you're reading...

Invasive Species

Could a novel disease help curb the lionfish invasion?

Paper: Harris, H. E., Fogg, A. Q., Allen, M. S., Ahrens, R. N. M., & Patterson, W. F. I. (2020). Precipitous Declines in Northern Gulf of Mexico Invasive Lionfish Populations Following the Emergence of an Ulcerative Skin Disease. Scientific Reports, 10(1934), 1–17.


Lionfish: beautiful but dangerous. Forty years ago, lionfish could only be found in their native range throughout the Indo-Pacific. Now, these fierce predators have invaded the coastal waters off the Americas and are routinely seen throughout the Atlantic Ocean, Caribbean Sea, and the Gulf of Mexico.

Lionfish are native to the Indo-Pacific but often imported to other areas for the aquarium trade (image from wikipedia.org)

But how did lionfish even get here?

Scientists have not been able to pinpoint the exact source of the invasion, but the ornamental fish trade is the likely culprit. Lionfish – coveted by aquarists for their unique and stunningly bold markings, their gracefully flowing fins, and their more social nature in tanks – are commonly imported from the Indo-Pacific to fill tanks in homes in other countries. Lionfish likely found a new home in the Atlantic when unwanted aquarium fish were intentionally released into local waters or when ships transporting live lionfish capsized during Hurricane Andrew in 1992, unintentionally releasing lionfish cargo. Either way, these lionfish, once destined for life inside a tank, established residency in the open ocean, found mates, and thrived.

By the early 2000s, lionfish populations had soared as breeding populations were established. In this new environment, lionfish faced no known threats. Native predators appeared to be deterred by the venomous spines in the lionfish fins and the invasive fish were not susceptible to any native diseases or parasites. Lionfish also proved to be a formidable predator, quickly and voraciously consuming native fish, taking over habitats preferred by important reef fish, and rapidly reproducing (females can produce an estimated 2 million eggs per year!). Lionfish are also extremely adaptable, allowing them to expand their range into new areas in which scientists did not expect they could survive, like areas with lower salinities or temperatures.

In an attempt to regulate the rapidly spiking lionfish populations, scientists teamed up with divers and fishermen to monitor the invasion, catch as many lionfish as possible, and create a demand for lionfish as a food fish in the newly invaded areas. While lionfish derbies and collection efforts have helped to reduce lionfish numbers, they have not made a dramatic dent in the continually expanding lionfish populations. Today, lionfish have been documented along the Western Atlantic from Venezuela up to Rhode Island in saltmarshes, estuaries, mangroves, and reefs. Disturbingly, remotely operated vehicles (ROVs) have even seen lionfish in the deep-water mesophotic reefs at

depths of 300 m (over 900 feet!), far beyond the reach of recreational divers attempting to reduce lionfish populations. All of this has left scientists wondering just how far the lionfish invasion will go, and how it can be controlled.

Has a natural control finally developed in the Atlantic?

One of the major reasons lionfish are so successful in their invaded range is because they lack a natural mechanism to regulate population growth. In their native range, other species (predators, pathogens, and parasites) have evolved alongside lionfish, creating numerous checks to uncontrolled population growth. However, as is the case with most invasive species, native species are not used to this new invader and do not know how to eat or attack it effectively. But eventually, that may change as the species in the area get used to the presence of the invasive species. We may have finally reached that turning point in the lionfish invasion.

Green arrows point to the skin ulcers found on lionfish (Images from Harris et al., 2020 and made available under a creative common license)

In August 2017, over 15 years since the start of the invasion, scientists saw the first signs of a wide spread disease in lionfish populations in the Northern Gulf of Mexico. Infected fish had ulcers – deep open sores on their body. At the peak of the outbreak in 2017, up to 40% of lionfish appeared to have ulcers. Throughout 2017-2019, scientists continued to monitor the occurrence of the disease and its possible impacts on lionfish populations.

The disease appeared to hit areas with higher lionfish densities the hardest, decreasing populations in these areas by 75% between 2016 – 2018. By October 2018, lionfish populations at high-density sites had declined so drastically that they had lionfish populations on par with or lower than the low-density sites.  Fishermen also landed fewer fish during this time, and scientists found nearly 80% fewer larval and juvenile lionfish. Combined, all of these pieces of evidence suggest that the lionfish in the Northern Gulf of Mexico experienced a rapid and drastic population crash.

Will lionfish populations continue to decline?

Even though the population crash may seem like the light at the end of a long invasive species tunnel, it will probably not be the end of the story. Even once diseases establish themselves in invasive populations, the species tend to experience cyclical booms and busts. Since 2017, the prevalence of ulcers in lionfish has declined, and infection rate has fluctuated between 0 and 14%. Even after the decrease in reproduction rate in 2017, lionfish populations appeared to rebound in 2018, with reproduction rates on par with those experienced in 2014. Given that the population decline coincided with the appearance of the ulcers, scientists speculate that the skin disease was a likely cause of the population crash; however, there is no definitive proof of that yet. Furthermore, scientists have not been able to determine the pathogen responsible for the ulcers, so it is unclear exactly how infections are caused, spread, and if they can jump into native species. Regardless, this novel disease is a first in the invasive lionfish populations. While it may not completely wipe out the invasion overnight, it may help curb the population growth.


No comments yet.

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 6 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 9 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 10 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 11 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 12 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com