Sunday, 24 March 2013

Hamon-Grabs at Dawn

Brittle stars and Dahlia Anemones are just some of the myriad of life found so far
So far we've been making good progress at Wight Barfleur Reef. Another two 'nested' boxes of acoustic survey have been completed, with a fourth well under way. These data are being processed onboard which is really helpful as it allows us to build up a detailed picture of the sea floor while we're still on survey,  enabling us to make more informed decisions of where to target additional camera stations.

Up close and personal with a Terebellidae (photo Mike Nelson, JNCC)
Many of the stations we've visited so far have been teeming with life. While some of the larger species, such as brittle stars and sea anemones, are easy to identify, others like encrusting sponges appear as little more than orange smudges on the rocks when captured on film. To help better identify these species, it's really useful to take samples back to dry land where they can be further analysed under a microscope. In particular, the spicules (tiny structures that form the skeleton of the sponge) are often distinctive and therefore easier to ID accurately.

Deploying the Hamon Grab (photo Neil Golding, JNCC)
To collect some sponge-harbouring rock specimens, the full size Hamon Grab (we'd been previously used the Mini Hamon) was deployed for the first time on this survey. After several attempts, a successful grab was finally achieved in the small hours of Friday morning. Although not quite the haul of boulders we'd hoped for, there was enough sponge present for a tiny scraping to be taken which should help accurately identify some of the more abundant species we've seen so far at the site. A small victory, but sufficient to cheer the weary night watch at least!

Collecting sponge samples for spicule analysis (photo  Mike Nelson, JNCC)