A while ago, we visited Mera's retconned origin told in the pages of "Brightest Day." Issue #6 of the new Aquaman series elaborates more on that origin. In the DCnU Mera was still leader of Xebel 's Death Squad, and her mission was to kill the so-called King of Atlantis!
Although everyone in Xebel has the capability to manipulate water to create solid constructs, Mera is far more powerful than her compatriots; not only at a large scale, but also at a molecular level.
Art by Ivan Reis, Joe Prado, and Rod Reis