Sampling spectacular species

Laetitia Plaisance took samples for DNA Barcoding from this file shell.
Image: Gary Cranitch


Western Australia's Ningaloo was a new experience for French woman Laetitia Plaisance, a postdoctoral research fellow on the CReefs Project. She works in the US for the Smithsonian Institution, National Museum of Natural History in Washington DC and the Scripps Institution of Oceanography for the University of California in San Diego.
Laetitia said for her, the Ningaloo trip has been the completion of the next round of strategic sampling in her work. She has been sampling in other locations including the Line Islands, Tahiti and Lizard Island in the Pacific, collecting species that live in small heads of dead coral. She said there were very strict guidelines to follow for collecting these dead coral heads. The head has to be still attached to the reef and situated at approximately10 metres below the water's surface, "that has been a challenge here where much of the reef is very shallow."
Divers enclose the dead coral head in a large bag in an attempt to capture all of the animals contained within it. They then use a hammer and a chisel to break the base, then bring the bagged coral to the surface.
Once back in her makeshift lab, Laetitia uses a hammer and chisel to break the head into small pieces, measuring about 5cm. "We get everything that lives inside, every crustacean, mollusc, worm and sea urchin, as well as many other things. Every piece of algae, every sponge, usually from one head here I have up to 150 different creatures that live inside," she said.
Laetitia separates the different animals into their types, to make samples easier to process and so the creatures do not harm each other. She said while on this trip a file shell had stung a shrimp and paralysed it.
She either freezes or relaxes the creatures before she takes a sample so they do not suffer.
"On a shrimp, for example, I would take a leg, and put it in a special tube which has a barcode on the bottom, I can scan that and it goes into my database and I link it to the tube that contains the shrimp," she said.
"I can use the tissue samples to sequence the DNA once I am back in the US.
Laetitia said because the animals are still alive after she had taken her samples, she was able to give the creatures to the specialists who could then do morphological analysis.
"I am not analysing morphology (to determine what species it is): that is a job for specialist taxonomists.
"I study the (DNA) sequence and once I have sequences for each species, I study how many were living in the coral heads, and then with a statistical approach we can determine how many species live in Ningaloo, and we can compare that result to those from other areas.
She said she had a feeling that, when compared with other locations she had already sampled, Ningaloo had more invertebrate animals per coral head, than at Lizard Island. At this stage it was only a feeling, as the data was yet to be analysed.
Laetitia said when she returned to her home laboratory she would have more than 700 individual samples to process, and then she needed to analyse the data.
She said her work here was part of an international program whose goal is to barcode every species on Earth.
"After a while, people will be able to go into the field, obtain a DNA sequence and know right away what species it came from. It will make life much easier for taxonomists and ecologists."
Click on this link to read about Laetitia's work at the Lizard Island CReefs expedition.