November 13, 2009
HI09-012 1-2m, "Pinnacle" Twin Peaks, 9.30 am-12.30 pm
Today I went out on the Chromis again, this time with Rob, a young American doctorate student who wanted to collect crabs, and Charlotte who was after marine worms. I offered to help Charlotte find some marine worms but it was not an easy task. To find marine worms I was advised to locate a particular alga, Halimeda sp. which grows on the hard corals. The majority of marine worms are not easily visible to the naked eye because many are quite small (less than 5cm in length and 3 mm in width) and live in calcareous tubes which are fused to the coral at the base of the algal holdfast. Consequently lab analysis was required to ascertain the biodiversity of the collection. Halimeda sp. is a dark green alga with a tough leaf-like thallus arranged in multiple fan shaped fronds of about 2 cm in length and 2 mm in thickness. The alga is normally sporadically dispersed in shallow depths of about 1-2 m growing attached to the sides of coral in clumps which may vary from 10-100 cm in length. Halimeda sp. is fairly easy to remove by hand but using a knife is more effective for separating the calcareous encrusted holdfasts from the hard coral substrate. Since I did not have a knife I removed some small samples by hand and placed them in collecting jars for subsequent examination. While I was doing this I watched Charlotte meticulously excising larger pieces of Halimeda sp. and coral with her diver's knife and placing the contents into a large yellow collection bag.
In the afternoon I analysed a small sample of Halimeda sp that I had collected from the snorkeling expedition using an Olympus SZ51 dissecting microscope. This microscope has the capacity to magnify specimens up to 4 X. In this sample I was able to identify two marine worms. With the help of Dr. Maria Capa, one of the other marine worm biologists, the worms were soon identified as belonging to two different families, the Syllidae and Nereididae.
Later that afternoon Julian Caley introduced me to freelance journalist Raelene Morey who had just arrived on the island and would be staying for ten days to interview everyone associated with research on Heron Island. She informed me that she wanted to write a blog about me and how I came to be involved in working with the scientists on Heron Island. You can read the blog on www.aims.gov.au/creefs/latest-field-trip-heron-2009.html. If you go to page 14-15 I am there.