AEFW experiments and study

[tektite]

I've posted this on a few other reef forums, but figured I can't forget my first reef forum I participated in

Awhile back I took in some frags from a fellow hobbyist that weren't doing good for them. Turns out some of them had Acropora eating flatworms (AEFW). I did what research I could to find out more, but there's not much scientific information out there.

A big thanks goes to an LFS who gave me their entire collection of Acropora when they discovered a customer had given AEFW to them. While eradicating the AEFW for the LFS, I became quite interested in the little guys. Even found a dip that kills the embryos inside the eggs, but more study is needed on that (will be a later experiment).

I was able to clean the LFS frags of AEFW and returned them, but left AEFW on my own personal SPS. I don't have many, but what I have are now hosts to a deliberate population of AEFW. Hopefully I can keep most of them alive while infected over time. I contacted Dr. Kate Rawlinson, who's done the only real scientific study on AEFW I could find. After a number of emails, we will now be working together to do some more research on them.

Any information we discover I'll post in this thread. It won't be a fast process, but I hope over time we can find some valuable information to help hobbyists against this common SPS pest.


Few quick pics:

Adult AEFW:


Large AEFW moving over SPS polyps. Its mottled appearance makes it blend in extremely well to the host acro:


Badly infested acro showing bite marks and eggs:


Short video, sped up 4x. The flatworm wasn't happy with the compartment, it had just been moved from its host acro, and was holding itself up trying to find something other than the plastic to grab onto:

[video]www.youtube.com/embed/r2UTZHAnxqY[/video]

 

[tektite]

This is my current list of question I want to eventually answer:

Top 3:
How long it takes adult AEFW to die with no host
How long it takes eggs to hatch
How long it takes AEFW to go from hatch to adults capable of egg-laying

More involved questions, that will be harder to experiment with so will take more time:
Natural length of life with full access to food
How frequently can an AEFW lay batches of eggs?
Does temperature affect any of the Top 3 time periods?
Is AEFW health/strength/capability to lay eggs affected by how sick their host coral is?
Which Acropora species are most likely to be heavily infested?
Are some species of acro capable of remaining healthy when heavily infested?
Does the species of host acro affect any of the Top 3 question results?
Natural predators of AEFW and effectiveness – acro crabs, wrasses, etc.
Is there more than one kind of AEFW, are some more hardier than others?
As they are nocturnal, how does an extended or constant light period affect their life cycle?
How frequently can a healthy adult AEFW lay eggs?

Control and eradication:
Different dip efficacy on AEFW, of ones hobbyists commonly use – Bayer Advanced insecticide, CoralRx, Revive, Lugol's, prazi, maybe RPS All Out (very curious to scientifically prove or disprove their claims it kills AEFW eggs, as they seem incapable of providing any of their own study's data).


If anyone has other questions they're interested in, please post them and I'll add them to my list!

 

[tektite]

I began Experiment 1 a week and a half ago, I'll post my observations from it in the next few posts.


Experiment 1:

Survival period for hatched AEFW of all sizes with no access to Acropora hosts.

Questions to be answered:
Length of time from removal from food source to death?
Do smaller AEFW die sooner than larger ones? Or do the smallest ones not die as fast as they still have yolk reserves post-hatch?

Side questions:
Will gravid AEFW lay eggs in the compartments away from Acropora?
Are AEFW more active during the day or night?


I built an acrylic container to hold the AEFW. It has 5 compartments, 4”x4”x4” each. It is watertight, so even the tiniest AEFW will not be able to get out. The AEFW will be sorted in each compartment by size, and obviously gravid AEFW will be in a compartment of their own. Macro pictures will be taken every day of each compartment's inhabitants. The container will be floating in the main display tank, so the AEFW will have the exact same conditions as when they were on the acros. Same temp, lighting cycle, water parameters. 80-90% waterchanges will be done once a day in each compartment, and the container will be partly covered to keep evaporation down.

 

[tektite]

Day 1 of experiment 1 (Nov 5th), start 12pm:

Container being used:


Adult AEFW harvested off of several various species of Acropora. Removed from the acros by directed water jet, as gently as possible. Sorted by size in the 5 compartments of the container. Each compartment is 4”x4”, water 3” deep. Container is hooked to the side of the aquarium the AEFW came from, giving them the same temperature, light cycle, and water conditions as they came from. Partially covered with a translucent white acrylic lid, to help cut down evaporation and a little light as they are closer to the light in the container than they were on the corals.

Compartment 1: 6 AEFW, ranging from 8-12mm
Compartment 2: 10 AEFW, ranging from 6-10mm
Compartment 3: 10 AEFW, ranging from 4-6mm
Compartment 4: 10 AEFW, ranging from 2-4mm
Compartment 5: 10 AEFW, ranging from 1-2mm


AEFW may be more active at night. Many AEFW taken from corals were observed either underneath the branches of the corals, or tucked into forks of branches.

 

[tektite]

Day 2, Experiment 1 (Nov 6th):

Compartment 1: One cluster of eggs observed on bottom of container
Compartment 2: 3 AEFW found on surface of water in morning, eggs observed laid in 3 separate sections in a straight line along the edge of the bottom.
Compartment 3: 6 AEFW found on surface of water in morning, otherwise no change
Compartment 4: No change, all AEFW present
Compartment 5: No change, all AEFW present

Notes:

AEFW can crawl out on the surface of the water. May need to adjust the experiment container for a second test run that has running water of some kind to help prevent this

Compartments 1 and 2 had eggs present this morning that were laid overnight

90% waterchange at 9:30am
80% waterchange at 8:00pm

AEFW confirmed as nocturnal, are almost motionless during the day in the test compartments, but moving around freely after lights-out. All eggs laid to date were done so during the night

 

[tektite]

Day 3, Experiment 1 (Nov 7th)

Compartment 1: 3 new egg clusters (4 clusters total to date), 1 AEFW dying
Compartment 2: 2 new egg clusters (3 clusters to date), 1 AEFW dead, 1 AEFW missing, 8 present
Compartment 3: 5 new egg clusters
Compartment 4: No change, all AEFW present
Compartment 5: No change, all AEFW present


Notes:

All eggs were laid overnight, observed in the morning

Starting to lose a few large AEFW. It is possible because of their size that they sustained more damage from the directed water jet used to remove them from the acro originally than the smaller AEFW, or egg-laying shortened their lifespan with no access to food

80% waterchanges performed 9am and 9pm

 

[tektite]

Day 4, Experiment 1 (Nov 8th)

Compartment 1: 3 new egg clusters (7 clusters total to date), 1 AEFW dead, 5 AEFW present
Compartment 2: 2 new egg clusters (5 clusters total to date), 1 AEFW missing, 7 AEFW present
Compartment 3: No change (5 clusters of eggs to date), all AEFW present
Compartment 4: 1 small cluster of eggs (~7 eggs), all 10 AEFW present
Compartment 5: 1 AEFW missing, 9 AEFW alive

Notes:

All eggs were laid overnight, observed in the morning

Especially with only 6 AEFW in compartment 1, since it now has 7 clusters of eggs, at least one worm has laid more than one batch of eggs at this point

Compartment 4 had eggs this morning. That is the 2-4mm size range compartment. Knowing it is possible for them to lay eggs that small is helpful for future experiments, especially figuring out how long it takes to grow from hatch to egg-laying sexual maturity.

80% waterchanges performed 9am and 9pm

 

[tektite]

Day 5, Experiment 1 (Nov 9th)

Compartment 1: 2 new egg clusters (9 to date), all remaining 5 AEFW present
Compartment 2: 2 new egg clusters (7 to date), all remaining 7 AEFW present
Compartment 3: 1 new egg cluster (6 to date), all 10 AEFW present
Compartment 4: No change, all 10 AEFW present
Compartment 5: All remaining 9 AEFW present

Notes:

All eggs were laid overnight, observed in the morning

Waterchange performed at 7pm

 

[tektite]

Day 6, Experiment 1 (Nov 10th)

Compartment 1: 3 new egg clusters (2 very small, 12 total to date), all remaining 5 AEFW present
Compartment 2: 2 new egg clusters (9 to date), 1 AEFW dead, 6 AEFW present
Compartment 3: 3 new egg clusters (9 to date), all 10 AEFW present
Compartment 4: No change, all 10 AEFW present
Compartment 5: No change, all remaining 9 AEFW present

Notes:

All eggs were laid overnight, observed in the morning. Egg clusters are much smaller now than when they were first removed from the Acropora, ½ – 1/3 the number of eggs.

Waterchange performed at 12pm and 9pm

 

[tektite]

Day 7, Experiment 1 (Nov 11th)

Compartment 1: 2 new egg clusters (14 total to date), all remaining 5 AEFW present
Compartment 2: No change (9 total egg clusters to date), all remaining 6 AEFW present
Compartment 3: 1 new egg cluster (10 total to date), all 10 AEFW present
Compartment 4: No change (1 egg cluster to date), all 10 AEFW present
Compartment 5: No change, all remaining 9 AEFW present


Notes:

Egg laying slowing down

Waterchange performed at 10am and 10pm

 

[tektite]

Day 8, Experiment 1 (Nov 12th)

Compartment 1: No change (14 total egg clusters to date), all remaining 5 AEFW present
Compartment 2: 1 new egg cluster (10 total egg clusters to date), all remaining 6 AEFW present
Compartment 3: No change (10 total egg clusters to date), all 10 AEFW present
Compartment 4: No change (1 egg cluster to date), all 10 AEFW present
Compartment 5: No change, all remaining 9 AEFW present


Notes:

No deaths of AEFW of any size for the last 3 days

Waterchange performed at 10am and 10pm

 

[tektite]

Day 9, Experiment 1 (Nov 13th)

Compartment 1: 2 new egg clusters (16 total egg clusters to date), all remaining 5 AEFW present
Compartment 2: No change (10 total egg clusters to date), all remaining 6 AEFW present
Compartment 3: No change (10 total egg clusters to date), all 10 AEFW present
Compartment 4: 3 AEFW dead (1 egg cluster to date), 7 remaining AEFW
Compartment 5: 4 AEFW dead, 5 remaining AEFW


Notes:

Smaller AEFW hit a wall today, many dead, the remaining hardly moving at all

Waterchange performed at 10am and 10pm

 

[tektite]

Day 10, Experiment 1 (Nov 14th)

Compartment 1: No change (16 total egg clusters to date), all remaining 5 AEFW present
Compartment 2: No change (10 total egg clusters to date), all remaining 6 AEFW present
Compartment 3: No change (10 total egg clusters to date), all 10 AEFW present
Compartment 4: 6 AEFW dead (1 egg cluster to date), 1 remaining AEFW
Compartment 5: All remaining 5 AEFW dead – compartment empty


Notes:

As of today, all of compartment 5, the smallest AEFW, are dead. They were the 1-2mm group in size. Just 1 remaining AEFW in compartment 4, the 2-4mm size group, the largest of them is the sole survivor. Multiple experiment runs will verify or disprove these results, of the smaller AEFW all dying around days 9-10. The larger AEFW continue to live, but are much much less active at night than when first removed from the Acropora.

Waterchange performed at 10am and 10pm