A new member of the Nudiviridae from the Florida stone crab (Menippe mercenaria).

Menippe mercenaria, the Florida stone crab, supports an unconventional fishery across the southern USA and Caribbean that involves claw-removal and the return of de-clawed animals to the sea. We provide pathological, ultrastructural, and genomic detail for a novel hepatopancreatic, nucleus-specific virus - Menippe mercenaria nudivirus (MmNV) - isolated from M. mercenaria, captured during fisheries-independent monitoring. The virus has a genome of 99,336 bp and encodes 84 predicted protein coding genes and shows greatest similarity to Aratus pisonii nudivirus (ApNV) (<60% protein similarity and 31 shared genes of greatest similarity), collected from the Florida Keys, USA. MmNV is a member of the Gammanudivirus genus (Naldaviricetes: Lefavirales: Nudiviridae). Comparisons of virus genome size, preferred host environment, and gene number revealed no clear associations between the viral traits and phylogenetic position. Evolution of the virus alongside the diversification of host taxa, with the potential for host-switching, remain more likely evolutionary pathways.

A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea.

Echinoderm mass mortality events shape marine ecosystems by altering the dynamics among major benthic groups. The sea urchin Diadema antillarum, virtually extirpated in the Caribbean in the early 1980s by an unknown cause, recently experienced another mass mortality beginning in January 2022. We investigated the cause of this mass mortality event through combined molecular biological and veterinary pathologic approaches comparing grossly normal and abnormal animals collected from 23 sites, representing locations that were either affected or unaffected at the time of sampling. Here, we report that a scuticociliate most similar to Philaster apodigitiformis was consistently associated with abnormal urchins at affected sites but was absent from unaffected sites. Experimentally challenging naïve urchins with a Philaster culture isolated from an abnormal, field-collected specimen resulted in gross signs consistent with those of the mortality event. The same ciliate was recovered from treated specimens postmortem, thus fulfilling Koch's postulates for this microorganism. We term this condition D. antillarum scuticociliatosis.

Crustaceans, One Health and the changing ocean.

Crustaceans permeate every habitat on Earth but are especially impactful in the marine environment. They can be small and extremely abundant like the ubiquitous marine copepods found throughout the world's oceans, or large and highly prized by fishermen like spiny lobsters found in tropical and temperate seas, globally. The latter are among the decapod crustaceans, a group which includes crabs, shrimps, and lobsters - those targeted most commonly by fishery and aquaculture industries. Hence, crustaceans are ecologically important, but they are also directly linked to the economic and nutritional health of human populations. To most effectively manage and conserve crustacean populations in the face of a changing ocean environment, whether they are harvested or not, requires a One Health approach that underscores the linkages between crustacean, human, and environmental health. Here, we give an overview of the need, benefits, and challenges to taking the One Health approach to crustacean health and argue that when viewed through the One Health lens, there is perhaps no other group of marine animals more worthy of that perspective.