Best 8 Ocean Monitoring Methods

Text by guest author: Bash Sarmiento, edited by Remco Timmermans

Countless lives rely on the bounties of the ocean. Still, more than 80% of its waters remain unexplored. 

However, it doesn’t mean that humankind has focused on space and land instead of the waters. Efforts remain to explore, discover, and learn more about the deep waters. Here are some of the current tools used for ocean monitoring:

1. Satellite Remote Sensing

The oceans cover two thirds of the surface of the planet. This vast area can never be monitored using Earth-based measurements. Even aerial remote sensing will not adequately provide the data needed to measure the state of our oceans. Most cases that require Ocean monitoring do not require a very high spatial resolution. Instead, researchers are looking for changes over time, requiring a certain regular frequency in recurring measurements.

Over the past decades there have been several satellite missions that focussed specifically on measuring water surfaces, or sometimes the ice that covers the water around the poles. The latest example of this being the European Sentinel-6 satellite. 

Launched on 21 November 2020, the Copernicus Sentinel-6 satellite, named ‘Michael Freilich’, uses the latest radar altimetry technology. This technology was developed by ESA to advance the long-term record of sea-surface height measurements, which began in 1992 by the French–US Topex-Poseidon satellite and were followed by the Jason series of satellite missions.

2. Geographic Information Systems

These systems are spatial platforms that generate, manage, and analyse maps and the data coming from them. Geographic Information Systems (GIS) integrates location data, usually with help from satellite monitoring, with different layers of descriptive data. These computer systems also help keep track of the world’s oceans, monitoring storms or currents as they flow from one region to another. 

A particular application of GIS is following storms and predicting their trajectory, allowing locations in these paths to prepare beforehand. Additionally, these systems help monitor the waters near coastal areas, keeping track of the tides and helping inform fishing schedules.

3. Smart mooring buoys

Smart mooring refers to technologies that improve, if not completely replace, traditional mooring methods. Ropes and cables traditionally moor boats and ships. Meanwhile, buoys and markers are usually kept in place by long lines with an anchor at one end. With new technologies, there are emerging technologies to hold vessels in place.

Today, smart mooring is a technology used to gather more information from the oceans. Specific initiatives, such as the intelligence platform ‘Sofar Ocean’, use a network of smart mooring buoys equipped with sensors to measure particular parameters such as temperature. These buoys create a mapping system that covers large areas of the seas even without human intervention.

Returning to the example of smart buoys in monitoring, research teams can keep track of temperature changes from one part of the ocean. This data is essential because warm and cold waters are factors that affect life, from fishes to corals to planktons.

4. Animal telemetry sensors

With the development of more portable and durable sensors and gadgets, animal telemetry provides humanity with the necessary knowledge gathered from its inhabitants–marine animals. This tool involves installing electronic tags, sensors, or even cameras on marine animals. Animal telemetry was used at least in 1995 when green turtles were tagged at Redang Island in Malaysia. Since then, the technology has grown to include other forms of marine life like sharks, whales, and seals.

A subset of these tools, known as acoustic telemetry, uses sound waves to monitor marine life. This telemetry is used among fishes to watch their fish movements, which gives insights on habitat use, migration patterns, and survival data among different species. Acoustic telemetry involves installing acoustic tags on animals and an acoustic receiver that decodes the data and automatically records them.

5. Clod cards

Divers and snorkelers might have found large marshmallow-looking objects underwater. These identical trapezoids are clod cards. Usually made up of alabaster or plaster, clod cards are simple and effective tools for monitoring water motion. They are popular alternatives for drifters, buoys, and underwater sites. Clods are precisely weighed before being deployed at specific locations relevant to the study or project. After some time, usually between 24 to 48 hours, these trapezoids are recovered, dried, and weighed again. The weight of plaster lost from each clod card is determined.

Since the clods come from the same material, size, shape, and weight, they will erode at the same rate. Then, by reweighing the recovered clods, researchers know which locations experienced greater water flow than those that didn’t.

6. Remotely Operated Underwater Vehicles

Remotely operated vehicles (ROV) are used to explore locations that are not advisable or readily accessible to humans. For remotely operated underwater vehicles, they eliminate the need for a human pilot to steer the entire thing down. These robots are controllable from the surface, with instructions transmitted to vehicles through a communication cable. However, newer technologies can now retain connection with the submersible vehicle wirelessly.

Usually, additional tools and equipment are added to the ROV to collect the needed data. It can vary from ultrasonic and temperature sensors to underwater cameras and robot arms. They are designed to withstand the immense pressure in ocean depths, can be manoeuvred to enter small spaces, and even collect samples from the seafloor.

7. Underwater Hydrophones

Hydrophones are specially designed to pick up sounds from under the water. While it looks like the ocean is a dark, silent expanse, there’s a lot of noise coming in from all directions–marine life moving, the ocean currents, and even the movement of oceanic plates. Marine animals even use different sounds for communication and hunting.

Ceramic hydrophones start with small-voltage signals sent over a range of frequencies. These electrical signals are then picked up, amplified, and recorded. An array of hydrophones are commonly used to monitor underwater life and understand their behaviours and patterns.

8. Digital Twin of the Ocean

To make predictions on the future of our oceans we not only need accurate data about the oceans as they are today, but we need a model about how we think the oceans will evolve in the future. It is difficult to test these predictions in the real world, so in 2021 the European Commission set about creating a digital ‘twin’ of the ocean, filled with data from all systems described above. 

A digital twin is a digital representation of real-world entities or processes. Digital twins use real-time and historical data to represent the past and present, and create models to simulate future scenarios.

The European Digital Twin Ocean’s ambition is to make ocean knowledge readily available to citizens, entrepreneurs, scientists and policy-makers by providing them with an innovative set of user-driven, interactive and visualisation tools. This knowledge will help design the most effective ways to restore marine and coastal habitats, support a sustainable blue economy and mitigate and adapt to climate change.

Iliad Digital Twin of the Ocean

The DotSpace Foundation is one of the partners in a large pan-European consortium that is developing this digital twin of the ocean. The Iliad project brings together the best specialists in the fields of ocean monitoring with the best specialists in digital modelling, to develop a platform for scientists and researchers all over the world to develop new applications to protect this important ecosystem, while creating beneficial tools to support human activities on and around the oceans. These applications, all covered in Iliad pilot projects  include:

• Wind energy at sea
• Current, wave and floating solar energy projects
• Sustainable fisheries and aquaculture
• Monitoring safe marine traffic and harbour safety
• Pollution control
• Meteorological modelling
• Biodiversity assessment and monitoring
• Insurance for marine and maritime activities

You can find more information about the Iliad Digital Twin of the Ocean on its main website, and of course on the special Iliad page on the Groundstation.Space website.

Final Word

Of course there are many more tools that can be used for ocean monitoring. For research teams and conservation initiatives, the ocean monitoring tools listed above can help you gain unique insights that can lead to the next breakthrough in mankind’s pursuit of conquering the depths.

Featured image: Astronaut Samantha Cristoforetti watches the oceans from the ISS on World Oceans Day 2018 (image source: NASA)