Potassium permanganate
Trial 1 ? effect of 50mg/l dose on nudibranchs over two hours
I dissolved 50mg potassium permanganate (Sigma, Inc.) in 1000ml aquarium water in a shallow plastic dish. I removed 25 nudibranchs from a single plating colony of
Montipora (MS1) and placed them into the container with the solution. I placed another 25 nudibranchs into another shallow plastic dish with only 500ml aquarium water. The following timeline describes the effects as viewed under a Nikon dissecting microscope:
t=1 minute
- nudibranchs immediately in motion as though reacting to noxious agent
t=5 minutes
- nudibranchs twisting and curling, cerata tightly folded against body, some raising heads up in water column
t=30 minutes
- <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">nudibranchs moving very slowly, seven have detached and are floating in water but are reactive to a probe; treatment water becoming brownish
- three nudibranchs removed and placed into 500 ml fresh seawater
t=60 minutes
- <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">nudibranchs appear nearly dead, some are disintegrating; water appears brownish.
- nudibranchs removed appear motionless and unattached; unreactive to probe
t=120 minutes
- <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">complete disintegration and no nudibranchs visible in water
- nudibranchs removed are dead and cerata are detaching; no further disintegration as with those still in treatment water
Trial 2 ? effect of 50mg/l dose on coral and nudibranchs over two hours
An apparently healthy fragment of the same genet of MS1 with a solid mass of nudibranchs (est. >50) on the coral and visible egg clusters was placed into 1000ml aquarium water in a shallow plastic dish with 50mg of potassium permanganate (KMnO
4), as above. The following timeline describes the effects as viewed under a Nikon dissecting microscope:
t=1 minute
- nudibranchs immediately begin crawling randomly away from tissue boundary where they were feeding
t=5 minutes
- <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">nudibranchs twisting and curling, cerata tightly folded against body, some raising heads up in water column
- coral appears unaffected by treatment
t=30 minutes
- <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">nudibranchs mostly motionless, some still walking slowly and some detached and floating in water column <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">coral appears unaffected by treatment
- water is very brown from organic oxidation
t=60 minutes
- <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">no movement in any nudibranchs; three slightly reactive to probe, some disintegration <LI style="FONT-FAMILY: Georgia, 'Times New Roman', Times, serif">coral appears unaffected by treatment
- water completely brown and difficult to see coral or bottom of container
t=120 minutes
- no nudibranchs or egg clusters visible on coral
- coral is brownish but appears unaffected by treatment
- coral is placed into quarantine system (sharing same water volume as original colonies)
t= 240 minutes
- coral polyps expanded and coloration normal
Trial 3 ? effect of high dose (200mg/l) on corals and nudibranchs
Multiple fragments of four species (three MS1, two MS2, two MS3 and three each of
M. digitata; green, purple and pink morphs) were exposed to 200mg KMnO
4 dissolved in 1000ml aquarium water. Some colonies had nudibranchs present with egg masses; some had neither visible egg masses nor nudibranchs. Colonies remained in the solution for two hours, were rinsed in seawater and removed. All nudibranchs and egg masses were gone, presumably disintegrated. The treatment water was opaque purple brown, indicating an excess of KMnO4 for the amount of organic material oxidized over the two-hour time frame. The corals appeared dead; no mucus was palpable and the polyps appeared disintegrated. They appeared to have only bare skeleton with no overlying tissue. The coral colonies were placed into the quarantine system (sharing same water volume as original colonies). After two days, four M. digitata colonies began extending polyps. After four days, two MS1 colonies, two MS2 colonies, two MS3 colonies and five M. digitata colonies all extended their polyps and appeared normal and healthy, except for areas devoid of tissue previously consumed by nudibranchs. Total mortality from treatment was four M. digitata fragments and one MS1 fragment. This treatment dosage was very stressful to the colonies but indicates an upper concentration limit and time for what was almost an LD50 level (LD31.50) for corals, and effected a 100% kill rate for nudibranchs and egg masses.
Trial 4 ? effect of 50mg/ml dose on corals and nudibranchs for 90-210 minutes
Fragments of the same number and genets used in Trial 3, but all hosting aeolid nudibranchs and egg masses, were exposed to 50mg KMnO
4 dissolved in 1000ml aquarium water for 1.5-3.5 hours. In no case were nudibranchs or eggs visible on any corals after the treatment durations. Corals in the 3.5 hour treatment looked highly stressed and appeared grossly like those exposed to the 200mg/l dose of Trial 2. They recovered much more quickly, however, and all appeared normal within 24 hours. No coral mortalities occurred.
Trial 5 ? effect of minimal dosage on remaining corals and nudibranchs
