INVESTIGATING WATER COLUMN FAUNA IN THE MARIANAS

The midwater ecosystem is the largest biome on the planet, and supports a large percentage of the global ocean biomass. Despite this, difficulties in midwater exploration have resulted in a lack of knowledge about the organisms and ecology of this ecosystem. Recent expeditions in the Pacific by NOAA Ocean Exploration have begun to explore the faunal distributions of many water column taxa, including continued characterization of a zone of aggregated midwater fauna known as the deep scattering layer (DSL). In 2016, NOAA Ocean Exploration conducted a series of remotely operated vehicle (ROV) dives in and around the Marianas Trench. Four of these dives included midwater transects, ranging in depths from 275 to 4000 meters. These were the first midwater explorations conducted in the Marianas region. These dives included a deep dive in the trench (between 482 and 4000 m) as well as one dive centered around a hydrothermal vent cloud (between 275 and 408 m). Species annotations of video footage were used to calculate Shannon-Weiner diversity indices and abundance estimates for each of the depth transects. There was no difference in diversity or abundance found between transects in, above, and below the DSL. Low levels of diversity and abundance were found inside a hydrothermal vent cloud. This novel exploration may help further the current scientific understanding of the distribution, diversity, and abundance of deep ocean species in the Marianas region as well as in water column trench environments globally.   

Please direct questions to: immoyer@eckerd.edu

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