Temporal variation in community structure of zoosporic fungi in Lake Biwa, Japan

Song, Peixue; Yi, Rong; Tanabe, Shoko; Goto, Nobuo; Seto, Kensuke; Kagami, Maiko; Ban, Syuhei

doi:10.3354/ame01970

Cited by 3 publications

(2 citation statements)

References 45 publications

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“…Chytrid epidemics have been mostly reported from large (e.g. inedible) bloom forming diatom species [ 12 , 71 , 72 ], but we observed that also small-sized diatoms (e.g. Cyclotella spp.)…”

Section: Discussionmentioning

confidence: 58%

Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits

et al. 2022

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Zoosporic fungi of the phylum Chytridiomycota (chytrids) regularly dominate pelagic fungal communities in freshwater and marine environments. Their lifestyles range from obligate parasites to saprophytes. Yet, linking the scarce available sequence data to specific ecological traits or their host ranges constitutes currently a major challenge. We combined 28 S rRNA gene amplicon sequencing with targeted isolation and sequencing approaches, along with cross-infection assays and analysis of chytrid infection prevalence to obtain new insights into chytrid diversity, ecology, and seasonal dynamics in a temperate lake. Parasitic phytoplankton-chytrid and saprotrophic pollen-chytrid interactions made up the majority of zoosporic fungal reads. We explicitly demonstrate the recurrent dominance of parasitic chytrids during frequent diatom blooms and saprotrophic chytrids during pollen rains. Distinct temporal dynamics of diatom-specific parasitic clades suggest mechanisms of coexistence based on niche differentiation and competitive strategies. The molecular and ecological information on chytrids generated in this study will aid further exploration of their spatial and temporal distribution patterns worldwide. To fully exploit the power of environmental sequencing for studies on chytrid ecology and evolution, we emphasize the need to intensify current isolation efforts of chytrids and integrate taxonomic and autecological data into long-term studies and experiments.

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“…Chytrid epidemics have been mostly reported from large (e.g. inedible) bloom forming diatom species [ 12 , 71 , 72 ], but we observed that also small-sized diatoms (e.g. Cyclotella spp.)…”

Section: Discussionmentioning

confidence: 58%

Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits

et al. 2022

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“…Interactions between phytoplankton and fungal parasites such as chytrids are key processes in aquatic food webs and ecosystems, potentially driving phytoplankton population and community dynamics (Miki et al 2011, Frenken et al 2017, Song et al 2021 ) and the flow of energy from phyto-plankton to zooplankton via zooplankton grazing on chytrid zoospores, the so-called 'mycoloop' (Kagami et al 2007(Kagami et al , 2011(Kagami et al , 2014. Past studies have estimated the prevalence of infection in natural ecosystems (Ibelings et al 2011, Kagami et al 2012, experimentally quantified the interaction strength (Kagami et al 2004, Frenken et al 2020, and developed mathematical models (Bruning 1991a, Miki et al 2011, Gerla et al 2013, Almocera et al 2018, Frenken et al 2020.…”

Section: Introductionmentioning

confidence: 99%

Non-random patterns of chytrid infections on phytoplankton host cells: mathematical and chemical ecology approaches

Yoneya

Miki

Wyngaert

et al. 2021

Aquat. Microb. Ecol.

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Host-parasite interactions between phytoplankton and fungi (chytrids) are key processes in aquatic ecosystems. However, individual-level heterogeneity in these interactions remains unexplored, although its importance in predicting the spread of diseases has been demonstrated in epidemiology. In this study, we experimentally tested whether individual-level heterogeneity could be a good indicator of phytoplankton-chytrid interactions, using a freshwater green alga Staurastrum sp., the diatoms Ulnaria sp. and Fragilaria crotonensis, and chytrid fungi. The number of attached fungi per host cell showed a non-random clumped parasite distribution on Ulnaria sp. and F. crotonensis, but a random Poisson distribution on Staurastrum sp. To explore the potential mechanisms of these patterns, we developed a mathematical model describing sequential encounters between chytrid zoospores and host cells. The statistical fits of the model explained the parasite distributions for Ulnaria sp. and F. crotonensis well, indicating that the clumped parasite distributions may result from an infection rate, increasing with the number of infections that already occurred on each host cell. Simultaneous analysis of volatile organic compounds (VOCs) from uninfected and infected host populations revealed that, among 13 VOCs detected, 6 components characterized the differences in VOC compositions between species and infection status. In particular, the level of beta-ionone, potentially acting against fungal activities, was significantly reduced in the presence of chytrid infection of Staurastrum sp. These VOCs are targets for future studies, which potentially act as chemical signals influencing chytrid zoospores’ behaviors. The combination of mathematical and chemical analyses represents a promising approach to better understand the individual-level processes of phytoplankton-chytrid interactions.

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A sedimentary DNA perspective about the influence of environmental and food‐web changes on the microbial eukaryotic community of Lake Biwa

Capo,

Picard,

Nakane

et al. 2024

Freshwater Biology

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The impacts of environmental change on Lake Biwa have been explored for decades, with water monitoring and palaeolimnological studies revealing how environmental forcing, including climate warming, eutrophication, water level manipulation and human manipulation of fish populations, has influenced the food web of Lake Biwa. However, these studies have rarely accounted for microbial food‐web components. This knowledge gap is mostly due to the lack of time series spanning more than a couple of decades, coupled with the high taxonomical expertise required to identify organisms belonging to very diverse groups. The use of a sedimentary DNA approach allows for the reconstruction of past changes in the diversity, composition and structure of the microbial eukaryotic community of aquatic systems. The application of 18S metabarcoding has been proven successful to describe the response of unicellular eukaryotes (protists) and aquatic fungi in lake ecosystems, encompassing a large taxonomic and functional diversity such as phototrophs, heterotrophs and mixotrophs. We applied 18S metabarcoding to 31 sediment core samples from Lake Biwa, spanning the past 100 years and explored the response of microbial eukaryotic communities to changes in multiple environmental stressors, including nutrient levels, lake water level, climate, as well as fish and zooplankton biomass for the period 1973–2010. We found that the manipulation of the water level and changes in fish community composition were the primary factors impacting (indirectly) the structure of the lake microbial eukaryotic community with minor, but significant, effects of climate warming and phosphorus levels. Co‐occurrence network analysis highlighted the potential food web impacts on the microbial eukaryotic community, suggesting that organisms from this compartment were impacted by both bottom‐up and top‐down processes.

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Temporal variation in community structure of zoosporic fungi in Lake Biwa, Japan

Cited by 3 publications

References 45 publications

Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits

Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits

Non-random patterns of chytrid infections on phytoplankton host cells: mathematical and chemical ecology approaches

A sedimentary DNA perspective about the influence of environmental and food‐web changes on the microbial eukaryotic community of Lake Biwa

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