Geospatial characterization of Coral Reef Ecosystems in the Galápagos Archipelago: current distribution, typology, and historical extent

Coral reef ecosystems of the Galápagos Archipelago occupy a biogeographically exceptional position within the Eastern Tropical Pacific (ETP), occurring at the convergence of multiple oceanographic regimes that generate highly variable and often marginal conditions for reef development. This dataset presents georeferenced shapefiles delineating the current and historical distribution of coral reef ecosystems across the Galápagos Archipelago, developed in support of the IUCN Red List of Ecosystems (RLE) global assessment of coral reefs. Reef units were classified following the typological framework adopted for the RLE assessment, distinguishing Type A-alternative (accreting coral reefs with fringing reef, reef crest, spur-and-groove, and bommie geomorphologies), Type B (marginal coral reefs lacking net biogenic accretion), Type C (subtidal rocky reefs with coral communities), and transitional categories (B(C) and C(B)), following the IUCN Global Ecosystems Typology functional groups M1.3 (Photic Coral Reefs) and M1.6 (Subtidal Rocky Reefs). Type A reefs sensu stricto (barrier reefs, atolls of 1000s of years) are absent from the archipelago based on available coral dating evidence, and no classic Type A formations were identified. Spatial boundaries were delineated based on historical records, personal field ground-truthing, photoquadrat surveys, and photogrammetry-derived orthomosaic data. Attribute information includes reef type classification, historical reef type where records are available, and descriptions of historical and current reef condition. The dataset documents a total mapped reef extent of approximately 79.6 ha, of which Darwin Reef (Type A-alternative) accounts for 15.6 ha and Wolf Reef (Type A-alternative) for approximately 5 ha, with Porites lobata as the primary framework-building species at both sites. The remaining reef area across the archipelago totals approximately 59 ha, with the largest representations at Floreana Island (northeastern coastline, Corona del Diablo–Punta Cormorán to Champion Island; ~28 ha) and Marchena Island (Punta Espejo; ~24 ha). Type C and transitional C(B) reefs account for approximately 34 ha, while Type B and transitional B(C) reefs account for approximately 25 ha. Type C reefs are mapped selectively, given that isolated coral colonies occur broadly along shallow coastlines across the archipelago wherever oceanographic conditions permit, and were included only where coral abundance or structural complexity justified cartographic representation. The dataset further incorporates records of historical reef loss and degradation. The most significant documented loss corresponds to Urvina Bay (Isabela Island), where a tectonic uplift event associated with the 1954 eruption of Alcedo Volcano caused the permanent aerial exposure of approximately 122 ha of reef, previously dominated by Porites lobata, Pavona clavus, Pavona gigantea, pocilloporid framework, and Psammocora stellata, and classified as Type A-alternative and, mostly, Type B. Additionally, the extreme El Niño event of 1982–1983 resulted in widespread coral mortality across multiple reef sites in the archipelago. Differential recovery trajectories have been documented among affected sites: some localities, such as Corona del Diablo (northern Floreana Island), have shown partial recovery, while others, such as Punta Espinoza (Fernandina Island), exhibit minimal recovery and retain only isolated coral colonies and structural remnants of historical reef frameworks. The majority of reef areas affected by this event were likely classified as Type B circa 1975, with the exception of Darwin and Wolf reefs, which retain their Type A-alternative classification to the present. This dataset is intended for use within the IUCN RLE assessment framework and is subject to a restricted data sharing agreement. File access is restricted pending formal peer-reviewed publication of the underlying data.