Under construction! (2012-ACRO001)
Dying Acropora Coral Rehabilitation
parasite
Assessing Coral Health: An Introduction
Even on a smaller scale than global reef decline, the ability to assess coral health is essential. I am often asked how I know where to even start to rescue corals. In my opinion, determining how healthy the coral is, or what the problem might be, is usually the first step. This is an introduction on assessing coral health to determine what might be causing the coral stress.
Assessing Coral Health for Stung Corals:
Corals stung by another coral are probably the most easy to save. These corals are healthy overall, but a portion of them is damaged. As long the coral avoids infection and no further damage occurs, then healing is rather quick. When a coral “stings” another coral, the stung coral is sometimes actually “digested.” When corals have to compete for territory, they expel their digestive organs, called mesenterial filaments, and use them to digest a nearby coral. This typically results in one area of severe damage and no damage elsewhere. A coral stung this coral shown, but the remaining tissue was very healthy. You can read more about the Trachyphyllia’s recovery here.
Lack of Proper Husbandry:
A lack of proper husbandry is typically a slow process. It can result in the tissue between polyps receding first. As shown here, portions of recent die-off right are beside healthy tissue and coralline-encrusted skeleton. With these corals, good water parameters are essential. Removal of invasive algae is also critical. These corals typically do not need much additional care. You can read more about this Lobophyllia’s recovery here.
Assessing Poorly-Fragmented Corals:
When a coral is improperly fragmented, various outcomes are possible depending on damage. Sometimes the tissue rips apart improperly, or the skeleton is crushed underneath intact tissue. As long as there is about half the polyp left, the coral typically survives with the natural healing process. This Euphyllia coral unfortunately became infected and died.
Corals with Pest Damage or Parasites:
Attempting to rescue an infected coral is risky, as it may infect other corals. This type of rescue requires a proper quarantine tank and medications on hand. Typically, once the pests and any eggs are removed, the coral will heal quickly on its own. Here, this infected Acropora has both Acropora-eating flatworms and red bugs (Tegastes acroporanus). With proper treatments to remove both pests, this coral made a full recovery.
Assessing Coral Health due to Infections:
Attempting to rescue infected corals can be dangerous, complex, and expensive. Any attempts require a dedicated hospital tank, proper supplies (including a microscope), and extensive knowledge in coral diseases and treatments. Furthermore, keeping a low expectation for coral survival is key. These infections vary by cause (e.g., bacterial, viral, fungal, ciliate, etc.), so the owner must tailor treatment to the cause. Determining the cause can be nearly impossible without the proper equipment. Any attempts also require the utmost caution, as some infections are transferable to humans. This coral shown had “brown jelly disease.”
Bleached Corals:
Coral bleaching also has a variety of causes, and knowledge of the cause can help determine possible solutions. Assessing a bleached coral’s health can be challenging as high light, chronic low light, high temperature, low temperature (rare cases), lack of oxygenation, and some infections can cause bleaching. Since a bleached coral is lacking its typical zooxanthallae population (the symbiotic algae that lives inside the coral’s tissues and produces food for the coral), it will need regular feedings. Unfortunately, in my experience, sometimes these corals never thrive again, even with coloration return.
The photo below shows several corals that were poisoned with household bleach. An angry customer poured it into a local fish store’s tanks, which killed all the livestock. I attempted to save everything that still had tissue, but even these corals eventually died.
Starved Corals:
Although starvation is more commonly seen in non-photosynthetic corals (NPS), it is still possible in photosynthetic corals as well. This is more likely to occur in in ultra-low nutrient systems, also known as ULNS. Here, a Dendrophyllia coral is starving, shown by the algae-encrusted skeleton. Regular feedings are essential in these cases.
Poisoned Corals:
Poisoned corals usually have retracted tissue with areas of white skeleton showing. Tissue colors are usually brown or white, depending on the toxin. Any other typical colors (e.g., blues, reds, greens) are muted. This coral was poisoned by either the flatworm treatment a LFS used, or by the flatworm toxins themselves. You can read more about this coral’s amazing recovery here.
As shown, coral health has a multitude of causes, and only a few examples were shown here. If you would like to continue learning about coral pathology, a more technical source is available on NOAA.
Identification of Sea Spiders
Although sea spiders are certainly creepy and may have eight legs like land-dwelling spiders, sea spiders are only distantly related. The sea spiders identified here are more interested in eating coral than eating pods in a reef tank, which makes them all the more scary!
Acanthastrea-Eating Sea Spiders: Not Reef Safe
Here’s another one for your nightmares! For years I had heard rumors of a stealthy Acanthastrea predator, but I had yet to find one (to my relief.) A while back, I attended a coral fragging demonstration, and along with my frag freebie, I also received these lil buggers.
Phylum: Arthropoda (joint-legged invertebrates)
Subphylum: Chelicerata
Class: Pycnogonida (sea spiders)
Order: Pantopoda
Rumor has it that these spiders tend to prefer Acanthastrea (typically called “acans”) corals, but they have also been found on other large polyp stony corals (LPS). Thankfully I eradicated these spiders before I had a chance to find out if they would infect my other LPS corals as well.
This Acan-eating spider shown below (hereafter referred to as AES) has (or had, I should say) eight legs. This is likely a female as the males have a specially modified leg (called an oviger) for carrying eggs (unless I knocked that leg off accidentally too) (Cowles, 2009). As you can see, there is practically no body – it is mostly legs. On the left side of the AES in the photo are the chelicerae (mouth parts) and the proboscis (tubular mouth part for ingestion). As mentioned – these are not true spiders! (Although they still give me the heebie jeebies!)
How to Identify AES:
AES are nearly colorless, so they blend in quite well with the coral. Even after a thorough visual inspection of the coral prior to dipping, I only found these after they fell off in the dip. The ones I found were about 1 cm in diameter (nearly half an inch). So, I recommend a good coral dip prior to introducing the coral into your tank. As they can rapidly eat Acanthastrea corals, proper identification of sea spiders is critical.
How to Treat AES:
Various dips may be effective against AES; however, multiple dips may be required to eliminate any recently-hatched eggs (most dips are not effective on marine pest eggs).
Hydrogen peroxide dip: This is my preferred method for AES. This dip creates bubbles that will actually lift the AES off the coral – they usually can’t hold on! Use this dip with caution as overdoing it can cause serious coral damage. Also, only dip LPS in it. Soft corals and small polyp stony (SPS) corals do not typically respond well.
CoralRx, Lugols, and other commercially-available dips: Although I haven’t used these dips on AES, they should work…possibly with varying levels of effectiveness. Several brands tout effectiveness against pycnogonida (sea spiders).
Natural predators: Certain wrasses and other typical pod-eating-vertebrates may eat AES, but I’m not aware of any definite natural controls.
Manual removal: If your eyes are good enough (or are helped with a magnifying glass), you may be able to manually remove AES with tweezers or a pick. However, you may miss some and end up with a worse problem down the road.
Other: I am not aware of any in-tank treatments (other than possible natural predators). Additionally, Bayer insecticide is a common hobbyist treatment for marine pests; however, it was not designed for reef usage. Please read the label.
AES Conclusion:
Although Acanthastrea-Eating Spiders are quite creepy-looking, they are not a horrible pest to eradicate. They are highly susceptible to coral dips and can even be manually removed. If you know you have AES, please be a responsible reefkeeper and do not pass your coral on without at least notifying the new owner.
Zoanthid-Eating Sea Spiders: Not Reef Safe
Note how different the AES above is from the Zoanthid-Eating Spider (ZES) shown below. The AES is much larger and has a much smaller (proportionally) body. Both have eight legs.
The photo below is of a zoanthid-eating spider that came off a zoanthid colony during a dip in CoralRx. It is in a water droplet on the top of a water test card for size reference.
How to Identify ZES:
ZES are extremely tiny, so they hide quite well in the coral. And, they are able to attach themselves very well inside the zoathid polyp. Even after a thorough visual inspection of the coral prior to dipping, I only found these after they fell off in the dip. The ones I found were about 3-5mm in diameter. So, I recommend a good coral dip prior to introducing the coral into your tank. Since they can devour Zoanthid corals, proper identification of sea spiders is critical.
How to Treat ZES:
Various dips may be effective against ZES; however, multiple dips may be required to eliminate any recently-hatched eggs (most dips are not effective on marine pest eggs).
Hydrogen peroxide dip: This is not an ideal treatment for ZES, as soft corals (zoanthids) do not typically respond well.
CoralRx, Lugols, and other commercially-available dips: These ZES photos were taken after removal with CoralRx, so these preparations may have varying degrees of effectiveness based on brand/solution.
Natural predators: Certain wrasses and other typical pod-eating-vertebrates may eat ZES, but I’m not aware of any definite natural controls.
Manual removal: If your eyes are good enough (or are helped with a magnifying glass), you may be able to manually remove ZES with tweezers or a pick. However, you may miss some and end up with a worse problem down the road.
Other: I am not aware of any in-tank treatments (other than possible natural predators). Additionally, Bayer insecticide is a common hobbyist treatment for marine pests; however, it was not designed for reef usage. Please read and follow the label.
Zoanthid-Eating Sea Spiders Conclusion:
Although Zoathid-Eating sea spiders are quite creepy-looking, they are not a horrible pest to eradicate. They are highly susceptible to coral dips and can even be manually removed. If you know you have AES, please be a responsible reefkeeper and do not pass your coral on without at least notifying the new owner.
References:
Cowles, Dave, “Phoxichilidium femoratum (Rathke, 1799),” https://inverts.wallawalla.edu/Arthropoda/Chelicerata/Pycnogonida/Phoxichilidium_femoratum.html, accessed 18 January 2021.
Fluke Parasites in Reef Tank – Cercariae Stage
“I’ll just feed my tanks before bed.” Famous last words. I spent the next two hours with a microscope and the glow of my computer screen instead of my nice, cozy bed. Even then, it took quite a while to find someone to identify them as likely the cercariae stage of fluke parasites in my reef tank.
A few minutes after feeding my reef tank, I noticed some rather large “pods” swarming around the top of the still water (all pumps were in “Feed Mode” – off). Odd, but nothing too weird. After all, I thought they were Ostracods at first (seed shrimp). On second glance, they looked too big. I paused, and then I realized what really caught my eye. They were red. Other than “red bugs” (Tegastes acroporanus), I’ve never seen red pods. I sighed in hesitation, then accepted my fate. Bed would have to wait.
I took a sample. There was no doubt; these were truly red. Ok, red Ostracods, right? I wouldn’t have to get out my microscope and prepare a slide, right? Wait. Ostracods don’t have tails. Noooooo.
Up Close with a Microscope: Fluke Parasites
I prepared a slide, and nothing could have prepared me for what I would find. I expected something in the definitive worm or pod realm. But not this. This was respiring. It was opening and closing its… mouth?
Close-up of its anatomy… for what it’s worth.
Up until this point, they looked all cute. Like, little swimming strawberries, right? Nooooope. More like Sauron’s Eye (check out the video below).
So what are they? I have no idea. Every idea leads me down the wrong path. The closest I’ve landed is maybe some sort of larval sponge? (See update below.)
Identification: Fluke Parasites
Update (12/27/2020): Thanks to Reeffraff on Reef2Reef back in July 2020, it appears these are likely the cercariae of a trematode or fluke (in other words, they’re likely parasitic). Their life cycle probably involves snails and fish. I was right: these fluke parasites in my reef tank were the thing of nightmares! My treatment was to run fishless for several months (as the snails can shed for weeks/months). Another option, which I did not utilize, was to run PraziPro. I decided against that approach, as the number of worms (e.g., spaghetti, bristle) in my tank would probably cause a crash. I plan to quarantine all future snail purchases in a fishless system to avoid these.