Nancy Foster Mission 2015: Life on the Rocks

by Ryan McElroy, Student Intern

Coral reef mapping efforts aboard the NOAA Ship Nancy Foster this past week have been exciting for everyone involved. By night, survey specialists “mow the lawn,” collecting multibeam data they compile into bathymetry images. Geospatial scientists take the data from there and run mathematical analyses that produce products delineating habitats. Just after day breaks, ROV operations begin to ground truth these maps and any echograms collected. Ecologists sit on the edge of their seats watching the live feed and noting, among other things, coral abundance, ground cover, and fish species present. Repeat this process everyday for twelve days, and you’ve got yourself a very robust data set with which a variety of questions can begin to be answered.

As an intern on this cruise, I have been fortunate to experience a bit of everything going on. Deploying the ROV throughout the morning, organizing files, working on maps, learning my reef fish, and tracking the autonomous glider are just a couple highlights. It is fascinating to see all the data get collected and to begin to understand how much prep work, organization, and effort goes into the project from so many different people.

I am midway through undergraduate study of geology. Most of my field experience up to this point had been in the Green Mountains of Vermont, with a little time spent on out Lake Champlain. Getting the opportunity to see some marine geologic features only before discussed in class is amazing. Here are some of my favorites from the trip so far:

The ROV

The ROV sits on the deck of the NOAA ship Nancy Foster before a dive. Credit: Ryan McElroy

The ROV sits on the deck of the NOAA ship Nancy Foster before a dive. Credit: Ryan McElroy

We can visually explore the ocean floor with the remotely operated vehicle all the way down to 300 meters. Off the coast of St. Croix and St. Thomas, this means shallow reef features and shelf breaks.

Rhodaliths

Rhodaliths are small round “rocks” formed from calcium carbonate created by living red algae. Credit: NOAA

Rhodaliths are small round “rocks” formed from calcium carbonate created by living red algae. Credit: NOAA

Rhodaliths are small round “rocks” formed by living red algae. Calcium carbonate secreted by the organisms builds up into balls that cover the ocean floor. Over time, this calcium carbonate can be buried and will contribute to forming limestone that may one day be brought again to the earth’s surface

Coral Reef

A patch of coral reef seen from the camera of the ROV in the U.S. Virgin Islands. Credit: NOAA

A patch of coral reef seen from the camera of the ROV in the U.S. Virgin Islands. Credit: NOAA

Coral reef is a rocky biogenic structure with complex three dimensionality. Hard corals secrete calcium carbonate and attach themselves to a pre-existing hard surface. As each of the tiny polyps in the colony grow and reproduce, so does the rocky home the live on and in. Topography attracts fish of all sizes, as protection and food abound here.

I have seen coral fossils in 400+ million-year-old Vermont limestone!

Furrows

Furrows are a sedimentary bedform formed by the movement of currents. Credit: Ryan McElroy

Furrows are a sedimentary bedform formed by the movement of currents. Credit: Ryan McElroy

Furrows are a sedimentary bedform. Sands and particulates of the seafloor are sorted and distributed by currents. Helical (spiraling) flow along the floor brings finer material up and out of the troughs and deposits it on ridges. The troughs become coarser (heavier pieces remain) while ridges grow ever finer. On the dive where the above image was taken, the troughs were about a half meter deep and nearly one meter across. The ridges continued linearly for tens of meters.

Multibeam Sonar

Multibeam imagery around the south coast of St. Croix. Highlighted features include a slump, underwater canyons, and a seamount. Credit NOAA.

Multibeam imagery around the south coast of St. Croix. Highlighted features include a slump, underwater canyons, and a seamount. Credit NOAA.

In waters deeper than 300 meters, the only way to “see” the ocean floor is with sound. Acoustic beams are sent down under the boat, and based on the time it takes for the beams to return after reflecting off the bottom, a deeper bathymetry map is created.

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Submarine canyons are long, deep incisions in the slope off the shelf break. This canyon, found to the south of St. Croix, had walls as high as 200 meters. Credit: NOAA

Submarine canyons are long, deep incisions in the slope off the shelf break. Conduits for moving sediment out further to sea via turbidity currents, they can extend more than ten kilometers out off the shelf break, dropping about one kilometer over this distance. The canyon walls in the above image measured to 200 meters high at some points. Evidence of canyons and the fans of sediment that accumulate at their base can be found in old sea floor rocks exposed at the current surface. I have seen some of these “turbidite sequences” in Vermont rocks.

This slump, or underwater landslide, found near St. Croix could have been triggered by overburden, earthquake, or active faults. This slump reaches over seven kilometers across. Credit: NOAA

This slump, or underwater landslide, found near St. Croix could have been triggered by overburden, earthquake, or active faults. This slump reaches over seven kilometers across. Credit: NOAA

A slump is an underwater landslide. Slope failure can been triggered by overburden, earthquake, or active faults. This slump seen above is HUGE–over seven kilometers across! The scarp wall starts at a depth of 370 meters. Over 90% of the released material is likely out in deeper water beyond the range of the mapped area (more than 1500 meters down). With sonar lines that can penetrate the ocean floor, core samples, and a lot more time, three-dimensional maps of sediment and bedrock could be made to trace the extent of the debris flow generated by this slump.

A failure this big can trigger tsunamis – massive waves. One of my professors is working on better understanding slumps, what triggers them, and their effects on sea state. He logs data in Lake Champlain and models waves generated by events like this. The main difference is that there everything is scaled down quite a bit!

This sonar image depicts a potential seamount. Seamounts are unusually high points of relief given the gradual slope of surrounding sea floor. Credit: NOAA

This sonar image depicts a potential seamount. Seamounts are unusually high points of relief given the gradual slope of surrounding sea floor. Credit: NOAA

Seamounts are unusually high points of relief given the gradual slope of surrounding sea floor. The image above is a potential seamount,  which measures 195 meters in diameter and rises roughly 60 meters from its base at 880 meters depth. However, we don’t know much beyond that! One possibility is that it is a cone emitting something—possibly gas or mud. Material may be precipitating out and “growing” the cone. If we had passed over while collecting “water column” data with the multibeam, we may have been able to detect emitted material. Unfortunately it is out of range of our ROV, although there are vehicles that could investigate features this deep. Other possibilities could be that this feature is a relic reef or even the remains of an old slump.

It amazes me that even with top of the line technology and brilliant minds at work, there is still so much that we do not yet know about our planet. With every new discovery, more and more questions come up. Years of work could be spent measuring, sampling, and observing these features, but at the end of the day, there’s something wonderful about a mystery. What is so cool to me is that we would never have known these things were down there unless we looked! There is beauty and complexity at every level. For a curious kid like me, it’s great to know I can always learn something new.

 

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Nancy Foster Mission 2015: Multibeam Sonar

Just because the sun has set on the Caribbean horizon and the ROV is put to bed, doesn’t mean work stops on the Nancy Foster. Overnight, another shift of scientists works diligently on mapping the seafloor with the ship’s multibeam sonar. For the purpose of this mission, we use the sonar data in two ways.

Initially, we can determine overall depth and topography of the seafloor, because the multibeam sends out three sound frequencies (hence the “multi”) that reach different depths, and the signals bounce off the bottom and return to the ship. The returning signals essentially paint a picture of the seafloor and its features.

Hydrographer Mike Stecher converts sonar data into imagery. The data collected during the mapping cruise is also used to update NOAA nautical charts. Credit: NOAA

Hydrographer Mike Stecher converts sonar data into imagery. The data collected during the mapping cruise is also used to update NOAA nautical charts. Credit: NOAA

We can also determine the type of seafloor based on the backscatter detected by the sonar. Backscatter is the intensity of sound reflected off different bottoms types, and so we can differentiate between soft, hard, smooth, and rough surfaces. This helps in characterizing whether a swath of seafloor is sand or coral reef.

NOAA acoustic mapping specialist Will Sautter processes and interprets multibeam sonar backscatter. Backscatter is the amount of sound returned from the seafloor and can tell researchers how hard, soft, rough, or smooth the seafloor is. Credit: NOAA

NOAA acoustic mapping specialist Will Sautter processes and interprets multibeam sonar backscatter. Backscatter is the amount of sound returned from the seafloor and can tell researchers how hard, soft, rough, or smooth the seafloor is. Credit: NOAA

Combining these two capabilities allows the scientists to create three-dimensional maps of the seafloor and its distinct habitats. Integrating the data collected each night with GIS analysis generates a basic map of the surveyed areas with lines separating different habitat types. The maps are referenced by the ROV team for choosing their survey paths. Their direct video feed observations confirm the habitat types at each location and contributes to the accuracy of the seafloor maps.

habitat mapping

Bryan Costa, a geospatial scientist, creates a draft habitat map using sonar data collected overnight. During the eight-day mission, researchers deploy a remotely operated vehicle during the daytime and collect sonar data overnight. Credit: NOAA

It’s all in a (literal) full day’s work!

Posted in Areas of Special Biological Significance, Benthic Mapping, Caribbean, Center for Coastal Monitoring and Assessment, Nancy Foster Exploration, National Centers for Coastal Ocean Science | Tagged , , | Leave a comment

Nancy Foster Mission 2015: The ROV

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The ROV allows NOAA scientists to observe the sea floor, coral, and fish remotely. Credit: NOAA

At the beginning of the cruise, we deployed an autonomous glider that requires no physical attention from us until the end of its 20-day solo mission. However, we are using another tool daily that is critical to our research and needs a much more hands-on approach.

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The ROV team of coordinates operations for lifting the ROV into the water. Communication is key. Credit: NOAA

The ROV (remotely operated vehicle) is another machine that lets us explore beneath the waves without actually getting wet ourselves, but this one is tethered to the ship and controlled by the scientists onboard.

The majority of daylight hours on the Nancy Foster are spent readying the ROV for as many dives as possible (usually three or four). It takes three scientists on deck to guide the ROV and tether over the side without crashing or getting tangled and a member of the ship’s crew operating a crane to lift the 365 pound robot and lower it gently into the water below. Another scientist operates the ROV from a control center within the ship’s wet lab.

From that control center, the ROV is sent down towards the sea floor and then flown over vast fields of sandy bottoms and hard coral, which we can see from its HD-capable video feed. We can also take still photographs of interesting features and fish as well.

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The ROV’s tether protects the camera feeds and extends 300 meters. Credit: NOAA.

The video feed is how we can ground-truth (confirm) the seafloor features and bottom cover identified and mapped by the multibeam sonar team. The ROV is also currently the only way we can identify the species of fish that we locate with our fish echosounder (another tool in our box).

Depending on the depth, it can take around 45 minutes just to get the ROV from the ship’s deck to the sea floor (the tether extends    300 meters). The dive will last for an hour or so, and then return to the surface so the ship can navigate to the next site identified for an ROV dive. This process repeats until sunset.

After the ROV is put to bed, the multibeam sonar and mapping team prepare to work through the night.

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ROV technician Jason White (left) and NOAA oceanographer Tim Battista (right) monitor the ROV’s location and video feeds. Credit: NOAA

Posted in Center for Coastal Fisheries and Habitat Research, Center for Coastal Monitoring and Assessment | Tagged , , | Leave a comment

Nancy Foster Mission 2015: The Glider

glider1

The autonomous ocean glider sits on the deck of the Nancy Foster, prior to its launch for a 20-day mission around St. Croix. Credit: NOAA.

March 28 was day one on board the NOAA ship Nancy Foster, and we were already diving right into the science. After leaving the Crown Bay Marina in St. Thomas, we took a four hour transit to the south of St. Croix—the launch point for our glider.

With the support of the ship’s crew and some heavy machinery, the glider—looking very much like a yellow torpedo—was carefully lowered into the ocean swells off the aft deck (ship lingo for back end). After a few harrowing moments when a few waves nearly crashed the glider against the ship’s side, the glider released and slowly floated away before disappearing beneath the surface, marking the beginning of a 20-day solo mission around the island of St. Croix. Now completely independent from the ship’s activities, the glider will continue collecting environmental data from a variety of sensors, including water temperature, depth, and salinity; and acoustic recordings of fish and other marine life it may come across.

glider2glider3NOAA scientists launch the glider off the aft deck of the Nancy Foster. Credit: NOAA.

The glider sends NOAA scientist Chris Taylor updates via email every time it surfaces throughout its journey, but the acoustic data will only be accessible once the glider is retrieved. In the meantime, we return our attentions to operating multibeam sonar and deploying an ROV throughout the rest of the research expedition, and hope the glider will successfully complete its mission.

GliderTrack_03292015

The glider’s path as of the afternoon of March 29. Each green pin represents a time when the glider surfaced. The yellow glider symbol is just a representation, and not to scale. Credit: NOAA.

Posted in Center for Coastal Fisheries and Habitat Research | Tagged , , , , | 1 Comment

2015 Nancy Foster Mission: 12 years of habitat mapping in the Caribbean

nancyfosterje

The NOAA ship Nancy Foster embarks on its 12th seafloor mapping mission in the Caribbean on March 28 from Charlotte Amalie, Saint Thomas, USVI. Credit: NOAA

March 28th marks the beginning of the latest Caribbean Seafloor Mapping Mission on board the NOAA ship Nancy Foster. With nearly 3,430 square kilometers (1,324 square miles) mapped since 2004, scientists from the National Centers for Coastal Ocean Science and their partners continue exploring the waters surrounding Puerto Rico and the U.S. Virgin Islands, identifying and mapping critical coral reef and fisheries habitat with SONAR and video observations. Starting in 2008, fish acoustics surveys were added to the repertoire to map the actual location of fish throughout the water column.

map plan

Planned project areas for the 2015 mission around St. Thomas and St. Croix (red diagonals, click to enlarge). Credit: NOAA

This year, fourteen researchers and support staff will combine methods of multibeam and fish sonar with video captured from an ROV (remotely operated vehicle) and environmental data collected from an autonomous glider for the duration of the eleven-day cruise around the islands of St. Croix and St. Thomas. Integrating these mapping and observation activities gives the scientists a more complete picture of these ecosystems, and they can actually visualize how fish are distributed around bottom features across the entire region.

The USVI are home to a historic and extensive fishery, but overfishing throughout the 1970s and 1980s left numerous stocks of once abundant fish depleted—particularly, the Nassau Grouper (Epinephelus straitus), the Red Hind Grouper (Epinephelus guttatus), and Mutton Snapper (Lutjanus analis). All three fish species are known for forming spawning aggregations that are predictably exploited by fishers, leading to decreases in reproductive output and total collapse of the fishery. To prevent the collapse of fisheries, seasonal closures and catch regulations were quickly established within various Marine Conservation Districts (MCDs) in the 1990s and aid fisheries recovery. Fishing with pots, traps, bottom longlines, gill nets, or trammel nets is prohibited year-round in these MCDs. Continued monitoring and research will allow for greater optimization of MCD boundaries and seasonal closures, thereby aiding both the fish and fishers.

hind

Red hind grouper. Credit: NOAA

muttonhead aggregations

A muttonhead snapper aggregation. Credit: NOAA

The data gathered from these annual missions are used to generate maps for use by local policy makers to determine the best approach for managing and protecting these important habitats and the marine species that live here, as well as supporting future research initiatives.

Not only do these missions support future environmental management decisions, but the imagery and video feeds can capture some pretty fascinating undersea life–from grouper and snapper and brightly colored triggerfish to playful dolphins, roaming sharks, and curious sea turtles, not to mention the coral formations and diversity of marine invertebrates.

eagle ray

Spotted eagle ray. Credit: NOAA

horse eye jacks

A school of horse eye jacks. Credit: NOAA

scrawled file fish

Scrawled file fish. Credit: NOAA

tubes sponge

Tube sponges. Credit: NOAA

scorpion fish

Half-hidden scorpion fish. Credit: NOAA

Stay tuned for future updates from the field as we set sail from March 28th through April 7th!

For more information visit the Mission Web Portal!

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There is No HAB-cyst Cruise without the CREW: Reflections

Team

NOAA’s HAB-cyst sampling cruise science team on the Okeanos from left to right: Dennis Apeti (NOAA), Kali Horn (WHOI), Blaine West (NOAA), Lindsay Peter (WHOI), Steve Kibler (NOAA), Jennifer Maucher (NOAA), Terry McTigue (NOAA), Leslie Irwin (NOAA), John Wickham (NOAA), Chris Alex (NOAA), Andrew Meredith (NOAA), and Bruce Keafer (WHOI). Credit, NOAA.

After nine days at sea in the Gulf of Maine, our team of NOAA and WHOI scientists successfully completed our Alexandrium cyst collection cruise. We took sediment core samples from over 80 sites and processed them for future counts of cyst abundance, to support next season’s harmful algal bloom (HAB) forecast. The twelve scientists gave plenty of ‘mud, sweat, and tears’ to make sure science was happening around the clock.

IMG_7224 Kelson and John guide corer back on deck - Oct 17 2014 - Chris' photo

The NOAA Okeanos Explorer crew operate the crane to guide the corer back on deck. Credit, NOAA.

But we can’t take all the credit. Not even close.

The crew of NOAA’s Okeanos Explorer was exceptional–welcoming, helpful, knowledgeable, friendly, and constantly going beyond the call of duty to support our research.

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Junior Officer Sean Luis navigates the Okeanos’ course from the bridge. Credit, NOAA.

IMG_7112 Bruce, C.O. Ramos, Emily consult on route - Oct 14 2014 -ris' photo

WHOI’s Bruce Keafer (left) discusses navigation strategy with Okeanos Captain Ricardo Ramos and Operations Officer Emily Rose. Credit, NOAA.

The crew is constantly making sure the ship and its equipment are functioning safely and effectively. They were also working around the clock, operating the crane that lifts our Craib Corer over the side and lowers it to the sea floor. The crew ensures other instruments and monitoring equipment reported data accurately, like wind speed and sea depth, that we needed to include with observations. The crew navigates and guides the ship to each of our requested sites.

IMG_7187 Tyler waits to operate crane during a 30 min (15 to bridge) repositioning manuveur- Oct 16 2014  - Chris' photo

Okeanos’ Chief Boatswain Tyler Scheff oversees operations on deck.

Joao Alves waits cheerfully on deck for the Craib corer to surface. Credit, NOAA.

Joao Alves waits cheerfully on deck for the Craib corer to surface. Credit, NOAA.

The crew makes sure we are well fed and entertained. We enjoyed three home-cooked meals, and were even treated to a night of ice cream and a night-time viewing of Jurassic Park if you weren’t in the middle of a shift. We toured the ship’s (very loud) engine room.

IMG_7305 fancy garnishes Rainier made - Oct 19 2014 - Chris' photo

The cooks on the Okeanos knew how to get creative at meal time. Credit, NOAA.

As a special treat, when we returned to dock in Rhode Island, we got to visit the NOAA hangar with the underwater remotely operated vehicles (ROVs) that are often deployed to support exploratory and biogeography expeditions of deep sea habitats.

For nine days we lived and worked beside the crew like a well-oiled machine, but as we leave them behind, they will move on to their next supporting research adventure. We can hardly begin to thank them enough for everything.

There are so many facets to the research, the equipment, and the people necessary for a successful research cruise, and hopefully that reality was captured in the earlier three posts featuring what it takes to prepare, what science is conducted, and what the science supports from this HAB-cyst sampling cruise.

A pod of pilot whales investigated the Okeanos while we were stopped at a sampling site. Credit, NOAA.

A pod of pilot whales investigated the Okeanos while we were stopped at a sampling site. Credit, NOAA.

Now the scientists will continue sample analysis back in their labs on lab and develop the 2015 HAB forecast for the Gulf of Maine, and start planning next year’s sampling cruise!

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‘What’s Cyst’ All About? Days 5-6 of HAB-Cyst Sampling

So there’s been a lot of talk about collecting sediment from the sea floor for processing and future analyses, but we haven’t explained the full importance of what NOAA’s scientists are actually after–the cysts!

cyst to bloom

The lifecycle of the HAB species Alexandrium fundyense, from cyst to blooming vegetative cells. Credit WHOI.

We’ve mentioned that they come from the harmful algal bloom (HAB) species Alexandrium fundyense, and that they are important for developing the next year’s HAB forecast, but not how we get there.

Alexandrium has two life stages. During a red tide HAB event, Alexandrium is found near the water’s surface in its vegetative state, which produces saxitoxin. This is the culprit with the potential to affect economically important shellfish fisheries and cause paralytic shellfish poisoning (PSP) when people consume the contaminated shellfish. 

IMG_7120 Dennis and Andrew process top 1 cm core slice into syringes - Oct 15 2014 - Chris' photo

NOAA’s Dennis Apeti (left) and Andrew Meredith (right) take samples from sediment core slices. Credit NOAA.

IMG_7121 Chris and Andrew processes 1 - 3 cm core slice into syringes - Oct 15 2014 - Chris' photo

NOAA’s Chris Alex (foreground) and Andrew Meredith wash sediment samples. Credit NOAA.

IMG_7173 Jen sieves cysts into 20 ml sieve - Oct 16 2014 - Chris' photo

NOAA’s Jennifer Maucher and Blaine West filter the samples to isolate Alexandrium cysts. Credit NOAA.

In the Gulf of Maine, HAB events begin in the spring and continue throughout the summer. As the bloom dies off, Alexandrium leaves behind seed-like cysts that fall through the water column and remain dormant on the sea floor until they germinate into the following spring bloom. By conducting NOAA’s cyst-sampling cruise in October, we’ve ensured that all of the cysts from the previous spring and summer blooms have settled, and will primarily be concentrated in the first three centimeters of the sediment surface.

Due to environmental factors like winds, ocean currents, and storms, the cysts won’t settle directly below the bloom that formed them, which explains why NOAA samples the entire Gulf of Maine and not just where we detected the blooms.

PA150004 Jen and Steve at the microscope doing live count - Oct 15 2014 - Terry's photo

NOAA’s Steve Kibler searches for Alexandrium cysts under the microscope from one of this cruise’s site samples. Credit NOAA.

ST54 cyst scope pic

An Alexandrium cyst (center) found in a sample from this years’ cruise during microscope counts on board the Okeanos. Credit NOAA.

At the completion of the cruise, the processed sediment samples from each site are prepared for viewing on a slide under a microscope, to count observed cysts. Once the cyst counts are completed for every station, the numbers are incorporated into NOAA’s HAB forecasting model. This model relies on nutrient, salinity, temperature, and the extent of the most recent HAB event along with other environmental factors to predict the concentration, severity, and movements of the future HAB season. NOAA will also deploy a suite of environmental sensors during the actual HAB events to determine the accuracy of the forecast and identify where improvements can be made in the model.

GoM forecast

A map of Alexandrium cyst counts based on the 2011 sampling cruise. Credit WHOI.

These forecasts provide critical insight into the potential threat of saxitoxin in the region, and informs decisions for shellfish fishery closures to prevent PSP. In the past year, NOAA’s HAB forecast and monitoring in the Gulf of Maine has allowed the reopening of some fisheries, including the lucrative clambeds of Georges Bank, which were closed for several decades before.

The forecast for the Gulf of Maine is in development, and is part of NOAA’s role in supporting ecological forecasting services       throughout the nation. NOAA’s HAB forecasts are found in either the developmental or operational stages for Florida, Texas, the Gulf of Mexico, the Chespeake Bay, the Delaware Bay, the Great Lakes, and the Pacific Northwest.

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