Posts Tagged ‘larval crabs’

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 Calciumâ„¢ 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 – Baby Food Specifics, and Those Salinity Research Papers

March 2, 2008

First, I knew that Fish Pros in Raleigh NC would come through for me. I really wanted some kind of live plankton food for the babies as that’s what they would get in the ocean. I figured ground up TetraMin Tropical Flakes and ground up Tetra MiniKrill (freeze dried plankton) mixed with some Wardley’s Small Fry Liquid Food and distilled water would be as good as it gets, and I think it’s a pretty good mix. But I wasn’t sure I could grind the foods small enough for the pinpoint babies. Yesterday I took a ride to Fish Pros and lo, they had a bottle of DT’s Live Marine Phytoplankton – Premium Reef Blend. So this morning I mixed ground mini-krill in a 1/2 tsp of the phytoplankton and added a few drops of Small Fry in a little distilled water and put it in the tank. For other feedings, I’ll use ground up Tropical Flakes in the phytoplankton and Small Fry liquids. That should give enough of a mix of animal and plant material in their feed. The pet food link below for the Wardley’s Small Fry says that “live food” is best but for quick backup and unexpected births, the Wardley’s Small Fry is a good substitute. The DT’s phytoplankton is live.

For those truly geeky enough to want to know a bit about what’s in these foods:

DT’s Live Marine Phytoplankton: contains live Nannochloropsis oculata (yellow-green algae), Phaeodactylum tricornutum (diatoms or algae), Chlorella (green algae)

Wardley’s Small Fry: water, egg product, yeast extract, freeze-dried Calanoid Copepods (planktonic crustaceans that make up the biggest protein source in the ocean), and some vitamins and preservatives

TetraMin Tropical Flakes: fish meal, brown rice, shrimp meal, dried yeast, wheat, oat meal, fish oil, and a variety of vitamins and minerals.

Tetra MiniKrill – Freeze-dried Plankton: freeze-dried krill – Euphausia pacifica (shrimp-like invertebrates that are part of the zooplankton)

The Tropical Flakes can stay out at room temperature. Supposedly so can the Small Fry, though once I opened it, I am refrigerating it. The minikrill are in the freezer (yes, next to the loaves of bread but I don’t think I’ll mix them up), and the DT’s phytoplankton must be refrigerated. But again, I don’t think I’ll grab the phytoplankton when reaching for my husband’s bottle of blueberry juice. 🙂 So, that’s food.

The two articles for salinity in larval crabs:

Salinity Preferences in the Stage I Zoeae of Three Temperate Zone Fiddler Crabs, Genus Uca, Paul S. Capaldo, Department of Natural Sciences, Roger Williams College, Old Ferry Lane, Bristol, RI 02809; Estuaries Vol 16, No. 4, p. 784-788 December 1993

Dispersal and Recruitment of Fiddler Crab Larvae in the Delaware River Estuary, C.E. Epifanio, K.T. Little, P.M. Rowe, College of Marine Studies, University of Delaware, Lewes, Delaware 19958, Marine Ecology – Progress Series Vol. 43: 181-188, March 24, 1988

The first article mentions the three species of fiddler crabs in the study: Uca minax (red-jointed fiddler crabs, which is what I have), Uca pugnax and Uca pugilator, the latter two preferring high salinity areas. Uca minax prefers low salinity found higher up in estuaries, nearer to fresh water sources. The latter two are located in areas closer to the ocean, pugnax in salt marshes and tidal creek banks, and pugilator in the silt and silt-clay areas. The article notes that even though all three may inhibat the same salt marsh, because of their preferences for different salinities and locations, the competition for space and food between the three groups is greatly reduced.

So, today’s entry for all those who wanted geeky specifics on food and salinities. Enjoy!