<Jellyfish blooms: Get used to them!> http://www.greenfudge.org/2013/07/1...

I've been picking up this kind of stuff. Be warned human pollution and global warming are causing a jellyfish population explosion that will result in a permanent takeover of the niches presently occupied by bony fish by jellyfish. The magnificent habitat of our tasty, nutritious, and often beautiful bony fishes, our oceans, will in the future be ugly jelly.

The question seems to be: Are Jellyfish going to replace bony fish in the oceans' niches?

I am not sure what to make of it, although my first inclination is to recall what every student in the life sciences learns early on: that natural animal populations almost always have natural boom and bust cycles to various degrees.

Below are examples of 'uncertain' articles regarding the jellyfish population explosion.

<Are Jellyfish Blooms Increasing? Two Studies Reach Different Conclusions> http://www.seaweb.org/science/Jelly...

<Gelatinous Menace? Jellyfish on Boom-Bust Cycle Worldwide> http://www.livescience.com/25889-je...

The simplest model for a boom and bust natural population is the classic prey population being controlled by a predator population. As a population of prey increases, so does a predator that likes that prey, and in reply to that prey's population boom, begins eating it preferentially. Eventually, the surplus of prey crashes due to heavy predator pressure. The predator population then follows suit as its easy-to-get food supply grows scarcer. If one documents such a case for jellyfish and one of its natural predators, then I believe that the increasing numbers of such a predator will eventually act as a check.

Interestingly, I quickly found articles on such a jellyfish predator in the internet. <the research team found that a 4-to-6-inch long fish known as the bearded goby (Sufflogobius bibarbatus) likes nothing better than a meal of jellyfish. The researchers said that their discovery shows jellyfish can play a part in the oceans' food cycle. "We don't know if they are eating dead jellyfish from the bottom, or if they are coming up to oxygen-filled layers to eat jellyfish, but they are eating jellyfish," > http://www.scienceagogo.com/news/20...

There are other known specialized jellyfish eaters, including many species of sea turtles, and the most massive bony fish in the world -the ocean sunfish (Mola mola). Specialized feeders always preferentially feed on a certain prey. In addition, there probably are certain other predatory bony fishes that will preferentially take the low-in-nutrients jellyfish if they notice these occurring in larger easier to obtain quantities. The chum salmon (Oncorhynchus keta) has been reported to regularly eat jellyfish and so have tunas, sharks, swordfish. These fast moving energy consuming fish would normally prefer more nutritional prey, but poorly nutritious fare in large quantities would provide them the same energy value as more fleshy meat in small quantities.

This massive Mola mola has attained its colossal size by converting hundreds of tons of jellyfish meat into its flesh.

http://images.search.yahoo.com/imag...

Interestingly, the most massive sea turtle in the world, the leatherback sea turtle (Dermochelys coriacea), is also a specialized jellyfish feeder.

http://images.search.yahoo.com/imag...

Hmm, I really think you should read the Ender series by Orson Scott Card - originally I recommended them to you for the ingenious premise of the original, 'Ender's Game', but I'm starting to think you'll like the sequels even more. The sequels spin off in two different directions, one following the original protagonist, Ender, and the other, called the Shadow (sub)series, following another protagonist - this second is the line I think is more up your alley, it's more of a psychological tour de force, and nicely dysfunctional at that. ;)

Mediterranean beaches?

Personally, I think I may have experienced a year when there was a jellyfish bloom. Suddenly there were lots of jellyfish. I obviously hate them since they sting, I like them only when I am eating them (",).

Yet the year before that and the next, there were hardly any.

I do know that certain predators such as various sea turtles and the Mola mola are immune to jellyfish nematocysts.

http://www.youtube.com/watch?v=RBdC...

In such cases, the disadvantaged animal must have characteristics going for it in order for it to survive, usually in smaller numbers and in more isolated places. In case of large soft-bodied plankton such as jellyfish, comb jellies, salps, their main defense is also intrinsic to them. They lack the highly nutritious swimming muscles predators crave to eat, and so are nutrient poor. They are about 93% water, and only 7% protein. Thus it is not energy efficient to seek them out and eat them. Notice that both the sea turtle and the Mola mola compensate by feeding on huge masses of jellyfish in order to satisfy their energy requirements. Further note that these jellyfish obligate feeders grow slowly compared to predatory fish such as tuna that consume high calorie foods.

I have read though that chum salmon preferentially eat comb jellies, which do not have the jellyfish nematocyst, unlike other salmon that usually eat crustaceans and fish. I would guess that the chum salmon must consume large quantities of these comb jellies and less poisonous jellyfish. If salmon, tuna, and sharks, significant large and relatively numerous predators of the sea, can tolerate jellyfish stings enough to eat them, it would mean that jellyfish can never take over the oceans unless these predators are totally killed off. Jellyfish are slow, and in fact are hapless in the face of predator fish and turtle attacks, and have no defense except to say "Don't bother to hunt and eat me, you just waste more energy doing so than what you can get from me".

Fast swimming powerful fishes such as salmon and tuna also need well oxygenated water in order to support their high metabolic rate. Tuna have been found to be endothermic, maintain a higher temperature than their environment, like us mammals. With a much lower metabolism, jellyfish would be able to escape from such fast predators by going into less oxygenated waters.

Even then, there will always be fish that will preferentially eat them, that also happens to tolerate poorly oxygenated environments, such as the above-mentioned sea goby. The goby (and the Mola mola) might also be slow compared to tuna, but they are way much faster than jellyfish.

The only way jellyfish can take over the oceans is probably for some colossal anoxic event to take place in the oceans. And even then, the evolution of fishes that can also tolerate such an event, such as gobies, might still stop the jellyfish from a comeback.

I would rather eat them (",). They don't have much of an intrinsic taste, but make for good crunching; I believe specialty chefs know how to spice them up.

<<VBD> and a good thing>

Smoking gun evidence that life has existed since at least 3.4 billion years ago. Though it's unclear how life started in the first place; that's another long topic to discuss.

Anaerobic (such as the sulfur bacteria discussed in the above article) life ruled Earth for the next billion years with more or less the same pieces playing out their evolutionary games over this environmental board.

In <twinlark's> forum, I have posted discussions on the metabolism of anaerobes. Some anaerobic sulfur bacteria were using non-oxygenic photosynthesis during this era of anaerobes; and until today they use hydrogen or hydrogen sulfide instead of water H2O as reducing agents. The most significant change of players on the Earth board occurred when a clade of microbes, which evolved into cyanobacteria, appeared on the board, having the capacity to harvest the Sun's photons around the visible light spectrum to split water and then use the hydrogen to reduce CO2 and fix it into organic molecules. Oxygenic photosynthesis was born.

<Microfossils, stromatolites, and chemical biomarkers in Australia and South Africa show that cyanobacteria containing chlorophyll a and carrying out oxygenic photosynthesis appeared by 2.8 Ga, but the oxygen level in the atmosphere did not begin to increase until about 2.3 Ga.> http://link.springer.com/article/10...

We can see from the above article that since 2.8 billion years ago the new pieces on the board, the cyanobacteria, began changing the board itself by pumping in free oxygen into the atmosphere. After all the oxygen sinks had been used up, free oxygen began accumulating in the atmosphere, the Oxygen Catastrophe for anaerobic life that could not tolerate free O2, but for us aerobes better termed as the Great Oxygenation Event. The anaerobic to aerobic shift is probably the greatest phase change of the Earth board, and it was brought about by a new piece.

It took a long time for a living organism to evolve oxygenic photosynthesis logically enough; it's takes a large amount of energy capital to split water H2O, much more so than non-oxygenic photosynthesis that uses H2S. It's still unclear how the enzymes and chemical reactions evolved in the ancestors of cyanobacteria.

Later there were several more big evolutionary change of players (but not as big as the evolution of oxygenic photosynthesis) that changed the Earth board itself. I believe that some of them are:

1. The evolution of eucaryotes, which later gave rise to multicellular life.

2. The invasion of the continents by multicellular plants, which allowed the total area of the Earth wherein oxygenic photosynthesis occurs to expand by 30%; and physically and chemically changed the rocky surface of the continents into the the soil dominated verdant landscape we know today. Animals from the sea seeking new food sources soon naturally followed the plants into land. Eggs hatching and live birth on land evolved.

This reminds me of earlier posts I made several scrolls above regarding CO2 levels, which I will discuss again.

Let us assume that the Wikipedia articles on past O2 and CO2 levels are more or less correct.

<Triassic> Period 250 to 200 Ma (million years ago). Mammals first evolved in this Period, and must have been adapted to its atmosphere. Note the relatively low O2 level and high CO2 levels compared to modern values:

O2 16 Vol % (80 % of modern level)

CO2 1750 ppm (6 times pre-industrial level)

<Jurassic> 201.3± 0.6 Ma to 145± 4 Ma. Note that CO2 level slightly increases and there is a big jump up by the O2 level. First this demonstrates that an increase in atmospheric CO2 does not result in a decrease in O2. What could have happened is that as CO2 levels increased, so did oxygenic photosynthetic rates, thus inputting more O2 into the atmosphere.

O2 26 Vol % (130 % of modern level)

CO2 1950 ppm (7 times pre-industrial level)

<Cretaceous> 145 ± 4 to 66 million years (Ma). The spike up of atmospheric O2 continues, indicating that oxygenic photosynthesis is still in full swing, but stops at 30%. At such high O2 levels, forest fire rates must have increased to an all time high and might have exerted a negative feedback on further O2 increase. CO2 level also slightly deceases back to the Triassic level (6 times pre-industrial level), probably because of continuous burial of massive amounts of plant material.

O2 30 Vol % (150 % of modern level)

CO2 1700 ppm (6 times pre-industrial level)

<Paleogene> or Lower Tertiary 66 to 23.03 million years (Ma). Something unusual happens. There is a big drop in atmospheric CO2 to less than a third of its previous level in the Cretaceous! Why? Still one of the big mysteries of science. Most probably multi-factorial, and I hypothesize it could have been partially due to the evolution of C4 plants, in the Oligocene around 25 to 32 million years ago. C4 carbon fixation is one of biochemical mechanisms by which CO2 is fixed. C4 plants fix and sequester CO2 and use water much more efficiently than the usual C3 plants.

Note that as the CO2 drops, so does the atmospheric O2 level. This simply indicates that atmospheric CO2 is the main source of free O2. Naturally, plant material get buried all the time and so lots of atmospheric carbon must have been entering long term sequestration into the Earth's crust.

O2 26 Vol % (130 % of modern level)

CO2 500 ppm (2 times pre-industrial level)

<Neogene> 23.03 ± 0.05 million to 2.588 million years (Ma). We get to the modern period. CO2 level continues crashing down to barely sustain oxygenic photosynthesis. Modern plants seem to have been on the verge of CO2 starvation in our modern period. C4 plants, which are especially efficient in obtaining and fixing CO2, continue to proliferate. Today, C4 plants represent about 5% of Earth's plant biomass and 3% of its known plant species, yet they account for about 30% of terrestrial carbon fixation. http://www.ncbi.nlm.nih.gov/pmc/art...

O2 ca. 21.5 Vol % (108 % of modern level)

CO2 ca. 280 ppm (1 times pre-industrial level)

<Quaternary Period> from 2.588 ± 0.005 Ma to the present. Probably no statistically significant changes from past Neogene levels. One can always expect some small ups and downs.

O2 ca. 20.8 Vol % (104 % of modern level)

CO2 ca. 250 ppm (1 times pre-industrial level)

It's possible that the evolution of C4 plants, the most efficient living organisms to do oxygenic photosynthesis, might be another board changer initiated by the pieces themselves.>

To continue, it's probably not only C4 plants. The beginning of the actual drop in CO2 occurred earlier than the evolution of C4 plants.

Another possible player or piece that began affecting the Earth board may be diatoms. Diatoms are the phytoplankton that accounts for nearly 50% of the oceans primary productivity, probably because they are more efficient than other phytoplankton in fixing CO2. It's theorized that making cell walls out of silica, unlike other other phytoplankton (dinoflagellates, free living cyanobacteria, etc) is related to this. Diatoms probably evolved in the Triassic, but became the dominant player in the Nature's silicon cycle perhaps only in the Cenozic Paleogene. If they were (as they are at present) more efficient than other phytoplankton in fixing CO2, they would then function like the equivalent of C4 land plants in the oceans in terms of efficient CO2 sequestration.