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We are happy to announce that our keynote lectures will be presented by dr Adriana Zingone (Stazione Zoologica Anton Dohrn, Naples, Italy), dr Carlos E. Wetzel (Luxemburg Institute of Science and Technology, Luxemburg) and Mr Paul B. Hamilton (Canada Museum of Nature, Ottawa, Canada) who each will bring us exiting lectures on their state-of-the-art research on soil, marine and freshwater diatoms.
Dr Carlos E. Wetzel
Luxemburg Institute of Science and Technology, Luxemburg
Carlos E. Wetzel is a Senior Research and Technology Associate at the Luxembourg Institute of Science and Technology. He holds a PhD in Botany issued by the University of São Paulo (Brazil). During the last decade Carlos has authored and co-authored over 160 peer-reviewed articles regarding taxonomy and ecology of diatoms from many continents and environments (including rivers, lakes, soils and the marine realm). Carlos has been teaching numerous training courses on diatom ecology and taxonomy designed for biologists, technicians, and ecologists, contributing to the continuous improvement of the Water Framework Directive in Europe. His current project aims to show soil scientists the hidden diversity terrestrial diatoms and its potential use as bioindicators of soil conditions.
Key-note 1
“Terrestrial diatoms as indicators of soil conditions”
Numerous studies have focused on the ecology of aquatic diatoms and their use in assessing water quality over the past decades. Much less is known about the ecological behaviour of terrestrial diatoms and their sensitivity to environmental factors. In this work, we explore the use of diatoms as indicators of soil condition by combining a traditional microscopic approach with high-throughput sequencing (HTS) metabarcoding techniques. We hypothesise that terrestrial diatom communities can be used to indicate anthropogenic disturbance levels and soil fertility. This method could serve as a tool for implementing future policies for protecting and enhancing soil biodiversity, which is still in its infancy. To show some results, we intend to explore the distribution of soil diatoms, providing new information on the physiographic and environmental parameters that control the distribution patterns of these communities. A total of 438 samples were sequenced and include samples collected during the years 2018, 2019 and 2020 in several localities under different land uses (i.e. arable land, grassland and forest) and soil textures [light (L), medium (M) and heavy (S)]. These samples were also clustered into organic (BIO) and conventional (CONV) farming practices and had their own set of soil chemical parameters analysed simultaneously. A second dataset comprises 288 sites collected in 2021 and grouped primarily as arable land, grasslands, and forests in Luxembourg.
A total of 9.74 million rbcL gene reads were acquired for 3960 amplicon sequence variants (ASVs), of which 36.4% were determined to be 'Eukaryota unclassified' (i.e. 1443 non-diatoms), 57.8% of the ASVs were identified as Bacillariophyceae. Almost two-thirds (62%) were placed as 'Bacillariophyceae unclassified'. One hundred and twenty-one diatom names were assigned at the species level from Diat.Barcode. However, this gap can be reduced for key species, as shown by preliminary results on the congruence between the information provided by rbcL gene sequencing and microscopic analysis, where the identity of some 'unclassified' taxa can be assigned using microscopic techniques. The surprising diversity and importance (in terms of genetic variants and total reads, despite their small size) of the genus Mayamaea Lange-Bertalot are highlighted and discussed. The establishment of ecological preferences of VSAs for the different parameters and the development of an index that considers fertility classes, integrating biodiversity components are also approached.
Dr Adriana Zingone
Stazione Zoologica Anton Dohrn, Naples, Italy
Staff member from 1988 to 2020, Adriana Zingone is presently Research Fellow at Stazione Zoologica Anton Dohrn in Naples (Italy). Her research field is microalgal diversity and ecology, with a focus on temporal and spatial dynamics of marine phytoplankton and Harmful Algal Blooms (HABs). Research combining classic and advanced molecular approaches primarily builds on long-term plankton observations conducted since 1984 in the Gulf of Naples (LTER-MC, http://szn.macisteweb.com/), which she has directed until recently, as well as in European and World’s oceans. Adriana has organized and lectured in eight editions of the international Advanced Phytoplankton Courses-Taxonomy and Systematics. Currently member of the European Marine Board, Adriana has been part of several international working groups on long-term plankton observations and on Harmful Algal Blooms (HABs) and has long been in the IOC-Intergovernmental Panel on HABs (which she has chaired in 1995-2002). Adriana has co-authored more than 150 papers and book chapters (Google Scholar H index: 55, total citations 13,745).
Key-note 2
“Insights into diatom diversity and ecology through DNA metabarcoding”
Diatoms are among the most deeply investigated protists in the marine realm. Yet their knowledge has leaped forward with the advent of molecular technologies which have revealed, among other features, a high level of hidden and cryptic diversity. In this respect, eDNA metabarcoding has been proven effective in unveiling diatom occurrence in space and time with a higher taxonomic resolution and precision compared to morphological methods, thus producing detailed appraisals of their actual biogeographical and ecological characteristics. Results obtained span from global overviews of diatom diversity and their driving environmental factors to spatial and temporal distributions of individual genera and species. Despite several limitations, the amount of new information and questions opened by the recent discoveries demonstrate the unique advantages and great potential of molecular approaches, at the same time highlighting the need to deepen the knowledge of diatoms with traditional methods.
Mr Paul B. Hamilton
Canadian Museum of Nature, Ottawa, Canada
Paul Hamilton is the caretaker of the Phycology Collection of Canada (www.nature-cana.ca) and works globally on diatom taxonomy and systematics, water quality assessments, and ecosystem services. He is thrilled to say that the microalgal collection makes a significant contribution to the total CMN holdings. Paul has been with the museum for more than 35 years developing the microalgae collection and conducting research. His research has been extensively broad from acid rain to toxic metals in the environment and species discovery to species radiation in ancient lakes. He has coauthored more than 200 refereed scientific papers and produced five books on diatom taxonomy, ecology and biodiversity. Paul has described more than 100 diatom species and seven species have been named in his honour. With the invitation of colleagues, the most recent scientific question is examining the relevancy of documenting human disturbance on global health.
Key-note 3
Freshwaters, ecosystem services, resilience and sustainability: where is diatom research today and where will it be in the future
Freshwaters globally have many secrets to tell. To find the secrets, it is all about the right question or scalable hypothesis. Over the last 30 years, the diatom world has seen many changes in taxonomy, ecology, paleolimnology and genetics. We have lived through these changes and are adapting to new directions of research. Using the research colleagues and I have conducted over the last 30 years in classical taxonomy, ecology, paleolimnology and genetics, this presentation will explore these changes through space and time. In ecology, researchers (the diatom community) have completed a plethora of water quality assessments using diatoms and related organisms. Mercury, arsenic, sulphur, and nutrients all have effects on diatoms. Our research will demonstrate changing environments and further hint at research to come. In paleolimnology, analyses have varied from broad studies to fine detailed year to sub-yearly evaluations using large datasets. Climate change and anthropogenic impacts will continue to drive diatom-based paleolimnological studies into the future with big-data and less speculation. Whether it is Crawford Lake in southern Canada or an unnamed lake in the Arctic Archipelago, climate and anthropogenic effects are captured at regional and global paleo-records. Taxonomic studies using more morphological metrics and even micro-level metrics are hinting that freshwater diatoms are greatly more diverse than expected, although a consistent definition for diatom species still eludes taxonomists. Genetic studies have advanced the most in diatom research. From single gene related sequencing, to multiple sequence comparisons across chloroplasts, nuclear and mitochondria, the study of diatom taxonomy has changed. Neidium, Frustulia, and Navicula genetic studies reveal interesting relationships between morphology and genetics. However, even these DNA approaches are considered old and dated. New questions using larger sequence datasets (even complete genomes) will be the next phase of exploration and discovery. Will we have a better idea about what discrete species are or will we see continuums of ever-changing geneflow. Populations, individuals, or genes, what is driving/controlling freshwater biodiversity. Big-data is here to stay, but it is the right questions or hypotheses that will determine our future understanding of freshwaters and their ecosystem services to earth.
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