Sensor-equipped buoys have long been used to address challenges ranging from shellfish-farming safety and urban runoff contamination to environmental impact studies and more. In the past, buoy-based monitoring systems were complex and costly to deploy and manage, requiring significant resources to collect data from even a handful of sites.

Today, the combination of Internet of Things (IoT) technology and remote data management is changing that dynamic. Faster, cheaper data collection has expanded monitoring capabilities for organizations of all sizes, while delivering more detailed and accurate insights into coastal ecosystems than ever before.

Getting the most from your buoy-based monitoring deployment, however, isn’t necessarily straightforward. The application, monitoring parameters, and site characteristics all affect platform setup, while the instruments themselves must be carefully selected to ensure reliability and minimize costs. Finally, organizations must decide how they will remotely collect and manage their data, for optimal insight and timeliness of event response.

Application-Specific Monitoring Buoys

The advent of smaller, more advanced, and cost-effective sensors is driving growth in the use of buoys for application-specific monitoring of marine processes. For example, buoys carrying a suite of chlorophyll a, blue-green algae (BGA), and dissolved oxygen (DO) sensors can provide advance warning of harmful algal blooms (HABs) in nearshore waters.

Another emerging application centers on monitoring environmental impacts related to crude oil leaks. Buoys equipped with crude oil sensors can help detect very low concentrations of crude oil in waters near storage and pumping facilities, providing early detection and faster response to leaks.

For estuarine studies, buoys equipped with fluorescent dissolved organic matter (FDOM) sensors are helping researchers and municipalities track the influence of freshwater on coastal systems. Coastal municipalities in particular are working to address water quality issues related to stormwater pollution with buoy-based monitoring. In this context, FDOM sensors are helping agencies track water quality, current movements, and the influence of different riverine inputs on overall water quality.

Buoy-based monitoring is also becoming an important tool for ensuring food safety in mussel and oyster farming. IoT technology company Adroit uses In-Situ’s Aqua TROLL 500 multiparameter sonde in a buoy setup to monitor salinity at a New Zealand mussel farm to limit the duration of harvesting closures due to runoff after precipitation events. Harvesting doesn’t have to stop as early or for as long when farmers have timely, location-specific salinity data provided by In-Situ’s sonde.

In-Situ has developed a shared ecosystem of products for seamless remote monitoring in a number of applications. (Image credit: In-Situ)

Larger buoys are also useful for environmental impact monitoring in challenging conditions. Aridea Solutions, for instance, used In-Situ’s Aqua TROLL 600 sonde on a buoy to monitor a natural gas leak in Cook Inlet, Alaska, which is a breeding ground for beluga whales. The company chose the Aqua TROLL 600 because of its self-cleaning function—to prevent biofouling—and ability to withstand harsh conditions.

As technology evolves, IoT is opening new avenues in coastal research, making data more accessible while reducing the cost of monitoring. The primary impact has been an explosion in the amount of data coming in, not just in terms of monitoring environmental parameters but also for remotely managing equipment. With remote monitoring, it’s now quite easy to evaluate sensor health, alter monitoring frequency, and access data—all without having to physically visit buoys.

Putting the Pieces Together

While IoT is a welcome advancement, the ultimate success or failure of buoy-based monitoring deployments depends heavily on the instruments used in each platform. Sensor reliability and stability are key considerations, as are setup, maintenance requirements, and anti-fouling capabilities.

Fluorometer design is a prime example, where multiparameter water quality sondes are equipped with chlorophyll-a and BGA sensors used in HAB monitoring. In-Situ fluorometers are designed with integrated optical compensation to adjust for LED brightness and provide stable measurements even at low detection limits.

Using chlorophyll-a, BGA, and DO sensors on the same sonde can also introduce interference that impacts data reliability. In-Situ fluorometers, however, use isolated optical frequencies and low-interference spectral bands to minimize this obstruction and improve data accuracy.

Sensor stability is also a concern when equipping buoys with pH and DO sensors. In-Situ’s pH sensor, for example, has a stable reference design that reduces measurement drift when compared with traditional glass-bulb sensors. And the company’s rugged dissolved oxygen (RDO) sensor is more stable than traditional DO probes, with a fast response that makes it ideal for dynamic conditions and vertical profiling.

Finally, anti-fouling should be a factor in instrument selection for buoy deployments. While wipers and copper guards reduce biofouling, instrument design has evolved in recent years to provide even better protection. The Aqua TROLL 500 and Aqua TROLL 600 multiparameter sondes, for instance, have flat-faced interlocking sensors and a tight-fitting sonde guard that minimizes space for biofouling compared with traditional sondes.

Making Your Data Work for You

Telemetry and data management are also vital to any buoy-based remote monitoring project. Ease of use should be top of mind when it comes to selecting a telemetry solution, and VuLink cellular telemetry from In-Situ has been heralded for its simple setup. VuLink displays instrument connection, battery life, network connection and connection to the cloud with one button press, and it’s designed to mount in a 2-inch pipe or well, so it doesn’t require conspicuous installations or solar panels. With more than two years of battery life at 15-minute reporting intervals and expanded coverage through the use of M1/NB-IoT technology, VuLink significantly decreases the cost and complexity of remote data collection and transmission.

VuLink can be paired with the Bluetooth-enabled VuSitu mobile app available on Android and iOS devices for data access, and a cellular connection to HydroVu, In-Situ’s cloud-based data management platform, simplifies the process even further.

The Future of Buoy-Based Monitoring

As buoy-based monitoring applications proliferate, technology that makes remote data collection simpler, more reliable, and more affordable will help researchers, consultants and government agencies expand their understanding of coastal ecosystems, generating more detailed insights while improving the efficiency of deployments.

The end goal is to make coastal monitoring more accessible for organizations of all sizes, in order to enhance our knowledge of the environment and how to protect it for future generations.

For more information, visit: www.in-situ.com.

This feature appeared in Environment, Coastal & Offshore (ECO) Magazine's 2022 Winter edition, to read more access the magazine here.