Network modelling of Caribbean long-spined sea urchin die-off and strategies for recovery

Motivation:

The long-spined sea urchin (Diadema antillarum) used to be abundant throughout the Caribbean, until epidemics caused mass-mortality in the 1980’s and in 2022. Because of its role as key herbivore on coral reefs, the decline of D. antillarum populations had major ecological consequences on coral reefs and was a large contributor to their degradation. To aid recovery, reintroduction techniques were developed, which were shown to positively influence reef health. However, the process is labour intensive, and may be negated by future epidemics. As-of-yet, there are large knowledge gaps on the propagation of the disease, and options for control and recovery. This project aims to use various modelling techniques to advise on an optimal strategy for assisted recovery and disease mitigation to help reverse damage to the diverse and important Caribbean coral reef ecosystem.

Aim & objectives/research questions:

• To assess population connectivity among islands through larval dispersal modelling
• To estimate transmission parameters of the pathogen causing the recent die-off
• To assess disease propagation through pathogen transmission modelling
• To advise on population recovery and outbreak mitigation strategies using the gained insights

Methodology:

To answer my research questions I will use a combination of modelling techniques: larval dispersal modelling, network modelling, population modelling and transmission modelling. Through these techniques, I will explore different scenarios for assisted recovery, as well as for the mitigation of future disease outbreaks. I will be providing science-based advice on optimal ways of reintroducing the long-spined seas urchin to the Caribbean, while also making sure the populations are robust to future outbreaks of disease.

More information on sea urchins:

https://www.agrra.org/sea-urchin-die-off/