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Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts

Past Expedition

Primary Goal

Investigate the pelagic diversity around seamounts in the Gulf of Alaska

Dates

May 12 - 21, 2024

Location

Arctic

Vessel

Research Vessel Sikuliaq

Primary Technology

Hydro-Bios MultiNet system, Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS), Methot trawl, In-Situ Ichthyoplankton Imaging System Deep-Focus Particle Imager (ISIIS-DPI)

Overview

From May 12-21, 2024, researchers investigated the pelagic diversity in the Gulf of Alaska. Using a novel, multipronged exploration program, they inventoried the small animals (zooplankton and micronekton), like fish, crustaceans, gelatinous animals, and squid, in the water column, finding or observing many species that are new to science as well as some that were not known in the region. These discoveries occurred across the full taxonomic spectrum of zooplankton, from tiny crustaceans to large jellyfish.

The northern Gulf of Alaska is a region of high productivity and supports some of the nation’s largest commercial fisheries. But, ocean warming and deoxygenation are raising concerns about the future of the region’s poorly understood deep waters and the fish and invertebrates that live there.

Zones — A rendering of Giacomini and Quinn seamounts (the two large seamounts, left to right) in the Gulf of Alaska. The Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts expedition focused on the deep waters around these seamounts. *Image courtesy of Nick Bezio.*
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This expedition built on the team’s previous work in the region, with the goal of improving understanding of the diversity and distribution of these deep-ocean animals. To help achieve this goal, they used state-of-the-art acoustic sensing and sampling methods, including a variety of plankton net systems and a towed imaging system, with a focus on the waters around two seamounts near the edge of the U.S. Exclusive Economic Zone: Giacomini and Quinn.

MultiNet Recovery — After recovery of the custom-built, tandem MultiNet system, team members wash down the nets, rinsing and moving collected organisms into their net’s codend (collection bucket). *Image courtesy of Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts.*
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Preparing the ISIIS-DPI — Grace Cawley and Hannah Kepner (left to right) prepare the In-Situ Ichthyoplankton Imaging System Deep-Focus Particle Imager (ISIIS-DPI) for deployment. This specialized camera system is used to image and study plankton in its natural environment. *Image courtesy of Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts.*
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Three net systems were used to collect samples for physical and molecular (DNA) analysis and inventories. Two of the net systems enabled the researchers to open and close nets at consecutive depths, dividing the water column into layers: a tandem vertically hauled MultiNet system and a towed Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS). The MultiNet (0.15 millimeter/0.006 inch-mesh nets) system targeted smaller-bodied zooplankton whereas the MOCNESS (0.505 millimeter/.02 inch-mesh nets) targeted larger-bodied zooplankton. Unfortunately, the MultiNet system was lost early in the expedition. The third system was a Methot trawl with a large net that was used to catch larger crustaceans, jellyfish, and midwater fish.

The In-Situ Ichthyoplankton Imaging System Deep-Focus Particle Imager (ISIIS-DPI) — a remotely operated towed vehicle affectionately referred to as “Big-Friend” by the students on the team — complemented the net collections. By continuously imaging the water column, the ISIIS-DPI was able to better resolve vertical patterns. It also showed that life was sparse in the deep water beyond the continental shelf.

Ctenophore collected during the Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of its Seamounts expedition. It may not look like it, but this comb jelly (*Beroe abyssicola*) is a voracious predator that feeds on other gelatinous organisms by engulfing them whole. *Image courtesy of Allen Collins, NOAA Fisheries National Systematic Laboratory and Smithsonian National Museum of Natural History.*
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Juvenile Squid — Squid collected during the Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts expedition. Some of the most beautiful creatures living in the deep-ocean water column are cephalopods, squids and octopods, like this juvenile squid of an undetermined species. *Image courtesy of Allen Collins, NOAA Fisheries National Systematic Laboratory and Smithsonian National Museum of Natural History.*
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On the ship, the team sorted and processed physical samples in real time and generated genomic data for select species using a MinION sequencer (Oxford Nanopore Technologies). But that was just the beginning. Now that they’re back on land, much work remains to be done, including additional sample sorting, processing, bioinformatics, and sequencing, and training the ISIIS-DPI to recognize the deepwater species imaged using artificial intelligence.

At Work in the Lab — Tracey Sutton, Russ Hopcroft, and Dhugal Lindsay (left to right) use microscopes to analyze collected samples during the Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts expedition. *Image courtesy of Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts.*
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DNA Sequencing at Sea — Jennifer Questel loads DNA onto a portable DNA sequencer (MinION flow cell). This allowed scientists to obtain genetic data from freshly caught zooplankton during the Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts expedition. *Image courtesy of Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts.*
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While the final outcomes of this expedition are still a way off, they are expected to improve our understanding of the ecology and biodiversity of the northern Gulf of Alaska, the connections between its shelf and ocean habitats, and its response to changing conditions. It will also help us better manage the important resources provided by the region.

Bathymetric map of the Gulf of Alaska, showing its deep basin with seamount chains. Gray is land, green is the continental shelf, yellow is the continental slope, and orange is the Gulf’s deep basin. *Image courtesy of Seth Danielson, University of Alaska Fairbanks.*
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Expedition Plan — The primary focus of the Exploring Pelagic Biodiversity of the Gulf of Alaska and the Impact of Its Seamounts expedition was on life around seamounts, but the team also explored the waters at the edge of the continental shelf and over the abyssal plain. The planned net sampling stations are in yellow, and the proposed tracks for theIn-Situ Ichthyoplankton Imaging System Deep-Focus Particle Imager (ISIIS-DPI) are in red. *Image courtesy of Russell Hopcroft and Caitlin Smoot.*
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What Is DNA Barcoding And Why Is It Important?

During this expedition, every day was focused on collecting samples and were largely the same tempo. Here, I describe a day’s work on F.G. Walton Smith during Exploration of Deepwater Habitats off Puerto Rico and the U.S. Virgin Islands for Biotechnology Potential.

August 14, 2024

Using a Diverse Set of Collection Tools to Sample Zooplankton and Micronekton Diversity in the Gulf of Alaska Seamount Province

One of the main objectives of this expedition was to generate species inventories and characterize the vertical distribution of poorly known deepwater fauna around two seamounts in the Gulf of Alaska: Giacomini and Quinn. To meet this objective, the team used a variety of tools to survey the diversity of small animals (zooplankton and micronekton), like fish, crustaceans, gelatinous animals, and squid, at deep depths in the water column of the northern Gulf of Alaska. These tools included three types of plankton net systems, acoustics, and an underwater imaging platform.

August 14, 2024