Ocean With Seafloor

Ocean with seafloor (abbreviated OWS) biomes are underwater biomes that have a ground portion. These can be highly diverse, as in coral reefs, or extremely empty, such as abyssal seafloor environments. The list of OWS biomes is unfinished.

Coral Reef

occurs: in shallow, warm waters with few available nutrients
resources: Sunlight, saltwater
elevation: Usually less than 50m below sea level (in earth-like lighting conditions), no more than 150m below sea level
climate: Tropical
topography: various formations of corals and other sessile organisms.
biodiversity: 3
autotroph niches: Phytoplankton, Algae, and Seaweed are the main ones.
heterotroph niches: All sorts, from the corals themselves to fish to birds to sharks (a more comprehensive list is here)
other: To compensate for nutrient-poor waters, they recycle nutrients much more than in other, more nutrient-rich environments.

Algal Forest

occurs: Under the sea, close to shore
resources: cold, nutrient rich water, sunlight
elevation: 20 - 80 feet below sea level (6-25 m)
climate: 50 - 60 F water, (10 - 18 C)
topography: more level than not
biodiversity: 2
autotroph niches: all up to large. It's hard to tell because kelp grows until it reaches the ocean surface, then starts expandiing outwards
heterotroph niches: Carnivores up to midlarge, herbivores up to about midsize, though it's potentially possible to have midlarge ones
other: has sublevels depending on sun: canopy, midlevel and floor. Also, pretty darn hard to disturb, because most storms just make kelp bend or break off pieces, and it can re-anchor itself.