Live Sand Examination
... but so far the number of life actually in the sand bed is disappointing.
I think the question might be "How are you looking for the sediments, and what do you expect to see?" Here is a copy of some instructions I have given out at some meetings about how to assess live sands. This might help.
Materials
- Small clear glass or plastic bowl or container.
- Transparent stand to support bowl.
- Intense light source; halogen bulb is best.
- Forceps or tweezers, fine-tipped are best.
- Hand lens (20x best) or stereo microscope.
- Turkey baster.
- Pipette (optional)
Procedure
Use a narrow felt-tip marker to make a rectangular grid on the bottom of the bowl. The grid lines should be about 1 cm apart.
Fill bowl with tank sea water and place it on support. Arrange light source to illuminate the bowl from underneath (use a mirror if necessary). Turn light off.
Take about 1 cubic centimeter of substrate from a selected site in the aquarium. Don't go overboard - less sand is preferable to more.
Place substrate sample in the bowl and stir it to distribute the sand evenly. There should be a THIN layer of sand in the bowl. Too much sand will obscure organisms.
Let the sample sit undisturbed for about five minutes.
Turn on the light. Examine the bowl carefully using hand lens or microscope. Look for movement.
- Thrashing movement often is caused by nematodes.
- Slow coiling or slow movement is often caused by worms.
- Rapid jerky movement is often caused by crustaceans.
- Rapid gliding movement is often caused by flatworms or large ciliated protozoans.
Count and tabulate organisms.
Examine the dish contents closely by carefully clearing the sediment away from each grid square using the forceps. If you desire to examine any organisms more closely use a pipette to transfer them to a clean bowl with sea water in it.
Count and tabulate organisms.
Total the numbers of organisms found.
Repeat several times, and find the average of all the values.
Multiply by 10,000 to find numbers per square meter, the common benthic measure.
Evaluation
| If your number is between | Prognosis |
| 0 - 1,000 animals/m 2 | Poor sand bed fauna, probable collapse of sediment filtration bed soon. Tear down system and rebuild sand bed. |
| 1,000 - 5,000 animals/m 2 | Mediocre sand bed fauna, rejuvenate with new live sand, faunal booster "kit". Feed system more heavily. Sample and evaluate system again in 3 months. |
| 5,000 - 10,000 animals/m 2 | Normal sand bed with low population numbers. Feed system more heavily. Sample and evaluate system again in 3 months. |
| 10,000 - 100,000+ animals/m 2 | Normal sand bed with natural range of numbers. |
July 2008 Advanced Aquarist is Now Available