Imagine that the players on your favourite football team were
smaller than their opponents, and had to play without helmets or
pads. Left defenseless, they would become easy prey for other
teams. Similarly, changes in Canadian lake water chemistry have
left small water organisms vulnerable to their predators, which
may pose a serious environmental threat, according to a new
study. "At low calcium levels the organisms grow slower and
cannot build their armour," says study lead author Howard
Riessen, professor of biology, SUNY College at Buffalo. "Without
suitable armour, they are vulnerable to ambush by predators," he
says. Riessen and colleagues, including York University biology
Professor Norman Yan, studied the effect of changes in water
chemistry on plankton prey defenses. Specifically, they examined
how lower calcium concentrations affect Daphnia (water flea)
exoskeleton development. These low calcium levels are caused by
loss of calcium from forest soils, a consequence of decades of
acid rain and multipl