Serena Rasconi

This article reports on the final meeting of the COST Action Applications for zoosporic parasites in aquatic systems (CA20125 ParAqua, 02.11.2021–30.10.2024), held on 1–2 September 2025 in Zagreb, Croatia. The meeting was organised by the Science Communication Coordinator, Prof. Ana Gavrilović, and was an opportunity to discuss the achievements, recap all the organised activities, and undertake collaborative work for the finalisation of the scientific objectives of the Action.

Social media presents a popular channel for science communication, although it is relatively unclear how their users perceive and interact with scientific content on different platforms. The aim of this case study was to present and compare the available metrics of ParAqua COST Action social media platforms (LinkedIn, Facebook, Instagram, Twitter/X) collected in September 2022 and August 2025. Since the availability of metric data varied substantially between 2022 and 2025, only the indicators consistently available across both years were used for direct comparison. All platforms showed significant increases in follower numbers between the 2022 and 2025 assessments. LinkedIn experienced the most pronounced growth, while Instagram had the highest share of organizations. The Action’s Facebook audience in 2025 was mostly adults between 35 and 44 years old, with the largest share of viewers coming from Croatia, followed by Italy, North Macedonia, Egypt, Serbia, and Turkey. The results showed that all ParAqua social media accounts have proven their worth, but also leave room for further customization of content for each particular platform. References: Bertemes J. P., Haan S. & Hans D. (Eds) 2024. 50 Essentials on Science Communication. University of Luxembourg, Luxembourg National Research fund. Berlin, Boston: De Gruyter Mouton, 136 pp. https://doi.org/10.1515/9783110763577 Burns T. W., O’Connor D. J. & Stocklmayer S. M. 2003. Science Communication: A Contemporary Definition. - Public Understanding of Science 12 (2): 183-202. https://doi.org/10.1177/09636625030122004 Cavanah S. B. & Kemink K. 2025. The science communication in social media theory of change evaluation framework: a system of establishing goals and assessing efficacy for knowledge brokers, intermediaries and boundary spanners. – Frontiers in Communication 10:1534363. https://doi.org/10.3389/fcomm.2025.1534363 Coletti A., McGloin R., Oeldorf-Hirsch A. & Hamlin E. 2022. Science Communication on Social Media: Examining Cross-Platform Behavioral Engagement. - The Journal of Social Media in Society 11 (2): 236-263. COST 2017. Guidelines for communication, dissemination and exploitation of COST Action results and outcomes COST Association AISBL. Brussels, Belgium. COST 2021a. Annotated rules for COST actions. COST 094/21. European Cooperation in Science and Technology. Brussels, Belgium. COST 2021b. Toolbox for the Science Communication Coordinator. A leadership rule in all COST Actions. COST Association AISBL. Brussels, Belgium. COST 2023. Toolbox for the Science Communication Coordinator. A leadership rule in all COST Actions. COST Association AISBL. Brussels, Belgium. COST 2024. Toolbox for the Science Communication Coordinator. A leadership rule in all COST Actions. COST Association AISBL. Brussels, Belgium. Gavrilović A., Rasconi S., Gsell A., Fernandez F. G. A., Balode M., Vardić I. & Scholz B. 2022. Science Communication Plan. CA20125 ParAqua - Applications for zoosporic parasites in aquatic systems. LUCES. Science Communication Plan of the COST Action - CA22131. https://lucescostaction.com/wp-content/uploads/2025/01/SciComm-plan-LUCES_CA22131.pdf (Accessed December 11th 2025) Portman J., Miara V. Y. & Baram-Tsabari A. 2025. How does social-media-based science communication affect young audiences? A scoping review of impact making. – Journal of Science Communication 05:02. https://doi.org/10.22323/145420250918092124 Said-Hung E., Martín-Gutiérrez A. & Marcano B. 2024. A study of social media use for scientific communication and dissemination among Spanish education researchers. - Knowledge Management & E-Learning 16 (2): 237–258. https://doi.org/10.34105/j.kmel.2024.16.012 Van Eperen L. & Marincola F. M. 2011. How scientists use social media to communicate their research. - Journal of Translational Medicine 9:199. https://doi.org/10.1186/1479-5876-9-199

Zooplankton transfer substantial energy in aquatic food webs and are used as indicators of environmental change. Syntheses of zooplankton community dynamics globally require datasets that span a wide range of environmental gradients; however, these datasets are limited due to methodological differences across programs, taxonomic inconsistencies, and a lack of standardized metadata. To reconcile these challenges, we created the Zooplankton International Geospatial (ZIG) dataset, which includes original zooplankton, water physical and chemical variables, and lake morphometric data from 311 inland lakes and reservoirs. ZIG includes waterbodies ranging in size from 0.005 to 82,100 km ² and spanning broad latitudinal (−47.26 to 64.90) and longitudinal ranges (−165.04 to 176.53). Temporal coverage for individual waterbodies ranges between 1 and 60 yr with sampling frequency ranging from annually to weekly. With its extensive coverage and content, we consider ZIG to be a cornerstone for future investigations of global scale lake biodiversity change.

Zoosporic parasites are a polyphyletic group of microorganisms characterised by a motile spore stage, which play a crucial ecological role in aquatic environments. They are known to influence population dynamics of aquatic primary producers, nutrient cycling, and energy transfer within microbial food webs. Despite their importance, data on their diversity, distribution, and interactions with their hosts remain sparse and fragmented. Here, we present a harmonised dataset of field observations on zoosporic parasites infecting aquatic primary producers. The dataset integrates both published and previously unpublished records, encompassing more than 4427 observations collected between 2007 and 2021 across 28 sites in Europe and North America. It includes data for 91 unique parasite taxa, along with confirmed and putative parasite–host associations derived from direct microscopic or molecular evidence. All records were standardised using the Darwin Core schema to ensure interoperability and long-term usability. This open-access resource provides a foundation for comparative and meta-analytical studies on parasite–host ecology, biodiversity assessments, and industrial applications related to algal production systems.

S of talks presented at ParAqua Grantees Conference held in Zagreb (Croatia), 1-2 September 2025

Amplicon sequencing tools such as metabarcoding are commonly used for thorough characterisation of microbial diversity in natural samples. They mostly rely on the amplification of conserved universal markers, mainly ribosomal genes, allowing the taxonomic assignment of barcodes. However, linking taxonomic classification with functional traits is not straightforward and requires knowledge of each taxonomic group to confidently assign taxa to a given functional trait. Zoosporic parasites are highly diverse and yet understudied, with many undescribed species and host associations. However, they can have important impacts on host populations in natural ecosystems (e.g., controlling harmful algal blooms), as well as on industrial‐scale algae production, e.g. aquaculture, causing their collapse or economic losses. Here, we present ParAquaSeq, a curated database of available molecular ribosomal sequences belonging to zoosporic parasites infecting aquatic vascular plants, macroalgae and photosynthetic microorganisms, i.e. microalgae and cyanobacteria. These sequences are aligned with ancillary data and other information currently available, including details on their hosts, occurrence, culture availability and associated bibliography. The database includes 1131 curated sequences from marine, freshwater and industrial or artificial environments, and belonging to 13 different taxonomic groups, including Chytridiomycota, Oomycota, Phytomyxea, and Syndiniophyceae. The curated database will allow a comprehensive analysis of zoosporic parasites in molecular datasets to answer questions related to their occurrence and distribution in natural communities. Especially through meta‐analysis, the database serves as a valuable tool for developing effective mitigation and sustainable management strategies in the algae biomass industry, but it will also help to identify knowledge gaps for future research.

S of talks presented at ParAqua Conference held in Dubrovnik (Croatia), 16-17 April 2024

Diel Vertical Migration (DVM), a widespread zooplankton behavior in freshwater and marine systems, affects ecological interactions and biogeochemical cycles. In lakes, DVM has mainly been studied in the upper 50 m of the water column. However, based on acoustic and net sampling data collected in Lake Geneva, Switzerland (~ 309 m depth) during summer 2022, we demonstrate that DVM occurs down to ~ 125 m depth daily throughout the summer season. The daily descents terminated at around zenith when the Relative Rate of light Change (RRC) was the lowest, and the late afternoon ascent started when RRC values exceeded −0.005 s⁻¹. DVM migration descent/ascent rates were asymmetric with faster mean upward rates () than downward rates (). Migration rates overall increased as summer progressed, corresponding to the intra‐seasonal increase in RRC. Cyclopoid copepods Cyclops prealpinus abundances correlated with the observed deep DVM and their migration responded to exogenous light cues. These new findings, which can also be expected to be relevant for other deep lakes, indicate that Lake Geneva's DVM greatly exceeds maximum migration depths previously reported for a lake. Thus, it is important to study zooplankton DVM dynamics throughout the entire water column in large, deep lakes since it plays an important role in buffering global climate change effects. Furthermore, it is suggested that present zooplankton DVM sampling protocols in large, deep lakes should be revised accordingly.

One of the biggest challenges in the microalgae industry is the lack of reliable methods to detect and avoid biological contaminants, including parasites, which can affect cell growth and consequently lead to crash of the culture. In recent years, the metabarcoding approach has been widely used to study diversity and distribution of microalgae communities and is also a promising tool for contaminant detection in routine biomonitoring. The aim of this article presents steps of DNA extraction for molecular analysis of microalgae communities.

Freshwater algae exhibit complex dynamics, particularly in meso-oligotrophic lakes with sudden and dramatic increases in algal biomass following long periods of low background concentration. While the fundamental prerequisites for algal blooms, namely light and nutrient availability, are well-known, their specific causation involves an intricate chain of conditions. Here we examine a recent massive Uroglena bloom in Lake Geneva (Switzerland/France). We show that a certain sequence of meteorological conditions triggered this specific algal bloom event: heavy rainfall promoting excessive organic matter and nutrients loading, followed by wind-induced coastal upwelling, and a prolonged period of warm, calm weather. The combination of satellite remote sensing, in-situ measurements, ad-hoc biogeochemical analyses, and three-dimensional modeling proved invaluable in unraveling the complex dynamics of algal blooms highlighting the substantial role of littoral-pelagic connectivities in large low-nutrient lakes. These findings underscore the advantages of state-of-the-art multidisciplinary approaches for an improved understanding of dynamic systems as a whole.