E/V Nautilus: Seamounts of Anegada Passage 2014

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3. E/V Nautilus: Seamounts of Anegada Passage 2014
4. Background
5. Mission Plan

Several unexplored seamounts punctuate the seafloor within the Caribbean Sea, providing records of geologic, biologic, and oceanographic processes.

Seamounts are topographically and oceanographically complex with environmental characteristics (e.g., substrate types, carbon flux, and current patterns) that differ greatly, both within and among seamounts. Variable environmental conditions may influence faunal community structure among seamounts, yet to our knowledge, no studies to date have examined these factors across multiple spatial scales of a seamount chain.

Seamounts have often been suggested to be oases, biodiversity hotspots, islands, and centers for endemism (being unique to a geographic area) in the deep sea. However, many of these hypotheses are only beginning to be explored in detail.

Current Mission

This mission represents an in-depth, multidisciplinary exploration of seamount environments that includes enhanced mapping efforts, remotely operated vehicle (ROV) surveys, discrete biological and geological collections, and ecological studies. The data collected will provide unprecedented insight into the geological origin, spatial distribution, ecology and biodiversity of seamount environments.

This expedition represents the only sampling cruise of the two-year project investigating and exploring seamounts in the Anegada Passage, eastern Caribbean. This project is sponsored by the NOAA Office of Ocean Exploration and Research and the U.S. Geological Survey, in collaboration with several academic institutions.

The Seamounts of Anegada Passage mission will start and end in San Juan, Puerto Rico. Each day will involve a combination of multibeam mapping and sub-bottom profiling, coupled with ROV operations exploring as many as five seamounts. There will be 31 scientists, technicians, and students on the E/V Nautilus, helping support this mission.

During our previous expedition to Noroit Seamount (E/V Nautilus, Oct. 2013), at least 27 putative deep-sea coral species, as well as several sponges, echinoderms, and fishes were documented in the small section of the seamount surveyed. This region may serve as a conduit between Atlantic, Bahamas, Caribbean, and Gulf of Mexico fauna. Exploration of the faunal communities will enhance our understanding of the connectivity among these important regions.

Scientific Objectives

Using the scientific instrumentation on the E/V Nautilus and the dual-bodied ROV system Hercules/Argus, scientific objectives of the expedition include:  

1. Acquire multibeam/sub-bottom data to fill gaps in existing coverage. Collection of new multibeam bathymetry is a critical component of any exploration of the Greater Antilles/Lesser Antilles transition zone. High-resolution multibeam bathymetry data is needed to accurately plan dive targets and to help better identify and characterize seafloor morphology which records the recent geologic (e.g., sediment transport, volcanic activity) and tectonic (e.g., fault-related features) development of the Greater Antilles/Lesser Antilles transition zone. Much of the area has never been surveyed with multibeam sonar and new maps will allow us to track possible additional seamounts to the southeast.
   

   Stichopathes sp. (black corals) are common inhabitants of deep sea environments. Image courtesy of the Ocean Exploration Trust. Download larger version (jpg, 404 KB).

2. Characterize geomorphology and geology (composition, age, emplacement mechanism). ROV exploration at five target seamounts, including Dog, Noroît, Conrad, Shark, and Exocet, will provide the opportunity to observe and sample exposed stratigraphy along tightly defined transects, from the base to the summit, of several poorly known seamounts. These data and observations are critical to the reconstruction of recent geologic and tectonic histories of the region.
   

   Chlorophthalmus agassizi (greeneye fish) is commonly observed resting on soft sediment habitat. On the right is a hexactinellid glass sponge. Image courtesy of the Ocean Exploration Trust. Download larger version (jpg, 1.2 MB).

3. Examine the habitat specificity of the fauna and population dynamics of corals associated with seamount environments. Our surveys will allow us to examine the distribution and abundance of coral species and the degree to which these species depend on habitat features.


Close-up images of gastropods (Phylum Mollusca) such as this are rarely captured in deep sea habitats. Image courtesy of the Ocean Exploration Trust. Download larger version (jpg, 1.3 MB).

4. Characterize the structure and food-web ecology of associated fishes and invertebrate communities. We will explore and characterize the faunal communities associated with seamounts, including deep-sea corals, squat lobsters, and sediment infauna. ROV transects along with targeted collections will improve our understanding of diversities, abundances, and community composition among and within the Greater Antilles/Lesser Antilles seamount chain. Our ultimate goal is to place the surveyed area within a broader biogeographic context and determine the level of connectivity or isolation among several key species comprising seamount communities in this region and beyond.