Allelopathic effects of Margalefidinium polykrikoides on Pyrodinium bahamense under different nutrient condition

• Main Authors: Al-Has, Asilah, Mohammad Noor, Normawaty, Mohd Shaleh, Sitti Raehanah, Mustapha, Shuhadah, Darnis, Deny Susanti, Ayub, Mohd NorAzman, Adam, Aimimuliani, Mustakim, Ghaffur Rahim
• Format: Conference or Workshop Item
• Language: English; English; English
• Published: 2021
• Subjects: Q Science (General)
• Online Access: http://irep.iium.edu.my/94585/1/Al-Has%20ICHA%2070.pdf; http://irep.iium.edu.my/94585/2/Asilah%20Al%20Has_HA%20ECOLOGY%5B2009%5D.pdf; http://irep.iium.edu.my/94585/3/SCIENTIFIC%20PROGRAM%207%20oct.pdf; http://irep.iium.edu.my/94585/

Co-occurring of Margalefidinium polykrikoides, a fish killer and toxic Pyrodinum bahamense have been commonly observed in the coastal waters of Sabah, Malaysia. During most of the events, M. polykrikoides will dominate the bloom and suppress P. bahamense. The reason for this condition is unknown. Therefore, this study explores the interaction of these species and try to understand under which nutrient conditions M. polykrikoides will become dominant over P. bahamense. To achieve this, the allelopathic abilities of M. polykrikoides on P. bahamense were investigated in different ratio of Nitrogen (N) and Phosphorus (P) concentrations in bi- algal and filtrate conditions. The bioassays were tested via bi-algal experiments at three ratios: 1:1 (500 cells mL-1 of each species, M. polykrikoides and P. bahamense), 1: 5 (100 cells mL-1 of M. polykrikoides and 500 cells mL-1 P. bahamense) and 5:1 (500 cells mL-1 M. polykrikoides and 100 cells mL-1 P. bahamense). For culture filtrates condition, three different volumes of M. polykrikoides filtrates (10, 20 and 50 mL) harvested at exponential phase were combined with 150 mL P. bahamense. Result indicates M. polykrikoides inhibit the growth of P. bahamense and caused morphological changes of P. bahamense in bi-algal culture. The best inhibition of P. bahamense by M. polykrikoides was observed at nitrate concentration at 30 μM and phosphorus concentration at 5 μM. This information will increase our understanding in bloom mechanism of these two important harmful algal blooms (HABs) species.