Bioerosion and fungal colonization of the invasive foraminiferan Amphistegina lobifera in a Mediterranean seagrass meadow

0545041 - BÚ 2022 RIV DE eng J - Journal Article
Vohník, Martin
Bioerosion and fungal colonization of the invasive foraminiferan Amphistegina lobifera in a Mediterranean seagrass meadow.
Biogeosciences. Roč. 18, č. 8 (2021), s. 2777-2790. ISSN 1726-4170. E-ISSN 1726-4189
R&D Projects: GA ČR(CZ) GA18-05935S
Institutional support: RVO:67985939
Keywords : bioerosion * Foraminifera * marine fungi
OECD category: Marine biology, freshwater biology, limnology
Impact factor: 5.092, year: 2021
Method of publishing: Open access
https://doi.org/10.5194/bg-18-2777-2021

Foraminiferans are diverse micro- to macroscopic protists abundant especially in (sub)tropical seas, often forming characteristic benthic communities known as living sands. Numerous species have migrated through the Suez Canal to the Mediterranean and one of them, i.e., Amphistegina lobifera, turned invasive, gradually outcompeting the indigenous species. At some places, A. lobifera creates thick seabed sediments, thus becoming an important environmental engineer. However, little is known about the turnover of its shells in the invaded ecosystems. Using vital staining, stereomicroscopy, scanning electron microscopy, and cultivation and DNA fingerprinting, I investigated the vital status, destruction/decomposition and mycobiota of A. lobifera in the rhizosphere of the dominant Mediterranean sea-grass Posidonia oceanica in an underwater Maltese meadow (average 284 shells g(-1), representing 28.5% of dry substrate weight), in comparison with epiphytic specimens and P. oceanica roots. While 78% of the epiphytes were alive, nearly all substrate specimens were dead. On average, 80% of the epiphytes were intact compared to 21% of the substrate specimens. Abiotic dissolution and mechanical damage played only a minor role, but some bioerosion was detected in 18% and > 70% of the epiphytic and substrate specimens, respectively. Few bioerosion traces could be attributed to fungi, and the majority probably belonged to photoautotrophs. The seagrass roots displayed fungal colonization typical for this species and yielded 81 identified isolates, while the surface-sterilized substrate specimens surprisingly yielded no cultivable fungi compared to 16 other identified isolates obtained from the epiphytes. While the epiphytes' mycobiota was dominated by ascomycetous generalists also known from terrestrial ecosystems (alongside with, for example, a relative of the rock-eating extremophiles), the roots were dominated by the seagrass-specific dark septate endophyte Posidoniomyces atricolor and additionally contained a previously unreported lulworthioid mycobiont. In conclusion, at the investigated locality, dead A. lobifera shells seem to be regularly bioeroded by endolithic non-fungal organisms, which may counterbalance their accumulation in the seabed substrate.
Permanent Link: http://hdl.handle.net/11104/0321815