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Sampling the Sea During California’s Apocalyptic Wildfires

A recent expedition off of the California coast was able to take a rare look at how ash from the massive Thomas fire may have affect the coastal marine ecosystem. University of California, Santa Barbara oceanographer Kelsey Bisson explains why it was a unique opportunity.

Written by Ian Evans Published on Read time Approx. 5 minutes
The Thomas Fire sent a plume of smoke and ash out into the ocean. The question is, how will it effect the marine ecosystem?NASA/Earth Observatory

In December, a team of researchers and students at the University of California, Santa Barbara made the best of a local tragedy. The Thomas Fire, the largest in the state’s history, burned nearly 300,000 acres (120,000 hectares) in Ventura and Santa Barbara counties north of Los Angeles. The smoke plume could be seen from space.

Around that time, oceanographer Kelsey Bisson was one of two graduate students leading an expedition into the Santa Barbara Channel – a diverse marine ecosystem just off the coast. They were planning to study how zooplankton and phytoplankton move up and down the water column in the course of the sun’s daily cycle, but after seeing a NASA photo of the smoke plume, Bisson realized they had a “once-in-a-lifetime” opportunity. The ash would be headed right toward their ship’s planned path, which would allow them to study its effect on the ocean life.

Climate change is expected to increase the rate and severity of wildfires, and not much is known about how these blazes affect coastal marine ecosystems. To study that, researchers have to be at the right place at the right time. Luckily, Bisson was – and Oceans Deeply spoke to her about what she learned.

Oceans Deeply: What were you originally planning to study and why?

Kelsey Bisson: The Santa Barbara Channel is one of the most productive ecosystems in the world. We have a really beautiful diversity of life along the coast.

There are some long-term programs that have been going on in the channel that study it once a month. But the way the ocean is sampled, compared to the rate at which the ocean turns over and how much activity is going on, is analogous to if somebody were sitting in their house, looked out their window once every 300 years and then wrote down what they saw. Our understanding of how these microbiotas in the ocean are functioning is limited by how often we sample it.

We had an echo sounder on the [research vessel] Sally Ride that enabled us to look at the sound-scattering layer, which is basically looking at the acoustic signals that are coming from different depths.

Zooplankton scatter sound. You can look at that to see how the [zooplankton] layer shifts across different timescales, and then infer that that’s the plankton movement.

Oceans Deeply: How did you adapt your mission when the fire started?

Bisson: We had planned things down to the hour for our crew over the past year, and we had very tight schedules and a game plan. Then on December 4 the Thomas Fire started.

What is this going to do? What does this mean for the sea? Everything that we had been working really hard on, we ripped apart some of it in order to make space for experiments on how ash derived from forest fires will affect or could affect ocean ecosystems.

With the current projection for California’s climate there will be more fires in the future. The work that we are now doing could be a helpful benchmark for other, [future] fires. I wish it wasn’t the situation, but it seems like we’re getting to be more of a fire-ridden state.

It was an opportunistic cruise at that point, when we realized that we could take a week of really intensive planning and think about how to adjust our current team and our goals, in order to make room and space for those experiments.

A lot of that work was pioneered by Eleanor Arrington, a scientist who came aboard with us, drove to different places around the county and collected a ton of ash, and did a lot of preliminary work to understand that the ash doesn’t behave simply. There’s a fraction of the ash that’s buoyant, and it lingers around the surface of the ocean. There’s also a fraction that sinks. And the fraction that’s suspended, we don’t know yet what the chemical composition of that ash is, but we sent it out for analysis.

The experimental work that we’re doing, by adding ash to seawater, definitely shows that ash affects the organisms living in the water across a range of concentrations.

It was the kind of thing where we had colleagues calling us from all over the place who wanted samples, because it’s so rare that anybody would be able to mobilize and get a world-class oceanographic vessel and a team of people who are willing and ready to go out. But we already had that. We were sitting on a gold mine with a ton of really diligent, incredible students and faculty, who’ve been thinking about this system for a long time.

Oceans Deeply: Do you know much yet about how the ash is affecting organisms in the seawater?

Bisson: We only have preliminary work. One [idea] is that ash, especially if it comes from organic matter, like from trees, might be carrying with it a lot of heavy metals, like iron, which phytoplankton need to grow.

So one thought is that, if ash is raining down on the ocean, it could be fertilizing the ocean. We might expect to see a bloom of different types of organisms that you wouldn’t normally see in December.

The fire was burning more in the front country with houses and cars – a lot of things that aren’t organic and found in nature. Another idea, especially thinking about when the fire started burning, is that if there is asbestos or different materials in cars and paints and varnishes and houses that are burning and that’s contributing to the ash – this could have a toxic effect on phytoplankton.

Obviously, those are two very different proposing hypotheses. That gave a lot of space for us to ask questions.

We did see more diversity than we expected in phytoplankton, and we saw some dinoflagellates that [usually bloom] in September. Maybe [the ash] was causing a small bloom of different species that normally wouldn’t be thriving in December, and if so, those algae blooms do carry toxins. It could provide a space for harmful algae to bloom, which then would hurt other animals up the trophic ladder. It’s an interesting question to ask, and we’ll have a lot more data in the next few months, which will be fun to analyze.

An onboard illustrator drew this sketch of the R/V Sally Ride sailing away from the wildfire, but still surrounded by smoke. (Celia Jacobs)

Oceans Deeply: Is there anything else you want to add?

Bisson: We did a lot of science things on this cruise, but also one component that we really wanted to excel at and work toward was outreach. Trying to connect with schools that were local in Santa Barbara, but also landlocked schools across the country.

We brought an illustrator aboard, a musician aboard and a videographer aboard, to make a documentary and a musical album and a series of illustrations that break down the barriers of what is thought to happen in science. I’m really excited about the impacts of that, as well, in the context of an increasingly political environment, where people feel detached from the day-to-day life of science.

I think that a missing link in a lot of these things can be people who are really skilled at understanding the complexities [of research], and then pulling out important parts and making them really compelling. Doing this can enable both understanding and also empathy for the ocean, and give it a personality apart from the facts and the figures.

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