Gulf of Eilat Sediment Trap Cruise

If you want to study zooplankton fecal pellets, you have to know where to find them. One great place to find large quantities of these tiny pellets is in marine sediment traps. A sediment trap is a scientific instrument used for measuring sinking particulate matter in aquatic systems. Collecting and analyzing sinking material helps oceanographers better understand a variety of physical and biogeochemical processes. 

I will be searching for fecal pellets in samples collected with a McLane sediment trap. 

Diagram of a McLane sediment trap.

With this trap design, sinking marine snow falls into a large underwater funnel. The material is collected in sample bottles at the bottom of the funnel which rotate every 1 or 2 days with a timed motor, to be replaced with a new bottle. This allows for separate samples in a time series, so that material fluxes may be studied across different time scales.

Today I had the opportunity to go on a short day cruise to retrieve moored sediment traps in the Gulf of Eilat.

The view of IUI from the Sam Rothberg RV vessel shortly after embarking.

We only had to travel a few kilometers offshore to retrieve traps deployed in water depths of over 700m. 

The marine crew recovering different sediment traps, as well as floats which

maintain the traps' depth during deployment and help locate them for retrieval.

The retrieved McLane trap in all of its glory, after sample bottles were removed for safe storage. 

Heading back to Eilat. Jordan's Port of Aqaba in the distance. 

Normally, all of the sample material collected from these sediment traps has been freeze dried for archives and various analyses. But for the first time ever, a fraction of the Gulf of Eilat time series samples have been preserved in their wet form with the help of some mercuric chloride. 

Preserved time series sediment trap samples, ready for 'scoping. Hope I can find some pellets in them!