Trimix divers discovered Sodwana’s coelacanths in 2000 and twelve years later, these advanced deep divers continue to document new coelacanths and other exciting finds in the submarine canyons of the iSimanagaliso World Heritage Site. Last week, Triton Dive Charters, a diving concession holder with a special permit to dive below 60 m in the iSimangaliso Wetland Park, hosted a very experienced team of mixed gas divers, the Alternative Dive Group. Five canyon dives were undertaken and coelacanths were found on 3 occasions.
On Tuesday March 6, a single coelacanth was spotted in a cave in Jesser canyon. Peter Timm, one of 3 divers who first discovered the coelacanths, photographed the fish on both sides enabling the fish to be identified from a catalogue of images of iSimangaliso’s coelacanths. As each coelacanth is uniquely marked, individuals can be monitored over time. Tuesday’s fish was identified as Noah, the fourteenth coelacanth in the catalogue and named for the arc that is distinct on the coelacanth’s left side. Noah was first documented by scientists operating from the Jago submersible in 2003. Peter Timm helped scientists search for coelacanths by remotely operated vehicle in 2005 and Noah was seen then and again in another ROV expedition held in 2011. On Thursday, the trimix divers saw three different fish in the same area. One of them seems to be a new individual but a more thorough analysis of ROV footage from previous expeditions is needed to confirm this. The other two fish include a coelacanth known as “ Eric Eyelashes” first photographed in 2009 by a French team of trimix divers diving with Triton in 2009. The other fish is Sydney, a very large (almost 2m long) specimen that was first discovered in 2003. This coelacanth is named after Sydney Bremmer, a famous South African born scientist (now 85 years of age) whose prize-winning work made significant contributions to understanding the genetic code of the coelecanth and other important aspects of molecular biology. In 2003, a single scale was sampled, from Sydney coelacanth’s tail to support genetic and molecular research. At that time, Sydney was in Wright canyon, approximately 7 km north of Jesser canyon and was not seen in research expeditions conducted in 2004 or 2005. In 2010, trimix divers documented Sydney in Jesser canyon in the same cave that Sydney was photographed in this expedition. The divers greatly improved on the image for this individual in the coelacanth catalogue. Sydney was also seen alone in the same location on Friday.
Trimix divers started the search for the Sodwana coelacanths in 1998, and from the outset, have added to the scientific knowledge about coelacanths and their poorly studied habitats. In 1998, trimix divers collected the first invertebrate specimens from the submarine canyons during the first coelacanth expedition. In 61 minutes of bottom time, the mixed gas divers documented 69 species of invertebrates, at least 15 new records for South Africa plus several potential new species. Of the 25 coelacanths currently included in the coelacanth catalogue, 7 were first recorded by divers and 10 different individuals have been seen by trimix divers during the many recreational trimix expeditions hosted by Triton between 2000 and 2012. Peter Timm has seen the first coelacanth documented by divers “Jessy” at least 6 times between 2000 and 2011. Friday marked his 29th 100 m plus trimix dive in the last year which includes 17 coelacanth sightings in this year.
By Dr Kerry Sink
Marine Program Manager
South African National Biodiversity Institute