I n order to contribute to the sea bottoms knowledge of the Seaflower Biosphere Reserve (RB Seaflower), a mapping update was made at 1:50,000 scale of the Seascape Ecological Units (SEU) for the Serrana, Roncador and Quitasueño atolls, based on the processing and interpretation of ALOS AVNIR – 2 satellite images acquired in 2012. For the attribute assignation was used as reference cartographic products, fieldwork data, and ecological descriptions of the benthic community. A total of 138,967 ha and 30 SEU, which corresponds to 32,908 ha for Serrana, 4,861 to Roncador and 101,198 to Quitasueño. The products generated represents a good approximation of the location, extension and distribution of the benthic seascape elements, constituting the base line information for the management of these atolls, they are also part of the Continental, Coastal and Marine Ecosystem Map of Colombia at scale 1:100,000 (MEC 100K) and the Colombian Coral Areas Atlas (AACC) updated on a digital platform to 2020. However, more extensive field work is needed for cartographic purposes, which allows for greater spatial and thematic detail, and to evaluate cartographic reliability

Seagrass meadows are important ecosystems due to their high productivity and ecological value among tropical ecosystems, because of their high species diversity. In Colombia seagrasses are located around some islands, oceanic coral banks and along the Caribbean shelf, mainly in La Guajira Department, where more than 80% of the seagrass meadows of the country are present. In the world, the delimitation of this ecosystem has been successfully mapped during years, with assistance of remote sensing, using satellite image of different spatial scales. Nevertheless, the specific environmental conditions in La Guajira, such as high water turbidity and reduced light penetration restrict the use of traditional satellite images employed for those seascapes. With the aim of delimiting and establishing the extension of seagrass meadows in La Guajira, based on analyses between July 2013 and February 2014, a methodology of massive image interpretation that included fieldwork fast verification was applied, generating as a result one layer of seagrass habitats in Cabo de La Vela – Dibulla area at 1:100000 scale. Methodology included geometric correction, image fusion, fieldwork information, definition of thematic classes, determining of criteria for spatial delimitation, visual interpretation of images, thematic uncertainty qualification, and final cartography production. The process of cartographic production showed that Landsat 8 OLI satellite sensor images made easier the identification of seagrass meadows in deep areas (>10m). In total, 53621 ha of seagrass meadows were identified, and the largest meadows of Colombia were delimitated, which reach dimensions of up to 6018 ha.

Coral reef decline is an issue of concern around the globe. Remote and uninhabited coral areas are not exempt from facing changes in species composition and functionality due to global drivers. Quitasueño is a remote atoll within the Seaflower Biosphere Reserve, in the Southwestern Caribbean Sea. To evaluate the current status of the coral reefs in Quitasueño we sampled 120 stations through Rapid Ecological Assessment and evaluated four stations through Planar Point Intercept to compare the current percent cover of benthic groups with previous studies in the area. We found pronounced changes in coral and macroalgae covers in time, and great conspicuousness of multiple conditions of deterioration along Quitasueño, including diseases, coral predation, and aggression and invasion of coral colonies by macroalgae and sponges. The reef ecosystem seems to be facing a phase shift, in which the benthic cover previously dominated by hard corals is currently dominated by fleshy macroalgae. It is essential to evaluate the possible drivers of the extent of degradation of Quitasueño to understand the process of deterioration and mitigate the impacts.

Hurricanes are important natural destructive forces for coral reefs that can change the structural component of the habitat. On November 16th, 2020, the hurricane Iota passed ~10 km north of the islands of Providencia and Santa Catalina with sustained winds of a category 5 hurricane. The purpose of this study was to document the magnitude of the impact on coral reefs around the islands two weeks after the hit, as part of the “Operación Cangrejo Negro”. Visual assessments were performed at 11 representative coral reef formations between 2 and 17 m depth. Estimates of the impact were evaluated within an approximate area of 200 m2, which was categorized with score values ranging from 0 to 5 according to the level of damage. Preliminary estimates at coral reef formations indicated impact in 72 % of the stations surveyed, concentrated mainly on shallow areas (5-7 m). Approximately 45 % of the sites had low to low-medium damage and 27 % showed medium to moderate damage with high variability between and within stations. From this preliminary assessment we conclude that the impact was widespread along the island on shallow areas structured by big boulders of Orbicella spp., mainly related to colony-level damage with less reef structural damage