SonarPoint™ Localizing Toolkit For Environmental Monitoring
With the ever increasing demand for energy, it makes since many people are turning to renewable energies and among some of the most popular project discussions involve Marine Hydrokinetics wherein energy can be harvested from the tides, waves, currents and offshore wind farms placed out at sea. These sites are not only out of the public view but what happens annually beneath the surface is also largely unknown and must be studied. What species commonly migrate or frequent these areas, perhaps unnoticed even to those living nearby.
What if your daily commute were dramatically altered? Have you been living at your current residence for many years or maybe you chose where to live based on your needs for survival, needs like proximity to your work or where you can find a source for food such as a local grocery store? Imagine your life could be interrupted in such a way that you can no longer travel to work in a timely manner, or you live in a rural area with one grocery store and that grocery store is now closed. How would these changes affect your life? These dramatic changes to your routine can be very stressful. As humans, we are very adaptable and so although it can be stressful we are likely to make changes to our lives that will enable us to survive.
But what about wildlife? Certainly, some wildlife have evolved over time to enable them to survive and even thrive in ways that are very specific to their environment. However, these adaptions are generally slow to take place. For instance, what if a whale were no longer allowed to "go to work" or "buy food"? Could this whale pack up it's family and relocate to another city and find a new job? Perhaps that is as far as this analogy should go, but these are the important questions that must be studied and ultimately answered when we decide to build platforms, turbines or kites in the oceans to harvest energy. Animals are not as easily adaptable as humans and these stresses could have a severe impact on our oceanic environment.
Currently, the work required for passive acoustic monitoring can be expensive and very labor intensive. These current cost-prohibitive monitoring systems and methods make it difficult, if not near impossible, to study many potential areas that could be suitable for a marine hydrokinetic project site.
A set of four free-field hydrophones ordered in a tetrahedral array used for PAM recording and localizing with SonarPoint Long Endurance Recorders.
Identify Candidate Sites with Acoustic Surveys
You've done it! You found the perfect site to build your MHK project. It will become a renewable source of energy that will seemingly last forever and save the planet from the harmful oversaturation of CO2 gases. But before they rename the Pulitzer Prize in your honor, let's first make sure it's safe to build there.
An acoustic survey can begin with an array of recorders that are deployed using lightweight sub-surface mooring lines equipped with acoustic releases for recovery. Equipped with a small external battery pack, the recorders have sufficient memory and power reserves for 12+ months of continuous monitoring at a 100 kHz sample rate. No duty cycling required and no servicing required. The recorders are simply recovered after one year using acoustic commanding from the surface. This method of PAM monitoring is user friendly and the only labor involved is deploying and retrieving the underwater moorings.
A set of four SonarPoint recorders used in a localizing array in Monterey Bay, CA. The SonarPoint recorders were set with submerged moorings, hard float buoys and recovered with ARC-1XD Acoustic Releases.
Availability of Real-Time Acoustic Data Streaming
At the completion of a PAM survey, it is determined you can safely begin construction and you have identified an appropriate location for your MHK project. Let's continue monitoring for wildlife so a cetacean such as a blue whale or harbour porpoise can safely pass if it were to come within close proximity of the construction site.
With a moored surface repeater buoy, you are now enabling real-time data streaming. This allows potentially hazardous activities such as noisy pile driving to be stopped when animals are approaching. Several recorders can be linked by simple two-conductor seafloor cables to one buoy and this will allow for increased acoustic quality than if operating from a noisy ship or platform.
When construction is complete, SonarPoint recorders may now be tied into an MHK installation such as a wind turbine for permanent real-time or archival monitoring. Evolving hazards to marine mammals can be recognized and mitigated.
Automated Data Reduction
Batch processing software can be used to scan an archive of acoustic recording (.wav) files, or streamed real-time data can find and extract sound signatures that reflect possible cetacean vocalizations, such as tones, sweeps or pronounced clicks that are heard by several recorders. These sound signatures are indicative of a strong signal rather than the local clicking from snapping shrimp. A reduced dataset of acoustic recordings can then be forwarded to bio-acousticians for species identification, density estimates and additional analysis. During the MHK construction and operation phases, marine technicians with limited bio-acoustic skills may monitor and engage bio acousticians when sound signatures indicate a possible presence of a wildlife species.
This reduced dataset, created from batch processing, will be much smaller and available acousticians can have their time utilized in a more focused way. During the MHK construction and operation, the monitoring system may auto-identify signals of possible interest for immediate review and mitigating action.
SonarPoint PAM recorders attached to a metal frame to be placed on the seafloor in the Irish Sea.
The SonarPoint PAM Toolkit can save time and money so that the important work of environmental impact monitoring can be achieved in more areas, simultaneously and efficiently. This work is important for the well being of marine mammal populations as well as a benefit for the future MHK site. If a site can be chosen for it's rarity of marine species to come within close proximity or range to the MHK site, then the environmental impact is minimized and the MHK site can experience continuous operation with less work stoppage or slowdown.
Do you have questions or comments about the environmental impact of MHK sites or PAM monitoring? Click the link at the bottom of this newsletter or reply to this email.
And don't forget to watch the full playlist of SonarPoint Tutorials including topics about hydrophone selection, SD cards, time synchronization, localizing and mapping vocalization and data analysis. Follow the Video Tutorial link below.