Deep-Sea Symphony: Exploring the Musicians Seamounts





The High Notes

The landscape views at a number of seamount summits visited in the Musicians Seamounts.

The landscape views at a number of seamount summits visited in the Musicians Seamounts were similar to this one. Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download larger version (1.6 MB).

September 24, 2017

Kasey Cantwell
NOAA Office of Ocean Exploration and Research

Today was our last dive in the Musicians Seamounts during the Deep-Sea Symphony expedition. We have had two amazing weeks conducting the first-ever remotely operated vehicle (ROV) exploration in this region. One of the main objectives of this cruise was to locate, map, and characterize deep-sea coral and sponge habitats.

Prior to this cruise, there was no documentation of these high-density communities in the Musicians Seamounts and now we have found over a dozen! Data collected during this expedition will be used by scientists for years to come as they conduct future work in this area and continue to explore how these habitats are connected to each other and to the Hawaiian Islands.

We’ve also completed other objectives for this cruise. We conducted the first-ever midwater exploration in the Musicians Seamounts with two full days of ROV exploration and four rounds of midwater transects at the conclusion of our benthic dives and collected valuable EK60 sonar data about biomass in the water column every evening. All of this helps us better understand one of the least explored biomes on the planet. Overnight operations not only provided information about life in the midwater, but revealed new features as we expanded bathymetry coverage from the Okeanos Explorer mapping cruise to the Musicians Seamounts.

While we have five remaining dive sites close to Hawaii and haven’t quite reached the finale of our expedition, we have reached the end of our Musicians Seamounts stanza.

As we leave an operating area, it is always fun to take a look back at some of the highlights of what we have seen. Below are some of my favorites!

 

At a couple different sites, like Liszt Seamount and Beethoven Ridge, mushroom corals, like these Anthomastus, were common.

At a couple different sites, like Liszt Seamount and Beethoven Ridge, mushroom corals, like these Anthomastus, were common. Click image for credit and larger view.

Dandelion siphonophore,  the one observed at Gounod Seamount, are always a treat to see.

Dandelion siphonophores, like this one observed at Gounod Seamount, are always a treat to see. Click image for credit and larger view.

 

It is always exciting to see small, young corals in high density, like we saw at Rapano Ridge, as it is an indication of healthy populations. Over the next hundreds of years, this community will grow and change, and potentially end up looking like one of the communities of large corals we observed upslope on this dive.

It is always exciting to see small, young corals in high density, like we saw at Rapano Ridge, as it is an indication of healthy populations. Over the next hundreds of years, this community will grow and change and potentially end up looking like one of the communities of large corals we observed upslope on this dive. Click image for credit and larger view.

Rock samples can tell us a lot about the geologic origin of the seamount or ridge it was collected from. They can help us figure out how the feature fits in with the puzzle of the Musicians Seamounts. We can also use information about age and composition to see how this region fits with the rest of the seafloor of the Pacific.

Rock samples can tell us a lot about the geologic origin of the seamount or ridge they were collected from and can help us figure out how a feature fits in with the puzzle of the Musicians Seamounts. We can also use information about rock age and composition to see how this region fits with the rest of the seafloor of the Pacific. Click image for credit and larger view.

 

So far during the expedition, we have had several “bonus” observations of water column fauna, like this jellyfish  observed at Sibelius Seamount.

So far during the expedition, we have had several “bonus” observations of water column fauna, like this jellyfish observed at Sibelius Seamount. Click image for credit and larger view.

One of the most abundant vertebrates on earth, Cyclothones was a common fauna observed during our midwater exploration in the Musicians Seamounts.

One of the most abundant vertebrates on earth, Cyclothones were a common fauna observed during our midwater exploration in the Musicians Seamounts. Click image for credit and larger view.

 

Due to the challenges of working in the deep sea, we don’t often have the opportunity to observe life history events. These two sea elephants were spotted on during our second full day of water column exploration. Our science team was unsure whether this pair was mating or if we were witnessing one predating upon the other, or something else entirely.

Due to the challenges of working in the deep sea, we don’t often have the opportunity to observe life history events. These two sea elephants were spotted on during our second full day of water column exploration. Our science team was unsure whether this pair was mating, or if we were witnessing one predating upon the other, or something else entirely. Click image for credit and larger view.

Observations of predation in the deep sea are often rare and always exciting for our team. However, on nearly every dive we observed at least one sea star predating upon coral. Here a Hippasteria sea star has engulfed a branch of Primnoid coral while it digests the coral’s flesh.

Observations of predation in the deep sea are often rare and always exciting for our team. However, on nearly every dive in the Musicians Seamounts, we observed at least one sea star predating upon coral. Here, a Hippasteria sea star has engulfed a branch of Primnoid coral while it digests the coral’s flesh. Click image for credit and larger view.

 

During our ROV dives in the Musicians Seamounts we observed multiple instances of this once-thought-to-be rare jellyfish predating upon a coral. Here, the jellyfish are eating Iridogorgia polyps at Liszt Seamount.

During our ROV dives in the Musicians Seamounts, we observed multiple instances of this once-thought-to-be rare jellyfish predating upon a coral. Here, the jellyfish are eating Iridogorgia polyps at Liszt Seamount. Click image for credit and larger view.

This new species of sponge has only ever been seen twice before in the Northwest Hawaiian Islands. To see it here in the Musicians Seamounts at Schumann Seamount indicates a connection between the two regions.

This new species of sponge has only ever been seen twice before in the Northwest Hawaiian Islands. To see it here in the Musicians Seamounts at Schumann Seamount indicates a connection between the two regions. Click image for credit and larger view.

 

A sea spider feeds on an anemone that had colonized a bamboo coral branch at Shostakovich Seamount.

A sea spider feeds on an anemone that had colonized a bamboo coral branch at Shostakovich Seamount. Click image for credit and larger view.

ROV Deep Discoverer explores the edge of a sharp ridge feature at Mozart Seamount.

ROV Deep Discoverer explores the edge of a sharp ridge feature at Mozart Seamount. Click image for credit and larger view.

 

Deep sea corals and sponges provide habitat to a number of organisms. Using ROV Deep Discoverer’s high definition cameras, we are able to see even the smallest associates, like this squat lobster on a Chyrsogorgia colony.

Deep-sea corals and sponges provide habitat to a number of organisms. Using ROV Deep Discoverer’s high-definition cameras, we are able to see even the smallest associates, like this squat lobster on a Chyrsogorgia colony. Click image for credit and larger view.

Everyone loves a good squat lobster! This potentially new species was observed on a black coral at Liszt Seamount.

Everyone loves a good squat lobster! This potentially new species was observed on a black coral at Liszt Seamount. Click image for credit and larger view.

 

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