Wecoma daily report, 21 August 2001

Wecoma is continuing to sample along the Bigbox 4 grid, completing line 4 (the NH line) at 1040. We hope to finish the grid at 0400 on Wed 8/22. The Captain did a nice job last night navigating through the black cod fishing gear located on the offshore end of line 6 (the CP line). The inshore and mid-shelf CP-line moorings were visually confirmed and the shelfbreak mooring was seen on radar. Winds have turned around and are coming from the south at about 20 knots. Seas are building but we're merrily SeaSoaring along.

We launched 3 Argos-tracked 15-m drogued drifters along the NH line at NH-10, NH-15 and NH-20.

We've posted results from the southern 4 lines (lines 5-8) on the web. The jet over the Bank is still present and high chlorophyll is still presentin and on the onshore edge of that jet. Chlorophyll levels around 124 42'W on the CP line are four times higher than we observed during BB3. The high-chl feature in the jet does not extend north of line 5. We do see somehigh chl nearshore on line 5. In a sense, this is still an "upwelled" ocean. We should see more and more of the response to downwelling-favorable winds soon.

Jesse Lamb's report of the 19 Aug daytime MOCNESS work in the Heceta Bank Overflow region is attached below.

After completing Bigbox 4 we have approximately 1.5-2 days to conduct process-oriented work before starting our final Bigbox #5. Depending on the sea state (16' seas are forecast for tonite) we will make a decision whetherto beat into the seas to return to the south to sample near the Thompson over the Bank region or to conduct a process study on line 2 (the CH line) measuring the response to strong southerly winds. We will endeavor to go and work with the Thompson weather depending.

Submitted at 1130 on 21 August 2001 by Jack Barth, Chief Scientist,
R/V Wecoma

Heceta Bank Overflow Zooplankton Collection Results, 19-Aug-01 (PST)
Jesse Lamb

Four stations were sampled on the 19th; using the 1-m MOCNESS net. These stations were different than the previous HBO stations (1, 3, and 4), due to a much higher reading of chlorophyll just to the east of the strongest flow of the Heceta Bank jet. Therefore, these stations (HBO 5-8) were on the 124 42'W line, instead of 124 48'W, but at the same latitudes as HBO stations 1,3, and 4. HBO 5-8 were sampled during the daylight hours, for use as a day/night area comparison. While sampling we were using the HTI acoustic data to determine the different depth strata from which to sample.

HBO 5 (43 58'N, 124 42'W) was the first station sampled. We sampled the stations from north to south; this one being located right on Heceta Bank. The station depth was 134m and our net sampled to 120m at 13:05 (PST). From the depth of 120-100m we found a large amount of juvenile and adult euphausids, along with some copepods (most likely Calanus sp.). >From 100-60m we found larger numbers of the aforementioned animals, along with some gelatinous animals in the form of siphonophores and a crab megalope. Our next net range, from 60-30m, caught many much smaller copepods and furcilia, which is a larval stage of euphausids. We also found about fifteen pleurobranchia, another gelatinous animal. Our final nets from about 30-10m contained much of the same organisms as the previous net, with an increase in the number of small copepods and pleurobranchia (from about fifteen between 60-30m to around fifty just between 20-10m. Along with these animals we also found few amphipods and crab megalope.

HBO 6 (43 54'N, 124 42'W) was the next station sampled at 15:26(PST). This station was located south of HBO 5 just on the start of the Bank slope. The station depth was 220m and our nets sampled to 200m. Our first net sampled from a depth of 200-150m. It contained only copepods (Calanus sp.), one squid, one fish, and some pleurobranchia. The next net sampled from 150-80m. It contained a large amount of juvenile and furcilia stage euphausids, along with large and smaller copepods. We also found amphipods and chaetognaths in smaller numbers. The depth layer between 80-60m was sampled as a specific acoustic target, contained about five-hundred juvenile and furcilia stage euphausids, along with many large and small copepods. The water between 60-10m contained many small copepods, pleurobranchia, and amphipods. The number of pleurobranchia decreased with decreasing depth (from about fifty between 60-20m to around two hundred and fifty between 20-10m).

HBO 7 (43 51'N, 124 42'W) was the next station sampled in 320m of water, right on the Bank slope. The sampling began at 17:55(PST) to a depth of 305m. From a depth between 305-200m we found large copepods (Calanus sp.), around twenty-five sergestid shrimp, thirty-four squid, and a myctophid fish. Between 200-150m there were around twenty sergestid shrimp, Calanus sp., big chaetognaths, and some smaller copepods. Within 150-110m there were found big copepods in the form of Calanus and Neocalanus sp., along with some big chaetognaths. From 110-50m there was found amphipods, smaller copepods, some furcilia stage euphausids and chaetognaths. Between 50m and the surface there were only small copepods, pleurobranchia, and a few Calanus. Like in the other nets, the number of pleurobranchia increased with decreasing depth.

HBO 8 (43 48'N, 124 42'W) was the last station sampled, at 19:50(PST), right before sunset. This was the most southerly station, off the Bank, at a depth of 440m. Our net sampled to only 300m, due to time constraints of time to sample during daylight hours. From 300-200m our net contained Calanus sp., a few smaller copepods, and three myctophid fish. From 200-150m our net contained a mix of squid, myctophids, a few euphausids and copepods, and about fifty chaetognaths. The next net, between 150-100m contained only three squid, some muggiaea (a siphonophore), and a few euphausids. Between the depths of 100-30m there were small copepods, some Calanus sp., fifteen sergestid shrimp, two myctophids, and one squid. The next layer, between 30-10m contained around three hundred thousand adult and furcilia euphausids, small copepods, and around thirty pleurobranchia. The surface net contained only twenty adult euphausids, and about thirty pleurobranchia. The net was taken out of the water at 20:50(PST), which was after sunset.