The role of recruitment success in community dynamics is particularly striking on Caribbean reefs, where scleractinian coral populations have declined due to local human stressors (e.g., overfishing, pollution, poor water quality) and increasing global climatic events (e.g., bleaching and hurricanes). Those stresses have impacted critical ecological processes such as survivorship, growth, reproduction, settlement, and recruitment. However, the reported changes have been biased towards scleractinians. Octocorals or soft corals have been increasing in abundance, likely due to improved recruitment. I'm currently studying this dynamic; why are octocorals increasing while scleractinians are decreasing? We use time-series analyses and hypothesis-testing to determine the factors that are affecting octocoral abundance.
Adult and recruit field censuses
We've been monitoring octocoral abundance and sizes for the past seven years on the south shore of St. John, US Virgin Islands. Our dataset has captured several major hurricanes (Irma and Maria) and their resulting damage. With these data, we generate hypotheses to test with experiments.
The impact of algal turf on octocoral recruitment
Algal turfs negatively affect survival of octocorals (paper #7), but the mechanism for why is still poorly understood. One hypothesis is that turfs harbor a myriad of octocoral settler predators. We're currently testing this hypothesis by comparing the survival of settlers on heavily turfed tiles, some of which have had all invertebrates removed.
PC: Kaitlyn Tonra
Urchin barrens: are they a good place to settle?
Octocorals initially increased when the Caribbean long-spined sea urchin died in the early 1980's. Is that because urchins were no longer consuming baby corals or is there an indirect effect we are missing? Currently, we're testing this hypothesis with field experiments, comparing settlement of corals on caged settlement tiles with urchins to cages without urchins.
Development and settlement preferences of octocorals
When do octocorals spawn? How long does it take for an embryo to develop into a larva? What is their preferred substratum and how is that substratum oriented? These are some of a few questions we're answering with the Caribbean octocorals Plexaura homomalla, Plexaura kuekenthali, and Eunicea flexuosa. We have described the development of Plexaura homomalla, which seemed to have some polyembryonic development (pub #6). We have also observed a last-ditch method for surviving a stressful event - polyp bailout - where polyps jump out of the colony, reattach, and create new colonies in less stressful environments (paper #5).
40 years of Puerto Rican octocorals
How have Puerto Rican octocoral communities changed over 40 years? Are there similar patterns in the Virgin Islands? How does scale affect these analyses? We are analyzing a major dataset to answer these questions. The dataset includes the settlement, life, and death of over 16,200 colonies on two Puerto Rican reefs. It's an amazingly deep dataset collected by Beverly Yoshioka and the late Paul Yoshioka.