I have written about lionfish, moon jellies, and groupers in the past (Click here for lionfish, here for jellies, and here for groupers). The lionfish is a beautiful and graceful addition to any South Pacific reef where it exists as a predator that keeps reef fish communities in balance. As an invasive species to Florida and the Caribbean (possibly inadvertently introduced in the early 90's), the lionfish is a voracious predator with an enormous appetite and their numbers have exploded in recent years, posing a significant threat from Florida throughout the Bahamas to reef ecosystems unprepared for such a hungry eating machine.
Sea jellies, or jellyfish, are also beautiful and graceful, but the yin to their yang is the powerful sting in the tentacles of many species, an ability that is used for hunting and feeding rather than as some sort of offensive or defensive weapon. In recent years, scientists have been seeing a greater number of sea jelly "blooms" - huge congregations that some believe are the result of warming temperatures due to climate change or, possibly, a lack of common predators like turtles, tuna, and sharks. For scientists, the jury is still out as to a definitive cause but the anecdotal observation is that sea jelly blooms are being reported with greater frequency.
The goliath grouper, capable of reaching up to a massive 800 pounds, is one of Florida's apex predators, right up there with sharks, billfish, and the other denizens of the deep that nature has entrusted to maintain equilibrium between predators and prey. Unfortunately, the goliath grouper was also a prized catch for sportfishermen and commercial operators and so their numbers declined rapidly over the past few decades. Listed as critically endangered in Florida waters by the International Union for the Conservation of Nature (IUCN), in 1990 Florida imposed restrictions on the taking of any goliath grouper. However, like sharks and other apex predators, the grouper's slow reproductive rate has meant a slow recovery and a typical large grouper is currently in the 200-pound range if you're lucky to see one.
So what is the common thread between the three? Well, the goliath grouper would be an ideal candidate to serve as an exterminator of lionfish, if there were only sufficient number. The loss of the grouper to overfishing, combined with the invasion of lionfish due to, well, our thoughtlessness has left the reef communities of Florida and the Caribbean with a real threat on their hands and without a natural defender. This makes the loss of even one grouper a critical one to the marine ecosystem. Then, what about the loss of up to 75 groupers? Seventy-five groupers gone due to moon jellies. Moon jellies, you say?
That's just what happened this past August in the surrounding waters at the St. Lucie nuclear power plant near Ft. Pierce in southeast Florida. A swarm of moon jellies inundated the seawater intake to the plant, causing a shutdown that lasted two days. With thousands of moon jellies plastered up against intake grates, the jellies' delicate tentacles broke off and traveled through the plant's seawater pipes to be expelled back out to sea where they apparently came in contact with a school of groupers, stinging and inflaming their gills. Biologists, who happened to be at the plant overseeing the facility's turtle protection program, were only able to save ten of the groupers before having to leave the water themselves due to multiple stings from the floating fragments of tentacles.
The end result was the loss of several tons of goliath groupers - predators desperately needed to combat the growing army of lionfish. This is often the result when natural resources are abused: not one problem, but a series of overlapping causes and effects. And the common thread was mankind. The cascading effects of our actions when we choose to consume rather than conserve could be our lasting legacy to this planet unless we act now.
Here's a brief video of moon jellies which shut down a nuclear power plant in Israel.
Source: Huffington Post.