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Successful 2020 Seward Line Cruise Completed

Post-cruise Update

Despite only having three scientists aboard and working around 2 gales, the Spring 2020 cruise succeeded! That means all the cruise objectives were met during the May 4 – 10, 2020 cruise, thanks to the efforts of the entire team, including marine technicians and the whole crew of the R/V Sikuliaq. Successful elements of our cruise include:

  • CTD profiling of ocean physics, collections of macronutrients, chlorophyll, phytoplankton, and three size classes of zooplankton at all 15 Seward Line and 5 western Prince William Sound stations,
  • Recovery of the GAK1 mooring, (a year’s worth of temperature and salinity data at 6 depths) and its re-deployment for the next year, and
  • Re-deployment of the GEO1 mooring recovered by R/V Sikuliaq in April. This mooring includes a Profiler that will measure temperature, salinity, chlorophyll-a fluorescence, colored dissolved organic matter (CDOM), nitrate (NO3), and dissolved oxygen (DO) throughout the water column for the next year.
May 2020 CTD
CTD data from the Seward Line, May 2020.

More Media Coverage

As discussed before, this cruise shows how science can adapt during the time of COVID-19. Since that last post, several more stories have been published.

Before the cruise departed, Alaska Public Media’s Casey Grove spoke to LTER Lead PI Russ Hopcroft. Dr Hopcroft explained why sampling this spring was necessary to understand measurements that might be more easily made later in the year, and how springtime measurements enable connections to be made between years:

The Sun sets through an R/V Sikuliaq window in May 2020. Credit: Seth Danielson

Then after the cruise, EOS, the weekly magazine of the American Geophysical Union published an article about the cruise. It describes how measurements were taken while scientists and crew followed the required social distancing.

Citation: Duncombe, J. (2020), What it’s like to social distance at sea, Eos, 101, https://doi.org/10.1029/2020EO144098. Published on 12 May 2020.

Seward Line Sampling Continues Despite COVID-19 Worries

Resilience in Gulf of Alaska Science

Like everyone, scientists world-wide want to reduce the spread of COVID-19. However, for their work, they also need to continue research projects that rely in part on uninterrupted data records. Fortunately, with the support of NSF and University of Alaska, NGA LTER scientists will be able to do both by reducing spring field operations.

A press release by the College of Fisheries and Ocean Sciences at the University of Alaska Fairbanks outlines our plans for the spring cruise: Sikuliaq to embark on limited research cruise in May.

Photo of R/V Sikuliaq at the dock in Seward Alaska
The research vessel Sikuliaq, here in Seward, Alaska, will depart May 4, 2020. [credit: Sarah Spanos]

Evolution forced by COVID-19

Like other research programs, our research plans shifted rapidly in response to the changing situation. Several articles trace this evolution by featuring NGA LTER PIs and research activities.

Importance of the Time Series

Multi-disciplinary monitoring of the Gulf of Alaska ecosystem has occurred every May since 1998. Fisheries managers and research scientists can make informed assessments of Alaska marine ecosystem health and status because of these measurements. This long-term sampling happens along the Seward Line – a set of stations stretching 150 miles across the shelf – and within Prince William Sound. Regular samples at these consistent stations insure the integrity of this time series. Therefore, preserving core physical, nutrient chemistry, phytoplankton and zooplankton data at these stations is a high priority for NGA LTER scientists.

The North Pacific Research Board (NPRB), the Alaska Ocean Observing System (AOOS), and the Exxon Valdez Oil Spill Trustee Council (EVOS) via the Gulf Watch Alaska program all provide additional funding that make this time series possible.

graph of GAK1 data
Nearly 50 years of data have been collected at GAK1, a Seward Line station. This allows the calculation of long-term trends and anomalies. [credit: Seth Danielson]

The Plan

Our planned field work aims to continue the valuable Seward Line time series while keeping personnel safe. Before the cruise, R/V Sikuliaq remained in Seward, AK, staffed by her crew. They have been under quarantine on board since their arrival at the start of April. Three of our Principle Investigators (PIs), Seth Danielson, Ana Aguilar-Islas, and Russ Hopcroft, quarantined at home for 2 weeks. They will join R/V Sikuliaq for the 7 day cruise, May 4-10, 2020. Before the cruise, crew and science party members logged body temperatures twice daily and maintained strict adherence to social isolation protocols in order to ensure a virus-free voyage.

The cruise plan includes sampling of the entire Seward Line with additional stations in western Prince William Sound. Planned measurements include water temperature and salinity using the conductivity-temperature-depth (CTD) instrument; water collections from deep waters to the surface for chlorophyll, nutrient, phytoplankton, and microzooplankton analysis; and net tows for zooplankton.

Other common NGA LTER activities will not be possible due to the short cruise length and limited personnel. Postponed activities include shipboard experiments, seabird and mammal surveys, jellyfish sampling, dissolved iron and other trace metal sampling, carbonate chemistry sampling, and optical measurements. NGA LTER’s other cross-shelf sampling lines will not be visited.

Despite these restrictions, we are fortunate to have the opportunity to continue our work and to contribute to the goal of understanding the Northern Gulf of Alaska ecosystem.

Expedition Gulf of Alaska Seamounts 2019

The Habitat

In the deep water south of the NGA LTER study area lies an abyssal plain punctuated by volcanic seamounts – mountains that rise from the sea floor. The seamounts provide rocky, hard substrate that makes a good habitat for cold-water corals and sponges. Above the seamounts, ocean currents upwell nutrients to the surface where they feed planktonic organisms. This productivity attracts fish and seabirds to create relative hot-spots of biodiversity in the open ocean.

Map of seamounts in the North Pacific
Bathymetric map of the Gulf of Alaska, showing its deep basin with seamount chains. Grey – land, Green – continental shelf, Yellow – continental slope, Orange – deep basin. [credit: Seth Danielson]

The Expedition

Immediately following the NGA LTER’s RV Sikuliaq cruise, summer 2019, several of our team members are setting out to extended our knowledge of the Gulf of Alaska. Dr. Russ Hopcroft, Dr. Petra Lenz, Dr. Vittoria Roncalli, Heidi Mendoza Islas, Callie Gesmundo, and Caitlin Smoot are joining our collaborators from Microcosm and other expedition members aboard R/V Sikuliaq to investigate seamounts in the Gulf of Alaska from an ecological perspective.

ROV Global Explorer
ROV Global Explorer by Oceaneering has a multitude of imaging and sampling capabilities ideal for deepwater exploration. [credit: Katrin Iken]

The ROV Global Explorer is a critical tool of this expedition. Operated by Oceaneering International, the ROV will take video and still images of organisms on the sea floor; this is the least-invasive method of sampling communities that could be damaged by bottom trawls and other collection methods. ROV Global Explorer will also collect fragile jellyfish by gently enclosing them in a sampler. This avoids the bias of previous sampling towards hard-shelled organisms that survive net tows.

Expedition Gulf of Alaska Seamounts 2019 will even be employing DNA sequencing to identify microbes. Previously, a NOAA Office of Ocean Exploration and Research expedition to the Gulf of Alaska seamounts in 2002 found that the corals there were distinct habitats for microbes.

Follow Along

The NOAA Office of Ocean Exploration and Research has created a website where visitors can follow the Mission Logs. Additionally, educators can also learn more about the expedition purpose and find videos and other classroom materials.

collage of benthic organisms
Benthic collage. [credit: Gulf of Alaska Seamounts 2019 Expedition]

NOAA Office of Ocean Exploration and Research funds this project, with additional ship support by the National Science Foundation and the University of Alaska Fairbanks. Science partners during this mission include scientists from the University of Alaska Fairbanks, the University of Manitoba Canada, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), the University of Hawaii, University of Barcelona Spain, Lamont Doherty Earth Observatory at Columbia University, the U.S. Fish and Wildlife Service, and a Microcosm film team from Montrose Pictures. The partner for the ROV is Oceaneering.

Jellyfish Make News

Methot net for catching jellyfish
Heidi Mendoza-Islas stands in front of a Methot net used for collecting large jellyfish in the Gulf of Alaska. Photo credit: Loring Schaible.

Lauren Frisch, Public Information Officer for the College of Fisheries and Ocean Sciences, UAF, wrote a news item describing interesting NGA LTER research:
Overlooked jellyfish play big role in Gulf of Alaska.

Yes, until now even the NGA LTER project website has overlooked jellyfish. Instead, our major research components focus on the primary producers and zooplankton that are the base of the food chain. Worse, at sea, jellyfish are often simply a nuisance whose tentacles drape on instruments and clog sensors. However, Heidi Mendoza-Islas, a graduate student in the NGA LTER project, studies the important role that jellyfish play in the Gulf of Alaska ecosystem. Read the article to find out more.

Video of Zooplankton Sampling

Alicia Rinaldi-Schuler, a fisheries graduate student at CFOS, volunteered for NGA LTER’s Spring 2018 cruise aboard R/V Sikuliaq. Ordinarily, Alicia studies humpback whales. However, we put her to work sampling zooplankton on the night shift. She filmed the equipment they used (bongo nets, multi-net, and methot net) and the creatures they caught (squid, jellyfish, euphasiids, and fish larvae). Her engaging video summarizes of some of the research that occurs during our cruises.

Sikuliaq Cruise, May 2018

R/V Sikuliaq

In a few short days, 23 scientists and educators will embark on our first LTER cruise aboard the R/V Sikuliaq, April 18 – May 5, 2018. Cruises are integral to our research and we anticipate having three each year – in May, July, and September. This cruise continues decades of time-series of measurements of the spring phytoplankton bloom along the Seward Line. As such, its many objectives center on the physical and biological processes that generate and sustain the spring bloom.

Scientific Purpose

This cruise continues the sampling begun in fall 1997 under the NSF/NOAA NE Pacific GLOBEC program, and supported subsequently a consortium of the North Pacific Research Board (NPRB), the Alaska Ocean Observing System (AOOS), and the Exxon Valdez Oil Spill Trustee Council’s (EVOSTC) Gulf Watch. This is the first cruise as part of the NSF’s Northern Gulf of Alaska Long-term Ecological Program (NGA-LTER). The core scientific purpose of the Seward Line project is to develop an understanding of the response and resiliency of this marine ecosystem to climate variability. This cruise marks the 21st consecutive spring cruise for the Seward Line in the NGA, including Prince William Sound (PWS), and the 48th year of observations at GAK1.

Cruise Objectives

NGA map
Map of Northern Gulf of Alaska sampling stations, 2018.

  1. Determine thermohaline, velocity, light, and oxygen structure of the NGA shelf.
  2. Determine macro- and micro-nutrient structure of the NGA shelf.
  3. Determine particle structure and flux rates of the NGA shelf.
  4. Determine phyto- and microzooplankton composition, biomass distribution, and productivity.
  5. Determine the vertical and horizontal distribution and abundance of zooplankton species (including macro-jellies).
  6. Record multi-frequency acoustics for estimation of nekton
  7. Conduct surveys of seabirds and Marine Mammals
  8. Conduct shipboard experimental work on phyto- and zooplankton.
  9. Determine carbonate chemistry (i.e. Ocean Acidification) at selected stations
  10. Recover and redeploy the GAK1 mooring. Drag for lost mooring at GAK 4 and Gak8i.
  11. Provide at-sea experience for UAF students.
  12. Share the experience through outreach/media activities.

Sampling Plan

To achieve the objectives, the cruise will visit four cross-shelf transect lines plus stations within Prince William Sound. At each station, operations will be divided into day and night tasks. In the day, we will perform CTD measurements, bottle sampling, and perform intensive sampling and productivity experiments at selected locations. At night, net tows for zooplankton will catch the critters when they rise in the water column to feed. The shortness of high latitude nights in May will mean more daylight work than nighttime work.

Cruise Planning

photo of notes

Right now, we are planning our next cruise which will be aboard the R/V Sikuliaq in mid-April 2018. There are a lot of elements that must be balanced when planning a cruise. Of course, time, money (including that for processing samples later on shore), and the program objectives all influence the cruise plan, but there are many other facets to consider.

Elements

For one thing, there are logistical elements that limit where the cruise must start and in what order the stations will happen. These include:

  • Towing for zooplankton must be done during the day, when they are high enough in the water column to catch
  • Productivity experiments must be done during the day when there is sunlight
  • Time spent traveling between sampling locations (deadheading) must be minimized
  • Equipment and personnel must be delivered to and retrieved from the ship

In addition, we must incorporate elements of previous studies to insure continuity between measurements:

  • EcoFOCI sampling stations over the productive sub-marine banks
  • Prince William Sound stations (which can’t be in the shipping lanes)
  • The timing of Seward Line stations with respect to the Spring Bloom

And unfortunately, bad weather can impact the best made plans.

photo of bad weather
Photo by Lisa Seff, Sept. 2017 aboard the Sikuliaq