Zooplankton fecal pellets as the primary driver of settling particles in reef systems

Zooplankton fecal pellets are a potentially vital source of nutrients for coral reefs. While zooplankton fecal pellets are recycled relatively quickly in pelagic systems, the shallow nature of reefs means more organic matter from the surface can reach the benthos. Fecal pellets can aggregate together and entrain additional organic matter, aiding in the transference of organic material to reefs. These settling particles can be ingested by coral to supplement their diet and nutrients obtained by their symbiotic algae (zooxanthellae) as coral are known to ingest sediment. Settling particles can provide essential fatty acids to coral reefs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which are produced by phytoplankton and repackaged by zooplankton. Through lipid and stable isotope analysis, zooplankton were determined to be primary driver of settling particles in the Upper Florida Keys. Zooplankton fecal pellets most likely help to create a homogenous composition of organic material. As the primary drivers of settling particle composition, zooplankton abundance and composition play a vital role in determining the availability of organic matter and settling particles on coral reefs.