Wood-decay fungi in the Antarctic Peninsula

No, this title is not a click-baiting one – it’s wholly serious!

Courtesy of some recent research undertaken by scientists on Deception Island, which is an actively volcanic island in the archipelago that forms the South Shetland Islands, we now have a fascinating glimpse of the fungal activity that can be found upon the abanonded 19th and early to middle 20th century timber-framed buildings found upon the island’s shores. Indeed, with 57% of the island being covered by glaciers, these buildings were built along the coastline and were used for research and European whaling purposes (Whalers Bay), up until the Chileans departed from Pendulum Cove in 1967. Nowadays, it’s a tourist area for those that quite fancy spending large sums exploring such a desolate island, as well as a research base for Spanish and Argentinian scientists.

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Decaying timbers on the island. Source: The Planet D.

As regards to prior research on the historic timber buildings upon the island, research has uncovered fungal decomposition of the timber by Ascomycete fungi, thereby inferring some timber has begun to degrade via a soft rot. However, brown and whit rot fungi had not previously been identified on the island to any marked degree (one fruiting Pholiota sp. sample was found on the wood of a buried whaling vessel in 1967), and thus this research sought to ascertain whether fungal diversity was more appreciable than previously understood. At this point, it is also worth noting that some Asocmycetous fungi are indigenous to the island (such as Cadophora spp.), being found as saprotrophs on the plants growing freely on the island. Moreover, the research enabled for an insightful look into fungal ecology in a location where soil temperature range from below freezing to as high as 90°C.

Using two sites on the island where such timber-framed buildings could be found, which were Whalers Bay and Pendulum Cove (see the below image for rather precise locations), very small wood fragments from the timber-framed buildings (largerly made of Pinus spp. and Picea spp. timbers, though also Betula spp.) were sampled (188 from Whalers Bay and 30 from Pendulum Cove) and taken back to the laboratory under sterile conditions for assessment in a growth medium comprised principally of malt extract agar. Following the placement of the samples within the agar for a few weeks and the subsequent transfer of growing mycelium into pure cultures, genetic analysis was undertaken to ascertain what fungi were present within the wood samples.

Fungi on Antarctica
The two research locations used for the study (as denoted by the red arrows).

In total, 326 isolates were found from the total 218 sampled wood fragments. Indeed, as was probably expected, the large majority (79%) of the isolated were of Ascomycete fungi from 53 different taxa that were causing a soft rot. However, quite interestingly, 15% of samples (equating to 11 different taxa) were from the Basidiomycetes division and a few (6%) also belonged to the Zygomycota.

From the Basidiomycetes, which are probably more well-known to those who read this blog, 18% of isolates were from the genus Pholiota. Indeed, this genus is a frequently identified one in the UK and further afield, and the genetic analysis revealed that one particular clade of the genus was of the species Pholiota multicingulata, which was found exclusively at the Pendulum Cove site where the Chilean undertook their scientific research up until the late 1960s. Found across the South Pacific and notably in New Zealand, its presence in the Antarctic Peninsula is considered to be as a consequence of infected timbers brought over by the Chileans.

Other common wood-decay Basidiomycetes known to arboriculturists included Coprinellus micaceus and Coniophora puteana, though only one sample of each was identified from genetic analysis – both considered to have been introduced by the Europeans during whaling escapades. Postia pelliculosa, a brown rot fungus of gymnospermous wood, was also identified – as was Jaapia argillacea, which is a rare fungus within Europe and thus its finding at Whalers Bay presented the authors with some surprise.

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A group of caps of the fungus Pholiota multicingulata growing on deadwood. Source: Mushroom Observer.

With reference to the other fungal genera and species found, species from the genus Cadophora wthe most abundant and amounted to 20% of all identified fungal samples. Furthermore, Hypochniciellium species accounted for 13% of the total sample count and Phialocephala 7%. Pholiota, as a genus, contributed only to 4% of the total number of records. Importantly, it was also found that many of the historic timbers were extensively decayed by the same fungi at both sites, inferring potentially a long-standing decay arising from a fungal metapopulation on the island. Decayed timbers were found most observably around the locations where the timber was in contact with the soil, perhaps due to a higher moiture content within the wood facilitating for more effective hyphal ingression into the timbers and the localised warming of soils because of volcanic activity. At the Chilean base, white rots of the sampled timbers were found only just beneath the soil surface, with brown and soft rots being identified on timber from both sites in wood exposed to ambient conditions.

As alluded to within the preceding text, it is highly probable that the fungal isolates from the two sites were introduced alongside human migration to Deception Island. Certainly, there have been plenty of opportunities for spores to be deposited on the island, given the whaling and research activities over the past two centuries. Importantly, the current phenomenon of tourism to the island will facilitate potentially in the emergence of new fungal species, which makes future research prospects exciting as the inherent isolation of the site would have rendered it almost impossible for exotic fungi to have otherwise arrived on site and – assuming they had – there would have been no timber for them to colonise. In this respect, the research undertaken on this island outlines a very critical biosecurity risk: human migration.

A further aspect of interest from the results is that native Ascomycetous fungi to the island, which were found to be acting saprotrophically on native plants, broadened their host range to that of the exotic timbers introduced. Thus, the notion of fungal adaptation alongside a change in the potential inoculum base is given credence, which can again be related to current issues with fungal pathogens of trees within Europe and further afield.

Source: Held, B. & Blanchette, R. (2017) Deception Island, Antarctica, harbors a diverse assemblage of wood decay fungi. Fungal Biology. 121 (2). p145-157.

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Wood-decay fungi in the Antarctic Peninsula

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