This “short film” (30 seconds) takes a peek under the dock at the UC Berkeley research station. Just before I stuck my camera in the water, there was an adorable box fish and other times I’ve seen lots of other fish that seem to like the dock as shelter. The algae that drifts in is mainly Turbinaria and Sargassum brown algae, and the mats come and go quite rapidly, but may act as refuge for juvenile fish, invertebrates, and other algae. I’ve also seen trash get swept in by these mats, so I imagine them as giant brooms sweeping along small critters and debris as they make their way across the water. Unfortunately, it seems to grow on almost every coral head on the nearby reef (the floating stuff had to come from somewhere!), but it is hard to say whether these algae are a cause of coral die-off or if they are simply taking advantage of a vacant space after coral dies of other causes. Luckily, there is active research on this topic and regular monitoring of Turbinaria and Sargassum by the Moorea Coral Reef Long-Term Ecological Research team at the Gump station by UC Santa Barbara and Cal State Northridge scientists. There is also an excellent French research station in the next bay over (Opunohu Bay, we are in Cook’s Bay) called CRIOBE (Centre de Recherches Insulaires et Observatoire de l’Environnement) that has excellent long term reef transect data and has also published studies on the effects of Turbinaria on the coral reefs in Moorea.
These algae that frequently startle me with their abrasive touch while swimming have also caught the attention of some of the students in the UC Berkeley course. For some, it is one factor of many in coral reef diversity studies, but Imari Walker is interested in the communities Turbinaria itself supports and how that community shifts once a mat is washed ashore, leaving the marine for the terrestrial realm. I’m looking forward to seeing what she discovers!