[A-CG38] Coastal Ecosystems 2. Coral reefs, seagrass and macroalgal beds, and mangroves

[ACG38-P04] Effects of Flows on the Transparent Exopolymer Particle Distribution in a Fringing Coral Reef: Field Observations

*Heng Wu¹, Kota Ishikawa¹, Yosuke Yamada², Akinori Murata¹, Satoshi Mitarai¹ (1.Okinawa Institute of Science and Technology , 2.Geomaterials science research group, Kochi Institute for Core Sample Research, Japanese Agency for Marine-Earth Science and Technology)

Keywords:transparent exopolymer particles , coral, mixing

Transparent exopolymer particles (TEP), a major component in coral mucus, facilitates particle aggregation and the formation of marine snow. The induced aggregations are vital contributors for food webs and carbon cycle in coral reefs and the surrounding marine environments.

While previous research has extensively delved into the organic matter released by reef-building corals, with a particular focus on organiac carbon, coral-derived TEP remains unexplored, despite its potential impact onmarine carbon cycle.

In this study, we conducted month-long measurements of seawater flow and TEP concentration in a coral reef system situated in Okinawa, Japan, during the Summer of 2023. The flow measurements provided valuable insights into the reef circulation patterns, flow characteristics around the coral patch, and the transport of TEP-induced aggregates. Specifically, TEP concentration in the reef system was quantified during spring tides using the seawater samples collected at high tide, low tide, and intermediate stage.

Our observation revealed a decrease in TEP concentration with increasing distance from the shore. However, the trend disappeared on days that the ocean was wavy. The disappearing horizontal TEP concentration gradient may be linked to strong mixing induced by wavy oceanic flows, resulting in a well-mixed lagoon.