The role of temperature in the spread of red lionfish
The expansion of exotic red lionfish into the western Atlantic may be explained by their tolerance of cooler waters, according to a new study.
The red lionfish, Pterois volitans, is perhaps the best recognised and most notorious group member of scorpion fishes – a large and diverse group that take their name from the potent sting they deliver using a formidable array of venomous spines. Prized by aquarium hobbyists for their showy looks and hardy nature, the fish are a bane to biologists struggling to manage exotic introductions in the Mediterranean and western Atlantic.
The Atlantic introduction is especially troubling as the fish have established persistent populations from North Carolina on the US eastern seaboard, to the Florida reef track, into the Gulf of Mexico and throughout the Caribbean Sea – all in less than 20 years. Lionfish are voracious predators with few natural enemies and early indications are that they will significantly impact the ecological balance of Florida and Caribbean reefs.
Temperature is thought to be an important environmental factor influencing red lionfish ecology in the Atlantic. While surprisingly little is known about their thermal ecology, it is clear that this tropical fish can feed, grow and reproduce in cooler Atlantic waters. In 2012 researchers with Operation Wallacea quantified thermal niche, preferred temperature and metabolic thermal sensitivity of native population of red lionfish from Hoga Island, Indonesia.
The findings indicate that while the red lionfish thermal niche is not notably large, it is shifted towards cooler water temperatures. For example, lionfish could be acclimated to temperatures as low as 12.5°C and exhibited a preferred temperature of 23°C. A similar study on blue-spotted ribbontail stingrays from the same back reef habitat yielded considerably higher acclimation and preferred temperatures of 17.5 and 28.2°C, respectively.
This tropical fish can feed, grow and reproduce in cooler Atlantic waters
Together the results may explain the persistence of lionfish in cool US waters. Metabolic studies revealed that increasing temperature elevates biological rates exponentially, a feature consistent with the current hypothesis that warmer Caribbean Seasummer temperatures relative to the Pacific, have contributed to the rapid reproduction rate and alarming pace of lionfish expansion into the Caribbean.
The current plan is to repeat these studies with a Caribbean lionfish population at the Operation Wallacea site in Honduras. The potential exists to see significant changes in thermal tolerance characteristics between the two sites, owing to the small founding population in the Atlantic. Insights gained from these comparative studies will provide a better understanding of red lionfish thermal ecology between the two regions and how global climate change may effect lionfish distribution of both areas.