Atlantic snails are
increasing dramatically in size
Tuesday, March 24,
2009
These snails are feeding on
barnacles on the Maine shoreline. credit: Jonathan
A.D
A Queen's University biologist has
discovered that the shell lengths of snails in the northwest
Atlantic Ocean – an important member of the Atlantic food chain –
have increased by 22.6 per cent over the past century. Until now,
this significant change in the marine ecosystem has gone
unnoticed.
"We found a dramatic increase in size, which could affect the
entire intertidal food chain," says Jonathan Fisher, Queen's
Postdoctoral Fellow and the leader of the study. Growing larger
shells is a major way for the snails to avoid predators, he
explains. Previous and continuing research has also found that
large snails tend to prey on mussels and barnacles and spend less
time resting between feedings, compared to small snails.
The findings will appear online this week in the journal
Proceedings of the National Academy of Sciences.
The team used museum collections from the Academy of Natural
Sciences of Philadelphia as a base for their data. They measured
the shells from 19 lots of shells gathered between 1915 and 1922,
and compared them with samples from the same 19 locations today.
The increase in size was striking however, the researchers are
unsure exactly why the snails are growing so large, so
rapidly.
"Many documented environmental changes between these time periods
could affect snail survival or growth rates," Dr. Fisher suggests.
"We're finding fewer predatory fish now, which would allow the
snails to grow." The temperature of the water today is warmer than
100 years ago, which could also account for faster growth of the
snails, he adds.
"But regardless of the factors that contributed to the size
increase, the marine landscape is changing dramatically on a
historic timescale. That's what is really important here," says Dr.
Fisher.
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Queen's University
Thanks to Queen's University for
this article.