Viral metagenomic investigation of two Caribbean echinoderms, <i>Diadema antillarum</i> (Echinoidea) and <i>Holothuria floridana</i> (Holothuria)

<i>D. antillarum</i> was devoid of viruses typically seen in echinoderms, but <i>H. floridana</i> yielded viral taxa similar to those found in other sea cucumbers, including <i>Pisoniviricetes</i> (Picornaviruses), <i>Ellioviricetes</i> (Bunyaviruses), and <i>Magsaviricetes</i> (Nodaviruses). The lack of viruses detected in <i>D. antillarum</i> may be due to the large amount of host DNA in viral metagenomes, or because viruses are less abundant in <i>D. antillarum</i> tissues when compared to <i>H. floridana</i> tissues. Our results also suggest that RNA amplification approach may influence viral representation in viral metagenomes. While our survey was successful in describing viruses associated with both echinoderms, our results indicate that viruses are less pronounced in <i>D. antillarum</i> than in other echinoderms. These results are important in context of wider investigation on the association between viruses and <i>D. antillarum</i> mass mortalities, since the conventional method used in this study was unsuccessful.