Epiphytism, diseases and grazing in seaweed aquaculture: A comprehensive review

Seaweeds are macroscopic forms of phylogenetically diverse assemblage of marine algae that grow in oceans, thriving among profoundly harsh environmental conditions. They are cultivated in many maritime nations primarily for edible applications; besides hydrocolloid extraction is the second largest domain of utility for this renewable biomass. The farming practices have been traditionally evolved in different Southeast Asian countries. Nevertheless, advancement in the knowledge about their life-history traits and control over reproduction has paved ways for commencement of large-scale commercial farming. Food and Agriculture Organisation of United Nations reported the availability of 35.8 million tons of seaweed biomass globally of which 97% accounted for farming. Although cultivation is on the rise due to relevant to social gains, epiphytic infestation, diseases and grazing have been identified as leading causes that result in substantially lower yield, deteriorated quality of product and skewed economics. Epiphytes may considerably impact the interaction of seaweed hosts with other beneficial communities also. Epidemiological studies in natural seaweed populations are scarce and this makes the understanding of the cross-talk involving host specificity, and their role obscure. An overview of the diversity of epiphytes, understanding of mechanism of action, factors responsible, chemistry behind their interaction will help in deciphering the solutions to overcome infestation. A comprehensive report of seaweed epiphytism, diseases and grazing from the aspects of host-epiphyte interaction and their resultant consequences is presented along with the studies on economic impacts. The role of multi-omics approaches in delineating seaweed epiphytic interactions is also included.