A new robotic instrument deployed in Monterey Bay is providing an unprecedented, real-time view of the ocean’s critical role in storing carbon. Developed by scientists and engineers at the Monterey Bay Aquarium Research Institute (MBARI), the device provides high-resolution images and data on organic particles drifting into the deep sea, offering vital insights into a fundamental process that regulates global climate.
This technology directly observes the “biological carbon pump,” a natural process where marine life, primarily plankton, captures atmospheric carbon and transports it to the deep ocean for storage. By measuring the size, shape, and sinking speed of this material—collectively known as marine snow—the new instrument fills a major gap in scientific understanding, with profound implications for improving the accuracy of climate models. Previous methods relied on ship-based sampling, which only provided brief snapshots of this continuous, complex process.
A New Generation of Ocean Monitoring
For decades, scientists have understood that the ocean is the planet’s largest carbon sink, absorbing vast quantities of carbon dioxide from the atmosphere. A key mechanism is the constant rain of marine snow: a mix of dead algae, fecal pellets, and other organic debris that clumps together and sinks. This process sequesters carbon in the deep sea, preventing it from re-entering the atmosphere. However, observing this process in detail has been a significant challenge. Researchers were often limited to deploying “sediment traps” from research vessels, collecting whatever sank into them over a period of days or weeks. This approach provided valuable but incomplete data, missing short-term variations and the intricate biological and physical interactions that determine how much carbon reaches the deep ocean.
To overcome these limitations, a multidisciplinary team at MBARI developed an innovative solution capable of sustained, autonomous observation. This new tool allows researchers to see not just how much material is sinking, but to identify its composition and behavior particle by particle. This leap in observational capability promises to answer longstanding questions about the efficiency of the biological carbon pump, which varies significantly based on the types of organisms living at the surface and environmental conditions. Understanding these details is essential for predicting how the ocean’s capacity to store carbon might change as the climate warms.
The SINKing Ecology Robot
The instrument at the heart of this research is named SINKER, for the SINKing Ecology Robot. Moored to the seafloor 900 meters below the surface in Monterey Bay, SINKER is connected to MBARI’s cabled ocean observatory. This connection provides the constant power and data transmission needed for continuous, long-term operation, setting it apart from battery-powered autonomous floats.
Design and Instrumentation
SINKER is engineered to function as a persistent deep-sea observatory. Its design centers on a large, funnel-like collection tube that directs sinking particles toward an imaging area. As particles descend, a system of five advanced cameras and microscopes captures them from multiple angles. Three cameras are positioned to document the sinking speed of particles in the water column just before they settle. Once the marine snow lands on a brightly lit collection plate, two upward-facing, high-resolution cameras take detailed photographs. This setup allows scientists to precisely measure each particle’s size, shape, and transparency, which provides clues to its composition—for example, whether it is a dense fecal pellet or a fluffy aggregate of dead phytoplankton.
A Cycle of Observation
The robot operates on a repeating two-hour cycle to prevent the accumulation of material and ensure clear, distinct measurements. After the cameras document the particles that have settled on the imaging plate, a mechanical brush wipes the surface clean. The system then resets for the next collection period. This high frequency of observation is crucial, as it allows the team to detect rapid changes in the amount and type of sinking carbon, linking them to events at the ocean’s surface, such as algal blooms. The continuous stream of high-resolution images and data provides a dataset of unprecedented detail, capturing the rhythm of the biological carbon pump around the clock.
Decoding Marine Snow
The primary focus of the SINKER robot is to quantify the composition and flux of marine snow. This organic material is the primary vehicle for carbon transport to the deep sea. It begins in the sunlit upper ocean, where photosynthetic phytoplankton convert carbon dioxide into organic matter. When these organisms die or are consumed by zooplankton, they begin a slow journey downward. As they sink, these particles often aggregate, forming larger, faster-sinking clumps. The characteristics of these particles determine how effectively they transport carbon. Larger, denser particles sink faster, carrying their carbon payload to the deep ocean more efficiently, while smaller, lighter particles may be consumed or remineralized in the mid-ocean, releasing their carbon back into the water column.
By capturing thousands of snapshots of this sinking material, SINKER allows researchers to observe the biology that shapes this process. “Who makes these particles? How fast do they sink? How big are they?” asks Colleen Durkin, the scientist leading MBARI’s Carbon Flux Ecology Team. She explains that these details matter because they change over both short and long time periods. For instance, a bloom of diatoms—phytoplankton with heavy silica shells—might produce dense, rapidly sinking particles, leading to very efficient carbon export. In contrast, other types of blooms might result in lighter, fluffier aggregates that sink slowly and contribute less to long-term carbon storage.
Improving Climate Forecasts
The data gathered by SINKER is poised to address a major uncertainty in global climate models. According to Durkin, a “huge limitation” of current carbon and climate models is how they account for the biology controlling sinking carbon particles. Many models use simplified assumptions or proxies to estimate the efficiency of the biological carbon pump. The detailed, quantitative observations from SINKER can replace these assumptions with real-world data, leading to more robust and reliable climate projections. By directly measuring variables like particle size distribution and sinking rates, the robot provides the exact parameters needed to refine these complex models.
This work will help scientists better predict how the ocean’s role in the global carbon cycle may evolve under future climate scenarios. A more accurate understanding of carbon sequestration is critical for forecasting the pace of climate change and for evaluating the potential of proposed climate mitigation strategies. The ability to link surface conditions to the deep-sea carbon flux in near real time represents a significant advancement in ocean science, turning what was once a black box into an observable and quantifiable system.
