Competition Between Invasive Seagrass and Native Upside‐Down Jellyfish in Caribbean Seagrass Meadows

Abstract

Photo 1. On the Caribbean island of Bonaire, we observed that invasive seagrass Halophila stipulacea often uses bioturbation mounds as start locations to settle and then spread into the native Thalassia testudinum meadow. The bioturbation mounds provide space and light for this plant to succeed in colonizing new habitat. Photo credit: Fee Smulders. Photo 2. On Curacao, we observed that the invasive seagrass may be in competition with native upside-down jellyfish that prefers the same habitat. The author Naomi Slikboer, using SCUBA, is counting the number of invasive Halophila stipulacea shoots and native upside-down jellyfish individuals in control plots in Spanish water bay, Curaçao. Photo credit: Erik Wurz. Photo 3. The native upside-down jellyfish with its photosynthesizing symbionts is swimming through the water column before selecting a space to settle. In the background, the researcher and author Naomi Slikboer is taking pictures of the experimental plot. Photo credit: Erik Wurz. Photo 4. End points of two different plots. (A) After 45 days, plots where no invasive seagrass shoots had started growing throughout the experiment, were often occupied fully by native upside-down jellyfish. (B) When invasive seagrass shoots did start growing into the plot, as was the case for the majority of the plots, upside-down jellyfish were pushed out and only invasive seagrass remained. Photo credit: Naomi Slikboer. Photo 5. The apparent competition between the upside-down jellyfish and invasive seagrass leads to many interesting follow-up questions. Will the outcome always be a single-species equilibrium or can the two species cycle or co-exist on these bioturbation mounds? And how will this impact the patch dynamics in the ecosystem on the landscape scale? Photo credit: Erik Wurz. These photographs illustrate the article “Battle for the mounds: Niche competition between upside-down jellyfish and invasive seagrass” by Fee O. H. Smulders, Naomi Slikboer, Marjolijn J. A. Christianen, and Jan Arie Vonk published in Ecology. https://doi.org/10.1002/ecy.3980