How resilient are sharks to climate change, and how adaptive are communities and businesses that rely on them as a resource?
Climate change in South Florida has the potential to impact the health and behavior of marine life, from corals to sharks. At SRC, we are investigating the capacity of tiger and great hammerhead sharks are to withstand temperatures projected for our region as the 21st century progresses. Human-induced climate change is altering ocean chemistry at an unprecedented rate – by 2100, ocean temperatures in South Florida and the Caribbean are projected to rise by up to 4°C, while ocean acidity rises and oxygen levels drop. Most sharks move to waters that are best for their performance, so understanding sharks’ relationship with temperature is critical for predicting changes in their habitat. This is one of the first projects to study how apex predatory sharks’ energy use and movements respond to their environment across migrations. Satellite tags combined with sensors for temperature, depth, and acceleration enable us to estimate the optimal temperature range for these species, and in what conditions their performance starts to decline.
So far, we’ve been able to calculate the energy use of a tiger shark over a year-long migration, in relation to temperature. When data from multiple tiger sharks were combined, we saw that this species spent much of its time above its optimal temperature range, likely to take advantage of feeding and reproductive opportunities. For example, research from Neil Hammerschlag and colleagues shows that pregnant female tiger sharks gestate at Tiger Beach, Bahamas – where some of the warmest temperatures of their journey are encountered.
This research project is just the beginning – over the next few years, we will be tagging and sampling many more tiger and great hammerhead sharks, as well as other species throughout the US Atlantic, giving us strong projections of risks posed to these important apex predators as climate change continues to alter their environment. Socio-ecological studies of communities that rely on sharks as a resource (i.e. ecotourism, fishing) will enable us to project the potential for adaptation to a changing ocean environment at the human level.
Figure A year-long migration of a female tiger shark beginning in the Bahamas, travelling as far north as the state of Massachusetts. Point colors show water temperature sensed by the shark-borne satellite tag.(Figure via Rachel Skubel)
SRC In Focus
Understanding the relationship between sharks and water temperature is critical for predicting changes in their habitat.
We are investigating the capacity of tiger and great hammerhead sharks to withstand increased water temperatures.