FKt230918 expedition – Vertical Reef of the Galapagos

1.0. Shipboard multibeam echosounders provide a smoothed (at ~50-100 m spatial resolution) representation of rough topography, particularly in deeper waters, and as such cannot adequately characterize the vertical dimension of complex 3D seafloor structures. Trawls or towed-camera systems are similarly ineffective in very rugged environments. Consequently, it was not until the 1990’s that vertical deep-sea habitats started being discovered using human-occupied submersibles. Only recently were methods developed to map the heterogeneity of these cliffs at high resolutions, exploiting the extra maneuverability provided by ROVs. However, for the most part, these striking deep-sea landscapes have remained unexplored, even though cliffs provide environmental conditions different from the surrounding terrain, and often host rich communities of fragile suspension feeders. In particular, cliff environments represent an unaccounted cold-water coral (CWC) habitat of global importance. Although difficult to quantify owing to a lack of systematic data, we estimate that, globally, over 6,000 distinct geomorphological features with rocky walls likely harbor CWCs, representing an estimated global surface area equivalent to ~10% of shallow coral reefs.
2) In addition to providing suitable habitat for a range of species, cliff environments are of further interest as, owing to their complex topography, they provide a natural protection for vulnerable coral species against trawling activities, potentially allowing larvae to help recolonize surrounding damaged habitats. However, environmental conditions likely affect the life cycle of these habitats distinctly from other CWC environments. For example, large coral colonies may only grow on rock faces with particular strength properties, currents interact with the steep topography to create complex flow patterns that affect suitability of feeding conditions, and naturally broken pieces of coral accumulate at the base of cliffs rather than contribute to reef development. As such, our proposed scientific voyage aimed to apply new technologies to unveil, for the first time, the environmental drivers of vertical CWC cliff ecosystems. The data we collected will help quantify the contribution of these understudied environments to regional biodiversity before environmental change alters further ecosystem function. 1.1. In addition, the distribution of Cold water corals across oxygen minimum zones was studied in the Galapagos and la Isla del Coco Costa Rica. Cold-water corals (CWC) form oases of life in the deep sea, providing habitat, food, and shelter to marine animals, including commercial species, but are sensitive to increased temperature and low oxygen. The Eastern Tropical Pacific (ETP) is one of the areas of the planet where oxygen minimum zones (OMZ) are naturally large and expected to expand due to ocean warming. However, how oxygen concentrations affect different species of CWC and how these ecosystems may respond to future changes constitute a knowledge gap for this region. Through this research, we will study CWC across the OMZ in two areas located in the ETP: Isla del Coco and The Galápagos. The Galápagos and Isla del Coco are connected through a coalesced chain of seamounts known as the Cocos Ridge, which is characterized by complex topographic settings and the convergence of different currents, promoting the occurrence of diverse sessile species. Owing to a high degree of endemism, these islands have been declared marine protected areas in Ecuador and Costa Rica, respectively, and World Heritage Sites by UNESCO. Our aim is to identify CWC species biodiversity and composition across depth gradients (200 to 2000 m) and traversing OMZ boundaries to determine whether there is a difference in coral communities and populations between islands (the Galápagos and Isla del Coco) and how the environmental variables relate to these differences.

Biological samples were collected from 19 sites around the Galapagos Islands, Ecuador, and two sites near Isla del Coco, Costa Rica. These efforts took place in deep-sea areas within the Galapagos Marine Reserve and Isla del Coco Marine Reserve, both situated in the Eastern Tropical Pacific. The collection was part of a collaborative effort with the Charles Darwin Foundation's "Deep-Ocean Exploration & Conservation" research project and the University of Costa Rica.

Canada Research Chair in Ocean Mapping Natural Sciences and Engineering Research Council (NSERC) Schmidt Ocean Institute (research vessel, crew, ROV and other equipment) National Geographic (funding for collection, preservation and genetical analysis of Corals) Woods Hole Oceanographic Institution (Institutional Funding) University of East Anglia (Institutional Funding) National Oceanography Centre (Institutional Funding) National Oceanography Centre (Institutional Funding) Institute of Marine Sciences (Institutional Funding) University of Malta, GEOMAR (Institutional Funding) University of Bristol (Institutional Funding)