Cultivating epizoic diatoms provides insights into the evolution and ecology of both epibionts and hosts

Abstract

Our understanding of the importance of microbiomes on large aquatic animals—such as whales, sea turtles and manatees—has advanced considerably in recent years. The latest observations indicate that epibiotic diatom communities constitute diverse, polyphyletic, and compositionally stable assemblages that include both putatively obligate epizoic and generalist species. Here, we outline a successful approach to culture putatively obligate epizoic diatoms without their hosts. That some taxa can be cultured independently from their epizoic habitat raises several questions about the nature of the interaction between these animals and their epibionts. This insight allows us to propose further applications and research avenues in this growing area of study. Analyzing the DNA sequences of these cultured strains, we found that several unique diatom taxa have evolved independently to occupy epibiotic habitats. We created a library of reference sequence data for use in metabarcoding surveys of sea turtle and manatee microbiomes that will further facilitate the use of environmental DNA for studying host specificity in epizoic diatoms and the utility of diatoms as indicators of host ecology and health. We encourage the interdisciplinary community working with marine megafauna to consider including diatom sampling and diatom analysis into their routine practices.

A method for bone marrow extraction of diatoms for forensic science applications

“…The true grit method is novel in its procedural attempt to address concerns of contamination during marrow extraction. This procedure combines elements of previous forensic studies [7][8][9] and established diatom preparation protocols in phycology [10,11] to develop a method to extract diatoms from bone marrow that is time-efficient, minimizes contamination risk, and produces samples of intact diatoms from skeletal remains. The true grit method uses new and/or disposable materials to cut bone and extract the marrow.…”

“…Referring to existing bone marrow digestion methods from forensics literature [7][8][9] and methods of diatom isolation in phycology [10,11], this research combines elements of various methods to create an extraction method that is time-efficient, minimizes contamination, and produces samples of intact diatoms. This version of diatom extraction from bone marrow is named the "True Grit Method," by which it will be referred to throughout the paper.…”

Comparison between p‐distance and single‐locus species delimitation models for delineating reproductively tested strains of pennate diatoms (Bacillariophyceae) usingcox1,rbcLandITS

“…Diatoms are one of the most species‐rich eukaryotic algal groups, with an estimated 30,000–100,000 species (Mann & Vanormelingen, 2013). They can be found in many kinds of habitats: marine, freshwater, ice, terrestrial (soils, sand, mosses, rock walls) and can even be found as endosymbionts of dinoflagellates and epibionts of animals and macroalgae (Ashworth et al, 2022; Hehenberger et al, 2016; Mann & Vanormelingen, 2013; Round et al, 1990). The diatoms are also notable among the microalgae in their distinctive morphology; diatoms have a siliceous cell wall (the “frustule”), which can show high levels of morphological variability between taxa.…”