By Beate Hoddevik Sunnset
– The parasite is completely dependent on the bubblegum coral (Paragorgia arborea), but nothing was known about how widespread this species is until we found it off the Norwegian coast. It was therefore very exciting to find the characteristic deformities on bubblegum corals in Stjernsund, off northern Norway, in 2005. Subsequent examination of the corals revealed that they had the same parasite as the one found in Canada, explains Lene Buhl-Mortensen. She and Pål Buhl-Mortensen, who are both senior researchers at the Institute of Marine Research, described the parasite after discovering the previously unknown species off Nova Scotia, Canada, in 2003 (Buhl-Mortensen & Mortensen, 2004). The parasite was given the scientific name Gorgonophilus canadensis (= Canadian sea fan lover). Both the species and genus were new to the scientific world, and so far no other species have been found within the same genus.
The parasite is a highly modified copepod that lives inside the bubblegum coral. It induces the coral to produce galls (deformities) like the ones created by the gall wasp on rose bushes, which it then lives inside. The galls can contain females, males, egg sacs and larvae. On the top of the galls there are structures that resemble horns or “chimney stacks”, which have a narrow channel. The function of the channels is unclear, but it is possible that the larvae use them to leave the gall so that they can be dispersed.
– There are still lots we don’t know about the ecology of this species, which appears to feed on the coral, and we will continue to study how it lives inside the galls. Since the infected bubblegum coral colonies appear to carry on growing perfectly healthily without showing any signs of disease, it is probable that it only feeds modestly on the coral, says Lene Buhl-Mortensen.
Bubblegum coral is common in Norwegian waters. It lives at depths of approximately 40 metres at the shallowest in Trondheimsfjorden down to approximately 500 metres on the continental slope.
Marine protected area
The area where the parasite has been found, Stjernsund, is part of a suggested marine protected area (MPA). The area has lots of prominent coral reefs and unusual species, some of which are very rare.
A number of areas in Sørøysund/Stjernsund and Andfjord were surveyed in 2006-2008 when the MAREANO project’s activities in the open Barents Sea were prevented by bad weather. Samples were taken using a beam trawl and grab, and videos were also recorded. The material included a total of 471 taxa, and 301 species have been identified. The distribution range of 41 species has moved compared to previous observations. For 38 of them it has moved north, whereas only three species had their limit extended further south. Three of the species are rare, and in addition to the coral parasite we found one other species that had not previously been observed in the area.
– We cannot at this stage say why the distribution range of several species have moved; one reason might be climate change, another reason might be that this area has been surveyed less than areas further south, says Pål Buhl-Mortensen.