Sea cucumbers are valuable coral reef cleaners.
Montana State University’s Department of Microbiology and Cell Biology is studying a partnership that may provide insight into keeping the world’s critical coral reefs healthy. The paper for Nature Communications titled, Removal of detritivore sea cucumbers from reefs increases coral disease, shows that sea cucumbers, which are part of a sediment-cleaning animal group known as detritivores, are key to keeping reef environments clean and help to reduce the spread of pathogens that threaten coral. In short, removal of these cucumbers leads directly to coral reef decline and disease.
What follows is the abstract.
Abstract
Coral reefs are in global decline with coral diseases playing a significant role. This is especially true for Acroporid corals that represent ~25% of all Pacific coral species and generate much of the topographic complexity supporting reef biodiversity. Coral diseases are commonly sediment-associated and could be exacerbated by overharvest of sea cucumber detritivores that clean reef sediments and may suppress microbial pathogens as they feed. Here we show, via field manipulations in both French Polynesia and Palmyra Atoll, that historically overharvested sea cucumbers strongly suppress disease among corals in contact with benthic sediments. Sea cucumber removal increased tissue mortality of Acropora pulchra by ~370% and colony mortality by ~1500%. Additionally, farmerfish that kill Acropora pulchra bases to culture their algal gardens further suppress disease by separating corals from contact with the disease-causing sediment—functioning as mutualists rather than parasites despite killing coral bases. Historic overharvesting of sea cucumbers increases coral disease and threatens the persistence of tropical reefs. Enhancing sea cucumbers may enhance reef resilience by suppressing disease.
