Our Little GoPro Helpers
September 2020
Have you ever wondered what happens in the ocean when no one is looking? With only only 5% of the ocean explored and an estimated 9% of species discovered, we know we have so much more to learn. However, understanding the complex ecosystems and relationships within in the ocean poses some interesting challenges. For starters, it’s not an environment we can enter for long. When studying the behaviour of manta rays for example, we can only remain in the water with them for a few hours while snorkeling, or even less if the mantas decide to head off to deeper waters. With SCUBA we can observe manta rays for up to an hour or so but again, we often watch them disappear into the blue wondering where they’ve gone and why. To add to this challenge, the environment can be hostile. Swell and ripping winds give our research dhoni a run for its money before we cancel our research plans for the day and return back to base.
Although scientists across the globe are motivated to increase our understanding of these mysterious animals, the obstacles and challenges often seem endless. Luckily, within the last century scientists have been developing a side kick that takes on these challenges and wins; technology. For the first time in history, drones collect whale snot for hormone analysis, submersibles bring our eyes to the bottom of the Marianas Trench and satellites track fishing vessels moving throughout oceans. Technology grants access to explore new territory and allows us to ask questions we only dreamed of answering.
The ‘Eyes On The Reef’ time lapse camera set up.
The time lapse cameras last a lot longer than the simple GoPros but taking a photo once a minute sometimes means timing isn’t great. One second after this when the fish has swum past and the manta is in full frame would have been perfect!
In the Maldives, our studies of manta rays lead us to ask more questions. In the field, we spend several hours a day attempting to collect as many identification images as possible while we record manta ray behaviours. Often our team remains at one site while we know fully well that other manta rays are likely visiting other popular sites. How much information might we be missing? In 2017 we began attaching GoPros to dive weights to record what happened at cleaning stations when we left the area. With multiple cameras, these substitute researchers allowed us to be in 3 or sometimes 4 places at once. The cameras would record continuously for up to 4 hours giving us a better picture of events we missed while surveying the area. At the end of the day we’d return to pick up the cameras before heading back to base where we would play back the footage. We soon realized we were getting a lot more than we bargained for. The cameras were picking up everything from bait fishermen, to hungry turtles, to groups of manta rays cleaning at the same time.
Testing, testing, is this thing on?
Strangest manta we’ve ever seen!
Of course, for our research purposes mantas are the ideal subject. As mantas circle over the cleaning station, screenshots are pulled from the video giving us near perfect ID images. Each day we’d put the GoPro researchers to work and it didn’t take our team long to realize that we could expand the information we collect through these underwater cameras. If we can use these cameras to monitor the cleaning stations over a longer period of time, we could record patterns and trends in cleaning station visitation. Cleaning stations are extremely important sites at which the mantas socialize, court, and mate. Additionally, these sites provide manta rays the opportunity to rid themselves of bacteria and parasites through the symbiotic relationship they hold with cleaner fish that live on the reef. It’s clear these are significant sites, but does their significance vary within a season? The action we saw on the GoPros encouraged more questions. Could water temperature or current strength play a roll? Are certain cleaning stations more active at certain times of the season? If the moon phase affects food availability and therefore feeding behaviours, could the moon phase also impact patterns of cleaning behaviour? In an attempt to answer some of these questions and more, Eyes on the Reef was born in 2018.
Our 4 hour GoPro camera attached to dive weights was no longer be enough to watch the cleaning station. Instead, we attached a GoPro to 4 high capacity power banks that could supply the camera with enough energy to last for days. Nothing was really to be gained by recording over night when we see nothing but black so to maximize its life, we attached a time lapse trigger that told the camera to wake up with sunrise and begin taking a photo every minute until the sun went down. A PVC pipe with acrylic lenses screwed together across the pipe tightly formed a trusted and durable housing for the equipment and we began recording.
Me checking up on the camera deployment and giving the lens a wipe. Biofouling makes the photos very unclear after a few days.
By 2019 we had worked out most of the kinks and over the course of the Southwest Monsoon season, we built up an incredibly large database. Each day the Eyes on the Reef was deployed, approximately 700 photos were gathered all waiting to be individually investigated. We deployed these systems in Baa Atoll, Laamu Atoll and Raa Atoll. In Baa Atoll alone, we captured over 57,000 images over a span of 92 days.
Working from home during the pandemic has given us the window of time we needed to go through the images and analyse what we see. We can record when the mantas arrived at the cleaning station, how many were there and for how long. By comparing these events to environmental and physical factors like the phase of the moon, temperature of the water and time of high tide, we hope to answer some important questions about what drives manta ray behaviour at the cleaning stations. A deeper understanding of the importance of these sites and environmental drivers that impact them will bring us closer to understanding how we can better protect manta rays and their relatives in a dynamic and changing environment. Stay tuned for more exciting updates as we analyse the Eyes on the Reef data and attempt to reveal more about what happens in the ocean when no one is looking.
KAITLYN ZERR
MMRP Research Officer