Northwest Fisheries Science Center

Newportal Blog

A gateway to oceanographic adventures from the Newport Line and beyond

Blog Entries for August 2015

What's on the sandy seafloor?

By Jennifer Fisher
Posted on August 28, 2015


It’s 7:22 pm, we are 45 miles offshore of Newport, Oregon, and we just finished sampling at a station. I am writing from the Timmy Boy which is a 60’ fishing vessel owned and Captained by Bob Eder. Dillon Eder (Bob’s son) and Drew Rasmussen are also on board as deckhand, cooks, boat driver, science helpers; everything really.

We are working on a Cooperative Research project that utilizes fishing vessels to sample the pelagic (midwater) and benthic (bottom) habitats off Newport Oregon. Larval fish spend weeks to months in the pelagic environment until they metamorphose and become bottom-dwelling juveniles. By sampling both the midwater and bottom habitats, we hope to understand whether the fluctuations we observe in pelagic larval fish abundance are expressed as similar changes to benthic juvenile fish abundance. To do this, we sample 12 stations located 1 – 85 miles offshore quarterly aboard fishing vessels. This is our second day out, we have one station left, and we hope to be back at the dock by 2am.

 

To sample the bottom, we use a beam trawl that crawls along the seafloor and scares small fish into the net. There is a camera mounted on the net frame with lights and lasers that are used to measure the fish that are recorded going into the net. The net is towed for ten minutes and all the contents are pulled on board, put in to a cooler, and sorted. We also measure and identify all of the fish.

 

You never know what will be brought up in the net. As Bob Eder put it, it’s like opening a X-mas present over and over again. At one station we pulled up a bunch of mud-like sand that was filled with marine leaches. Another time, the contents were filled with mats of glass-like tubes- likely polychaetes (worms). We are targeting flatfishes, and we often see many different species.

Earlier this year, we were collecting many small red octopuses, a phenomenon that has spurred a separate study on these organisms since they have not been observed in this high of abundance before.

The strangest thing we collected this trip was a large blue sphere that was covered inbarnacles. At first we thought it was Styrofoam, but it was much heavier than Styrofoam. After more inspection that led to the sphere cracking, and a large yolk spilling on to the deck, we finally realized it was a bird egg! From the barnacle growth, we assumed the egg had been in the ocean for a long time, but the yolk appeared in good condition (bright yellow) and the egg didn’t smell rotten, maybe the cold water preserved the egg?

 

 

I’d like to give a huge thanks to Bob, Dillon and Drew of the F/V Timmy Boy. They keep a very nice boat and were a pleasure to work with! Thanks guys!

Stay tuned to learn about what we found in the midwater during this research cruise aboard the F/V Timmy Boy.

 


Tagged: NH Line, CoOp Survey

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Evolution of the toxic April/May Pseudo-nitzschia bloom

By Xiuning Du
Posted on August 6, 2015


Domoic Acid (DA) toxin in shellfish
The Oregon Department of Agriculture made three shellfish closure announcements in May due to DA levels above the threshold of 20μg/100gm in shellfish tissue. The first announcement was on May 9, for the closure of the northern coast of Oregon. The second announcement occurred on May 14 and the entire Oregon coast was closed to razor clamming. The third closure announcement occurred on May 22, because the measured DA level was above dangerous levels on South Beach in Newport Oregon. We captured the initiation and evolution of this Harmful Algal Bloom (HAB) by the species Pseudo-nitzschia (PN) from five of our biweekly NH line cruises (Figure 1).

Wind and upwelling conditions
Cumulative alongshore wind stress indicated that the onset of upwelling (spring transition) began April 12, 2015 with light northerly winds. Upwelling favorable winds became much stronger from April 17 to April 22. Wind direction then reversed to the south (upwelling relaxation) on April 24 and remained calm until April 27. The northerly winds resumed from April 28 and dominated throughout May.

Pseudo-nitzschia (PN) bloom initiation and evolution off Newport
On April 7, prior to the onset of upwelling, low concentrations of PN cells were present in shelf waters. Following the end of the upwelling relaxation on April 27, it was clear that a PN bloom was in progress (Figure 2).

The May 4 cruise was conducted immediately following the first episode of strong northerly wind that occurred from 30 April to May 3. PN abundance decreased during this time (Figure 1) which might have been related to mixing of the water column from the strong upwelling event and the loss of PN cells offshore by dispersal. On May 7, at the beginning of the second strong upwelling episode (May 7-12), PN abundance had bounced back to above 105 cells L-1 level, and the bloom continued to thrive until at least May 19 (Figure 1 and 3). The percent increase of PN contribution to the total diatom community was dramatic from the 4th to 19th of May. During this time, the percent contribution of PN increased from 23.1% to 89.7%, eventually forming the monospecific bloom.

 

Pseudo-nitzschia PN bloom along the west coast
Spatially, this PN bloom was simultaneously observed along the west coast of North America in early May. The “warm blob” which has been present in the North Pacific since winter 2013-2014 has induced unusually warm ocean conditions, which is suspected to be the proximate driver of bloom formation and longevity. However, the ultimate drivers/factors that lead to the large and persistent PN blooms cannot be answered at the present time.


Tagged: HAB, Warm Blob

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August 2015
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