Browsing by Author "Rogers, Alice"
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- Deep reefs of the Great Barrier Reef offer limited thermal refuge during mass coral bleachingPublication . Rodrigues Frade, Pedro; Bongaerts, Pim; Englebert, Norbert; Rogers, Alice; Gonzalez-Rivero, Manuel; Hoegh-Guldberg, OveOur rapidly warming climate is threatening coral reefs as thermal anomalies trigger mass coral bleaching events. Deep (or "mesophotic") coral reefs are hypothesised to act as major ecological refuges from mass bleaching, but empirical assessments are limited. We evaluated the potential of mesophotic reefs within the Great Barrier Reef (GBR) and adjacent Coral Sea to act as thermal refuges by characterising long-term temperature conditions and assessing impacts during the 2016 mass bleaching event. We found that summer upwelling initially provided thermal relief at upper mesophotic depths (40 m), but then subsided resulting in anomalously warm temperatures even at depth. Bleaching impacts on the deep reefs were severe (40% bleached and 6% dead colonies at 40 m) but significantly lower than at shallower depths (60-69% bleached and 8-12% dead at 5-25 m). While we confirm that deep reefs can offer refuge from thermal stress, we highlight important caveats in terms of the transient nature of the protection and their limited ability to provide broad ecological refuge.
- Exposure of an intertidal fish to simulated heatwaves and suspended sediment – a multistressor approachPublication . Resende, Anna Carolina; Vinagre, Catarina; Rogers, AliceExtreme climatic events, such as marine heatwaves (MHW) and increased suspended sediment concentration (SSC), are increasing in frequency and intensity, resulting in sudden changes to coastal environments, especially intertidal zones. Intertidal animals experience conditions that substantially fluctuate over temporal and spatial scales and therefore require the ability to physiologically tolerate these fluctuations. Since multiple stressors often co-occur and natural populations tend to respond to local environmental fluctuations, we aimed to investigate individual and combined effects of MHW and increased suspended sedimentation in Forsterygion lapillum from two neighbouring coastal areas with distinct water temperatures and wave current regimes by assessing fish oxygen consumption rate, mortality and weight loss. Results showed that in both F. lapillum populations, oxygen consumption rate and survival probability were unaffected by any treatment. However, fish from both populations lost weight during heatwave and multistressor treatments (i.e. heatwave and sedimentation), while fish from the sedimentation treatment alone did not lose weight. Although a direct effect on fish respiration was not found, our results indicate that F. lapillum performance is reduced when exposed to heatwaves individually and in combination with increased sediment suspension. Weight loss indicates that fish experiencing these stressors were unable to meet their metabolic demands.