algae
Lolo
algae is considered the main producer in the oceanic ecosystem
Seaweed, coral, and anemones.
It has water in lakes, rivers, and oceans
Depends on what they produce. Phytoplankton are the largest producers of oxygen. Various forms of bacteria and some other life forms are the largest producers of methane. Fish as a whole are likely the largest producers of ammonia. The ocean is a complex biome, be more specific with your question.
Because they help each other
Producers are those organisms which can produce organic matter or food from simple inorganic substances like sunlight and carbon dioxide. Only plants, algae and certain bacteria can perform this and hence are producers. For example, phytoplanktons are the chief producers in oceans.
They are the primary producers that trap the Sun's energy and thus the basis of all life in the oceans.
In any biome, plants are the producers.
Some animal producers that you might know are chickens, pigs, worms ect.
some producers in the rain forest are bromeliads guarana' and strangler figs.
Some of the producers in an ocean are seaweeds, different types of algae, and phytoplankton. These are only a few.