Under the waves of Algoa Bay, there is “chemical warfare” on a daily basis between reef-dwellers like sponges, soft corals and sea slugs, who protect themselves from fishy predators with toxic organic chemical compounds.
Studies of these organic compounds – called marine natural products – have captured the imagination of scientists the world over, particularly as some have been found to have anti-cancer properties.
On May 15, Prof Mike Davies-Coleman, long-time researcher in the waters of Algoa Bay and Dean of Natural Sciences at the University of the Western Cape, will be revealing this underwater world to the public through a talk at Nelson Mandela Metropolitan University, entitled “Molecules and marine life in Algoa Bay – a journey of discovery”.
The main reason for this high-profile talk is to promote Algoa Bay as one of the world’s “Hope Spots” – an initiative championed by Mission Blue, a global initiative of the Sylvia Earle Alliance, and supported in South Africa by the Sustainable Sea Trust, to set up formally-protected conservation areas to keep the ocean healthy. Dr Earle, a world-renowned ocean researcher who last year received an honorary doctorate from NMMU, will be launching South Africa’s first five Hope Spots in December.
Davies-Coleman – a trained organic chemist who spent 28 years at Rhodes University and has also worked at the renowned Scripps Institution of Oceanography (SIO) at the University of California, San Diego – has spent his career studying the natural products chemistry of marine cyanobacteria, plants and invertebrates in the Eastern Cape.
“The marine organisms that produce natural products do so for a purpose we don’t know unless we see the consequences in action and can then work out who the players are in this fascinating chemical ecology that is very common on marine reefs.
“In Algoa Bay, there are some sea slugs that don’t make natural products themselves. Instead, they will eat a sponge and then make use of the sponge’s toxic chemicals, storing it in special glands in their skin to deter predators. The first clue we have that a sea slug is carrying a chemical arsenal is its bright colouration. Bright colours clearly say ‘don’t eat me’ in the marine world.”
Davies-Coleman said by “sheer luck”, scientists had found that some marine natural products had anti-cancer properties. “They have the ability not only to deter predators but also to serendipitously kill cancer cells.”
In Algoa Bay, the National Cancer Institute in the United States in collaboration with researchers at Rhodes University and the University of Cape Town, have conducted extensive cancer research on marine natural products. “We’ve found a number of molecules that kill cancer cells. The problem is they kill other normal cells too.”
However, the research has not been in vain as they have been able to study how some of these molecules kill cancer cells, which has assisted in the understanding of the biology of cancer cells, opening new avenues for anticancer drug development in the laboratory.
Davies-Coleman said research by his team on a sponge collected from Aliwal Shoal, north of Algoa Bay, had also revealed a marine natural product that potentially could kill antibiotic-resistant bacteria that are causing increasing numbers of fatalities in hospitals around the world.
He said the semi-pristine reefs off Algoa Bay were quite spectacular – especially compared with other reefs off industrial cities. “In particular, there is an amazing and unique diversity of sea squirts. What’s special about these particular marine invertebrates is that many not only produce toxic natural products but they also accumulate metal ions.” Along with other reef-dwellers like sponges, they act as filters, taking in the toxic heavy metals potentially polluting the ocean.
“A 1kg sponge, which can fit into a shopping packet, filters the equivalent of an Olympic-sized swimming pool every day.
“If you took out all the sponges, sea squirts and soft corals, Algoa Bay would be a cess pool. They do an amazing job.”
Prof Mike Davies-Coleman’s talk, which will take place under the auspices of the Sustainable Seas Trust and Royal Society of South Africa, will be held at Nelson Mandela Metropolitan University’s Council Chambers at 6pm on May 15. To attend, contact Prof Janine Adams at e-mail: Janine.adams@nmmu.ac.za or tel: 041 504 2429. Entrance is free but seating is limited.
Alan Straton
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