Extinct to secure: how we saved Ascension’s endemic parsley fern

As we approach the end of 2010 and reflect on the successes of International Year of Biodiversity, the story of Anogramma ascensionis reminds me why I work in conservation. With all the gloom and depression surrounding many aspects of our efforts to save our planet, the regenerative effects of a species success story like this are much more potent than any of the seasonal brews we’re enjoying at our office parties.

The type herbarium specimen of Anogramma ascensionis showing Joseph Hooker's collections at the top of the page and A.B. Curror's below (Image: RBG Kew)

My reflections started when pulling out the original type specimen from the storage cupboards in the Herbarium at Kew. Like many of the older specimens in Kew's Herbarium, this sheet contains several specimens of the fern collected at different times. There was A.B. Curror’s collection – the first record of this species in 1842. On the same sheet are Joseph Hooker’s specimens collected a year later when he visited Ascension in 1843. It was Hooker who described this as a new species to science and gave it the name Anogramma ascensionis, its specific epithet revealing that it is only found on Ascension Island.

This herbarium sheet has been scanned and digitised along with all of our other specimens from UK Overseas Territories and will soon be freely accessible on the UKOTs On-Line Herbarium, a really exciting project that is a key focus of the UKOTs team under the watchful gaze of project officer, Sara Barrios. 

Cultivation in the CBU at Kew

Sara and I then went down to the Conservation Biotechnology Unit (CBU) where Unit head, Viswambharan Sarasan, and sandwich student, Ed Jones showed us how well the plants growing in culture are doing. It was an inspirational visit. There are dozens of jars with very healthy plants growing in them at many different stages. Sarasan and his previous sandwich student, Katie Baker, have been cultivating the ferns since they received the first tiny fertile frond less than the size of a finger nail on 23 September 2009, less than 24hours after it had been collected from the re-discovered wild plant on Ascension’s Green Mountain.
 

Sandwich student, Ed Jones, checking the growth of Anogramma ascensionis in the Conservation Biotechnology Unit. All the jars and petri dishes behind him contain the parsley fern at various stages of its life history (Image: RBG Kew)

The re-discovery of Anogramma ascensionis is itself a story out of the boy’s own adventures that I used to read as a youngster, dreaming of exotic travel and exploration. The re-discovery in July 2009 attracted a lot of publicity and can be reviewed on the BBC online.

Hooker had written in his journal that A. ascensionis was relatively widespread when he visited in 1843. There are only sporadic records of it through to 1958 when we have our last verified record and specimen collected by the biologist Eric Duffy who later published his classic paper on the Terrestrial Ecology of Ascension Island in 1964. In 2003 A. ascensionis was officially classified as extinct and entered onto the IUCN Red List of Threatened Species. We mourned the loss of a unique species.

The re-discovery of the Ascension Island parsley fern

I vividly remember getting Stedson’s email from Ascension with the message that the Ascension team had found 4 plants of a tiny fern that Stedson and Phil were convinced was A. ascensionis. And so it proved - the parsley fern was back from the dead, but in very small numbers and in an extremely precarious habitat. The species could still be lost at any time. Indeed two of these plants died quite quickly.

For the next two months Stedson and Olivia tended the remaining plants, watering and nurturing them until the fronds started to produce spores and they were able to collect a fertile frond to send to the CBU at Kew. With the help of Island Administrator, Ross Denny, the frond was collected into a sterile jar that we had sent down to Ascension from Kew and this was rushed to the waiting flight from Ascension to RAF Brize Norton in Oxfordshire where UKOTs team member, Marcella Corcoran was waiting in a car to drive the precious cargo back to Sarasan, who was waiting patiently in the lab.

Within 24 hours of being collected on Green Mountain the spores from the fertile frond had been extracted and were being incubated in sterile medium in the lab at Kew. Phase one of the recovery was successfully complete. In the tender care of the CBU team the fern has flourished. The spores have germinated to form the leafy gametophyte structure which itself has produced the spore-bearing sporophyte generation. These sporophytes have flourished and have produced spores to complete the cycle. It is the sporophyte that is the plant we recognise as the parsley fern, only in culture they are bigger and healthier than any we’ve so far seen in the wild on Ascension. Early results from the lab have also indicated that the spores survive well in liquid nitrogen and that long-term cryopreservation is a viable option for this species. And in Ascension a few more plants have been found in the wild and it’s growing in the nursery on Green Mountain.

For the image below I’ve assembled Hooker’s specimen and three jars from CBU to show the key stages in the life cycle of the parsley fern. The leafy gametophyte generation in the jar on the left, the young sporophytes emerging from the gametophytes in the jar in the centre and a very healthy cluster of mature ferns in the jar on the right.

The key stages in the life cycle of the parsley fern (Image: RBG Kew)

It still gives me goose bumps to look at this image and to think that because of the work of an extremely dedicated, collaborative team of people this species is now secure. I recall sitting on Green Mountain with Stedson several years ago talking about the challenges for conservation on Ascension and the possibility of ever seeing any of Ascension's extinct species again. And now one has turned up - perhaps others will too, so long as we are able to conserve habitats long enough for thorough exploration or for dormant seeds and spores to re-appear when the conditions are right.

I feel privileged to be part of this team and happy to be working in conservation. Anogramma’s story has certainly been a highlight of the UK Overseas Territories Programme’s year and is one of Kew’s top 10 stories to end International Year of Biodiversity on a high.

- Colin -