From: Wecoma Chief Scientist
Subject: Wecoma report for 31 Jan to 3 Feb '03

COAST R/V Wecoma report 31 January - 3 February 2003

During Friday to Monday, 31 Jan to 3 Feb, we completed the following sampling:

-- a SeaSoar/ADCP/HTI/iron survey on the SmallBox North grid (7th repeat) -- 5 deep CTD stations along the shelfbreak to help delineate the downwelling front
-- two tow-yo CTD sections along the Cascade Head line between the 150 and 100-m isobaths
-- ongoing zooplankton growth rate experiments (see Jaime Gomez-Gutierrez and Jesse Lamb's report below)
-- a SeaSoar/ADCP/HTI/iron survey on the BigBox grid (lines 2-8)

Since 1 February the winds have become upwelling favorable (from the north) up to 20 knots in strength. As promised, we've been getting some much needed sunshine! Looks like this weather pattern may hold through the end of the experiment.

At the conclusion of our SmallBox North repeat #7 we sampled close to shore off the Siletz River. This was near the peak of the flooding rivers and the Wecoma passed through a chocolate brown surface layer as we towed SeaSoar, the HTI bioacoustics sled and the iron fish in to about 30 m depth. Salinities on the Wecoma flow-through system dropped as low as 17. There was a sharp edge to the buoyancy front with small-scale meanders in it as we looked downstream. As the Wecoma passed into the fresh layer, subsurface green oceanic water was mixed up and left a green streak through the brown surface layer. Colored dissolved organic matter (CDOM) levels went up in the fresh water and we grabbed a surface sample as a check on our flow-through nutrient and iron systems.

Late in the morning on 1 February, we launched the SeaSoar, HTI and ironfish and began a BigBox tow on lines 2-8. Our goal was to document the details of the wintertime hydrography and circulation over Heceta Bank. We completed the entire lines 2 and 3 because we had already marked crab pot locations on those lines. We surveyed on lines 4 and 5 only into the 100-m isobath at night. On Sunday, 2-Feb, we had good success towing SeaSoar along the complete Cape Perpetua line (line 6) all the way into the 40-m isobath. Crab pots were very thick inshore over Heceta Bank, but we were able to slalom through the pots. The inshore region from just outside the breakers to about 100 m is thick with pots. With the good weather the crab fleet has sailed from Newport and is working their gear.

Just after we completed line 6, we needed to recover our gear and steam at top speed to Newport to take care of a medical emergency. Bob Ashley, Chief Engineer, had to be airlifted off Wecoma on a Coast Guard chopper after he experienced a mild heart attack. Bob was in stable condition when he was tranferred to the chopper as Wecoma steamed toward Newport at 12+ knots. We all wish Bob a speedy recovery! Wecoma went into Newport to pick up Hal Gray, Port Engineer, to sail as Chief Engineer. Thanks, Hal, for being available and ready so fast to be shanghaid for a week! Turnaround in Newport took about two hours and we sailed again at 4pm on Sunday.

On Monday, 3 February we completed sampling on lines 7 and 8 by combining SeaSoaring offshore of 100 m and CTD profiles from 100-30 m. The amount of crab gear in this area is mind boggling and we're proceeding with utmost care. The crab fleet is working all around us and the radar screen looks like a game of space invaders at time. As they've done all cruise, the captain, mates and crew are doing an outstanding job watching for and avoiding fishing gear and also interacting with the fishing fleet on the radio when necessary.

We have just started a line of CTDs, vertical zooplankton net and MOCNESS zooplankton net tows along the Cape Perpetua line from the 30-m isobath to out over the deep continental slope. Our longer term plans are to finish sampling over the Bank and then to return to the northern region to complete a number of SmallBox North and BigBox (lines 1-3) maps before concluding operations on Saturday.

Jack Barth
Chief Scientist, R/V Wecoma
2000, 3 Feb 2003

----------------------------------------------------------------------- Zooplankton shipboard incubations report. Jaime Gomez-Gutierrez and Jesse Lamb

Currently we have been collected life zooplankton in four stations (L3-8, CH5.5, CH6, and CH6-b) during every night between January 27-31 (excepting Jan 29). From those samples we have been incubated at constant temperature (10 degree C) females copepods to estimate egg production, and furcilia, juveniles and euphausiids to estimate molting rates. We have not been collected any euphausiid mature female (purple female) to estmate egg production confirming that euphausiids only reproduce during spring and summer.

Copepod egg production: In all the stations have been found and incubated (24h) females of the copepod Calanus marshallae, which is early for this time of year. Only in the first live tow (L3-8) females of Pseudocalanus spp. were incubated associated with a big phytoplankton bloom.

Molting rates experiments: Each molting rate experiment lasted 72 hrs (instead of 48h) incubating between 40 and 42 individuals of different sizes (furcilia, juveniles and adults) of Euphausia pacifica, Thysanoessa spinifera and few specimens of the oceanic Thysanoessa inspinata. The first two species are the dominant euphausiids off Oregon. It was unsuspected to collect large animals during downwelling conditions, previously assumed animals would be wintering. Mortality in the shipboard incubatins have been moderately low (<17%) and molter proportion ranged between 17 to 25%).

Additionally we have been doing observations of ectoparasitic apostome ciliates of euphausiids. Using filtered sea water (<10 um) in molting rates incubations we discovered that the molts are infected by epibiontic apostome ciliates that feed on exhuvial fluids. These are known for other crustaceans like copepods, decapods but and in euphausiids from North Atlantic. We expect to do more observations to know if some of those encysted stages can infect endoparasitically the euphausiids as observed during summer cruises.