1. The upper subdivision of the marine littoral zone, typically dominated by algae having a lower limit at the depth at which illumination is at about one percent of the surface level; sometimes used for the depth zone between low tide and 100 meters.
2. The depth zone of a lake permanently covered with rooted or adnate (attached) macroscopic vegetation; often divided into upper (with emergent vegetation), middle (with floating vegetation) and lower (with submerged vegetation) zones.

Adnate means to be closely applied to something; growing on; or attached along the entire length.