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Assessment of two spatially different satellite SSTs for the use in monitoringcoral bleaching in Buccoo Reef, TobagoShaazia Salina Mohammed & Ricardo ClarkeDepartment of Physics, The University of the West Indies, St. Augustine, Trinidad & Tobagoshaaziamohammed@hotmail.com, ricardo.clarke@sta.uwi.eduAbstractIncreasing Sea Surface Temperatures (SSTs) have resulted in a high frequency of coral bleaching events that havedeteriorated Buccoo Reef’s inhabited species. With the integration of indirect remote sensing, monitoring of theseevents can be used to improve predictions for better management practices. Currently, Buccoo Reef is being monitoredutilizing thermal products derived from a low spatial resolution 50 km dataset. However, the use of such adataset tends to overlook localized bleaching conditions for small-scale reefs in shallow waters. It was found that anincrease in spatial resolution significantly advances real time monitoring of coral bleaching and thermal stresseswhich were formerly undetected. This research attempts to highlight the application of thermal products derivedfrom the higher spatial resolution 4 km dataset for Buccoo Reef. This highlights its capability to capture the thermalstress more accurately that was once undetected by those produced from the 50 km data set.IntroductionCoral reefs, better known as the rainforest of the ocean, are one of the most biologically diverse ecosystems thatprovide a variety of goods and services. These ecosystems are sensitive and can be impacted negatively by stressorsoriginating from both natural and anthropogenic factors. This is no different for Buccoo Reef, a fringing reef systemseparated from the shoreline by the Bon Accord Lagoon on the southwestern side of Tobago. It encompasses an areaof 7 km 2 and contains five emergent reef flats sloping to a depth of 15–30 m (UNESCO, 1998). It is a popular touristattraction and is valuable to Tobago’s economic status. However, the continuous degradation of the reef throughcoral bleaching has been acknowledged as a threat to its continued existence.Parameters highlighted such as solar irradiance (Fitt et al., 2001), wind speed, tidal current (Strong et al., 2001)and the susceptibility of different coral communities to thermal stress (Weeks et al., 2008) have been suggested tocontribute to coral bleaching. Unfortunately, the implication of global warming poses an even greater threat to thelongevity of coral species (Oxenford et al., 2008). Recent research investigated thermal stress as the main cause dueto the extent geographically of these bleaching events (McWilliams et al., 2005; Le, 2012).Experiments performed on corals both in the laboratory and the ocean were subjected to an increase of 1 o C overtheir upper thermal limit. It was found that the increasing seawater temperature resulted in bleaching and can alsoresult in death of corals (Glynn and D’Croz, 1990). Laboratory studies also indicated that the algal symbiont is lesstolerant to heat stress than its coral host and any rapid or large changes in temperature can induce ‘animal stressbleaching’ (Fitt et al., 2001). This probable link has established the correlation of near real time satellite derivedSST used in monitoring tools with real coral bleaching events (Stobart et al., 2008).Currently, Buccoo Reef is monitored for coral bleaching by the National Oceanic and Atmospheric AdministrationCoral Reef Watch (NOAACRW) using thermal products derived from near real time 50 km spatial resolutionSST. These products are called Hot Spots (HS) and Degree Heating Weeks (DHW). Anomalous temperatures representingpositive potential thermal stresses are derived from the static Maximum Monthly Mean (MMM) temperatures.Any temperature below the MMM indicates no thermal stress on the corals. When SSTs exceed the MMM,the anomalous temperature differences known as HS values indicate corals are now vulnerable to bleaching, and arenow under a bleaching watch. DHW accumulates any HS over 1 o C over a twelve week period. This cumulativemeasurement demonstrates the duration and intensity of thermal stress on corals. DHW below 4 o C (4 DHW) initiatesa bleaching warning. DHW between 4 o C and 8 o C signifies substantial coral bleaching. DHW above 8 o C (8DHW) suggests mass coral bleaching.This relationship nonetheless, relies on the assumption that the SST values accumulated from the 50 km griddedsatellite dataset are reflected at the depth where the reef actually occurs (Stobart et al., 2008). However, the values143