Marine scientists in Florida are taking action to address the alarming long-term decline of coral reefs by using a creative underwater doorbell-style surveillance camera to catch “porch pirates” in the act.
The recorded footage revealed that three species known for feeding on coral—the redband parrotfish, foureye butterflyfish, and stoplight parrotfish—were responsible for consuming over 97% of the coral bait placed by the researchers at an offshore reef near Miami.
These insights could play a crucial role in guiding efforts to restore coral reefs, which have seen a staggering 90% reduction in coverage in Florida since the 1970s, largely due to severe bleaching events linked to climate change, especially the record-high ocean temperatures experienced over the past two summers.
“Intense fish predation on newly outplanted corals has emerged as a major restoration bottleneck. The main goal was to address our lack of knowledge of the fish species that target corals after outplanting,” said Diego Lirman, a global leader in coral restoration research. He is a project leader and associate professor at the University of Miami’s (UM) Rosenstiel school of marine, atmospheric and earth science.
“Identifying the fish species responsible for coral predation would allow practitioners to avoid reef sites or areas within sites with high abundances of those species and, similarly, select the right coral species for the right outplanting site,” Lirman said.
“The coral-baited underwater cameras provide insight into corallivore behaviour and preferences and allow documentation of predation at various sites rapidly and without incurring the cost of outplanting.”
Led by Lirman and supported by a grant from the Fish & Wildlife Foundation of Florida, the team developed several recording devices using GoPro cameras encased in waterproof housing, mounted on a PVC frame and weighted for stability. After some initial challenges, divers successfully anchored the improved models to the seabed at Paradise Reef, located near Key Biscayne in Miami-Dade County, using masonry nails and cable ties.
The C-Bruvs, or coral-baited remote underwater video systems, were designed to capture time-lapse videos. Footage was gathered at 24 and 48 hours after deployment, followed by weekly recordings throughout the six-week study.
Lirman noted that the team faced some initial challenges, such as overheating external batteries and leaks that led to flooding in the camera housing. Additionally, they encountered issues with theft, reminiscent of the petty crimes often reported by homeowners who have security cameras monitoring their doorsteps.
“One of the C-Bruvs with a surface buoy attached was stolen from the reef,” he said.
Despite these hurdles, the researchers deemed their experiment a success. Upon analysing the footage, they found that redband parrotfish, abundant in the Caribbean and off the coast of Florida, were the most aggressive predators, responsible for 56.3% of bites on the nine coral species used as bait.
Following them were foureye butterflyfish at 36.9% and stoplight parrotfish at 4%. Lirman pointed out that these three species displayed distinct preferences for two or three specific types of coral, which accounted for over 65% of all recorded bites.
Erin Weisman, a marine scientist and research master’s graduate from UM, shared the results at the Reef Florida symposium for conservation leaders held at Miami’s Phillip and Patricia Frost Museum of Science in November.
“By identifying, for the first time, the main fish predators as well as their preferred diet, reef restoration practitioners can select sites and species that would minimize predation impacts and maximize restoration success before large-scale, costly outplanting is implemented,” Lirman said.
Looking ahead, Lirman mentioned that future studies could incorporate elements of artificial intelligence.
“It will be beneficial to explore AI software that can be trained to identify fish and their behaviors to automate the analysis process.”
[image: A GoPro camera monitors predatory fish eating coral reefs at Paradise Reef off Key Biscayne. Photograph: Erin Weisman/University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science]
