All things Meio with a specific focus on Chile

Quantitative sampling of exposed sandy beaches

Quantitative sampling of exposed sandy beaches is best achieved using a piston corer. Piston corers can be easily made by cutting the end off a plastic syringe. The distribution of meiofauna is usually highly heterogeneous, therefore, a large number of small samples is preferable to a small number of large samples. This of course needs to be balanced against the logistics of available sampling time, transportation, and processing time. I typically take 50 ml samples with 5 replicates, though this can and will be modified depending on the requirements of the hypothesis being tested. The method for collecting the samples using a piston corer is illustrated below.

 core_sampler_01 core_sampler_02
Step 1: The piston corer is placed vertically on the sediment surface with the plunger touching the sediment surface. Step 2: The core tube is then pushed into the sediment with the head of the plunger remaining on the surface. This is to avoid compression of the sediment which may be important if you are assessing the vertical distribution of meiofauna. Also, if the plunger were not in contact with the sediment surface the air between the plunger and the sediment surface would have to be compressed to drive the corer into the sediment.
 core_sampler_03 core_sampler_04
Step 3: Once the corer has been inserted to the required depth the sample is retrieved. With finer sands the corer can be withdrawn vertically and the sand will remain within the coring tube. However with coarser or less compacted sands the sample may fall out of the coring tube if lifted vertically. To avoid this problem, rotate the coring tube out of the sediment (illustrated).  Step 4: The sample should then be transferred immediately to a sample jar. If using this method in the subtidal (via SCUBA for example) a rubber bung can be inserted in to the end of the corer to retain the sample until it can be transferred to a sample jar on shore.
 Step 5: The sample can then be fixed on site with formalin (etc) and labeled. The corer should be washed between samples and thoroughly washed between sites. Plastic syringes are both cheap and easily lost, so make sure that you go into the field with more than one. Over time the the rubber head of the plunger will degrade and will not slide smoothly down the coring tube at this point you should make a new corer.