Could Reef Tanks become Refuges for Fish and Corals?
 

I am not sure if anybody else has thought this, but with all the crazy things climate change is going to do to fish and corals, has anybody ever thought reef tanks could become refuges for aquatic life?

yes.. its long been talked about for as long as I've been in the hobby (around 12 years now)

There are some groups in the Asian Pacific area that grow frags and re-plant them in the ocean.

Not likely since we cannot really breed most fish and coral. With wild populations gone, remaining individuals in captivity would not have enough genetic diversity (especially corals that are frags from a single mother colony anyways). This is called minimum viable population, it ranges for different organisms but it is still in the order of thousands.

If that happens, we will continue to have alive specimens in captivity, but those spices would most likely be extinct in wild.

Corals can be kept this way for a very long time. But such a fish will be extinct in captivity as well in 10-20 years.

Well, I figured it wasn't an original idea. It sucks that it really is not a valid option. Hopefully we can turn it around, but I am not holding my breath. Even if we manage to turn it around for the better, we might not even be able to stop what is going to happen to the ocean. It is sad that a lot of the fish in the hobby could disappear due to this. Just curious, what is the main reason behind us not being able to captive breed most species in the hobby?

My thoughts exactly. My son just did a class project on the Thylacene (Tasmanian Tiger) that became extinct in the wild but individuals survived in zoos. Not adequate breeding populations to reintroduce to the wild.

Fry of the most marine fish have long palegic life stages where they drift in the open ocean with plankton. This life stage can last for months for some species until they develop into juvenile form and settle into an appropriate environment.

Although marine fish regulatory breed even in home aquariums, fry cant be kept alive long enough to develop into juvi form.

There is two major reasons for this. First; equipment like pumps, skimmer, etc kill eggs and fry. Second most fish fry start life extremely small and require very specific types of planktonic food that we know very little about. To make things worse, what they eat change quite rapidly as they grow. So even in very specific setups that dont have pumps and etc, they most starve. Some people have success growing the fry up until a specific size, but after that they cant find what the fry would eat and they starve to death. Also keep in mind, fish fry are inefficient feeders, so you need to feed a lot, which also makes it hard to keep water quality sufficiently good (which fry are very sensitive to).

There are other minor issues such as problems with artificial lights, fry getting killed by micro-bubbles, cannibalism due to uneven growth rates, swim bladder problems, fry clumping at the sides of a tank, developmental anomalies, pathogens...

Even at laboratory settings with great effort and research, it took decades to captive breed yellow tang and blue tang. And even to date, mortality rates among these fish are very high and they are prone to have morphological anomalies.

Mote Marine Laboratories is sexually reproducing corals and repopulating reefs in Florida. Dr. Chris Page gave a presentation to the local reef club in 2016 and one of the problems they have is getting enough permits to transplant all the juvenile colonies they produce. As far as our systems being "Arks" for corals while we are able to keep them for long periods of time there is a potential issue with senesence. A recent request by UT for A. milli frags for genomics research found one of the local aquarists frag did not produce any viable DNA even though it and the mother colony "looked" to be very healthy.

thanks for the info, do you have any more info/pics on the ut mille, most of the corals I see in lab conditions are very bleached and unhealthy im guessing from being placed in a new setup, maybe the frag lost a lot of tissue from being fragged and going into the lab setting, and if given time to grow back into a colony could produce enough viable dna? I have had acros, leathers, lps spawn in captivity but they are usually colonies before they send out eggs, not 2" frags

humans are a parasite

Sadly seems to be the truth

Thanks for the info! What does this whole thing say for the future of the hobby? It sounds like we could lose most species we currently keep.

Huh, it seems like the biggest problem is genetic diversity.

Its a bit complicated. There are definitely some that absolutely depend on corals, such as the orange spotted filefish that feeds on acropora polyps, or corallivore butterfly fishes. Populations of those fish correlate exclusively with coral reefs.


But not all reef fish absolutely depend on corals. Some regions that reef fishes are collected from are not actually rich coral producing reefs. Best example is Hawaii which have very low coral growth. Those fish will be fine.


But also keep in mind that not all environment would remain the same if corals disappear. Without live corals to continue building limestone, some reefs would eventually reduce into coral rubble and than sand (most of the great barrier reef and the red sea are like this). With the rocky environment gone, fish will disappear as well.However, certain regions that are built one volcanic rock or lifted continental shelf rock would be spared as volcanic/continental basaltic rocks are much harder to erode into sand (this includes hawaii,fiji and other types of volcanic island reefs, southern japan, some of the indopacific reefs, Caribbean).

So, if I have this right, it sounds like we will lose a portion of fish kept, but will still have a number of keep-able species?

Even though the reef tank "ark" concept isn't generally viable there are real conservation benefits to the hobby

- Reefers get to witness behaviours, experiment and observe in a closed environment. These types of observations are difficult in the wild and have led to important discoveries.

- Public and private aquariums have an enormous educative impact and generate advocacy for the worlds oceans.

- Simple economics. The aquarium trade is such that there is an economic imperative to maintain and rehabilitate wild habitats.

I guess most of the fish that have absolute requirement on live corals, such as corallivores, are not regularly kept in aquariums. These kind of fish like the beautiful corallivore butterflyfishes, orange spotted filefish, some angelfishes and morish idols (latter two are mostly spongivore but do eat corals as well) already adapt very poorly to captivity and/or to captive diet. So just based on hobby perspective, there wont be a large loss, at least in the short term.

In the short term, dead coral reefs will continue to provide shelter to remaining reef fishes. But in the long term, like 200 years from now, those reefs will start to reduce into ruble and sand with the exception of certain reefs I explained above. It will cause large scale habitat loss to all reef fish; for example fish like chromis or anthias do not need live coral, but they do hide inside the Acropora branches. They can continue to hide in dead coral until it erodes away, after that they will disappear from that region as well. .

Thanks for the explanation!

This is a great point and probably the best explanation of how aquarists can help towards conservation by way of education.

I probably should have prefaced the third point by saying that the aquarium trade is only an economic driver of conservation if we source and buy ethically.

That was assumed on my end but good point.

Do you have a link to this?
If an animal did not produce viable DNA, it must be dead already.


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My guess is this was referring to viable gamete production.

Home aquaria a refuge, no. Probably not in the long term or big picture. On the other hand I think aquariums like the one on Monterey, Atlanta, or say Churaumi in Okinawa Japan could be. I'm sure there are others but these are a couple examples anyway.

I'll say this though - this is a hobby that can be self sustaining by sharing of coral frags, anemones that split, captive breeding of fish, among other things. Rock and sand can, and are, being aquaculture that help the hobbyist and environment by the reefs they form. While collectors of rare fish, and even us that collect fish that can't be captive bred, would throw a fit we can at least do our part with the rest and lower the burden.

Just the way I see it anyway.

It wont work even for the large aquariums with science programs. Gene pool of animals in captivity are always severely reduced. For example there are more tigers in captivity (just 5000 in US) than there are in wild (3200), but almost all captive tigers (let this bee zoos, reserves or Private ownership) are decedents of 100-200 individuals. So there is extensive inbreeding. If wild population goes extinct, captive species could not be used to reintroduction to wild to to severely eroded gene pool of the captive population.

@Tripod1404 - yes, agreed. Reintroduction never actually crossed my mind. I was thinking more of keeping around until end of life. I know inbreeding is causing a major issue with certain dog breeds and I thought I also read somewhere with certain types of fish (clowns maybe?). All good points never the less.

Also didn't know that tidbit about tigers.