Partners or passengers? Revisiting the association between diatoms and aquatic animals
- 1Department of Life Sciences and Systems Biology (DBIOS) University of Turin Via Accademia Albertina, 13 Turin 10123 Italy
- 2Alpstream Research Centre Frazione Sant'Antonio, 17 Ostana 12030 Cuneo Italy
Abstract
Numerous studies have revealed the importance of research on the communities capable of colonizing animal surfaces (epibionts) and the animals on which they live (basibionts). Very few studies have considered epizoic diatoms, and there are gaps and biases in our knowledge, including the choice of basibionts, the methods used, and the habitats in which they live. This literature review aims to (i) identify the main basibionts that host diatom communities and the diatom taxa associated with them, in both marine and freshwater environments; (ii) explore the key ecological factors shaping these diatom assemblages; and (iii) reassess critically the commonly applied concept of commensalism in epibiont–host relationships. Our literature review revealed that most research has been focused on charismatic basibiont groups, especially Chordata (notably Testudines and Cetacea), followed by Arthropoda and Mollusca, while taxa such as Bryozoa, Porifera, Cnidaria, Echinodermata, and Annelida have received far less attention. Most studies were carried out in marine settings, particularly in the Americas, and the number of publications has increased since the early 2000s. Taxonomic data on diatom communities shows that the genera Navicula, Nitzschia, Cocconeis and Amphora are the most frequently found as epizoic diatoms. In some cases, highly host‐specific diatoms have been documented, for example Pseudohimantidium pacificum, Protoraphis atlantica, Falcula hyalina, and Sceptronema orientale on copepods. From a functional point of view, ‘motile’ diatoms were dominant on Chordata, Mollusca, and Arthropoda, followed by the ‘high‐profile’ ecological guild. This dominance suggests active interaction between the organisms, supporting the development of well‐structured communities on the hosts. There are several types of interaction, depending on the host and epibiont considered. We propose the concepts of triggers and drivers as a framework to describe the initial diversity and development of the epibiont community on the host, and we interpret the nature of these relationships as falling along a continuum from commensalism to parasitism and mutualism. Although diatoms are considered valuable tools for environmental monitoring, we suggest that host displacement and interactions with substrates may be considered as limiting factors for the use of epizoic diatoms in environmental monitoring. However, they may provide useful insights into host ecology, such as the range of host displacement and habits, feeding behaviour, and ecological traits, helping to clarify the trophic and behavioural interactions among basibionts and epibionts. This integrative perspective enhances our understanding of both diatom dispersal and their ecological tolerance and adaptability across diverse environmental contexts.
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BibTeX
@article{vacca2026partners,
title = {{Partners or passengers? Revisiting the association between diatoms and aquatic animals}},
author = {Gianluca Vacca and Elisa Falasco and Francesca Bona},
journal = {Biological Reviews of the Cambridge Philosophical Society},
year = {2026},
month = jun,
doi = {10.1002/brv.70191},
url = {https://doi.org/10.1002/brv.70191},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Partners or passengers? Revisiting the association between diatoms and aquatic animals
AU - Gianluca Vacca
AU - Elisa Falasco
AU - Francesca Bona
PY - 2026
DA - 2026/06/05
JO - Biological Reviews of the Cambridge Philosophical Society
DO - 10.1002/brv.70191
UR - https://doi.org/10.1002/brv.70191
AB - Numerous studies have revealed the importance of research on the communities capable of colonizing animal surfaces (epibionts) and the animals on which they live (basibionts). Very few studies have considered epizoic diatoms, and there are gaps and biases in our knowledge, including the choice of basibionts, the methods used, and the habitats in which they live. This literature review aims to (i) identify the main basibionts that host diatom communities and the diatom taxa associated with them, in both marine and freshwater environments; (ii) explore the key ecological factors shaping these diatom assemblages; and (iii) reassess critically the commonly applied concept of commensalism in epibiont–host relationships. Our literature review revealed that most research has been focused on charismatic basibiont groups, especially Chordata (notably Testudines and Cetacea), followed by Arthropoda and Mollusca, while taxa such as Bryozoa, Porifera, Cnidaria, Echinodermata, and Annelida have received far less attention. Most studies were carried out in marine settings, particularly in the Americas, and the number of publications has increased since the early 2000s. Taxonomic data on diatom communities shows that the genera Navicula, Nitzschia, Cocconeis and Amphora are the most frequently found as epizoic diatoms. In some cases, highly host‐specific diatoms have been documented, for example Pseudohimantidium pacificum, Protoraphis atlantica, Falcula hyalina, and Sceptronema orientale on copepods. From a functional point of view, ‘motile’ diatoms were dominant on Chordata, Mollusca, and Arthropoda, followed by the ‘high‐profile’ ecological guild. This dominance suggests active interaction between the organisms, supporting the development of well‐structured communities on the hosts. There are several types of interaction, depending on the host and epibiont considered. We propose the concepts of triggers and drivers as a framework to describe the initial diversity and development of the epibiont community on the host, and we interpret the nature of these relationships as falling along a continuum from commensalism to parasitism and mutualism. Although diatoms are considered valuable tools for environmental monitoring, we suggest that host displacement and interactions with substrates may be considered as limiting factors for the use of epizoic diatoms in environmental monitoring. However, they may provide useful insights into host ecology, such as the range of host displacement and habits, feeding behaviour, and ecological traits, helping to clarify the trophic and behavioural interactions among basibionts and epibionts. This integrative perspective enhances our understanding of both diatom dispersal and their ecological tolerance and adaptability across diverse environmental contexts.
SN - 1464-7931
SN - 1469-185X
ER -