Posts Tagged ‘marine environment’

The Post – The Fiddler Babies are Dead, But We’ll Start Over And Prove Horseyhannah Wrong!!

March 10, 2008

The fiddler babies are dead.

I am sad, because I really did like the fiddler babies. I looked around on the web last night for clues to their demise and that’s when I got ticked.

The Discovery Channel’s Animal Planet Online Forum had a discussion of how to raise fiddler crab larvae. “Horseyhannah,” a senior member on the forum basically told a member who asked how to raise fiddler larvae that it’s so hard and requires hundreds of thousands of dollars of equipment to simulate ocean environments, waves, tides, etc. so it’s really not possible. Horseyhannah told the person to just enjoy the adult fiddler crabs and don’t bother to raise the babies. Needless to say, the person asking the question was polite, said thank you, agreed it will probably be hard, but would still like to know horseyhannah’s info source…just in case she decided to raise them anyway. My answer to that person is: GO FOR IT!!!! PROVE HORSEYHANNAH WRONG!!!!!

In fact, I am determined to do just that. In my book, Horseyhannah has thrown down the gauntlet and I am determined to prove her wrong.

I will concede failure on this first attempt. I am sad as I was so looking forward to having some fiddler grandchildren survive. I was frustrated and disappointed because contrary to the advice above, I think it was not only possible, but it was happening. Because I lost them so quickly, that tells me something overwhelming happened in the tank to kill them all off at once.

To review, by Friday afternoon, there were no babies moving around. It was a rapid decline, and up until that point, we still had quite a large number alive. I have to conclude it was a water quality issue and I think the biggest culprit was the live phytoplankton. But to go through this methodically, let me look at several things. If it were salinity, ie they didn’t like the marine environment I don’t think they would have lived that long in it to start with. I suspect the following things were problems:

1) I used gravel and we did lose MANY babies because they burrowed into the gravel crevices and died there.

2) The nitrite levels in the water spiked suddenly and got very toxic. Thoughts on this point:

a) I didn’t get the tank set up early enough to have a mature and well-functioning nitrogen cycle.

b) I either fed them the wrong food, or too much, or both. The wrong food or too much food meant it didn’t get eaten, sat in the tank and rotted. OR it created a huge algae bloom that raised nitrite levels beyond a tolerable level.

c) I didn’t change the water fast enough once I realized the nitrites were a problem, though given the phytoplankton issue, I was probablly fighting a losing battle from the beginning.

d) I no doubt lost babies doing the water changes because my only option was to bail water out of the tank and pour it down the drain

So boys and girls, what have I learned from this first attempt that can be done better next time?

1) I will use calcium sand not gravel. Aside from the fact that the babies won’t get trapped in the substrate material, the calcium sand will provide enough calcium for the babies to stay healthy during many molts.

2) Figure out the right food and amount. The gentleman from Finland whose article I quoted a few days back (he raised the Red Clayed Mangrove crabs) fed his larval crab Artemia…brine shrimp. He had a hatchery right in the tank to have a fresh supply. He also used something called JBL Nobilfluid for when the larvae were too small for the brine shrimp. This product is probably similar to the Small Fry liquid food I was using. It it made by a company in Germany and I’m trying to find out if it is marketed here. It has 50 different vitamins and minerals as well as brine shrimp and is geared for newly hatched aquatic animals too small to tackle live brine shrimp yet.

3) DON’T USE LIVE PHYTOPLANKTON this time. In spite of an almost 50% water change, I could not get the nitrite levels down. In fact, they kept rising. Now I am finding information that phytoplankton excrete nitrites. The better the phytoplankton did, the higher the nitrites. And with each feeding I basically inoculated the tank with more. I created my very own algae bloom which released such high nitrite levels, the babies were doomed.

Frankly, the tank seemed to be doing okay until I started using the phytoplankton. I would feed the liquid Small Fry food and while the tank would be cloudy initially, it cleared quickly, telling me the babies ate the food. At that point, in spite of it being a new tank with an unestablished nitrogen cycle, the nitrite levels stayed pretty low. However, once I started using the phytoplankton, the tank got cloudy quickly, the nitrite levels spiked, the water had a greenish tint, and the larval crabs numbers dropped dramatically. So, NO phytoplankton.

4) For water changes, instead of bailing water out, I will use the water bubbler as my “filter” to keep the babies in the tank, and let gravity siphon water out of the tube. I have the bubbler’s pump set up beneath the tank and have a regulator valve in the line to keep water from back-flowing from the air bubbler, into the pump. If I remove the valve and let the tube sit in a bucket, it will slowly siphon off water through the bubbler. This should let me slowly get water out for changes, without bailing larval crabs out of the tank and sending them down my kitchen drain.

So. I will start over. Admiral Byrd is doing his part, trying to get Scarlett O’Hara to notice him. Scarlett O’Hara has been eating and hanging around Admiral Byrd’s cave den. I figure it’s only a matter of time before Scarlett has eggs again. Therefore, tomorrow, I will take down the nursery tank, clean it out, get some calcium sand, and get that tank up and running again with the live rock in it, and get that nitrogen cycle stable.

We are going to try this again! My husband and I would love some fiddler grandchildren, 🙂 and even he said that we must prove Horseyhannah wrong!!! Stay tuned.

The Post – What to Feed the Babies and How Salty Should the Water Be?

March 1, 2008

Just a reminder that coming up over the next week, the next few installments on the journey of my Under the Pier novel. I had to take a break from those for taxes, actually finishing some more chapter revisions, and of course, taking care of the “grandchildren.” But stay tuned. More to come on Under the Pier.

Re the grandchildren:

What wonderful goings on! Soooo many little black dots in the nursery and they are definitely swimming around. Many are hiding out in the shadows of the live rock caves. So tiny and already they know to hide and avoid “predators.”

I am feeding them three times a day with a mixture of ground up mini-freeze dried krill, some ground up flake food, a few drops of the liquid Small Fry baby fish food, and a little distilled water mixed in. We shall see how it goes. And no, I am not grinding the mini-krill with my husband’s lovely stone mortar and pestle that he uses for grinding up herbs and spices in the kitchen!!

Regarding salinity – it’s a tricky call. While Uca minax, which are the type of fiddler crabs I have, are seen furthest up the estuary in areas of lowest salinity, there seems to be evidence that for at least the first two weeks of their larval development (zoeae) , they actually survive and do better at a higher salinity. However there is also evidence that for the next (megalopae) stage to metamorphose into crab Stage 1, this species does best with the lower salinity seen in the upper estuary environment that the adults live in. I will post more information tomorrow including the links to the two papers I found today on this subject. Long story short today though, is that zoeae of all the species of fiddler crabs, seem to need a couple weeks of “being at sea,” hence higher salinity.

I’ll also explain about the three species used in one of the studies and how their selectivity for salinity levels puts them in different spots in the estuaries and thus probably keeps them from competing with each other for resources and food.

Also to come – I dug out the small microscope I had as a kid and will pick up some microscope slides. So to follow, descriptions of babies, under the glass.

A couple of other notes – courtesy again of my engineer husband. He noted a bunch of white things all over the gravel and wondered if the babies had already molted. Maybe they have but these white dots were too big and irregular in size for baby shells. I believe it’s salt crystals that didn’t dissolve in the water before I added it. I added more water to bring the salinity up closer to a marine environment. I started at 1.010 (brackish) when they were born and over the course of yesterday raised the salinity first to 1.012, then by last night 1.015. Today I’ll finish raising it to 1.020. Then in two weeks I’ll bring it back down to 1.010-1.012, the optimal range for Uca minax adults.

Sand. Again, my husband was watching the babies swim – it is amazing to see these tiny things whiz around the tank – but he shined a light to see if they would follow the beam. The article I posted in yesterday’s gift mentioned that the babies will go to the light. My husband didn’t see evidence of that, but what he noted was that many little babies had worked their way down between the gravel bits, all the way down to the bottom of the tank. Unless they figure out how to get back up to the water, they’ve had it. Now let’s face it. Their parents had a brain the size of a pinpoint. How large a brain do you thing babies the size of a pinpoint have? So the odds of them getting back to the surface are not good. I said “evolution at work. Anybody who tunnels down in the gravel probably won’t live to reproduce. ” My husband noted that gravel is less than optimal for this (engineers talk like this by the way, things are optimal, less than optimal, sub-optimal 🙂 ).

The real important point though was his next comment: “The NEXT time we do this, we should use sand.” There you have it folks. My husband has fallen in love with the fiddler crabs. In all truth, he has. He watches them, thinks about how to make their lives better, anticipates the babies getting ground up in the water filter…..those babies are lucky to have him!!!

Anyway, stay tuned for the links on those two articles about optimal (yes, OPTIMAL) salinity levels for fiddler crab larvae.