March 2023 | By Leah Harper

Leah Harper is MarineGEO’s Central Technician. She planned and led the 2022 Carrie Bow Cay Field Campaign.

What happened to coral reefs while humanity battled the COVID-19 pandemic over recent years? To find out, ten MarineGEO researchers revisited the Carrie Bow Cay station on the Belize Barrier Reef in late 2022. Unfortunately, we found that corals are battling their own pandemic.

The expedition followed a two-year hiatus due to the COVID-19 pandemic, and focused on surveying marine life, continuing ongoing research, and testing new field methods. One of our key tools this field season is Reef Life Survey, a standardized method for surveying trends in reef fishes and corals developed by a non-profit citizen science program. Using such standardized approaches to survey fish and invertebrates is a core component of MarineGEO's research across the network. At Carrie Bow, we have used Reef Life Survey to track biodiversity in forereef, patch reef, mangrove, seagrass, and sand habitats since 2015. The resulting data confirm that different marine habitats in the seascape harbor distinct fish communities (Harper et al. 2022). For this trip, the MarineGEO team scaled up survey efforts dramatically. We completed a total of 42 surveys at 21 sites. By adding six new sites and many new surveys, we expect better ability to discern how the spatial arrangement of the seascape shapes marine animal communities. 

A key focus of MarineGEO work at Carrie Bow Cay involves the corals that build the ecosystem. Across 240 m2 on eight coral reef sites, we identified coral species and tracked signs of stony coral tissue loss disease (SCTLD). SCTLD has been afflicting corals up and down the Mesoamerican Barrier Reef and throughout most of the Caribbean for the last 4 years. We also took tissue samples from 90 tagged coral colonies as part of ongoing SCTLD fate tracking research begun in 2019.  Of those corals, roughly one third have perished since the start of our study, along with a decline in coral cover on MarineGEO study sites from approximately 13% to 10%. 

^{Tagged Pseudodiploria strigosa (brain coral) colony before (left) and after (right) infection with stony coral tissue loss disease.} 

Beyond expanding MarineGEO’s annual biodiversity time series at Carrie Bow, we also used the opportunity to pilot new protocols. SERC MarineGEO technician Emily Anderson led deployment of Hydromoths, small waterproof recording devices which record underwater sound data. Bioacoustic data from Hydromoths could help track animal activity through time, including at night when reefs are challenging to survey visually, and to identify hidden or rare species in the area. One goal of the Hydromoth deployments is to compare soundscapes across habitat types to provide a baseline for future bioacoustic studies in the Caribbean. We also paired 3D photomosaics with Hydromoths at coral reef sites to examine relationships between structural complexity and soundscape complexity, which will help us to understand the relationships between shelter provided by the reef and the activity levels of hidden, noisy animals such as snapping shrimp and toadfish. 

^{Emily Anderson surveys a shallow patch reef. Photo credit: Maggy Benson}

After a long wait, the entire MarineGEO team is thrilled to have resumed our long-term research program at Carrie Bow Cay. The crew worked hard to test new methods, survey new sites, and to train new Reef Life Survey divers. We are excited to pursue new research initiatives with the data collected as well as plan future campaigns at the station. Check out the numbers below to see all the great work we accomplished this year! 

Campaign by the Numbers: 

• 42 RLS surveys at 21 sites (5 forereefs, 5 patch reefs, 4 seagrass beds, 4 sand flats, and 3 mangroves) 
• 17 temperature loggers deployed 
• 368 squidpops and 373 ulva pops deployed 
• 240m2 of coral reef surveyed for hard coral demographics and disease 
• 36 calcium accretion units retrieved and re-deployed 
• ~800m2 of coral reef photographed to create eight 3D photomosaics 
• ~60 hydromoth deployments 
• 133 tissue samples from ~90 tagged corals 
• 54 seagrass shoot counts, epifauna samples, and shoot metric samples 
• 108 seagrass cover quadrats 
• 13 Long-spined sea urchins sampled for Diadema disease genetics