Most benthic life (by number) start as tiny, motile creatures. Screens would reduce head pressure and require maintenance. Barnacles of all kinds, as an example critter, settle on everything to which they can adhere. I'm guessing the engineers considered these complications since there have been past power project failures because of sea life. I wish the article went into those mitigations. If it's somehow a non-issue by nature of the design, my curiosity is even more piqued.