… that was the question of the week. And I learned that it is a difficult question to answer.

Dredging is serious business… we had professional divers and everything. Basically there is a pump on a boat, a water intake tube, the dredge head (it sucks up the mud and clams and whatever), and a water discharge head that has the sample bag attached to it. It’s really hard to explain how it works and I don’t have a picture, but all you need to know is that the sediment gets sucked up and thrown out the back, into the mesh sample bag. The bag is later sorted to find the good stuff.

Here’s a picture of some of what we got out of our dredge samples. We found gaper clams, cockles, macoma clams, brittle stars, baby dungeness crabs, and olive snails.

We did subtidal dredging in Yaquina on both Wednesday and Thursday this week, but we only got to 30 of the 40 spots we wanted to sample. The weather and tides were not  cooperative, and the divers had to stop early both days (but we still worked over 8 hours each day!). The whole process really showed me how much the combination of tides and wind and weather can effect the boats and divers. The wind was strong enough to counteract the effect of the tides on the boat; but the outgoing tide was so strong that the divers couldn’t hold the dredge system in place. All of this totally threw off our plan to have a separate boat place anchors before we got to a site, because by the time the dredge boat got to the point, the winds and tide had changed enough to require the anchor to be reset.

So basically all day I was dropping and hauling in anchors and the dredge system. Even with gloves my hands were pretty sore from all that rope!

A little background on why we were dredging for clams in the first place:
Back in 2010 (… I think), the NOAA Pacific Fleet moved from WA to Newport. In order to keep all their giant research vessels here they had to build a huge dock, which disturbed a large area of subtidal clam habitat. My team is studying the long term effect of this disturbance and the recolonization rate of the Gaper clam in the area. This is the 3rd post-construction sampling of the area around the NOAA dock. We also are taking some samples in a subtidal area in Sally’s Bend, an area in Yaquina Bay unaffected by the NOAA dock that can be used as a comparison. This creates a BACI study: Before-After-Control-Impact.

Now we just have to determine when we’ll get our last 10 samples. But until then, I’ll just have to be content digging for more clams in the mud and beach flats this coming week.

~Maryna