They're the bane of beachgoers. Two summers ago, jellyfish "the
size of salad plates" attacked swimmers in the New York City
Triathlon. Some people blamed them for one racer's death (an
autopsy later ruled it was natural causes).  Last year,
jellyfish started showing up in Long Island Sound in May, says
Mary Beth Decker of Yale. But that was an unusually early
arrival; they tend to arrive in June and July.  Decker has
studied jellyfish populations in the Chesapeake Bay (relatively
little is known about those in Long Island Sound). There's
nothing to conclusively say that jellyfish populations have
grown globally, Decker says, but "our gut feeling" is that this
could be the case in some regions.  Sign Up For Traffic Text
Alerts  The fishing of tuna, which eat jellyfish, has been
pointed to as a possible cause. Global warming is another.
Decker says the global warming theory makes sense because warmer
water means longer periods of productivity for jellyfish.  So
what to do: First, try to avoid jellyfish. If you