Friday, 10 February 2012

What do we do when a Hamon Grab comes up?

Over the past few days whilst we've been at sea we've spoken quite a bit about different types of marine life which have come up in the grab samples and showed some pictures of the equipment in operation but not actually explained what we do with the sample when it comes in so here's a guide to the Hamon grab sampling that we're doing.

The first thing to do is to take a small amount of the sediment and seawater and put it in a plastic box to be send for Particle Size Analysis
The boxes are then stored in the freezer until they can be sent off for analysis
We then measure the volume of the total sample before we start sieving...
...and record all of the important information on a whiteboard in the wet lab
First up the sample is sieved through a 5mm sieve which filters out all of the large pebbles, shells and animals such as crabs and brittlestars
All of the material that comes through the 5mm sieve is then sieved through a 1mm sieve and anything smaller than 1mm is discarded
Everything that has stayed behind in the 5mm and 1mm sieves is then put together in a tub and labelled up with the information on the site that the sample was taken from

The samples are then left ready to have the formaldehyde added to them. Once back on dry land all of the samples will then be sent off for analysis to come up with a comprehensive list of all the species that are present.