Posts Tagged ‘brackish’

The Post – Fiddler Babies Thrive in the “White Cloud.”

March 30, 2008

The white cloud in the babies’ tank continues, yet the water quality is GREAT.

What mystifies me is the absolute ?attraction the fiddler babies have for the aragonite sand and the reef rock. They swarm all over areas of the sand, stirring up clouds of dust, and bouncing down against the aragonite sand, then move on to another area. They are equally attracted to the reef rock, which is nothing more than a hunk of petrified coral.

On the flip side, while they swim by the live rock, they do not seem to be interested in it to any great extent, even though there is a wide variety of algae growing all over it.

The aragonite sand is Seachem’s Meridian Marine Tidal Substrate. The reef rock is “Carib Sea Reef Rock.” Both products help to maintain proper pH and calcium levels, as well as encourage the growth of coralline algae and beneficial bacteria. In fact, I suspect it is the cloud of aragonite dust in the water that may have helped spur the bacteria on, resulting in the nitrite levels in the tank dropping to zero. It just seems counterintuitive to me, to have a tank of water I can barely see through, yet have it be so healthy by the numbers.

I shine the flashlight in the tank and can see thousands of babies swimming around, digging in the sand, or clustering on the reef rock. All are in motion, so they are most definitely alive. I have to wonder if there are already lots of microscopic algae on the surfaces of the sand and the reef rock, and the congregating of the fiddler babies is about eating what’s there.

I am currently feeding them 4 drops of Wardley’s Essentials Small Fry Liquid Food and a 1/4 tsp of Kent Marine’s ZooPlex, 3 times a day. I’m being very careful not to overfeed, and monitoring ammonia and nitrite levels 2-3 times a day.

I’ve also started the live brine shrimp hatchery going, though I have to say, I’m not sure if that’s something I want to deal with on a regular basis. Just one more job I have to do and as one of the sites mentioned, if you can’t get live food, frozen brine shrimp is the next best thing. I know I saw cubes of frozen brine shrimp at PetsMart and I may yet change to that. But for now, I’ll see the “sea monkey” hatching project through and see how it goes. I expect I’ll have hatched brine shrimp by tomorrow so I will try some of that instead of the liquid feeds and see what happens.

Just as an aside, I found a page on About.com that mentions their top picks for “small fry” food.

While these are primarily small fry as in baby fish, they all contain the multitude of nutrients need, and in an accessible, easily digested liquid form for young aquatic creatures. So I’m not too concerned.

Frankly, even though the Kent Marine ZooPlex is supposed to be for larval invertebrates, I have to say I’m more happy with the “dispersal” ability of Wardley’s Small Fry food. Wardley’s is a milky liquid that spreads completely and uniformly through the tank, so the most food and nutrients are available to the most number of critters.

The Kent’s on the other hand, is like ground up bits of brine shrimp in a pink liquid. The instructions say a teaspoon per 50 gallons, and since I’ve only got a 10 gallon tank, I am giving 1/4 tsp of the stuff. However it seems like precious little food, that probably isn’t getting to anywhere near the number of baby fiddlers that are hungry and needing to eat. So at least so far, I’m not that impressed with the Kent Marine ZooPlex and will stick primarily with Wardley’s. From there it’s live or frozen brine shrimp.

I raised the salinity of the aquarium yesterday to 1.017 from 1.012. I’d be happy to get to 1.020, which is close enough to a marine environment. I’ll leave it there for a couple weeks then, and gauge the appropriate time to lower it back down to brackish. I want to match that to the development of the more advanced crab forms from the initial larval stages.

As to the adult crabs – they’re doing fine in the main tank. Admiral Byrd, flush with mating success these days, never stops waving his claw. In fact, yesterday, I no sooner put Scarlett O’Hara back in the main tank, and he was right there saying “hi.” She hid behind the water filter to eat…though not too hidden, he actually lay backwards and slightly upside down on the water heater near her, and waved his claw at her upside down. Talk about “never give up.”

Anyway, so far, so good. We’ll see how this progresses over the next few days. It would be nice to keep many alive to actually make it to adult crab stage. Stay tuned!

The Post – Scarlett O’Hara “Labor and Delivery” Watch, and Ammonia Monitoring

March 27, 2008

For the last several days, Scarlett has been sitting on top of, or in, the water filter. Even though I shut down the filter Tuesday (so no babies would get sucked up in the filter material should they hatch), she continues to stay inside the empty filter. I guess it’s like a cave – nice and sheltered. She hasn’t come out to eat, but then I imagine that filter material has a ton of bacterial and algal critters all over it.

She DOES need to be in water at some point and on that count I’m not sure how long she can stay out of the water and in the filter. I tried chasing her out of the filter Tuesday afternoon, partially to see if she was okay, and partially to see if overcoming inertia and forcing her out would keep her out, but within minutes she was back inside of the filter. Who knows if she climbs out at night when the lights are off, to go for a swim.

Wed morning she was inside the filter, still sitting at the bottom. She wasn’t moving so I jiggled the filter cartridge enough to see her move. I left her alone until Wed afternooon when I pulled the filter cartridge up a bit. Scarlett O’Hara rushed up and out of the water filter and down into the water. She sat underneath the water filter, so I guess she’s just “staying put in sheltered places.” However, she does appear to be okay.

I tried giving her a couple of shrimp pellets, assuming she must be hungry, but she basically pushed them aside. She did pick at the calcium sand, so I expect she’s looking for algae. I dropped in a couple bits of algae pellets but she ignored those too. So either she isn’t hungry due to the pregnancy, something’s wrong, or she’s full from eating whatever is on that filter packing material. Right now she is still out in the tank and has even wandered over to the air bubbler at the other end of the tank. I am heartened to see her doing her usual activities: climbing up on the bubbler, trying to climb up the side of the tank, and resting on the suction cups behind the air filter that hold it in place. So, for now, I guess, all is well.

My only “curiosity” is “will she stay out into the water to deliver the babies?” I expect she will given that female fiddler crabs look for places in their estuary homes that have active water currents so the eggs can be washed out to sea. So “instinct” alone should propel her back into the tank water at about the time of delivery, no matter how much she likes it inside the water filter. Given she did it right the first time, I can’t imagine she’s forgotten what she needs to do. I missed the delivery the first time so I don’t know exactly what she does to release them. I hope I catch it this time. Also, I do wish I could just ask her why she likes living at the bottom of a dark empty water filter. In lieu of that conversation, all I can do is watch and wait…..

Water parameters Wed afternoon were good: Nitrates 10, Nitrite 0, Hardness >300, Chlorine 0, Alkalinity 300, pH 8.0 and the Ammonia monitor is in the “safe” range at < 0.02 ppm.

The ammonia monitor is a Seachem Ammonia monitor that you can hang inside the tank. No test strips or kits. This one is called the Seachem AmmoniaAlert for Fresh and Marine tanks. It continuously monitors the free ammonia level in the water for over a year.

The monitor is color coded for concentrations:

– Safe (<0.02 ppm), Yellow

– Alert ( 0.05 ppm), Green

– Alarm ( 0.20 mg/dl), Sky Blue

– Toxic ( 0.50 mg/dl), Lavender

The insert says that the “Alert Level” of free ammonia can be tolerated for several days; “Alarm” for a few days; and “Toxic” is rapidly harmful. It would have been interesting to see what it read when I had the phytoplankton overgrowth and high nitrites, the first time I did this.

While I knew that monitoring ammonia was important and somehow related to the level of nitrites and nitrates, I wasn’t sure exactly what was going on. I found a good website, The Tropical Tank, done in the UK, that discusses water chemistry, and in particular, ammonia, nitrites, and nitrates. It’s called: More on the Nitrogen Cycle: Ammonia, Nitrite, and Nitrate

In short, there should be no ammonia or nitrite in a mature tank. Any ammonia is present in two forms: ammonia (NH3) and ammonium ion (NH4+). Ammonia is more toxic than the ion, and the higher the aquarium pH, the higher the ammonia level. Since brackish and marine tanks are basic, ie higher pH, ammonia toxicity is a constant risk.

Ammonia in a mature tank is oxidized by nitrogen-fixing bacteria, to nitrites and again, in a mature tank, nitrites are oxidized to nitrates. While you don’t want to see nitrates run high, a lower level , say < 50 ppm, are considered okay, 25 ppm is even better. If your tank isn’t cycling well, is new and not enough nitrogen-fixing bacteria, you have too many tank inhabitants, or you’ve overfed them, ammonia (and hence nitrites and nitrates) will start to spike.

The bottom line, the appearance of rising ammonia levels is the first clue that things in the tank are not well and even toxic. Given that my last endeavor with crab larvae resulted in mass death due to high nitrites (and yes, the phytoplankton caused an algae bloom that caused ammonia and nitrites to spike and I won’t use it again) I thought it might be interesting to monitor the ammonia levels in the tank on a continuous basis through this project.

This article also gives information on how to start up the nitrogen cycle in a fishless tank. I wondered how you get the cycle going when there are no fish or fish wastes to start the process.

If you are interested, this same UK website has two other interesting articles:

The Basis of Cycling: a good overview of the maturing nitrogen cycle in aquariums

Fishless Cycling Data provided to them by a US forum member, William Wallace; some concrete data on how Mr. Wallace actually did this process.

To return to the tank and Scarlett:

Wed evening, the water looked cloudy and while other parameters were still fine, I noticed a trace amount of nitrites now. I also noticed a few green spots in the yellow safe zone of the ammonia monitor. The green spots are the beginning of a change to “alert.” Given that I think we’re a few days away from birth yet, I decided to turn the water filter back on for a day or so to try and improve the tank conditions. I suspect that adding Scarlett to the tank was enough to catalyze the nitrogen cycle into high gear. It’s to be expected to see “some” ammonia and nitrites, and there also is a “good” level of nitrates, but still, I don’t want to lose the battle of water quality before the babies are even born. I will continue to monitor water quality closely today today. If necessary, I’ll do some water changes, but I would rather not do that. Since the nitrogen cycle is in its early stages, every time I take water out and put in new water, it removes some of the very nitrogen-fixing bacteria I need. The gentleman at the aquarium store said it would be best to just let the tank evolve. So as long as we don’t go beyond “alert” on the ammonia monitor, I’ll let it “evolve.” Otherwise…I’ll have to start water changes. I wish I’d known earlier about the fishless cycling Mr. Wallace did. I could have done that with this tank to get the nitrogen cycle established before moving Scarlett into it.

Tank parameters this morning are the same as yesterday afternoon and Scarlett is out walking around the tank, so, no better, no worse.

Stay tuned.

The Post – Odd Goings-On in the Fiddler Tank – Is Scarlett Acting Pregnant Again?

March 16, 2008

When I first I walked by the fiddler tank yesterday morning, I was sleepy and oblivious. Then I did a double-take. Sitting at the front of the tank was the discarded molted shell of somebody. On closer examination, and with my husband’s consultation too, we both agreed it was Melanie Hamilton’s discard. That means she is at the moment most likely to get pregnant if Admiral Byrd invites her in.

At the same time we noticed that Scarlett O’Hara was sitting on top of the water filter….again. The last time she did that, we noticed shortly afterward that she was pregnant.

Admiral Byrd of course, was marching up and down the tank, claw arm held high, and waving.

To continue – Scarlett O’Hara spent the entire day and evening yesterday, on top of the water filter. She is still there this morning. She has never done that before or since, except when she was pregnant. I know she is still alive because she is “blowing bubbles.” Crabs foam sometimes when they’re out of water, to moisten their gills.

Even when I freaked out Admiral Byrd yesterday, and scared Melanie Hamilton out of her live rock because I was cleaning the tank and accidentally bumped the live rock, Scarlett O’Hara didn’t leave the filter perch. She just moved down into the filter for a bit, then climbed back up. Admiral Byrd meanwhile kept trying to climb the heater power cord up to the top of the filter to be near her, but he couldn’t quite do it with that large claw.

Yesterday afternoon we noticed that Melanie Hamilton remained outside the live rock, sitting there on the gravel serenely watching Admiral Byrd flex his claw. Then she spent the rest of the afternoon and evening in his cave lair. This morning she was resting just outside his lair, picking algae off the rock. He was napping inside.

With any luck, we can try the larvae thing again somtime soon?

I am in the middle of re-establishing the nursery tank. I had emptied everything from the original set-up, cleaned out the tank, put down the one inch or so of the calcium-releasing sand, and added the water. Now I did forget to rinse the sand out, so the tank water was cloudy at first, but it has settle out by now. I’m not sure how one effectively rinses sand out anyway without half of it going down the drain. I will say the white sand really makes the inside of the tank bright when the light is on. If we get babies again, it should be much easier to see them in such a bright tank.

I couldn’t decide whether to make the 3 gallons of water I added marine or brackish. I guess I should start brackish because first we’ll have to move the mom, whichever one of them it is, from their tank, which is brackish into this one. I wouldn’t want to shock them. Right now the tank is on the “marine side” of brackish. I’ll adjust the salinity with a bit more water shortly.

The live rock is back in the tank hopefully doing its thing to establish the nitrogen cycle. Both the air filter AND the bubbler are running and so hopefullly the tank environment will establish itself as quickly as possible. Rather than replace the old water filter cartridge and lose whatever nitrogen-fixing bacteria that had started to thrive in it, I left everything in place and returned it to the tank.

An interesting about the old water in that tank. I tested it before I emptied it out just to see if the nitrite levels ever came down. They read zero, and the nitrates were in the “okay” zone. I guess once I stopped using the live phytoplankton and let the water filter run for a few days, that was what it needed. So the phytoplankton was most likely the culprit in the high nitrites. In any event, I dumped the old water and just started with fresh sea/brackish water all over again.

One thing – that Reef Calcium product that I’d hoped would raise the alkalinity but not raise the pH, when added to half strength Instant Ocean… maybe it didn’t raise the pH but it didn’t solve the problem of the pH being too high from the Instant Ocean even when I used that at half strength. So I still had to use a pH lowering solution and this morning it is about 8.0 vs 8.4 that it was yesterday. So that’s perfect . At least though, the Reef Calcium did raise the alkalinity.

I will keep you all posted on any news from the adult tank. Keeping good thoughts for a new crop of larvae babies. Stay tuned.

The Post – Admiral Byrd is Peeking & New Aquarium Products

March 12, 2008

Some Fiddler Updates – New Product Technical Details and Romance

1) Preparations, Take 2, for the Fiddler Crab Nursery Tank:

I came home from PetsMart yesterday armed with calcium sand to replace the gravel in the nursery aquarium. That project will commence later today. The sand is actually something called Seachem Meridian Tidal Marine Substrate. It’s basically calcium carbonate precipitated from ocean waters by coral. It will stabilize the calcium and alkalinity levels in the water, and keep the pH from getting too low. Its porous structure and size supposedly are good for the growth of denitrifying bacteria. We shall see.

At the very least, it’s a dual purpose as I can also use this sand for the bottom of the land hermit crab cage I just bought. The land hermit crab project will be ramping up soon.

I also picked up some liquid food that should work fine for the larvae. I’d mentioned a product called JBL Nobilfluid that a gentleman from Finland used to raise his crab larvae. However the Nobilfluid is made in Germany and appears to be available in Finland, Germany, England, Italy and the UK, but I couldn’t tell if it was available here in the US. I could get it from a UK website but between the exchange rate and the shipping, I expect the cost is prohibitive. A JBL representative answered my email yesterday and said their product is not available in the US yet.

I found this new product at PetsMart called Kent Marine ZooPlex. The problem I had with the fiddler babies was trying to find liquid plankton to feed them. My mistake was getting live liquid phytoplankton, which made the tank toxic and killed them. I realized larval crabs need zooplankton, which is animal plankton = roughly translated: MEAT. Phytoplankton, being plant based, is the wrong plankton. Larval crabs are carnivores, not vegetarians. Anyway, Kent Marine ZooPlex is “concentrated aquacultured Marine Zooplankton” and is geared toward invertebrates including larvae. The bottle notes it can be used as a brine shrimp replacement. So this sounds like it might be just the thing for liquid feeding of newborn larval crabs who are too small to chase live brine shrimp around.

I will still need to get the dried brine shrimp eggs to hatch when I know I have a pregnant female ready to shed her eggs. The brine shrimp hatchery project will come a bit later.

2) How to raise the alkalinity of the water for the brackish tank without raising the pH?

The dilemma I have when using Instant Ocean to make up the brackish tank water for the adult crabs, is that I have to use it at about half strength. That way I get a salinity of about 1.010 instead of 1.020-1.024. The trouble is, that makes the alkalinity way too low meaning there’s not enough calcium in the water for the crabs when they molt.

I’ve tried adding Seachem’s Marine Buffer, to raise the alkalinity and it’s very successful, but it also raises the pH way up to 8.3. That’s fine for a marine tank, but for the brackish tank, the fiddler crabs seem to like the pH closer to 7.8-8.0 I have a constant battle trying to get the salinity low enough, the alkalinity high enough and the pH “just right” somewhere between a freshwater tank and a marine tank. When I use the Marine Buffer I have to then add something to lower to pH.

I was hoping to find something that would raise the alkalinity, but not the pH when I use Instant Ocean to make up the brackish water. Yesterday I came across Seachem’s Reef Calcium. The website description reads:

Reef Calciumβ„’ is a concentrated (50,000 mg/L) bioavailable polygluconate complexed calcium intended to maintain calcium in the reef aquarium without altering pH.”

I am going to try the Reef Calcium product and see if that solves the problem. I will let you know.

3) Romance: a humorous update for a Wednesday:

Ever since his success with Scarlett O’Hara, Admiral Byrd has been out there claw-waving up a storm. Melanie Hamilton spends just about all her time inside the live rock. Yesterday afternoon is the first time I’ve seen her out of it in weeks. I think she took to hiding out in the rock when Scarlett O’Hara was living in the nursery tank. With Scarlett temporarily gone, Melanie was the total focus for Admiral Byrd. I don’t think she liked that.

Anyway, after giving birth, Scarlett O’Hara has been eating almost non-stop. I think she finally slowed up a bit yesterday, but she’s still pretty ravenous. In fact yesterday, I dropped a shrimp pellet in the tank and Scarlett scrambled up and caught the thing in mid-drop. It never even touched down on the gravel. And she’s pretty good. No fumbling and bobbling the shrimp pellet. She spotted it, she jumped, clutched it to her chest and landed on her feet, eating the pellet before she landed. She could probably earn a spot as an outfielder for the Red Sox.

Unlike Melanie Hamilton, Scarlett hasn’t been too concerned one way or another with Admiral Byrd’s where-abouts. She doesn’t run from him, or toward him. She just eats. Still, I don’t think she’s averse to his presence as she’s spent a fair bit of time in his lair, the fake rock cave, while he walks around waving his claw. I have to wonder if he realizes she’s sitting in his house?

Last night I turned off the tank lights, shut off all the house lights and went upstairs to bed. A little later I had to come downstairs for something and walked by the tank. Even in the dark, I could see Admiral Byrd standing there on his gravel hill, waving his claw. Total darkness, but the crab is still out there trying to get the attention of the ladies of the tank. What dedication.

He is also very funny in his pursuit of Scarlett O’Hara. He climbs to the top of the live rock, to wave his claw of course. Yesterday while claw-waving, he caught sight of Scarlett down on the gravel next to the live rock. He stopped waving, tip-toed to the edge of the rock, peeked over the edge at her to see which way she was going, then, like a teenage boy in love, scrambled down the rock and followed her around all the while waving his claw.

So watch out Scarlett, Admiral Byrd is peeking.

The Post – A Fiddler Update – Water Issues and Decreased Numbers

March 7, 2008

I am not sure that things in the nursery tank are going well. A sudden reversal in fortunes over the last day or so. Very decreased numbers of babies. In fact, this morning, it’s hard to tell if there are any left. The water got cloudy, like an algae bloom, and the nitrites spiked high and even a touch of chlorine showed on the dipstick, odd since I use distilled water. So the chlorine is coming from tank conditions, not the water I used. Some thoughts:

I am not sure if the decrease in numbers is:

1) Normal? They cannibalize each other.
2) High nitrites?
3) Touch of chlorine?
4) Wrong food?
5) Too much or not enough food?
6) Salinity? Are the science articles wrong and should I have left it brackish?

Water quality:

It started out that the water would get cloudy for a little while after I put food in the tank. Then it would return to being clear. Now, however, it’s cloudy all the time. I replaced 1 gallon of water last night (still “marine” at 1.019), and I added buffer to raise alkalinity for them to have enough calcium to molt. I also added Prime to get rid of chlorine and decrease nitrites. I succeeded with raising the alkalinity, and eliminating the chlorine. Nitrates are still in the “okay” zone, but nitrites didn’t drop.

This morning the tank is still cloudy. I will recheck parameters in a little while, and probably replace another gallon of water. I hate to do that because if there are babies left, I am most likely pouring some of them down the drain with water I tank from the tank. I do pull the water from the side of the tank where the babies did not hang out much, but still. Nothing to be done there though. a.m.

It occurred to me this morning that maybe the phytoplankton was either a bad idea or I just gave too much. The phytoplankton is alive. I noticed the water I drew off last night had a greenish tint. That means the phytoplankton, which is PLANT plankton, and alive, may be blossoming, in fact, maybe it’s a phytoplankton bloom in the tank. Given it’s not the open ocean, but a closed environment, the bloom, while successful in generating more food for the babies, maybe too much of a good thing in an aquarium. If too much growth, is it raising the nitrites and killing off the babies? I am wondering if I should have left the food at “Small Fry” and maybe the ground up krill and not added the phytoplankton.

I will also put a sample of the water under my “precision” microscope later to see if in fact the water is jammed with plant cells.

I will update on the results of water change, microscope viewing, and repeated parameters later, as well as whether it looks like there’s any babies left.

Live and learn. As my husband says, “Next time”….I think there’s always things we can do better. AND, once this experiment is over, we’re going to leave that spare tank up and running empty so it can settle out with a matured nitrogen cycle. Stay tuned for updates.

The Post: Fiddler Update – From Periods to Commas

March 4, 2008

Just a brief note today – buried in writing work, bills, and car stuff….reality creeps in. πŸ™‚

The fiddler babies continue to thrive. I notice the numbers are down in the tank, and we also noticed they seem to congregate on the right side of the tank, near to the live rock. They swim in and out of the live rock crevices, and some do wander to the other side of the tank to investigate the water filter which is not running at the moment. They probably figure it’s another cave because any babies over there tend to hover under or behind the non-running water filter. But even as tiny guys, they know to keep to shelter.

My husband diligently checks on them with the flashlight and noted that they are bigger…he commented that since birth they have grown from “periods” to “commas.” It will be interesting to see how many survive. The tank is “ocean” level salinity now at around 1.020. I’ll keep it there until the 17th, which will be two weeks “in the ocean” for the guys. About that point I will start doing water changes and bring the salinity slowly back down to the brackish level I keep the adult tank at: 1.010-1.012.

I am keeping an eye on the nitrite levels in the babies’ tank since it’s up quite a bit. I added Amquel to lower the nitrites but I never really see that happen with that or Prime. I sometimes wonder if the solutions to bring the nitrites down are really “placebos” for the owners of the tanks? In any event, monitoring water quality, especially since I’m putting liquid food into the babies’ tank 3 times a day.

The adult tank has been “business as usual” – Melanie Hamilton spends most of her life hiding inside the live rock, Admiral Byrd is ALWAYS waving his claw these days, and about the only difference is Scarlett O’Hara. She must be recovering from “pregnancy and childbirth” because she has NOT stopped eating. She is shoveling in shrimp pellets and picking algae off everything, with both claws at once. She gives “two-fisted eating” a whole new meaning. It is non-stop, almost “frantic” in its intensity. I guess she is making up for lost time and nutrients. Otherwise, she seems fine.

That’s the goings-on today. Working on the next Under the Pier installment, hopefully to be done for tomorrow. Need to finish some chapter revisions first. 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 πŸ™‚ ).

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.

 

The Post – Extra! News on Preparing the Fiddler Crab Nursery

February 23, 2008

So you’re like me and you’ve got a pregnant female fiddler crab. Now what?

Well, we just came home from Petsmart with a second 10-gallon tank, lid, light, and pump/filter assembly so I can set up a saltwater aquarium in which to put the babies. Maybe I’m crazy for trying to see if I can raise them …?then sell them? but the challenge of motherhood calls. My husband, a geek of a different nature, respects this need in me to see if I can do this. He quietly acknowledged that he would “understand and be willing to fund” a second tank for the “kids.”

The dilemma now is did I wait too long to get it set up and get the “nitrogen cycle” started before she releases the babies? I can take a patch of the filter gauze from my current tank, which is loaded with nitrogen-fixing bacteria, and put it in the new filter to “seed it” with bacteria.

Tomorrow I’m going to Fish Pros in Raleigh NC to get another good-sized chunk of live rock. Between the filter seeding and the live rock, that should get the water parameters in the safe zone and the bacteria up and running quickly. Also the live rock will provide calcium for the many molts the little ones will need to go through.

What I was not sure though was how I would be able to “catch” the babies since I won’t know when she releases them and I won’t know if they’ll be too small to see once she does. Also, should I make the second tank a regular “salt-water” tank to represent the “open ocean” like most fiddler babies go to, or make it brackish like what they’ll end up in? This last question got further complicated by the information I found on the blog below that indicates I should isolate mom before she releases the young. So I have much to ponder tonight while I get this up and running.

I did a search for info on pregnant fiddler crabs and come up with The “Dear Blue Lobster” blog entry” from July 25, 2007. The Dear Blue Lobster site claims to have been answering “your crustacean questions since 2002.” This entry is from someone who is concerned that her fiddlers make have “hooked up” and now what should she do? She is freaking out at the prospect of a 100,000 babies in her tank.

The gentleman who runs the blog gave good technical advice on taking care of the pregnant mom, saving the larval babies, raising them, and even indicated how much/lb. you can sell fiddler crabs for over the internet. The crustacean guru also gave the following emotional advice:

“So what do you do if your female is indeed pregnant? Comfort her. Her man has kicked her out and will no offer care for her children β€” in fact, he may try to eat them! ….Good luck to you and your Fiddlers. Motherhood is a special blessing indeed.”

Since it is well past July 2007….I wonder how the mom (human) and the mom (fiddler crab) made out with their situation? For myself, we shall see. I am off to set up the tank. I guess I’ll set it up brackish and isolate mom before she “delivers.” I have also emailed Dear Blue Lobster for help on what I should do. I’ll keep you posted on his reply.

I recommend the blog. The crustacean guru is Christopher Chimwish. His site description is as follows:

Christopher Chimwich received his MMN in 2000, specializing in decapod behavior. He is currently surveying benthic decapod populations in the Indian Ocean for his doctoral thesis. Chris answers questions about crustaceans, covering everything from DNA mutation in African crayfish to Fiddler crab sign language.

By the way, if you want to be a real geek, apparently the term for my fiddler crab when they have the brownish eggs attached to their abdomen is being “in berry.” So.

If you want to know what he has to say about fiddler crab sign language, click here.

The Post – and finally, Admiral Byrd

February 2, 2008

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To round out the fiddler crab trio in our household, I give you the sole male in the tank, Admiral Byrd. He is fearless, commands the tank, explored every inch of it the moment he first entered the tank, and so he deserved a name fitting for a courageous explorer.

The first picture shows Admiral Byrd under less than optimal circumstances. In one of the first blogs about the crabs I mentioned the problem of getting the salinity level right in the water. Being brackish water crabs, they like lower salinity. Not knowing this, I had made the water the same as regular sea water. That drove Admiral Byrd literally out of the water, up the gravel hill, and as seen here, climbing the walls of the tank to get out. I quickly diluted the water, thus calming him down and convincing him to stay.

The second picture seems to sum up Admiral Byrd’s standard pose: “Stand back! I have a claw and I’m not afraid to use it!”

The third picture shows Admiral Byrd trying to get closer to the ladies by nestling in against the live rock while they were sleeping inside. (He was too big to fit inside). I guess he figured if he slept outside their front door, they’d have to run into him sooner or later. Admiral Byrd may be brave, but he is not too smart. The ladies just exited the live rock by the side entrance.

The last shows dinnertime. Admiral Byrd is chewing on a shrimp pellet clasped in his smaller front claw.

That’s the crew.

In another post, I will talk about a couple of ways this photo project helps my writing.

The Post – Scarlet O’Hara Lives! And How I Came to Love Fiddler Crabs

January 25, 2008

After almost 10 days without a sighting, FINALLY yesterday afternoon, I spotted Scarlet O’Hara. I wasn’t sure at first if she was just a corpse, dangling upside down inside the Live Rock with her eyestalk hanging down, but shining the flashlight into the rock’s cavity at 5 minute intervals, I was able to determine that a) she actually had moved her position, and b) on the second and third times, she reacted to the light beam and flinched. This latter point was important because it meant the movement was deliberate, not the result of her just being bobbed around in the cavity by the water’s movement.

Relieved to know she wasn’t dead, I went ahead and did the water change. (More on that below) Then last evening, Scarlett O’Hara emerged from the Live Rock Cavity, and slowly started moving around. She resembled a patient just released from the hospital – someone tentative in her steps and tired after her ordeal.

Okay. Right about now, I’m sure anyone reading this is wondering what the hell I am talking about. Let me back up to the beginning and give you the Readers’ Digest version of events. I am contemplating setting up a separate blog – Crab logs – to capture all the events since the beginning of this endeavor, for those purists who only want the “lab notebook stuff.”

As I’ve mentioned I am writing a mid-grade novel called Under the Pier. At least that’s the “working title.” The protagonist of the “under” the pier side is a hermit crab. While I had no trouble pinning down facts about the creatures in that world, those chapters lacked “heart.” They read more like a nature guide. My husband read the first few animal chapters and noted that frankly, he didn’t care about the creatures. That’s a death knell for any book, whether the characters are human or animal. The whole point of reading a story is to feel what the characters feel, live through the story struggle with them, and stay along for the ride because… you CARE about them. If my husband didn’t care about them at chapter 2, I had a problem. So, back to research.

It occurred to me that I just hadn’t captured what it felt like to be an undersea creature. Since I can’t live underwater, an aquarium is the next best thing. I couldn’t have a marine hermit crab like the one in my story as a pet because that meant setting up a salt water tank, something reputed to be very difficult. PetsMart had something called “freshwater crabs.” A freshwater aquarium meant cheap, at least cheaper than a saltwater one, and easier. I’d had aquariums as a kid. I figured I could set up a small tank very inexpensively, get a couple crabs, and voila….live research that would teach me how to emotionally bond with something I normally eat in garlic butter. As I’ll describe below, “cheap” didn’t take place, but emotional bonding did. My husband noted that I bought myself $4 worth of fiddler crabs, and $100 worth of support gear. πŸ™‚ In reality, it’s been way more than that by now, but . . . more about that later.

Anyway, I bought two males, not through any particular strategy. Those 2 just happened to wander into the net the teenage employee swished through the store’s tank. I rushed home with my new “pets” and all my gear and rapidly set up the tank. Normally, when you set up an aquarium, they recommend getting everything established before bringing home your fish. However in this case, I figured why bother setting it up ahead of time when the saleslady made it sound like all these guys needed was some water and a bubbling air tube. Again, more later.

The larger male immediately ran around his new tank, explored every aspect, took command of the gravel hill (they need an area where they can be out in the air for up to 50% of the time), and showed no fear. Given his apparent “explorer” mentality, we named him after the South Pole explorer, Admiral Byrd. The smaller male immediately bolted under the water filter and stayed there for 2 or 3 days. Even when he came out, he skulked around in the background. My husband noted that he acted like the Peter Lorre character in the movie, the Maltese Falcon, so we named him Peter Lorre.

I’m going to skip over the travails of learning I should have set up the aquarium first before buying the crabs, the fact the people had us buy the wrong food (how are bottom-dwelling crabs supposed to eat krill shrimp that only float on the water’s surface and don’t sink?), and the many things that made me realize these crabs really do need more than a bubbling air tube if they were to live longer than the 2 weeks PetsMart’s written guarantee said they would.

As it turned out, Peter Lorre made it about 3 weeks before he died. I think his poor little body just wasn’t up to the stresses of toxic nitrite and nitrate levels, not to mention the fluctuating salinity levels (see below). By the time I learned about Live Rock and how it speeds up the nitrogen cycle in the tank and makes things healthy and non-toxic, Peter Lorre just stopped walking one day, tumbled off the live rock, and dropped headfirst to the bottom of the tank, dead. I was heartbroken…he was the quiet timid one, and I did like him. My husband couldn’t understand how I could care about him given that I ordinarily do not hesitate to go to a seafood restaurant and consume his cousins with great enthusiasm. Doing a twist on that line from the Godfather movie about things not being personal, but business, I said to my husband, “This is personal, not lunch.” When things get personal, you go to Google for answers.

Now, for any aquarium geeks – a couple things. Live Rock, as mentioned above, is rock taken from a tropical coral area, and contains microscopic sea life and bacteria. By adding a1 pound chunk of cured Live Rock (ie has been allowed to sit in a salt water tank and age and no longer smells like a salt marsh) to the tank, it essentially seeded the tank with nitrogen-fixing bacteria. They speed up the establishment of the Nitrogen cycle. That’s where toxic ammonia and nitrites generated by the biologic wastes in the water, are converted to nitrates. Eventually the levels of ammonia, nitrites and nitrates drop to zero. The Live Rock also has the benefit of leeching calcium into the water. This comes in handy for keeping things like pH and calcium at stable levels. Crabs need high calcium for molting. Anyway, once I added Live Rock to the tank, the toxic conditions subsided rapidly. But not in time for Peter Lorre.

I also learned that the crabs I bought were “red-jointed fiddler crabs,” otherwise known as Uca minax. Sometimes PetsMart sells the yellow-clawed ones, Uca pugnax, or mud fiddler crabs, but I definitely got the red ones. While these crabs can survive in freshwater, it apparently shortens their lifespan considerably. I read somewhere that they can live a year or more if kept at the right salinity. I figured salinity meant “marine.” After all, if they weren’t freshwater crabs, then they were salt water crabs. I went out and bought aquarium salt and made it up to the regular marine aquarium specifications, a minimum specific gravity of 1.020. I eagerly added the water to the tank figuring my guys would react with glee. Instead, Peter Lorre went into a daze and foamed bubbles out of his shell. Admiral Byrd bolted out of the water like I’d just added sulfuric acid and literally tried to climb the walls of the tank to get out. I didn’t understand it. I’d followed the directions and they “should” have liked the water, but obviously they didn’t. Even fiddler crabs deserve not to be in pain so I added some plain water to dilute things. They settled down.

In hunting around some more on Google, I discovered that these crabs are in reality, brackish water critters. That is that “estuary” type environment where the rivers meet the sea. The water is neither freshwater nor saltwater. Brackish water has a much lower level of salinity. Further, I found a study of fiddler crabs in the rivers of Delaware that really illuminated the problem. Uca minax – the red-jointed guys – prefers water with a specific gravity of around 1.008 – 1.018. Any higher than that and the LD50 (the time it takes for 50% of the population to die) is 2- 3 weeks. Same if you put them in freshwater.

Interestingly, according to the study, the yellow-clawed guys LIKE the higher salinity. If I’d had Uca pugnax crabs instead of Uca minax, they would have loved the higher salinity water. But my guys hated it. They needed….brackish. That’s how it goes with me. I start out to have a simple freshwater tank, then accept I must make it marine, only to find out I have to actually set up a brackish tank…something by the way, very few people do probably because there’s no books on the subject. In any event it’s been quite the adventure, and I sure have learned a lot, becoming a bit of an expert now on maintaining a good brackish water environment, a source of pride for me. However, this should explain now, my husband’s comment about $4 worth of fiddler crabs, and a $100 worth of support gear. It goes without saying I needed a gauge to monitor specific gravity not to mention water conditioner, solutions to decrease the ammonia until the Live Rock bacteria kicked in, and test strips to check the water…a lot. πŸ™‚

Anyway, end of geek moment and back to the story:

Well, now that Peter Lorre was dead, Admiral Byrd was beside himself. He sat in his little cave tunnel near Peter Lorre’s dead body and just twitched. I thought he’d eat Peter Lorre given that they are scavengers, but apparently fiddler crabs don’t eat their friends. I removed Peter Lorre and gave him a proper pet burial in our front yard, next to the gerbils, hamsters, and pet rat buried out there. Then I set out to buy Admiral Byrd more friends.

I found this amazing aquarium store on the outside of Raleigh, NC – Fish Pros – Fishprosnc.com SALT WATER TANKS and ALL KINDS OF GEAR and PEOPLE WHO KNOW WHAT THEY’RE DOING!!!!. In fact some of their staff are marine science students or professors at NC State University nearby. In any event, I left there with not just ONE more friend for Admiral Byrd, but three. And this time, there would be WOMEN!

I figured keep the numbers even, so I bought 2 females and one more male. The man at the store noted that having the females would produce some neat “claw-waving” mating behavior in the males – the crab equivalent of “Hey baby, check me out!” Also, since females weren’t territorial, it was possible to have more crabs in the tank without having fights. Needless to say, Admiral Byrd perked right up when he saw he had friends, and when he realized there were ladies, well, he hasn’t stopped waving his claw since.

In any event, the male struck my husband as the “Rhett Butler” type, so, the new guy became Rhett Butler. That meant following the Gone With the Wind motif for the ladies names. The larger female demonstrated an overbearing, fearless, almost aggressive streak. She became Scarlett O’Hara. The more timid, fragile female, is Melanie Hamilton.

Again, for whatever reason, we lost one of the crabs – Rhett Butler lay dead in the back of the tank. No outward evidence of “foul play” ie – Admiral Byrd killing him off for territory or women. Again, another pet burial in the front yard. However, since then, the remaining three crabs have done fine. Yes, the women get fed up with Admiral Byrd chasing them around. And Yes, Melanie Hamilton got tired of Scarlett O’Hara stepping on her to get to the food pellets. Melanie Hamilton spends most of her time living INSIDE of the Live Rock chunk. She does peek out the front or side entrances long enough to grab a food pellet and pull it inside, and every now and then she will climb out and wander around, but she’s very skittish and races back in the rock at the slightest provocation.

My Scarlett O’Hara concern started about 10 days ago. She enlarged the front entrance to the Live Rock, ie, pulled out a bunch of gravel and tunneled under it to get inside it with Melanie Hamilton. For a few days I could see them both crammed inside the Live Rock if I shined a flashlight into one of the rock’s openings. But for the last 10 days I could not find a trace of her. At first I figured she went in there to molt. Molting takes a few hours. So, I figured give her another day or so to rest and she’d be back out. No dice. No matter how often I shined the light into the rock, all I could see was Melanie Hamilton. By yesterday I’d decided Scarlett must have died and I needed to pull the rock out of the tank, if only to remove her dead body for burial.

However, just before I did that, I shined the light into the Live Rock and lo, that’s when I saw Scarlett O’Hara. She was clinging to the roof of the cavity, and I could see her eyestalks hanging down. Since she emerged from the rock, all is back to normal. Scarlett O’Hara and Admiral Byrd run the tank and wander constantly, seeking food. Melanie Hamilton peeks out of her cave and pretty much stays out of sight. As odd as it sounds – I am so HAPPY!!! I really felt bad at the thought she died. Seeing everybody doing their usual thing, it’s like “aaahhh, back to normal.”

Oh – one last geek moment, a moment of pride for me. I did a 33% water replacement in the aquarium yesterday – almost double the 18 % change the time Admiral Byrd freaked out about the salinity, and more than the recommended 25%. I didn’t have much choice given that the water really needed changing. I added the water and held my breath, keeping a close eye on Admiral Byrd. Apparently, this time I did it right. The tank water was at a 1.010 specific gravity, and so was the new water I was adding. Not only that, but the other parameters were great : pH 8.0, total hardness (GH) >300 ppm, total alkalinity (KH) 300 ppm, chlorine and nitrite 0, and nitrates “okay” at 20 ppm. (I’ve been using the Jungle Laboratories brand Quick Dip 6 Tests in One strips). And Admiral Byrd? He just kept right on eating through the whole thing. Never once climbed the walls…he never even left the water. SUCCESS!!!

Now I’m saving my allowance to buy …. two land hermit crabs!!!! Stay tuned soon for their adventures.

And stay tuned…working on getting pictures of Admiral Byrd, Scarlett O’Hara, and Melanie Hamilton…if she ever comes out of her cave!