Seaweeds can reduce plastic pollution and increase rice production

Eucheuma cottonii is commercially grown as a primary source of kappa-carrageenan for food, cosmetics and industrial uses.

What do seaweeds and plastic pollution have in common?

In the Philippines, seaweeds are cultivated extensively. The country stands as a significant global producer of various seaweed species, including Kappaphycus, Gracilaria, Ulva, and Caulerpa, which are essential for food production, industrial applications, and supporting coastal communities.

Plastic pollution is a persistent issue in the Philippines. The country produces roughly 2.7 million tons of plastic waste each year, with 20% of this waste finding its way into the ocean. This situation positions the Philippines as the leading contributor to oceanic plastic pollution, accounting for approximately 36% of the total global plastic waste in marine environments.

This raises another important question: is there a connection between seaweeds and plastic pollution?

During the 48th Annual Scientific Meeting of the National Academy of Science and Technology, Science and Technology Information Institute’s Karl Jerome M. del Mundo reported that Filipino scientists are advocating for prioritizing national initiatives and efforts in the research and development of bioplastics derived from seaweed.

Having identified a thousand local species of seaweed, Filipino scientists are focusing on algal polymer-based biodegradable plastics, or bioplastics, to address the escalating plastic pollution crisis. They, however, stressed the importance of addressing gaps in their research and development.

“There should be more investments in the fundamental research to identify niche areas (of the Philippines bioplastic industry) as an opportunity for inclusive run and sustainable development,” Academician Marco Nemesio E. Montaño said during his plenary talk.

The experts described bioplastic as a type of plastic sourced from biological materials, such as seaweeds, which can be decomposed into non-harmful substances through natural processes.

In a related statement, Academician Ernesto J. del Rosario emphasized that the Philippines should capitalize on its open seas and inter-island marine areas to establish seaweed farming, ensuring a sustainable supply of seaweeds and their derivatives, including the aforementioned bioplastics.

The Iloilo-based Southeast Asian Fishery Development Center (SEAFDEC) has reported that the Philippines cultivates a diverse range of seaweeds, primarily from the red (Rhodophyta), green (Chlorophyta), and brown (Ochrophyta) phyla.

Kappaphycus, known locally as “guso” or “tambalang,” is the leading export and is primarily utilized in the production of carrageenan, which serves as a gelling and thickening agent in both food and non-food applications.

Gracilaria and Gelidium are harvested for agar, while Ulva spp. (sea lettuce) and Caulerpa racemosa (sea grapes) are frequently included in local culinary dishes. Additionally, brown seaweeds such as Sargassum spp. have traditional uses in herbal medicine and for practical applications like weaving mats and ropes.

Del Mundo reported that the Philippines currently holds the position of the fourth largest seaweed producer globally, representing 4.2 percent of the international market, with Kappaphycus alvarezii being the primary contributor to the country’s production.

Sea grapes, also known as green caviar, is often used in salads, soups and as a natural food preservative.

“We are only utilizing a very small fraction of our available ocean and sea resources for growing seaweeds. We have a (large) economic zone where we can grow seaweeds as a source of (biopolymers). So, that makes us a very potential producer of bioplastics,” Del Rosario shared.
The specialists indicated that seaweeds serve as a significant source of diverse biopolymers that can be transformed into bioplastics, such as carrageenan derived from Kappaphycus and Eucheuma, alginates sourced from Sargassum, agar-agar, and fucoidan.

Nevertheless, Montaño highlighted the importance of mastering the chemistry of these polymers, including the incorporation of bioadditives like glycerol or sorbitol, to attain the desired toughness and flexibility of a bioplastic.

“We have the biopolymer plus additives that would result in bioplastics. This is important to develop a strong bioplastics industry; we must study the chemistry of biopolymers and additives,” he added.

In addition, Del Rosario called upon universities and research institutions to concentrate on isolating long-chain biopolymers, assessing their properties, and optimizing their preparation for the production of bioplastics.

He further noted that additional research and development must be conducted to identify and cultivate new resilient seaweed varieties capable of withstanding climate change while reducing production costs.

“You’ve probably heard of the effect of global warming on the corals. Many of their sea corals are disappearing. We do not want that to happen in the (seaweeds), here in the Philippines,” the academician said.

Once the Philippines advances bioplastics as a viable industry, the two scholars believe it will foster a sustainable economy for coastal communities, particularly in Sulu, Southern Mindanao, and other provinces engaged in seaweed cultivation.

According to Del Rosario, this initiative would propel the Philippines to become a leading producer of both seaweeds and various seaweed-derived products, including bioplastics, alongside Indonesia, China, and South Korea.

“If we have the (seaweed) bioplastics, at least we’ll reduce the pollution. And we produce more products from seaweeds,” they said.

If the environment can gain advantages from seaweeds, agriculture can too. Several years ago, researchers from the National Crop Protection Center at the University of the Philippines Los Banos undertook comprehensive research on carrageenan, utilizing advanced technology that led to an increase in rice yield by over 65%.

These Filipino researchers discovered that when polysaccharide is broken down into small sizes through a safe technological process known as irradiation, it serves as an effective growth promoter and enhances rice’s resistance to significant pests. In fact, at minimal doses, it acts as an efficient organic fertilizer.

Carrageenan, as a growth enhancer, provides numerous benefits that lead to enhanced productivity. When used correctly as recommended, it strengthens the rice stem, thereby improving its resistance to lodging. Additionally, it fosters resistance to the rice tungro virus and bacterial leaf blight, resulting in greater harvests for farmers.

A notable advantage of this seaweed additive is its compatibility with traditional fertilizer application practices, facilitating easier acceptance and reducing resistance among farmers. It also supports sustainable agriculture as it is environmentally friendly and increases the presence of natural predators that combat major pests in rice fields. Furthermore, it enhances the efficient absorption of plant nutrients, promoting better growth.

In a field trial conducted in Bulacan by the research team utilizing carrageenan, rice yield saw a significant increase of 63.6 – 65.4%. This treatment resulted in higher grain weights (450 grams and 455 grams, respectively) compared to the conventional practice of applying nine (9) bags of fertilizer per hectare, which yielded only 275 grams.

The application of six bags of fertilizer per hectare combined with 200 parts per million (or 20 milliliters) of carrageenan is roughly equivalent to applying just three bags of fertilizer per hectare with the same mixture.

Meanwhile, Academician Rafael D. Guerrero III recommends seaweed farming in the country. “It requires low inputs with high returns on investment,” he said. “It is labor intensive and offers good opportunities for the employment of the otherwise labor force in the coastal areas.”