Reef assessment and habitat mapping in the Marianas

Safety training

The scientists spent a day on board the Rainier to do some safety drills. Here, scientists practice helping launch and recover the small boats that will carry them to do their dive surveys. Safety first! Photo: NOAA Fisheries

Charging the seas!

The ocean and climate change scientists head to their survey sites on the first day of dive operations off the northwest coast of Guam. Photo: NOAA Fisheries.

Small boat recovery

One of the small boats returns to the ship after a day of dive operations. Specialized cranes safely raise the boat filled with gear and personnel. Photo: NOAA Fisheries

SfM in Action!

The ocean and climate change team conducts a structure-from-Motion (SfM) survey at one of their long-term monitoring sites. They take about 2,000 images in a spiral formation that is later processed into an accurate 3-D model of the reef. We can use these models to examine the benthic ecosystem and habitat structure.

Finding Nemo

The fish team stumbled upon an anemonefish during one of their dives. An exciting sight to see for our team of divers from Hawai'i as these fish have not been found there.

Anchor's (not) Aweigh!

Fisheries scientists find an anchor at one of their survey sites! Maritime artifacts like this anchor are common in the Mariana Islands due to the islands' strong historic military presence, especially during World Wars I & II.

Ocean chemistry

The ocean and climate change scientists prepare an instrument package that will detect changes in ocean chemistry and environmental parameters over time by measuring water temperature, depth, currents, pH, dissolved oxygen, and light. The team will carefully lower the package over the side of the boat and deploy it on the seafloor adjacent to the reef. They will return to this location to retrieve the package later in the mission. Photo: NOAA Fisheries.

Cool cartilaginous fishes!

Our team of fish divers saw a round ribbontail ray (Taeniura meyeni) swim through their survey. Our divers identify, measure, and count all fish within their survey area, including sharks and rays!

All good in Aguijan

A school of surgeonfish swims through a survey dive in Aguijan. Pictured here are Acanuthurus nigricans, Ctenochaetus spp., and Homo (scuba!) sapien.

Colossal coral!

An excited diver from our fish team swims over a large mounding coral (Porites lutea) in Windward Guam.

Benthic Leg Underway

A tug boat escorts the Rainier out of the Guam Navy Base in the Apra Harbor. The benthic leg has officially started!

Awaiting the Mother Ship

Scientists happily await a small boat pick up after a successful day of diving operations. They took images and surveyed coral biodiversity and conditions within Guam's Pati Point Marine Preserve.

Splash divers!

A benthic diver plunges into the sea for another coral reef assessment around the beautiful Puntan dos Amantes on the west coast of Guam.

Counting Corals

A benthic diver carefully assesses and identifies coral along a transect in Guam. In the foreground, diverse coral colonies display different colors and morphologies, including a brightly colored branching Acropora.

Next stop Tinian

A beautiful early morning view of Aguijan Island while we are underway to Tinian—our next coral reef assessment area.

Safety first!

Every morning, scientists and crew members gather on the Rainier fantail to discuss the day's boating and diving operations. Everyone is equipped with sun protection for a long day on the water, as well as life jackets and hard hats for craning small boats into the water.

Poisonous Spines

Close-up of the crown-of-thorns seastar's poisonous spines that protect its body. These animals feed on coral tissue—too many of them can destroy an entire reef. In low numbers, however, impacts are minimal. Crown-of-thorns are one of the largest seastar species and can have more than 20 arms!

Get Ready for your Close-up!

A well-camouflaged blue-eyed coral crab (Cymo quadrilobatus) living within the branches of an antler coral (Pocillopora grandis). Stony corals provide housing, food, and shelter for many animals, including fish, shrimps, crabs, bristlestars, seaslugs, and amphipods. Crabs provide cleaning services for the corals in return for shelter, making this a mutualistic symbiotic relationship.

Pagan reef

Scientists identify and measure coral colonies along a transect. They also note predation from crown-of-thorns seastars, one of which is under the diver in the foreground. This seastar has eaten the tissue from the coral colony, leaving behind a stark white patch.

Corals rock the reef

A massive and truly majestic cathedral-like structure - built by colonies of Porites rus corals - rises from a submerged volcanic caldera in the Maug Islands. Corals construct modules of various sizes as they grow and compete for space -- creating homes for a variety of organisms. As keystone species, corals are responsible for the maintenance and resilience of the ecosystem's biological diversity.

Inside the caldera

The Maug Islands' submerged volcano and caldera environments are more acidic than other regions of the ocean. Many people study the corals here to understand how they flourish in such harsh surroundings. Here we see a portion of the massive Porites rus coral colony unexpectedly thriving near a carbon dioxide vent.

Life strategies

Corals have a high diversity of intricate and beautiful surface structural arrangements that determine how they interact with the environment. Surface roughness can modulate water flow and determine how efficiently corals rid themselves of waste, capture food, photosynthesize, and exchange gasses. Here is a montage of the coral species we have encountered during our surveys.

Underwater chat on coral taxonomy

Divers 'discuss' coral taxononmy by writing on their slates to communicate. Scientists use special paper that doesn't tear when it is wet so that they can take notes while underwater.

Coral on coral on coral built rock

Branching colonies of Pocillopora corals grow over the massive structure built by Porites corals. The Porites also grow over the reef foundation created by corals of the past. Some branching corals grow fast and tall, extending their fragile structure along the substrate. These branching colonies receive more light and capture more resources in the water column. On the other hand, massive corals grow more slowly, but can potentially withstand storms, live longer, and create a legacy of reef structure for future corals to grow upon.

Benthic Leg Inport

The benthic leg of our cruise is officially complete, having successfully met all of our surveying goals. Here is our farewell with gratitude note to all the NOAA Ship Rainier and small boat fleet crew members for the vital support they provided.

In port training day

The fish team took full advantage of the day in port by brushing up on their fish ID skills by going out for a training snorkel survey. Here a Valentin's sharpnose puffer, or (black) saddled Toby, shows off its pretty patterns and colors to the divers.

Reef Building Blocks

Scientists identify and measure a large coral colony using a new method, called carbonate budgets, that will tell them if a reef is growing or shrinking. From previous research, we know how much each species of coral and calcifying algae is expected to grow. By identifying and measuring these corals, we can estimate how much a particular coral species should calcify. Scientists also survey the animals that erode the reef, like parrotfish and urchins, allowing them to calculate whether the reef is growing faster than it is eroding. This information will help managers understand the status of the reefs.

Keeping the Reefs Healthy

Steephead parrotfish (Chlorurus microrhinus) feed on algae that grow on the reefs. They scrape rocks and corals clean with their beak-shaped teeth. The material then passes through their digestive systems and comes out as the sand that you lay on when you go to the beach!

Painted Sweetlip

A diver finds an elusive painted sweetlip fish (Plectorhinchus picus). These solitary fish like to hide under ledges or in caves, but our fish divers search every nook and cranny to make sure they get an accurate estimate of all of the species on the reef!

Active Volcano(s)

The NOAA Ship Rainier anchored overnight in front of Mount Pagan. The active volcano was spewing gasses and ash as recently as September 2021. According to NOAA's Earth-Ocean Interactions Program, the Mariana region contains 9 volcanic islands and more than 60 submarine volcanoes. At least 20 are hydrothermally active. The summits of these submarine volcanoes range from 50 m to more than 1800 m below sea level.

Measuring Reef Growth

Two divers install a temperature recorder on the outer reef of Maug's submerged caldera. In the foreground is a structure called a Calcification Accretion Unit, or CAU. These plates of PVC provide a bare surface for colonization, much like a bare rock. Corals and calcifying algae will land and grow here over the next 3 years. When the scientists come back to collect the plates, they will be able to measure how much the reef has grown!

Butterflyfish

Divers spotted a pair of threeband pennantfish (Heniochus chrysostomus) during a survey dive. These uniquely shaped butterflyfish feed on coral polyps and are somewhat common in areas with high coral cover, such as this reef in leeward Guam. Credit: NOAA Fisheries/Johnny Charendoff

Swimming in circles for science

The ocean and climate change team conducts another Structure-from-Motion (SfM) survey at a site in Guam. One diver remains stationary at the center of the site while holding onto a circular drum. The diver with the camera swims in a spiral pattern while collecting imagery. The camera is tethered to the drum creating a seamless model when the images are compiled. Great form, divers! Photo: NOAA Fisheries/Ari Halperin

Hungy hungry parrotfish

A large school of parrotfish swim over the reef in Guam. These are mostly filament-finned parrotfish that feed on algae growing over the reef. Divers watched as this school stopped to munch on algae before moving on. Photo: NOAA Fisheries/Kaylyn McCoy

Instrument collection and replacement

A team of divers works at a permanent monitoring site in Pagan Island. They are collecting temperature loggers that have been recording information for up to 5 years! They will replace these loggers with fresh ones that will continue to record temperature data for the next few years. They are also replacing calcification accretion units (CAUs) that help us measure how much coral is growing on the reefs over time. Photo: NOAA Fisheries/Bernardo Vargas-Angel

Fish diver deploys

A diver deploys at a survey site to count and identify reef fish around Pagan Island. He holds his mask securely in place as he executes a back-roll entry off of the small boat. Perfect form! Photo: NOAA Fisheries/Ray Boland

Temperature logger

This neon temperature logger deployed at a reef will record ocean temperatures for the next 3 years, providing valuable data on changing ocean conditions. Photo: NOAA Fisheries

Survey finished

Divers from the Ocean and Climate Change Team wrap up a survey at Pagan Island and begin their ascent to the surface. They take a moment to admire the small fish on the reef - even the smallest critters serve and important role in ecosystem health! Photo: NOAA Fisheries

Lifting heavy equipment under water

Divers use tools underwater to help install and remove instruments. When the tools are heavy, the divers use a special lift bag that they fill with air. Once inflated, these bags help ease the burden of the heavy weight. Photo: NOAA Fisheries

Hyberbaric chamber

NOAA's motto is 'Safety First!' Here the dive chamber supervisor ensures that the hyperbaric chamber is up and running and ready in the unlikely event of a dive-related medical emergency. Photo: NOAA Fisheries/Raymond Boland

Divers return to the ship

Divers also double as boat crew members. Here, scientists prepare the lines that tether the dive boat to the ship so that it can be safely returned to its cradle aboard the NOAA Ship Rainier. Photo: NOAA Fisheries/Raymond Boland

Talking safety

The Fish Team gathers to conduct a safety assessment before launching in their small boat. Today they will be working around the dormant volcano Asuncion. Photo: NOAA Fisheries/Raymond Boland

Rainier and Pagan Volcano

The NOAA Ship Rainier is ready for the dive boats to return from a successful day of surveying. Photo: NOAA Fisheries/Raymond Boland

Cleaning recovered gear

The Ocean and Climate Change team cleans gear on the back deck of the ship. These weights were recovered after spending 5 years attached to instruments on the seafloor. Once clean, the weights will be attached to new instruments to continue collecting important data. Photo: NOAA Fisheries/Raymond Boland

Schooling Scad

Collecting fish biomass data can be hard work! Step one: count the fish. Scientist Ari Halperin was finishing his survey over the remote reefs in the Marianas when this school of akule scad swam through. Photo: NOAA Fisheries/Jeff Milisen

Coral polyps

This is a close-up shot of Galaxea coral. Each polyp is an individual animal, but together they form a colony. Photo: NOAA Fisheries/Raymond Boland

Water sampling in action

Scientists use good old-fashioned elbow grease to collect water samples and retrieve their instruments. Photo: NOAA Fisheries/Caroline Jahn

Identifying Fish

After a dive, divers identify fish they saw. Photo: NOAA Fisheries/RCB

Off to work!

One of the small boats leaves the NOAA Ship Rainer and prepares for a day of field work and water sampling. Photo: NOAA Fisheries/Raymond Boland

Baby fishes

Juvenile damselfish hover above an Acropora colony. If they sense a threat, they will dive down and take refuge among the branches. Photo: NOAA Fisheries/Nate Hayes

Measuring coral

A diver carefully lays a transect tape over a coral colony to record its width. Attention to detail is crucial and we make our measurements as accurate as possible! Photo: NOAA Fisheries/Raymond Boland

Back to the ship

The coxswains patiently wait their turn to be picked after a day of field work. As an integral part of our team, they drive the small boats to and from our dive sites and monitor the divers while they are underwater. Our coxswains are highly trained and ready to respond to any situation that arises on the water! Photo: NOAA Fisheries/Raymond Boland

Between two rocks

Not all sites are easy to survey! This diver navigates through large rock formations to safely retrieve an instrument. Photo: NOAA Fisheries/Raymond Boland

Crinoid shelter

A crinoid, a relative of sea stars, sea urchins, and brittle stars, sways with the current, providing shelter for a school of juvenile midnight snappers. Photo: NOAA Fisheries/Andrew Gray

Installing a temperature logger

A member of the Ocean and Climate Change Team installs a new sub-surface temperature recorder (STR). Photo: NOAA Fisheries/Raymond Boland

Survey in the shallows

A scientist carefully swims above a shallow portion of the reef, capturing every formation in this Structure-From-Motion survey. Photo: NOAA Fisheries/Jeff Milisen

Hungry hungry sea star

A crown-of-thorns sea star has devoured most of this coral colony, leaving stark white branches in its wake. In small numbers, they play an important ecological role, but too many can devastate a reef. Photo: NOAA Fisheries/Andrew Gray

Morning safety briefing

Scientists and crew attend morning safety briefings to discuss the plan for the day. The topic today is the conditions around Pagan. Photo: NOAA Fisheries/Raymond Boland

Instrument swap

A scientist free-dives in the shallows to deploy a temperature logger with Pagan in the background. Photo: NOAA Fisheries/Jeff Milisen

Sampling water

Fish scientists collect water samples in between dives. The package of electronic instruments is carefully lowered to hover above the reef, recording conductivity, temperature, and depth data 1 meter below the surface. Photo: NOAA Fisheries/Andrew Gray

Safety stop buddies

Barracuda surround divers on a safety stop. Photo: NOAA Fisheries/Joy Smith

Sleepy shark

Whitetip reef sharks don’t need to move to breathe so they often sleep on the seafloor during the day. Photo: NOAA Fisheries/Andrew Gray

Peek-a-boo

A pink anemone fish (Amphiprion perideraion) peeks out from the protection of its anemone as a fish diver conducts a survey. Photo: NOAA Fisheries/Raymond Boland

Picturesque reef

A vibrant sea fan stands amidst a school of small fish on a Pagan reef. Photo: NOAA Fisheries/Andrew Gray

Stingray swim-through

A diver pauses as a stingray swims through his survey area. Rays are cartilaginous fishes, so they are included in our fish counts. Instead of estimating their total length, we estimate their wingspan. Photo: NOAA Fisheries/Raymond Boland

Boat launch

The scientists have beautiful conditions for their surveys around Pagan today! The Rainier lowers a small boat while the team prepares to load their gear. Photo: NOAA Fisheries/Raymond Boland

Instruments that listen

Scientist and crew discuss recovering and deploying an array of long-term acoustic recorders used to listen for cetaceans. These instruments tell us when cetaceans are in the area. The yellow buoys help the recorders (shown at the bottom of the photo) orient vertically in the water column. Photo: NOAA Fisheries/Raymond Boland

Acoustic array down!

The acoustic array is deployed and ready to collect data off of Saipan. Photo: NOAA Fisheries/Ari Halperin

Sharing our science

Scientist Ari Halperin explains how we retrieve ocean chemistry information from one of our instruments. Scientists and crew held an outreach event after the last leg of the cruise pulled into port in Guam. This wraps up our trip and our data collection around the Mariana Archipelago for the year. Stay tuned to see where we go next year! Photo: NOAA Fisheries