An overview of beach-cast seaweeds: Potential and opportunities for the valorization of underused waste biomass

There is an extensive demand for new sources of natural products with biofunctional properties, in which macroalgae can be relevant components to encounter this need. Nowadays, there are no commercial-scale alga crops to supply the biomass market for exploitation in some countries. The high availability of beach-cast seaweed biomass with potential application makes them an attractive and sustainable alternative to satisfy this demand. Currently, the excess of beach-cast seaweeds on the beaches causes an environmental problem, as its decomposition affects the use of the beach and keeps tourists and bathers away, affecting financial income in the region. Considering this negative impact on the environment and the possibility of using this biological feedstock, some countries establish quotas that make it possible to reduce the volume and maintain the stock in the environment. This review aims to gather information on studies related to beach-cast marine algae in the world and Brazil, addressing ecological, economic, and potential applications. The exploitation of beach-cast algae can be a socio-economic and environmentally sustainable solution, since it reduces financial costs, generates an alternative income for the local population, and limits the impact of extraction on natural beds of macroalgae, threatened by over-exploitation. The relevance of this material is shown by gathering information on the prospecting of the biomass given the development of technology for algae matrices with a focus on the development of functional products and sustainable use of unexplored biomass considered as waste. The use of beach-cast seaweeds as a resource is an eco-efficient alternative that favors society and the environment, generating usable resources that were previously seen as limited and trash. In addition to encouraging pollution mitigation in coastal regions and socioeconomic development sustainably. The data presented in this review will significantly contribute, increasing the knowledge of beach-cast seaweeds worldwide and their potential uses.