Tag: cruise

Science Nugget – Spring Bloom, 2021

July 21, 2021

Massive, early spring bloom in the northern Gulf of Alaska, April-May 2021

Satellite measurements

Some of the highest chlorophyll concentrations recorded during the 24-year occupation of the Seward Line were seen in late April – early May 2021, in association with a massive spring bloom of diatoms. As an illustration, satellite imagery from NASA’s VIIRS (Visible Infrared Imaging Radiometer Suite) shows the bloom developing rapidly between April 18th and 25th.

Satellite measurements of Chlorophyll-a in the Gulf of Alaska, April 18, 2021 [Credit: Rachel Potter from NASA VIIRS data]

Satellite measurements of Chlorophyll-a in the Gulf of Alaska, April 25, 2021 [Credit: Rachel Potter from NASA VIIRS data]

Field sampling provided details

Our field sampling from R/V Sikuliaq coincided with this bloom. We found relatively cool ocean temperatures and, in places, fresher conditions than usual, as shown below for the GAK line. High chlorophyll was mostly confined to the upper 20 m of the water column (as seen in the fluorescence section below). Likely, this bloom was a response to intermittent sunny days and light winds. Late April chlorophyll-a concentrations reached almost 30 μg liter-1 on the inner MID line. In contrast, in some springs the peak concentrations are only one-tenth this level. Surface macronutrients (nitrate and silicic acid) had been drawn down to levels usually observed in summer (<1 μM liter-1).

Anomalies of temperature and salinity along the Seward Line, spring 2021 [Credit: Seth Danielson]

Fluorescence along the Seward Line, spring 2021 [Credit: Russ Hopcroft]

Microscopy conducted on board showed a diverse mixture of chain diatoms and colonial Phaeocystis comprising the bloom phytoplankton community. Concurrently, late-stage juveniles of the spring dominant Neocalanus copepod community had large amounts of lipid stores. At some stations, these copepods were already beginning their seasonal descent to deep diapause depths. Conversely, seabird abundances were some of the lowest ever observed during the >20-year time series, and few marine mammals were sighted.

The early, intense bloom of large, lipid-rich phytoplankton bodes well for survival and growth of krill and larval fish in 2021.

Planktonic organisms in the Gulf of Alaska, Spring 2021

For further information contact Russ Hopcroft (rrhopcroft@alaska.edu) or Suzanne Strom (stroms@wwu.edu)

100th Occupation of the Seward Line

October 19, 2020

2020 Field Season Complete

Graduate students Hana Busse (WWU) and Annie Kandel (UAF) sample the CTD aboard the R/V Sikuliaq.

Despite challenges and restrictions due to COVID-19, the NGA LTER was able to complete their 2020 field operations. These operations included four planned research cruises, and redeployment of several moorings.

To enable this, we shortened cruise lengths, reduced the number of participating scientist, and transferred on cruise to a different vessel. In the end, the NGA team pulled off the core Gulf of Alaska sampling and so maintained the long-term time series datasets.

Fall Cruise Update

During the first 9 days in September, twelve scientists from the University of Alaska (UAF), Western Washington University (WWU) and U.S. Fish and Wildlife Service (USFWS) sailed aboard the R/V Sikuliaq. Originally, the fall cruise was scheduled to take place on the USFWS vessel R/V Tiglax. Unfortunately, the pandemic forced the cancellation of all 2020 Tiglax sailings. Postponement of other research cruises on the Sikuliaq schedule and a slight shift of fall LTER sailing dates opened a window of availability for a fall expedition.

Fall sampling occurred in Prince William Sound and along the Seward Line. This marks the 100^th occupation of the Seward Line using a (nearly) modern suite of vertically profiling sondes! The Seward Line is a 150 nautical mile transect that starts at the mouth of Resurrection Bay and extends offshore into oceanic waters. The first occupation of the Seward Line was in December, 1970. Over the first few years, samples were taken only at discrete depth levels using Nansen bottles and reversing thermometers.

Temperature and salinity anomaly plots from the September 2020 cruise along the Seward Line.

A history of the sampling along the Seward Line includes:

First, sampling at Seward Line stations began with a cruise in 1970. Bottles collected water samples from depth.
Using profiling dataloggers, 17 full occupations of the Seward Line occurred from 1974 to 1997.
Then from 1997-2004, sampling expanded to 6-7 cruises per year as part of the U.S. Global Ocean Ecosystem Dynamics (GLOBEC) program.
From 2005 to 2017, cruises occurred in May and September on the Seward Line and in Prince William Sound. The consortium of funding partners include NOAA, 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.
Most recently, in 2018 the consortium expanded via funding from NSF’s LTER network. The expansion includes spring, summer and fall expeditions and the addition of survey stations east and west of the Seward Line.

More details and information on the history of our site – http s://nga.lternet.edu/about-us/site-history/

Successful 2020 Seward Line Cruise Completed

May 15, 2020

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.

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:

LISTEN: Pared down Sikuliaq sailing in Gulf of Alaska maintains research streak

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

May 1, 2020
Last Updated: August 16, 2021

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.

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.

“How Scientists Are Keeping Irreplaceable Research Going During the COVID-19 Pandemic” describes our early attempts to adjust when the effects of the pandemic were still unclear (Smithsonian Magazine, mid-March.)
“At UAF, two major programs highlight the struggle” describes the announcement by the University-National Oceanographic Laboratory System (UNOLS) to stand down the academic fleet until July 1, 2020. Since our Spring and Summer cruises were scheduled on the UNOLS vessel R/V Sikuliaq, this directly endangered our program (our local newspaper, the Daily News Miner, mid-April.)
“Pandemic carves gaps in long-term field projects” describes the importance of NGA LTER’s measurements of plankton in the spring. And it describes how R/V Sikuliaq’s crew and NGA LTER scientists quarantined in hopes that a spring cruise might be allowed (Science Magazine, mid-April.)

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.

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

July 24, 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.

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 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.

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.

Four Stories about the Spring 2018 Cruise

August 17, 2018
Last Updated: November 30, 2020

Lauren Frisch, Public Information Officer for the College of Fisheries and Ocean Sciences, UAF, authored a series of four stories about our May 2018 cruise. Although these stories focus on the on-board capabilities of R/V Sikuliaq, they also include engaging descriptions of our research. Find the links to these stories below:

Sikuliaq expands ways to study Gulf of Alaska ecosystems
	Studies of zooplankton such as copepods have expanded because of LTER funding and the workspace available aboard R/V Sikuliaq. For instance, CFOS researcher Russ Hopcroft isolates, identifies, photographs, and assesses live animals soon after net tows. Read full story >>
Submarine ‘airplane’ revolutionizes measurement of seawater content
	CFOS’s Seth Danielson operates an Acrobat instrument, which he described as the underwater version of an airplane. The Acrobat measures temperature and salinity on fine spatial scales. As a result, LTER scientists can track freshwater from the land and investigate how it mixes with ocean water. Read full story >>
Sikuliaq improves analysis of phytoplankton’s nutrient needs
	CFOS’s Ana Aguilar-Islas brings her own specialized clean sampling instruments onto Sikuliaq so she can quantify nutrients like iron that are essential to phytoplankton. Additionally, Aguilar-Islas and WWU’s Suzanne Strom performed incubation experiments to study how iron availability affects plankton growth. Read full story >>
Sikuliaq researchers find odd, abundant animal-plant plankton
	Nutritional flexibility in ciliates and dinoflagellates stabilizes food chains in the Gulf of Alaska. WWU’s Suzanne Strom isolates cells and preserves them soon after they are collected, so she can analyse them at sea and in her onshore lab. Read full story >>

Video of Zooplankton Sampling

August 6, 2018

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.

Expedition Gulf of Alaska

April 13, 2018

Our upcoming Seward Line cruise aboard the R/V Sikuliaq will include some special guests: educator and film-maker Michele Hoffman Trotter, media and education specialist Carlee Belt, and cinematographer Katherine Brennan. They have traveled all the way to Alaska to create a series of educational modules called “Expedition Gulf of Alaska: an Online STEAM Experience”. Additionally, they will be filming for “Microcosm”, a documentary project that features the diversity and roles of microscopic life in the ocean.

Michele is a Chicago based educator with 20+ years of experience in higher education and public outreach to general audiences. She met Dr. Russ Hopcroft, lead PI of the NGA LTER, aboard the USCGC Healy in the Chukchi Sea. They bonded over microscopic creatures and their shared interest in how the ocean functions as a system. At the time, Michele made a video introduction of her work on the cruise.

Educational Modules

Photo credit: Michele Hoffman Trotter

During the April/May 2018 Seward Line cruise, planned educational modules focus on three topics:

Changing Climate, Changing World
Biodiversity: Our Lives Depend On It
Plankton to Whales: How Energy Flows in the Environment

All of these modules will incorporate YouTube videos and other online material, posted daily from the ship. For example, video clips of scientific tools in use performing fieldwork will be posted. Then in the comments, students will directly question scientists about their work during the cruise.

The content targets students from grade five through twelve. As an introduction, younger students will develop a base understanding of key concepts involving the scientific method of inquiry, taxonomy, and fundamentals of ecology, chemistry, atmospheric science, and biology. Supplementary activities will give older or more advanced students chances to engage in analytical thinking. Furthermore, they will also be encouraged to apply newly acquired knowledge to contemporary scientific questions.

We are excited about the intersection between Michele’s program and the goals of the LTER Schoolyard Series. In addition to participants in Alaskan classrooms, we have participating homeschooling families in California and Illinois, and two public schools in Chicago. Additionally, approximately a dozen adults are participating in an adult education version.

View the Microcosm Teaser.

Sikuliaq Cruise, May 2018

April 11, 2018

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

Map of Northern Gulf of Alaska sampling stations, 2018.

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