The abiotic factor that is essential for all aquatic ecosystem with the exception of hydro thermal vent is SUNLIGHT, THIS IS BECAUSE IT PROVIDES A SOURCE OF ENERGY. 
Sunlight is very essential for aquatic ecosystems because it is the principal source of energy from which aquatic plants trap energy to make their food and provided mean of sustenance for themselves and other organisms in the water.
        
             
        
        
        
A hormone is a regulatory molecule that is secreted into the blood by an endocrine gland
        
             
        
        
        
Answer:
f. light
Explanation:
too little sunlight can cause seedlings to turn yellow
 
        
                    
             
        
        
        
She might discuss what she needs to not have it hurt that is called a epidural!
        
             
        
        
        
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