Mapping the ocean impacts of the 2022 Hunga Tonga Hunga Ha'apai Eruption
Hunga Tonga - Hunga Ha’apai (HTHH), one of 22 volcanoes in the waters around the Kingdom of Tonga, erupted violently on 15th January 2022. This eruption triggered shock waves through the atmosphere and generated a tsunami across the Pacific Ocean. Our team set out in April 2022 to document how this eruption impacted the surrounding ocean environment. We found significant volcanic depositions in the region, which smothered much of the life present on the seafloor. Areas of refuge for ocean life was found on structurally complex seamounts in the region. Volcanic ash and debris were still found in the water column, with indications of continued venting from the caldera itself. Work is now underway to understand how this eruption will impact important processes, like carbon sequestration, in the ocean envrionment. Stay tuned for more.
Image credits: NIWA/ Nippon Foundation and Rebecca Parsons-King
Coral Bleaching in the Society Islands
In early 2019 temperatures on the reefs of French Polynesia surpassed 30 degrees Celsius and sustained these high temperatures for almost a month. This led to widespread coral bleaching around the islands with >80% of the corals in our study area around the island of Mo'orea moderately to severely bleached in May of 2019.
The majority (>90%) of the Acropora hyacinthus colonies that we saw were fluorescing. This occurs when after a coral has bleached as the coral is approaching its demise, considered to be akin to a last gasp for life. Bacteria within the coral tissue are thought to lead to the color change. Below you can see various shades of fluorescing in several A. hyacinthus colonies and a Pocillopora sp. colony.
Many of the corals we saw just months earlier had already succumb to the high temperatures and completely died, indicated by skeletons covered in algae. Below you can see instances of coral demise in pocilloporid, porties, and acroporid colonies.
The occurrence of this bleaching event in the Society Islands region is of particular interest because: (1) a Long-Term Ecological Research station is on the island of Mo'orea that has been collecting time-series data for over 15 years on coral cover, fish abundance, water chemistry, among other things, and (2) the reefs of Mo'orea have been thought of as particularly resilient, rebounding from past mortality events that brought coral cover down to 0% in some areas in a few years time.
We have expanded our ongoing sampling efforts in this region in an effort to better understand what the impacts of this bleaching event will be on the surrounding water chemistry, the long-term health and longevity of the reef system, and the feedback effects from a molecular scale up to an animal scale. We have modified our methods to best capture the impacts of this event, and plan to continue monitoring these reefs in the coming years in hopes of following the recovery of the reef and subsequent shifts in the community structure that may occur.
This project is funded by NSF, and led by Drs. Andrew Thurber, Becky Vega-Thurber, and Adrienne Correa. It is conducted with the support of the Mo'orea Coral Reef LTER.
What makes seeps seep? Getting at the geologic underpinnings of methane seepage along New Zealand's Hikurangi Margin
In January of 2019 we embarked on 1.5 month expedition (the SAFFRONZ) off of New Zealand on the R/V Revelle to investigate the relationship between fluid flow and the geologic nature of the slow-slip Hikurangi Margin. This endeavor was led by Dr. Evan Solomon of the University of Washington, and Drs. Marta Torres and Rob Harris of Oregon State University. This was in collaboration with researchers from GNS Science and NIWA, both institutions of New Zealand. We had capabilities of heavy-duty coring (gravity and piston coring) through Oregon State's marine geology program to look into the deep subsurface processes on the margin, heat probe technology to understand flow dynamics within the subsurface, and a remotely operated vehicle (ROV JASON of WHOI) with manipulators that enabled precise sampling of the seafloor of video documentation of newly explored habitats.
Image 1: Carbonate and tubeworms within a gravity core collected at a suspected methane seep site along the Hikurangi Margin
Image 2: Gravity core operations
Image 3: ROV JASON on deck
Using what we observed in the sub-bottom profiler, multibeam, and gravity cores, we would select certain locations to dive at with the ROV JASON. We saw a huge diversity in habitat type and composition at the seep sites, from incredibly diverse sites to more minimal sites that generally represented newly formed areas or ancient seep habitats. We discovered the most abundant tubeworm assemblages ever seen in the area, and identified many potential new species. Interestingly, we observed many animals that had not been previously associated with seep habitats - a connection which we are still working to figure out. In addition to this we also saw potential influences of fishing pressure on the habitats, something we are exploring further in another expedition in July of 2019.
Images 4,5: Some of the cool critters that we found
Video 1: A dense tubeworm assemblage with many associate organisms including barnacles that have formerly only been associated with hydrothermal vents.
From 5 known to 2500 discovered:
Seep exploration on the Cascadia Margin
In 2016 and 2018 I voyaged with the E/V Nautilus to explore for methane seep habitats on the Cascadia Margin. Historically, we knew of 5 seep sites along the whole expanse of the Cascadia Margin. Advances in multibeam surveying of the margin revealed thousands more (Image 1). These sites were found using water column data produced by multibeam surveys, where sound pulses are sent down to the seafloor and rebound back up to the ship when they hit something, like seafloor, whales, or bubbles associated with methane seeps. You can see these bubble plumes in Image 2.
Image 1: Map of bubble plume distribution indicating the Cascadia Margin boundary, historically known seeps, seeps newly discovered, and those explored by ROV. (Right)
Image 2: Bubble plumes at Astoria Canyon, image created by Susan G. Merle of CIMRS, Oregon State University and NOAA PMEL. (Left)
We have slowly begun to explore these sites with ROV's, putting the first human eyes on these new seep habitats. The more we have explored, the more paradigms have been brought into question. Unexpected variations, species, and diversities have been found. The influence of the background environment has been strong in some places. Species distributions have been expanded, and perhaps new boundaries created. Our understanding of this area is still a work in progress, but with a systematic sampling effort on the margin we are slowly understanding the dynamics of these countless habitats, and reshaping our understanding of seeps globally.
The images below highlight some of the diversity that we have been discovering at seeps of the Cascadia Margin with many background species intermixed with seep features.
This work has been led by Drs. Robert Embley and Tamara Baumberger as well as Susan Merle, all of Oregon State University and NOAA PMEL.
Sub-cryosphere methane seepage on Antarctica
When Dr. Andrew Thurber discovered a methane seep in its early stages of formation under the sea ice of McMurdo Sound, he launched an effort to go back and study the dynamics of the system and capture a multi-year view of how the microbial community developed around the newly fluxing methane. Akin to jumping under the miles of ice covering Europa and seeing the methane rich ocean thought to exist beneath, with unknown potential life forms, this habitat presented an extraterrestrial view of methane seeps that had not been had before.
Andrew and myself exploring some of the ice features
With water temperatures of -2 degrees Celsius (28 degrees Fahrenheit), diving in this environments takes a lot of gear, support, and mental calm. We would arrive by pistenbully's, access the sea through holes drilled and maintained by heating units, and try our best to look half as graceful as the seals that would swim by.
A Weddel seal exiting our dive hole after using it for some easy to access air
With geochemical and microbial analysis of samples taken from flux chambers and sediment cores, we worked to characterize the seep environment and understand how it fit in our global understanding of seep systems.
Benthic flux chamber used to quantify the flux of methane and sulfide out of the sediment each day.
A two-year effort, this cruise sailed past the Arctic Circle to sample the floor of the Chukchi Sea and better understand how increases in sea temperature will impact how the sediment community stores carbon. This was a collaborative effort with phytoplankton ecologists, physical oceanographers, fish experts, and mud experts (where I fall in). We conducted incubation experiments with sediment at various temperatures as well as collected sediment samples for microbial, faunal, and geochemical analysis. This endeavor was led by scientists at the University of Alaska Fairbanks.
Myself and the crew deploying the multicore
View of Little Diomede from the ship
Working with an indigenous observer onboard from Little Diomede Island (shown to the left) we aimed to put our work in the context of the local impact of ocean warming on indigenous people of the Arctic. With low sea ice cover, the fundamentals of their everyday life have shifted, from how they get around to how they can source food. Many areas that we explored were historically still covered in thick sea ice at the time of year we were visiting but we only saw sparse instances of ice floes during our trip. It was a stark reminder of the the extent of the ramifications of climate change.
Sparse sea ice floes
The hunt for Paleoshorelines
Using their suite of remotely operated vehicles, the E/V Nautilus has been exploring for evidence of paleoshorelines off the coast of California, in an effort to better understand human migration patterns in the past as well as the geologic history of the coastline. This endeavor has led to many cool discoveries, including interesting fluid flow features.