Killer Jellies

     A common sight for divers off the New Jersey coast is the sparkling comb jelly, Mnemiopsis leidyi. Once in a while its numbers would significantly increase but then drop back to occasional sightings, on the whole thought to be a benign critter. Somehow it got into the Black Sea and then, in 1999, into the Caspian Sea. There it has taken on an entirely new aspect.
    In the Black Sea it prospered to a point that the whole marine ecosystem collapsed taking the fisheries with it. Then came another invader, also a comb jelly, Beroe ovata, which, as it turns out, feeds on nothing but Mnemiopsis. Not long after, the numbers of both species fell drastically and a recovery of the rest of the system began.
    In the Caspian Sea, Mnemiopsis has hastened the disappearance of the sturgeon fishery as well as several other significant fisheries. It has reduce the
copepod community to one remaining genus, the Acartia. It can consume fifteen times its body weight in a day, reaches maturity in two weeks and can release
a thousand eggs on a daily basis. In the Black Sea its biomass peaked at 800 million tons, 800 times the annual fish take.
    Why not introduce Beroe into the Caspian Sea?  Unfortunately, the Caspian is less saline than the Black Sea and Beroe has a breeding problem there.
There is also the political problem of getting the five nations that border the Caspian to agree to do it. Both problems are being worked on.

- January 2005

01/02/06 14:33