Introduction
Rhizopsammia wellingtoni, commonly known as Wellington’s solitary coral, is a stony coral endemic to the Galápagos Islands. Once abundant in shallow waters, the species experienced a catastrophic decline following the severe 1982–1983 El Niño event, which caused widespread coral mortality due to anomalously warm ocean temperatures. Having not been officially documented since 2000, the species was classified as Critically Endangered (Possibly Extinct) by the IUCN. This study aimed to investigate whether the species had found a “refuge in depth” within the mesophotic zone—deeper, cooler reef habitats that remain buffered from the extreme thermal stress seen at the surface.

Methods
In early 2024, an international team of researchers conducted surveys across 12 sites in the Galápagos archipelago. The methodology combined technical diving using rebreathers to reach depths of 50–60 meters with Remotely Operated Vehicle (ROV) surveys extending even deeper. The team performed systematic video transects at 10-meter intervals from the surface down to the mesophotic zone. They also conducted directed searches at historical sites like Tagus Cove on Isabela Island and previously unexplored locations like Cabo Douglas on Fernandina Island. In addition to visual counts, researchers collected small tissue samples for genetic analysis to determine the connectivity and resilience of these newfound populations.

Results
The surveys led to the rediscovery of over 250 colonies of R. wellingtoni across four main locations. While the species remained absent from the shallow transects (above 50 m) at most sites, abundant populations were discovered thriving at depths of 50–60 meters, where temperatures remained below 17°C. At Guy Fawkes, coral densities reached as high as 64.9 corals per square meter. The researchers documented two distinct color morphs—black-purple and red-black—and observed many colonies with budding polyps, a clear sign of active reproduction. Interestingly, while most populations were found in the deep mesophotic zone, a few colonies were also spotted as shallow as 12–15 meters during cooler La Niña conditions.

Discussion
The findings support the hypothesis that the mesophotic zone serves as a critical thermal refuge, allowing highly sensitive species like R. wellingtoni to persist despite the intensification of climate change and frequent El Niño events. The presence of young, solitary individuals at some sites suggests high recruitment and the potential for these deep-water “seed” populations to repopulate shallower reefs when conditions are favorable. The authors conclude that R. wellingtoni acts as a climate change sentinel, and its rediscovery emphasizes the vital importance of protecting deep-water habitats. Proactive management and continued monitoring of the Galápagos mesophotic zone are essential for the long-term survival of this and other vulnerable endemic species.

Introduction
Antipathes galapagensis is a key habitat-forming black coral in the Galápagos Marine Reserve (GMR), yet little was previously known about its specific depth distribution and population structure. While most black corals are deep-water species, this study focused on the uniquely shallow populations found in the central Galápagos. The researchers aimed to define the upper depth limits of these corals, quantify their density and colony size across environmental gradients, and investigate how they utilize habitats. Understanding these patterns is critical for managing these CITES-regulated foundation species, which are highly sensitive to environmental disturbances and historical overharvesting.

Methods
The study was conducted between 2.0 and 20.0 meters depth across nine sites in the central Galápagos Archipelago in 2021 and 2022. Researchers utilized SCUBA diving to perform two types of surveys: band transects (5.0 m x 1.0 m) at specific intervals (5, 10, 15, and 20 m) to measure colony density and height, and occupancy modeling using small quadrats to predict the probability of coral presence. Additionally, the team recorded habitat utilization (cryptic vs. exposed), estimated the percentage of epibiont overgrowth, and identified commensal functional groups. Environmental data was supplemented with CTD casts to characterize vertical water temperature gradients at the study sites.

Results
The researchers documented some of the shallowest black coral occurrences in the world, with the upper limit found at just 3.4 meters depth. Results showed that coral density and colony height increased significantly and non-linearly with depth, with maximum densities reaching 5.2 colonies per m². Interestingly, habitat utilization shifted along the gradient: corals at shallower depths (5–10 m) were predominantly cryptic, tucked into crevices or urchin bore holes, while those at deeper levels (15–20 m) were more likely to be found on exposed rock surfaces. While epibiont overgrowth (such as sponges and algae) was present at all sites, the degree of overgrowth generally did not vary significantly with depth.

Discussion
The findings suggest that the shallow distribution of A. galapagensis is likely limited by a combination of physical and biological factors rather than temperature alone. The authors propose five hypotheses for the scarcity of corals in very shallow water, including hydrodynamic forces (drag), high light levels (as larvae may be photonegative), and predation or grazing on exposed surfaces. The shift from cryptic to exposed habitats with increasing depth supports the idea that crevices provide a necessary refuge from wave surge and surge-related abrasion. Ultimately, these shallow-water “forests” act as vital foundation species, and their characterization provides a baseline for monitoring how climate change might impact vertical zonation in the Galápagos.