Observing Climate From the Seafloor

By: Jaclyn Pittman

Hi! My name is Jaclyn Pittman and I’m a PhD candidate in the Earth Sciences PhD program at USC. I work with Professor Will Berelson on exploring the seafloor, the deepest part of the ocean.

Science at sea, Covid-style.

Science at sea, Covid-style.

I study calcium carbonate, the mineral that makes up shells, corals, and plankton that grow in the surface ocean. When those organisms die, their shells sink to the seafloor where they dissolve, a reaction that absorbs carbon dioxide, a critical greenhouse gas. When these empty shells dissolve and absorb carbon dioxide, it will eventually lower atmospheric carbon dioxide.However, when living shells dissolve in the surface ocean, our ocean suffers a loss in biodiversity. This process is called ocean acidification.

As we continue to burn fossil fuels by driving gas cars, using plastic products, and many other daily activities, we emit carbon dioxide into the atmosphere. About one third of the carbon dioxide we have emitted is absorbed by the ocean. This reduces some of the negative impacts of high greenhouse gases on land, but has dire consequences for ocean life. Shell-forming organisms are already feeling the effects of ocean acidification with their weaker and thinner shells.

Months of work prepared me to deploy our device on a research cruise off San Diego. The main goal of my research is to find out why, where, and how fast carbonate shells dissolve on the seafloor. Our group has a research cruise planned for this coming winter off Costa Rica, to “walk” down an underwater ridge. By “walking” down the ridge, we can see how carbonate dissolves at different ocean depths. We hypothesize that the deeper we go, the faster carbonate will dissolve. However, there may be certain chemical reactions that happen in the porewater, the water in mud, that can make carbonate dissolve in shallower water than we predict.

Months of work prepared me to deploy our device on a research cruise off San Diego. The main goal of my research is to find out why, where, and how fast carbonate shells dissolve on the seafloor. Our group has a research cruise planned for this coming winter off Costa Rica, to “walk” down an underwater ridge. By “walking” down the ridge, we can see how carbonate dissolves at different ocean depths. We hypothesize that the deeper we go, the faster carbonate will dissolve. However, there may be certain chemical reactions that happen in the porewater, the water in mud, that can make carbonate dissolve in shallower water than we predict.

In order to achieve these research goals, I have spent much of my PhD building a device to collect the porewater I need to study. Most deep-sea porewater studies rely on pulling porewater from sediment cores, or tubes of mud collected from the seafloor. However, there are some issues with that method that can interfere with carbonate chemistry measurements.

To fix these issues, we have built a device that sucks porewater out of the mud while it is still on the seafloor. We have gone on lots of one-day test cruises in the San Pedro basin, in between Los Angeles and the Wrigley Marine Science Center on Catalina Island. This is all in preparation for our big cruise off Costa Rica this winter, so I need to make sure my device is working perfectly before then.

I was pretty busy this summer. I passed my qualifying exam, a major step in getting a PhD, finished analyzing cruise data, and modified my device for our big cruise this winter. It requires designing parts in AutoCAD, sending designs to the campus machine shop for manufacture, testing in the lab, and finally testing in the field. This whole process is iterative, meaning we usually need to do it multiple times before getting to the desired end product. It’s a fun process though, and I really enjoy building a device to answer my scientific questions.

On our last Yellowfin cruise in between Los Angeles and Catalina, we had some down time while our device was sucking porewater from the mud far below, so the crew taught me how to fish.

On our last Yellowfin cruise in between Los Angeles and Catalina, we had some down time while our device was sucking porewater from the mud far below, so the crew taught me how to fish.

I’m so thankful that Wrigley has given me this opportunity to work with them for the summer, and especially the Sonosky family for supporting my research. I hope my research will help the scientific community and the public understand more about how the bottom of the ocean is responding to a changing planet.

Suburban Creek-Hopping: Immersing Myself into My Home Watershed

By: Philip Gilbert

Shuffling around in a shallow stream in a rhythmic minute-long, square-meter, “Mr. Blue Sky” frenzy, I am a peculiar blur to post-work Tuesday commuters… and I am not crazy. I reassure myself of this—hair thrashing, molars flashing.

These are the tree-lined streets and winding creeks I’ve come to know personally and professionally. In some places of this parceled suburban matrix, it’s hard to feign amazement at water’s defiance of boundaries. Yet, this audacity emerges elsewhere only in torrential blips on a precipitation record. It is surely more often us humans who have transgressed boundaries.

Fortunately for me, this disconnection from the water cycle has dried out. On a stormy day, I watch the water flow down the tree trunks, pavement, and hillsides, infusing this trickling landscape with its lifeblood. On a sunny day, I find myself here, in the creeks, studying.

Me, during a riparian vegetation survey of a predominantly forested study site

Me, during a riparian vegetation survey of a predominantly forested study site

Inspired by the variance in land cover/use of this suburban watershed, and enabled by the Wrigley Institute’s Environmental Award program, my childhood stomping grounds became my workplace.

My current research project assesses the impact of land cover/use composition within subwatersheds on the bio-integrity of related tributaries. Using abiotic water quality data, sampling of macroinvertebrate assemblages, and field surveys and GIS analysis of riparian buffers, I am exploring the relationships between dominant land use/cover types (commercial, residential, forested, and agricultural) and stream ecosystem health.

An Appalachian brook crayfish (Cambarus bartonii) (left) and my field assistant (Homo jillius) holding a minnow (sp. unknown) (right).

An Appalachian brook crayfish (Cambarus bartonii) (left) and my field assistant (Homo jillius) holding a minnow (sp. unknown) (right).

Though the data analysis is ongoing and will need to be supplemented with annual datasets, I have established a baseline data-driven profile of my hometown waterways, which will help direct local stream stewardship and refine my conceptualization of future landscape-scale watershed practices.

This research and my studies at USC have emphasized the importance of investigating watersheds spatially, socially, and temporally, as complex, modelable systems. This framework strives for what is necessary for policy-backed change. Though, a certain poetry is missing.

Too often, we are removed from the water cycle, and when we are not, we act towards containment, contamination, and commodification. This may not always be the case, but the actions of few cannot replace the actions of many. Such disconnection demands a reckoning with and recertification of cultural values. We must become fluent in the poetry of the watershed.

In these meandering intact riparian corridors, a mystical timelessness sanctifies the seaward flow. An awareness of woodland lucidity takes root: to control is not to value. Rather, exhibiting self-control, seeking understanding, and extending belonging are invaluable actions, key to our future in this hydrosphere.

Habitat heterogeneity along and within well-buffered first-order streams.

Habitat heterogeneity along and within well-buffered first-order streams.

Summer Award made possible by the Bauer Family Endowed Scholarship Fund.