Lionfish Invasion and How Fishing May Help

Easily recognized by their bright colors and long spines, lionfish have become a hot topic of discussion in recent years. When speaking about lionfish, two particular species are often the focus: Pterois volitans (red lionfish) and Pterois miles (devil firefish). These closely related species are similar in appearance; both species have large fan-like and dotted fins, but P. miles has fewer dorsal- and anal-fin rays. Their spines are long and venomous, marked with bright orange, maroon, brown, and cream stripes. A sting from a lionfish can last for days and may cause extreme pain, difficulty breathing, and in some cases paralysis.

Pterois volitans, a.k.a. Red Lionfish

P. volitans is native to the southern Pacific while P. miles is native to the Indian ocean, with the two species intersecting near Sumatra. Despite the differences in their native ranges, both species have been found along the North American Atlantic coast in recent years (particularly along Mexico). Due to their popularity as an aquarium fish in North America, it is thought that they may have been introduced to the Atlantic through release by previous owners. As carnivorous fish that thrive in tropical waters, these two species have become invasive and threaten native marine life. Slow-moving hunters, lionfish are typically nocturnal but Atlantic populations seem to have increased diurnal activity. In many Atlantic coral reefs P. volitans and P. miles have become the top predators, using their large fins to ambush and corner prey. Invasive lionfish out-compete native fish and there are concerns that they may harm populations of ecologically important species such as parrotfish. In addition to their lack of natural predators in the Atlantic, lionfish can also reproduce year-round with females releasing approximately 2 million eggs per year. As the Atlantic populations continue to grow, their range expands further along the coast.

Fortunately, lionfish do have one potential predator – humans! While venomous, lionfish are not poisonous; removing the spines makes the fish completely safe to eat. While caution must be taken when handling the fish and removing the spines, if properly prepared the result is well-worth the effort. A popular meal in its native ranges, lionfish are known for excellent taste and populations could potentially be kept in check through fishing. Eating invasive lionfish provides relief to native over-fished species by removing competitive stress, giving over-fished populations a chance to recover. Lionfish is described as being a white flaky fish, similar to halibut in texture and slightly buttery. While beautiful to look at, lionfish also make a beautiful addition to the dinner table and are even growing in popularity to the point of being found at some restaurants. Hopefully, increasing awareness may bring the lionfish invasion under control and prevent P. volitans and P. miles from spreading further.

Deep-fried lionfish nuggets

Schofield, P.J., J.A. Morris, Jr, J.N. Langston, and P.L. Fuller, 2018, Pterois volitans/miles: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/factsheet.aspx?speciesid=963, Revision Date: 2/7/2018, Peer Review Date: 4/1/2016

U.S. Department of Commerce, National Oceanic and Atmospheric Administration. “What Is a Lionfish?” NOAA's National Ocean Service, 28 July 2016, oceanservice.noaa.gov/facts/lionfish-facts.html.

Harrel, Scott. “Eating Lionfish.” Lionfish Hunting, 2014. https://lionfish.co/eating-lionfish/

New Carnivorous Sponges

http://image.wistatutor.com/content/animal-kingdom/sponge-anatomy.jpeg

The above image shows the typical anatomy of a sponge.  These use the whip-like tails (flagella) of their collar cells to create a current of water.  This current of water allows the sponge to filter out bacteria and other food.  However, four new species of sponges (two species of Asbestopluma and two species of Cladorhiza) have adapted a different feeding strategy.  These new species inhabit the food-poor waters of the deep sea in the northeast Pacific.  Therefor it is not cost-effective for them to have this constant motion of cells to create a current.  Instead these sponges have a carnivorous feeding strategy.  When small crustaceans bump into the spiny sponge, they become trapped in their microscopic hook-like spicules.  A picture of the spicules from the species Abestopluma rickettsi can be seen below.

The sponge then proceeds to digest the crustacean.  A picture of the progressive decomposition of a crustacean by the species Asbestopluma monticola can be seen below.

These sponges are also often found in chemosynthetic habitats.  These are habitats where bacteria utilize the chemical-rich water as an energy source as opposed to sunlight.  The species Asbestopluma rickettsi was discovered in one of these habitats offshore of southern California where the bacteria use the methane that seeps from the seafloor.  Another species, Cladorhiza caillieti was discovered near a hyrothermal vent along the Juan de Fuca Ridge.  The fourth species, Cladorhiza evae was also discovered near a hydrothermal vent in the Gulf of California and is pictured below.

There is still much to learn about these sponges.  Researchers believe that these sponges may also be able to utilize the chemosynthetic bacteria as an additional energy source to the crustacean prey.  Only further research with these sponges will be able to confirm that hypothesis or not.



References:

1. http://www.biologyjunction.com/sponges__cnidarian_notes_b1.htm
2. http://biotaxa.org/Zootaxa/article/view/zootaxa.3786.2.1/7741
3. http://www.eu-hermione.net/science/chemosynthetic-ecosystems