DYNAMIKEN OCH EFFEKTEN AV MARINA VÄRMEBÖLJOR PÅ TROPISKA KORALLER (SCLERACTINIA)

Abstract

Marine heatwaves (MHW) have become increasingly common in recent decades due to greenhouse gas emissions that have caused climate change. A marine heatwave is when the sea surface temperature rises, which damage many different ecosystems in the sea. One ecosystem that is sensitive to temperature changes is tropical coral reefs, which are at risk of bleaching during marine heatwaves. Coral bleaching is when its symbionts leave the coral and they lose their color, while also starving to death as they lose their food source. The purpose of this report was therefore to investigate what the connection between marine heatwaves and coral bleaching looks like, and to see if there are any geographical differences. The aim of the study was also to investigate if the corals were able to adapt to the fluctuating temperatures and if they were even able to adapt to tolerate or benefit from it. The study was done through a systematic literature search in which 35 articles were finally selected. The results showed that there is a connection between the marine heatwaves and coral bleaching, where increased temperature in heatwaves caused heat stress in the corals. Several studies done on coral bleaching have been able to see positively correlated episodes of marine heatwaves during the same time. The extent differs among locations as the duration differs and different species are affected differentially. Furthermore, the results show that some corals seem to be able to adapt by increasing their thermal tolerance. The question is, however, whether this can happen at the same rate as the rapid development of climate change. The capacity for such adaptation also differs among species, where some species may have a greater chance of keeping the same pace than others. In summary, there is a connection between marine heatwaves and coral bleaching, and this relationship differs among geographic locations. Corals can adapt to the temperature changes, but more studies need to be done to determine if they can benefit from it.