"Blue Tears" is about to enter its peak period! Make these preparations to avoid wasted trips!

On the evening of March 17, level 3 blue tears appeared in the waters of Dongmei Village, Pingtan, Fujian. On the beach at night, the coastline turned into a dreamy fluorescent blue, as if the sea had shed crystal clear tears.

Blue tears are most common from April to June every year, and now is the early stage. It's spring, so it's a good time to see the romance of blue tears!

Pingtan's Blue Tears｜TuChong Creative

01

What are blue tears?

"Blue tears" mainly involve some tiny, bioluminescent plankton . When the seawater is disturbed by the outside world, it also disturbs them, and chemical reactions will occur inside or outside their bodies, producing a faint blue light.

Simply put, blue tears are the phenomenon that these plankton emit blue light. Sometimes, blue tears are also used to directly refer to these luminous plankton.

In the movie "Life of Pi", there was a scene where many creatures under the sea glowed at the same time, which was very impressive. In this scene, there were glowing fish, glowing jellyfish, and glowing microscopic creatures | "Life of Pi"

When the temperature is suitable , the Minjiang River in flood season brings sufficient fresh water and nutrients to the sea area near the estuary, creating excellent conditions for the large-scale proliferation of plankton in the sea.

With the help of wind and current, a large number of luminous plankton are sent to the seaside and rushed to the beach. Under the beating of the waves, they are stimulated to fluoresce. At this time, people can easily see patches of blue tears, rushing to the beach with the waves. Where fishing boats go out to sea, blue ripples with faint light will also be generated.

The luminescence phenomenon of Noctiluca scintillans appears on the Belgian coast. ｜Hans Hillewaert / Wikimedia

02

Who is shining?

What are the main luminous organisms that cause the Pingtan Blue Tears phenomenon? If you have read the relevant news, you will see two answers: Noctiluca scintillans and fireflies .

Noctiluca is a spherical single-celled organism . Although it is classified as a dinoflagellate, it does not photosynthesize , but instead uses its tentacles to prey on diatoms, green algae, bacteria, and even fish eggs. Therefore, some scholars also call them " Noctiluca ".

In fact, in addition to Noctiluca, many other members of the dinoflagellates can also emit fluorescence, but Noctiluca is indeed the dominant species near the Pingtan waters .

Noctiluca scintillans under a microscope | Maria Antónia Sampayo / Wikimedia

The news said that in addition to Noctiluca, fireflies also gather to form the blue tears phenomenon in Pingtan. Fireflies belong to the Cypridinidae family under the order Ostracodes of the phylum Arthropoda, and most of the members of this family can glow .

So what kind of firefly could be responsible for forming Pingtan’s blue tears?

All the online information I found said it was Vargula hilgendorfii of the Vargula genus. But when I looked deeper, I couldn't find any relevant papers or reports. There is no professional literature support, and no authoritative species identification results, so it is too hasty to conclude that the blue tears of the sea fireflies in Pingtan are formed by the aggregation of the species Vargula hilgendorfii.

The developmental process of the Hesperus scimitarus｜Norio Wakayama / Journal of Zoology (2007)

03

Practice makes perfect: It’s not the Squig-throated Sea Firefly!

Blue tears once aroused my strong interest. In order to be able to witness blue tears for a long time, I chose to marry in Pingtan (big mistake). Finally, in May 2019, I encountered the blue tears landscape for the first time in my life.

The blue tears were not very obvious during those days. During the two hours of freezing waiting every day, I only saw a few flashes of light when the waves hit each other - not very blue, even a bit like the reflection of white waves. But when I got close to the beach where the waves had just hit, I could clearly see dots of blue fluorescence .

After one of the viewings, I had the idea to sample . The blue tears looked slightly different that day. The light left by the little creatures on the beach by the waves lasted longer than before. I immediately grabbed a handful of sand. The little animals in the sand still had a breath of life, flickering in my hands, as if they were breathing. I could even pinch them with my fingers - small things the size and feel of sesame seeds .

I have a feeling that this is a genuine firefly , because compared to Noctiluca, the shell of a firefly is harder and the individual is a bit larger.

I held them in my hands all the way home, and as soon as I got home I put them in a certain concentration of alcohol. Later, I took the samples to the laboratory and observed them under a dissecting microscope. Finally, they showed their true colors under a stereo microscope.

One of the creatures that form Pingtan's blue tears is the firefly. The second picture shows eggs in its belly｜Miaoyujiang

So are they Hesperus scimitarus?

No ! My sister, who specializes in studying sea fireflies in the research group next door, identified these sea fireflies based on the photos I took. She believes that the morphology of these sea fireflies is very different from that of the Scimitar-throated Sea Firefly. They are not even from the genus Scimitar- throated Sea Firefly . They are more like the Cypridina dentata, a common species in the coastal waters of Fujian.

The fireflies I collected during the Pingtan Blue Tears outbreak on a certain day were more like the toothed fireflies in the picture. The tail of the shell of the Hessian curved-throated firefly in the picture below is not as prominent as the tail of the toothed firefly｜《China's Marine Planktonic Ostracoda》

Hesperus scimitarus｜《Marine Planktonic Ostracoda in China》

In rigorous scientific research, nothing is absolute. This time, we collected many tooth-shaped fireflies, which does not necessarily mean that the fireflies that gather to form the blue tears of Pingtan fireflies are of this type. My sister who studies fireflies suggested that I do more sampling to see if there are any other gains.

04

Why do they glow?

In fact, many marine organisms can glow. In the ocean, from bacteria to fish, some members have the ability to glow. Glowing can help them protect themselves, warn natural enemies, or communicate with their own kind.

Bioluminescence is a type of chemiluminescence because their light is produced by a chemical reaction. These organisms can synthesize luciferin and luciferase . Luciferin reacts with oxygen to produce light, and luciferase is the catalyst of this reaction.

However, this statement is relatively broad. In fact, when it comes to different groups or even different species, their luminescence mechanisms are still different.

The luminescence mechanism of various organisms. On the left is the structural formula of the luminescent substance, and on the right is the main organism that emits light using this luminescence mechanism. Image modified from Steven HD Haddock et. al. / Annual review of marine science (2010)

From the above picture we can see that although dinoflagellates represented by Noctiluca scintillans and fireflies both produce fluorescence by releasing luciferin and luciferase, the structural formulas of the luminescent substances of the two are actually different.

In addition, for dinoflagellates, the chemical reaction of luminescence occurs within the algae ; while fireflies excrete the luciferin and luciferase in the body together. Only after these two substances meet water outside the body will luciferase catalyze the luminescence of luciferin.

In other words, after repeated stimulation, there is not a single drop of sea firefly left.

05

Do blue tears mean the sea water is polluted?

There is a view that blue tears are formed by the aggregation of red tide algae . Well, Noctiluca is a red tide algae, but fireflies are not (as mentioned earlier, fireflies are ostracods). In addition, although Noctiluca is a red tide algae, it does not contain red tide toxins - not all red tide algae contain red tide toxins.

However, even if the red tide algae do not contain toxins, their large-scale proliferation may harm the aquatic environment - red tide algae with too high a density will adhere to the gills of fish, shrimp and other animals, suffocating them to death. Dead red tide algae and the bodies of animals that died unjustly will also consume dissolved oxygen in the water and produce harmful substances during the decomposition process, thus affecting the survival of other marine life.

Therefore, coastal aquaculture farmers should be vigilant if a large number of Noctiluca scintillans appear in the sea.

Red tide phenomenon in Ehime Prefecture, Japan in 2017｜melvil / Wikimedia

Some people have mistaken the cause and effect, thinking that the blue tears outbreak is caused by water pollution. In fact, the blue tears effect is only so charming in clear water, and the water pollution will only occur when the density of Noctiluca reaches a certain level.

But don’t be afraid, scientists will carry out real-time monitoring . As long as the density of Noctiluca in the water body is appropriate, the blue tears of Noctiluca will still be a good partner for Pingtan tourism (make fist, nod and look into the distance)!

06

If you also want to be a "tear chaser"

Please listen to me for a few more words. First of all, let me give you a dose of vaccination: even if you prepare a "tear chasing" strategy in advance, it is still possible to go there in vain .

Since blue tears are a wonder of natural biology, it is impossible for us to accurately predict the time and place of their appearance. Otherwise, we can directly predict the outbreak of red tides along the coast of my country, which can easily help coastal farmers avoid the economic losses caused by red tide disasters.

But Pingtan has such a beautiful sea. Even if you can't see the blue tears at night, the scenery during the day is worth seeing! Look at the sky, the sea view, and the stone house!

Let me show you the beautiful scenery of Pingtan that I took. It is good for sightseeing around the island, watching the sunrise, and catching the sea｜喵鱼酱

The best time to catch tears

Pingtan's blue tears phenomenon mainly occurs from April to September, with April and May being the peak season for blue tears . During this period, there may be high-brightness blue tears for several consecutive days, regardless of the weather (windless/strong wind, sunny/rainy/foggy). However, after June, the frequency of blue tears will decrease, especially the frequency of blue tears of Noctiluca, which is probably related to the combined effects of seawater temperature, salinity, ocean currents, and wind direction changes.

After sunset, in places without other light sources, Blue Tears comes on stage. The best experience is in the early morning hours , when the entire island is asleep, and the surroundings are quiet, with only the sound of the waves and heartbeats.

However, if you are unfamiliar with the place, don't be too bold (zuo) (si), be careful not to get lost. It is recommended that you watch the tears together.

The best place to catch tears

Blue tears can be seen along the east side of Pingtan Island, which is the coast facing the Taiwan Strait , from Maotoukan and Changjiangao Windmill Field in the north to Dafu Bay in the south. It is recommended that those who are interested pay attention to some Douyin or WeChat accounts that specialize in live broadcasting Pingtan Blue Tears. These accounts usually send people to squat and inform viewers and readers in time of the location where the blue tears appear on that day.

Pingtan Island sightseeing bus route map | Pingtan International Tourism Island

Oh, I have to tell you. Don't drive a car when you go to the beach. Otherwise, you will be dizzy and your bladder will swell. Although the ring road around Pingtan Island is flat and wide, there is no branch road from Beigang Village to the Changjiangao windmill field, so it is not easy to turn around. In addition, once you go down to the village in the direction of Liushui Town, the road in the village is even narrower, which not only makes it more congested for you, but also for the villagers.

It is better to rent a small electric scooter and ride along as you like.

How to take good photos

If you want to take satisfactory photos and share them with friends and family, then mobile phones are not very effective. It is recommended that you bring a professional SLR camera, set up a tripod , and increase the exposure appropriately when setting. Take a few photos first and then adjust the parameters according to the effect. You will definitely be able to take ideal photos.

The limit of what my phone (iPhone 8) can capture. | Miaoyujiang

These are the blue tears left on the beach. A passerby who was watching the tears with me actually used his mobile phone (Huawei P30 Pro) to take a photo of the nebula effect. | Anonymous passerby

Other considerations

1. Don't use lights, flashlights, or flash when taking photos . Most of the time, blue tears are not obvious and do not last long. External light sources can greatly affect the viewing experience.

2. Don't keep throwing stones into the sea to provoke blue tears. There have been cases where people have thrown stones into the dark sea and accidentally hit fishing boats. Therefore, it is recommended that you watch the tears on the beach instead of at the dock. Watching at the dock is also more dangerous and it is easy to fall into the sea.

3. The most basic and most important thing is not to litter! Protect the ocean, collect plastic waste and throw it into the trash can , don't leave it on the beach. Otherwise, all we will see in the future is a sea covered with plastic waste.

When your eyes get used to the darkness, the light of blue tears will become more dazzling and charming. Step into the water barefoot, paddle with your feet to see the ripples, then lift your legs to see the small creatures attached to your legs emitting star-like lights. Step on the beach, and wherever your feet touch, the fluorescence spreads several centimeters and disappears in a flash. This spring, go and hold on to this romance!

Author: Meow Fish Sauce

Editor: Calendar Girl, Little Towel

This article comes from the Species Calendar, welcome to forward

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