HURRICANES AND HEATWAVES: THE IMPLICATIONS OF STORMS AND WARMING OCEANS TO CORAL HEALTH AT CORAL GARDENS, BELIZE

Acropora cervicornis (Staghorn) coral has been in decline for decades and was listed as threatened in 2006. Few refugia remain for this critical reef framework builder. While A. cervicornis has continued to persist at Coral Gardens, Belize, the refugium status of this reef is at risk. Since 2012, the reef has experienced periods of pronounced decline in live coral. A recent study suggested that anomalous sea surface temperatures (SST) pre-conditioned coral for vulnerability to the passage of Hurricane Earl in 2016. We aimed to test if the 2022 passage of Hurricane Lisa had a similar impact on coral, and the degree to which SST’s were similar leading up to this second storm. We surveyed live coral at two sites (T1 and T5) prior to, and after each storm. Coral cover decreased from 13.3% to 6.6% at T1 and from 35.6% to 19.2% at T5 between June and October 2016 following the passage of Earl in August. Coral decreased from 13.3% to 10.8% at T1 and from 40.6% to 35.1% at T5 from June to December 2022 bracketing Lisa in October. Hurricanes Earl and Lisa had similar characteristics. Both were Category 1 storms with storm surges of 1.5-1.8 m, peak wind speeds of 148-157 kph, and made landfall near Belize City, ~60 km south of the reef. The primary difference between the two storms is timing; Earl was in early August (prior to peak SSTs) and Lisa was in early November (after peak heating). The mean SST for 2016 and 2022 were virtually identical (28.48 °C and 28.47 °C respectively), however the years differed in duration of accumulated DHW, a measure of SST intensity over a period of time that is indicative of extended heat stress. Additionally, 2016 had a higher peak DHW at 5.4 °C than 2022’s peak of 1.9 °C. In the last decade, 2016 had the longest duration of continuously accumulated DHW (32.1 weeks) while 2022 had among the shortest accumulation of DHW in this study (17 weeks). Our data suggest that when the duration of continuous accumulated DHW was greater than 25 weeks, the percent live coral typically decreased. The lesser decline in live coral observed in 2022 suggests that while storms can be damaging to coral, the temperature conditions that bracket storm events may be critical to refugium survival. The Caribbean is currently experiencing an extreme heatwave and mass bleaching event which increases concern during this hurricane season.