrates (not including corals) are traded around the world every year to support this hobby. As the vast majority are taken directly from coral reefs this has led to significant over-collection of some species and damage to the reefs during their removal.

Marine worms are common in many aquariums, but only two groups (Christmas tree and fan worms) are collected routinely. Fan worms are the most popular and are, therefore, the focus of this project with up to 75,000 being exported per year from Hawaii alone, retailing in UK shops for between £10-20 each. However, many of those species are vulnerable to over-collection as they are found at low density, are often long-lived (max. 40 years), taking many years to reach maturity. As some species’ tubes are embedded in the reef, removal can also damage the worm and the surrounding habitat.

Fan worm aquaculture will be approached using a method similar to that of taking cuttings from plants: the production of new individuals by making fragments of the parent. Fan worms, like many other worms, have excellent powers of regeneration. Predators often eat them resulting in individuals regularly losing large parts of their body, especially the exposed and delicate fan. Each worm may have hundreds of segments, but as few as 20 can regenerate a complete worm through segment reorganisation and regeneration of missing structures. It is this principle that will be exploited in this project to investigate the feasibility of fan worm regeneration as a method of aquaculture to supply the industry. This method has already been used for culturing corals to supply the aquarium trade; up to 150 species can now be propagated in captivity from fragments.

Figures show the regeneration for the model species Sabella pavonina over 3 weeks:


 Sabella pavonina

A) development of a small bilobed blastema on the anterior cut surface, B) series of papillae representing future tentacles appear and growth in length, C) tentacles grow longer and 5 red pigment spots are laid down.

Figures below show the 4 week regeneration process of a cut segment of Sabella spallanzanii, (Mediterranean sabellid). Photographs taken by collaborators in Lecce, Italy.


 Sabella spallanzanii

A) Week 1. The bilobed projection is visible at the anterior cut surface, B) Week 2. Pygidium beginning to form at the most posterior end and gill filaments of the branchial crown are visible, C) Week 2. Pygidium (the most posterior end of the worm) is now distinguishable and one level of eye spots (photoreceptive cells) are present on the branchial crown from the anterior surface, D) Week 4. Fully formed individual specimen with 5 eye spots present on the branchial crown to the anterior and a complete pygidium most posterior.