Copepod / Amphipod ID

[Dsantamaria29]

Can anyone ID this amphipod?

Backstory: I have been having some issues with corals losing color and have noticed a large amount of these amphipods all over the corals on both healthy and unhealthy tissue, which leads me to believe that they are feeding on the tissue itself and not just algae growing on the coral.

 

[izhmash]

If they are ok your corals flesh i would do a dip ASAP. They cannot be good in my opinion.

They look like a Munnid isopod (or potentially a large harpacticoid copepod). Which are harmless, but the fact that they are all over your coral makes me agree with you. It sounds like they are eating them.

 

[EnterName]

izhmash beat me to it, I would also guess it's an isopod of the Munnidae family. They are in most tanks sooner or later and climb on corals sometimes. They feed on microalgae, mucus, and biofilm which will certainly be increased when surrounding coral tissue is dying.

Maybe you can take a few pictures of affected corals (under white light) and post your water parameters (mainly nitrate, phosphate, alkalinity, salinity) so the community can try to figure out what's going on with your corals

 

[Dsantamaria29]

So I have THOUSANDS of copepods, I have a feeling they have started to attack the corals due to starvation. The reason I'm convinced its them vs something else is I watched these frags go from very good PE with great color to pale, these small copepods / amphipods are all over them at night with the color loss being noticed the next day where they were.

Parameters have been checked about every 12 hours the last few weeks


Salinity: 1.026
pH: 8.27 - 8.32
Alk - 7.7-8.2
Cal - 410 - 440
Mg - 1200-1260
Phosphate - 0.03-.13
Nitrate - 13-20

This was over the last 30 days, alot of the large gaps were dialing in where I wanted the parameters. Over the last 7 days.

Alk: 7.7-7.9
Ca: 410-420
Mg: 1230-1245
Phos: 0.06-0.1
Nitrate: 13-16

 

[Dsantamaria29]

Corals

 

[Dsantamaria29]

You can see them walking around on the frag

 

[EnterName]

For how long has the tank been running and for how long are those frags in your tank?

The rocks look like it's a fairly new tank and SPS frags like Acropora sp. are really delicate. Most reefers recommend waiting for at least 12 months before trying to establish Acropora frags. If you started with mostly dry rock (or fully dry) it can take even longer until the tank is ready.

It's normal to have thousands of copepods and isopods. They don't harm corals even when climbing on them. You are most likely observing a symptom, not the cause.

If you are using LED light that casts rough shadows it's also possible that shaded areas simply bleach. That's one of the reasons why many people still like HQI and T5 lights, which are much softer and don't cast such hard shadows. There are even diffused LEDs for this very reason now

 

[Dsantamaria29]

Added new rocks when tank was transitioned. Tank was transitioned from a 2+ year old tank. Also added TBS rubble to sump.

Tank and old corals transitioned 6/10.
New corals added 6/27.
Light still in acclimation with PAR avg ~180 right now

3x Nicrew Hyperreef 200 LED running highest intensity for 6 hours(~180 PAR)

 

[EnterName]

Added new rocks when tank was transitioned. Tank was transitioned from a 2+ year old tank. Also added TBS rubble to sump.

Tank and old corals transitioned 6/10.
New corals added 6/27.
Light still in acclimation with PAR avg ~180 right now

3x Nicrew Hyperreef 200 LED running highest intensity for 6 hours(~180 PAR)

Hmm okay...

I you are still suspecting those isopods to cause trouble, you might want to find someone with a compound microscope and take another image. You can just hold your phone's camera onto the eye piece (maybe with a small distance), and it should produce decent results.

If you have a way to transfer the images from the digital microscope to your phone or computer this could help as well. Taking a photo from a screen just doesn't work very well and loses a lot of quality

 

[Dsantamaria29]

I took a frag out, shook it and got these right off it. They hold on very tight so I cannot get them off with the turkey baster.

I tried to get the microscope to hook up to the computer to get an image directly off of it, but it’s still not great quality

 

[Dsantamaria29]

Here is a different photo from a different microscope

 

[EnterName]

Looks quite different than the last one you posted (color-wise for example, and the eye spots are more visible).

I think you just have a variety of Munnidae isopods in your tank, but I cannot tell you the exact species. The chance of having two different parasitic isopod species in your tank is very low.

Bopyridae - Shrimp and crab parasites, not corals.
Cryptoniscoids - Crustacean ectoparasites, not corals.
Gnathiidae - Look different and grow larger. They are fish parasites, not coral parasites.
Munnidae - Fits quite well, but I'm unable to find any coral predation associated with Munnidae.
Sphaeromatidae - Often grow larger, legs are being kept below their armor instead of being spread apart. No confirmed cortal-tissue eaters.