Electricity Manipulation

Electrokinesis is a power that can summon a bolt of lightning from the sky, and aim it at a spot on the ground or a target. It causes extreme lightning and power outages. In "Control" Rikki looks at the full moon and swims to Mako Island with the girls and was in the Moon Pool during the special planetary alignment which magnifies her original power to electrokinesis and ends up making a lightning storm. This can be made stronger with the help of her fellow mermaids. With the powers of Emma and Cleo, Rikki can create a full on storm that is very powerful and very dangerous. This effect is show in the second season premiere "Control " and now with their new abilities especially Rikki has the most dangerous power. Rikki doesn't seem to use this power much in season 2 other than a few times and it isn't seen using at all during season 3 most likely because of the damage it can cause and the danger it poses. The hand movement for this is the same as before, however Rikki is shown suddenly opening palm in the chosen direction when summoning lightning, this may signify the sudden release of energy needed when conjuring lightning

Even though Zac does not have this ability, the Trident seems to be able to control electricity. Therefore, it could be argued that Zac has this ability.