Barbados Fringing Reefs & Seagrass Beds

Long-spined sea urchin on breakwater in the area of Vauxhall Reef, Barbados,  in 2015

The long-spined sea urchin (Diadema antillarum) is an important herbivore on Caribbean reefs. In 2022, there was a mass die-off of this sea urchin all over the Caribbean, echoing a similar die-off in the early 1980s.

A paper reporting on the identification of the causative agent was published recently: A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea, by Ian Hewson et al. (48 authors in total), SCIENCE ADVANCES 19 Apr 2023, Vol 9, Issue 16. DOI: 10.1126/sciadv.adg3200.

ABSTRACT
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.

UPDATE Feb 16, 2023: SCTLD or White Plague Disease? – we don’t yet know. Based on some discussion I had recently with an authority on this disease, it’s not clear right now whether SCTLD is present in Barbados or whether what we are looking at is an outbreak of WPD (White Plague Disease)…Reviewing my photos to date with reference to descriptions of WPD and SCTLD in Croquer et al., 2021, my interpretation would lean toward WPD rather than SCTLD.However, I  must defer to experts for a definitive ID and as of yet, I am told, there is not enough info. to make  one. Read more

ORIGINAL POST

Records of  Stony Coral Tissue Loss Disease in the Caribbean by year as reported on AGGRA 25Jan2023.

Stony Coral Tissue Loss Disease was first observed off the southeast coast of Florida in 2014 and appeared in the northern Caribbean by 2019. It kills the soft tissues of at least 22 species of corals and has been described as “deadliest coral disease ever recorded” (Wikipedia 25Jan2023).

After reading about this disease in 2018 and the ominous forecasts of what it could do to Caribbean reefs, I kept an eye out for it in the Vauxhall Reef area during my visits in 2018, 2019 and 2020 but saw no sign of it.

In early 2023 we returned to Barbados, Holetown area, after missing a couple of years due to Covid-related issues at home. On January 11, conditions were perfect for snorkelling at the Vauxhall  Reef* and I looked out for infected corals… read more

From Barbados Today, for May 21, 2021

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