Cryptic fungal diversity revealed by DNA metabarcoding in historic wooden structures at Whalers Bay, Deception Island, maritime Antarctic

Abstract

We provide the first assessment of fungal diversity associated with historic wooden structures at Whalers Bay (Heritage Monument 71), Deception Island, maritime Antarctic, using DNA metabarcoding. We detected a total of 177 fungal amplicon sequence variants (ASVs) dominated by the phyla Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota, Monoblepharomycota, Rozellomycota, and Zoopagomycota. The assemblages were dominated by Helotiales sp. 1 and Herpotrichiellaceae sp. 1. Functional assignments indicated that the taxa detected were dominated by saprotrophic, plant and animal pathogenic, and symbiotic taxa. Metabarcoding revealed the presence of a rich and complex fungal community, which may be due to the wooden structures acting as baits attracting taxa to niches sheltered against extreme conditions, generating a hotspot for fungi in Antarctica. The sequences assigned included both cosmopolitan and endemic taxa, as well as potentially unreported diversity. The detection of DNA assigned to taxa of human and animal opportunistic pathogens raises a potential concern as Whalers Bay is one of the most popular visitor sites in Antarctica. The use of metabarcoding to detect DNA present in environmental samples does not confirm the presence of viable or metabolically active fungi and further studies using different culturing conditions and media, different growth temperatures and incubation periods, in combination with further molecular approaches such as shotgun sequencing are now required to clarify the functional ecology of these fungi.

Keywords: Antarctica; Extremophiles; Fungi; Heritage site; Taxonomy.

Fig. 1

Location of Whalers Bay, Deception Island, in the South Shetland Islands, maritime Antarctica, where the wood samples were obtained. Satellite images a, b, and c were obtained using Google Earth Pro, 2019 (www.google.com.br/earth/about/versions). a Antarctica with the South Shetland Islands within the red rectangle; b Deception Island in the South Shetland Islands within the red rectangle; c Whalers Bay, Deception Island (62°57′S and 60°38′W); and d aerial view of Whalers Bay ruins (62° 58′ 52.0″ S; 60° 39′ 52.9″ W). Photo d taken by Luiz H. Rosa

Fig. 2

Whalers Bay ruins, Deception Island, South Shetland Islands, where the wood samples were obtained. a Biscoe House, b beached whaling boat, c Biscoe House Annex, and d Hunting Lodge. Photos taken by Luiz H. Rosa

Fig. 3

Krona chart showing the abundances of different fungal taxonomic levels detected in wood fragment samples from a Biscoe House, b beached whaling boat, c Biscoe House Annex, and d Hunting Lodge at Whalers Bay, Deception Island, South Shetland Islands

Fig. 4

Venn diagram showing the distribution of fungal amplicon sequence variants (ASVs) across the four wood samples obtained from Biscoe House, the abandoned whaling boat, Biscoe House Annex, and Hunting Lodge at Whalers Bay, Deception Island, South Shetland Islands. *Total relative abundance (%) in blue

Fig. 5

Venn diagram showing the overlap in fungal amplicon sequence variants (ASVs) obtained from historic wooden structures at Whalers Bay, Deception Island, South Shetland Islands using metabarcoding approach and by Held and Blanchett [2] using traditional culturing methods

Fig. 6

Venn diagram showing the overlap in distribution of fungal amplicon sequence variants (ASVs) among the historic wooden structures at Whalers Bay, Deception Island, South Shetland Islands and soil samples analyzed by Rosa et al. [47], using a metabarcoding approach