Effects of biofloc effluent in different regimes as a fertilizer for Kappaphycus alvarezii: indoor maintenance and sea cultivation

• Published in: Journal of applied phycology 2021-10, Vol.33 (5), p.3225-3237
• Main Authors: De Martino, Rodrigo, Mariot, Luiza Vieira, da Silva, Fernando Zwierzikowski, Simioni, Carmen, do Amaral Carneiro, Marcella Araújo, Oliveira, Eva Regina, Maraschin, Marcelo, dos Santos, Alex Alves, Hayashi, Leila
• Format: Article
• Language: English
• Subjects: Algae; Biofloc technology; Biological fertilization; Biomedical and Life Sciences; Carrageenan; Chemical analysis; Cultivation; Ecology; Effluents; Fertilization; Fertilizers; Freshwater & Marine Ecology; Growth rate; Indoor environments; Kappaphycus alvarezii; Life Sciences; Light microscopy; Low temperature; Maintenance; Mineral nutrients; Nutrients; Optical microscopy; Phycocyanin; Pigments; Plant Physiology; Plant Sciences; Seawater; Seaweeds; Seedlings; Starch; Tanks; Transplantation; Water analysis
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-021-02539-4

This work aimed to establish the nutrient fertilization regime for indoor maintenance of Kappaphycus alvarezii seedlings during periods of low sea temperatures using biofloc effluent as a fertilizer. Moreover, we evaluated the development of seaweed seedlings after transplantation into the sea cultivation in Santa Catarina, Brazil. Seedlings were fertilized with biofloc effluent diluted by 25% in three different nutrient fertilization regimes for 4 weeks: single fertilization (SF): seedlings were fertilized for 1 week and remained in seawater for the following 3 weeks; alternating fertilization (AF): alternated 1 week with nutrient fertilization and 1 week without, and continuous fertilization (CF): seedlings were cultivated continuously with biofloc effluent. After this period, samples of each treatment were transferred into the sea cultivation and kept for 5 more weeks. The daily growth rates of plants cultivated in SF and AF were significantly higher than CF in indoor maintenance. However, in sea cultivation, the daily growth rates from AF and CF were significantly higher than SF. In both cases, there were no differences in the carrageenan yield between treatments. Light microscopy and quantification of floridean starch and pigments showed that after the sea cultivation period, floridean starch presence changed from cortical to medullar cells depending on the treatment, but no significant difference in the quantity was observed. Also, seedlings of SF treatment showed a significantly higher phycocyanin content compared to CF treatment. Based on the results, we suggest the continuous fertilization for indoor maintenance in tanks of seaweed seedlings with biofloc effluent.