WONDER OF NATURE:
An evolution towards the sexual reproduction of bioluminescent algae caused by a decrease in the number of prey would be at the origin of the marine phenomenon

• By Yu Chao-fu and Jake Chung / Journalist, with editor-in-chief

The “blue tears” in Matsu County could be the result of environmental stresses affecting the reproductive cycle of the organisms that cause the phenomenon, according to a Frontiers in Marine Science study written by a research team at National Taiwan Ocean University.

The blue luminescence in the sea near Matsu from April to August – known locally as “blue tears” – is a tourist attraction and has been listed by CNN as one of the 15 Natural Wonders of the World.

Blue tears occur when sexual reproduction in Noctiluca scintillans, a bioluminescent red tide algae, increases rapidly, Chiang Kuo-ping (蔣國平), a professor at National Taiwan Ocean University, said on Friday.

The study aimed to determine the factors that induce an increase in the sexual reproduction of organisms, which usually reproduce asexually, and the ecological role in this change, Chiang said.

“Reproduction in N scintillans involves both sexual and asexual processes. The vegetative cell, or trophont cell, primarily undergoes binary fission, but randomly undergoes gametogenesis, which produces gametes which then fuse in pairs to form zygotes, ”the authors wrote, adding that gametogenesis – which enables gametogenesis. sexual reproduction – could be triggered by environmental stresses, “including temperature, time of exposure to light, prey concentration, concentration of N scintillans, culture time, culture volume and movement of plants. simulated waves. “

The breeding cycle takes place every year, usually between March and July, with the arrival of sediment from the Min (閩江) River – which enters the Taiwan Strait near Fuzhou in China’s Fujian Province – causing tides red in the morning and “blue tears” at night, Chiang said, adding that the phenomenon usually occurs for one or two days.

The critical value for N scintillans to reproduce sexually was found to be 35,400 prey cells for every N scintillans, indicating that the fewer prey cells there are after some population growth, the more likely it is that N scintillans will occur. reproduce sexually, he mentioned.

The team found that after an exponential phase of population growth, the rate of encounter with prey decreases, causing the rate of sexual reproduction to increase from 1% to 10% of the population, Chiang said.

This results in the flowering of ‘blue tears’ and also lays the foundation for the next flowering period, he said.

The study, Sexual reproduction in dinoflagellates – the case of Noctiluca scintillans and its ecological implications, was authored by doctoral student Jeffery Lee (李良 能), and co-authored by Chiang and Assistant Professor Tsai Sheng-fang (蔡 昇 芳) .

It was published in the November 17 edition of the journal.