This summer, undergraduate students from all over the United States have come to the University of Rhode Island Graduate School of Oceanography to conduct oceanography research as part of the Summer Undergraduate Research Fellowships in Oceanography (SURFO) program. Learn more about what they’ve been up to in Part II of this two-day series of short blog posts they’ve written for oceanbites! You can check out Part I here.
Climate Change and the Secret Life of Zooplankton
Ariel Pezner — University of California Los Angeles
Imagine you just scooped up a glass jar full of seawater. What’s in it? At first glance, most people (including myself just a few years ago) would say “nothing”. However, this is far from the truth. By holding this tiny fraction of our ocean up to the light and looking a little closer, you would be able to get a glimpse of the tiny and diverse world of plankton. Contrary to popular belief, not all plankton are microscopic (but of course, many are), and they do not all look like the more familiar cartoon villain that we are all so fond of (though you might be interested to know that our favorite antagonist resembles the zooplankton species that he is based on [Figure 1]). Just as Mr. Plankton is one of the central characters in the beloved television series SpongeBob SquarePants, real plankton play an equally important, though much less villainous, role in our world’s oceans. Zooplankton are a key link in the oceanic food web between primary producers (phytoplankton) and larger consumers (fish that you and I might buy, sell, and eat). These tiny creatures sustain fisheries that bring in billions of dollars in profit and feed billions of people each year.
Given their immense importance, my research focuses on if and how these tiny creatures are being affected by climate change, specifically in Narragansett Bay. My research focuses particularly on mesozooplankton, a size class of these small animals that can be seen with the naked eye, but require a microscope to view in any detail. Zooplankton are characterized by their immense biodiversity, reflecting the large numbers of species and abundances of each within a particular community. In just a small sample of seawater I collected off the dock at GSO, you can see the diverse number of organisms in the photo, ranging from larval worms, copepods, larval shrimp, and others I have yet to identify (Figure 2).
You can see too that these mesozooplankton have a wide range in body size. Body size can not only give us a hint as to what species these individuals belong to, but also what the environment they were sampled from is like, and what role the individual plays in their community (such as predator or prey). We are taking advantage of these facts to track changes in the mesozooplankton community by looking for changes in the body size distribution over time. To do this, I am using a rather unique machine called a “Bench-top Video Plankton Recorder” or BVPR. If you’ve ever been on a log flume ride at an amusement park, you can think of this machine as such. Zooplankton are loaded in at the start, travel through the weaving water systems, have their picture taken just before the end arrives, and exit the ride. The photos are a little more advanced (and significantly less pricey souvenirs); instead of one photo of all of the riders, it takes thousands of individual photos of each individual in the sample (Figure 3a,b). With some extra processing and Matlab computer code, the system outputs high quality photos and measures body size – data that I can use to characterize the change in body size distributions over time.
Though I am only in the preliminary stages of data analysis, by the end of the summer I will be able to determine if the mesozooplankton community is changing over time, and to what extent environmental factors are driving this change.
Summer Flounder – Are Their Populations Floundering Due to Fishing Pressure?
Adena Schonfeld — University of Miami
When most people hear “flounder,” they think of the charismatic blue and yellow fish from The Little Mermaid. However, Flounder is not actually a flounder, but a cartoon tropical reef fish. Flounders are flatfish and spend their time laying camouflaged on the sea floor, not zipping around the ocean following their mermaid friend. My research is on the summer flounder, which (presumably) unlike the movie star Flounder, is a delicious meal. My project has two main objectives: the first focuses on the impact of humans eating summer flounder, the second focuses on what the summer flounder are eating.
If you’ve ever eaten summer flounder (also known as fluke) then it should be no surprise that it is the most profitable finfish in the state of Rhode Island. The majority of local restaurants boast at least on entrée featuring these tasty flatfish. If the summer flounder population was to crash and they could no longer be fished, the local economy could lose over 7 million dollars. It is, therefore, very important to understand the population dynamics in order to protect the population from overfishing.
Summer flounder males have a higher mortality rate than the females. Also, females grow bigger and faster than the males. These two population characteristics mean it is likely that more females are above the minimum size for harvest, which means the majority of harvested summer flounder are female. On top of this, there has been evidence that summer flounder naturally separate themselves into different areas based on sex, so there’s a high potential for disproportionate removal of female summer flounder from the population. This would cause the population to decline, with no way to replenish itself.
To better understand the sex-based population dynamics of summer flounder I am measuring the total length of each fish caught on the weekly University of Rhode Island Graduate School of Oceanography fish trawl and the monthly Rhode Island Department of Environmental Management fish trawl. I also am dissecting the fish and determining their sex by looking at the gonads. We have caught 65 summer flounder that are larger than the minimum size for recreational harvest (18 inches) and 63 of them have been female. Also, there is a greater percentage of females in nearshore water than there is in offshore water. Fishery management strategies could be implemented that consider these results, such as harvest restrictions in nearshore water, to protect the population from future overexploitation.
For the second part of my project I am studying the diet of summer flounder. Summer flounder have been increasing in the Narragansett Bay. Due to their aggressive, predatory nature this could be a concern for the other species in the Narragansett. I am conducting a diet analysis to better understand what the summer flounder are eating, how much of it they’re eating, and how often they’re eating. To do this, I am dissecting fish collected on the trawls and removing their stomachs. I classify the stomachs as full or empty. If full, I identify the contents and weigh them. The summer flounder often eat species that are commercially valuable, such as scup and squid. The purpose of this diet analysis is to better understand the impact that an increase in summer flounder may be having on other important species in the Narragansett Bay.
Visualizing Ocean Circulation
Nicole Flecchia — University of Rhode Island
Water in the ocean is constantly moving. At the beach we can see this when the tide goes in and out, and when waves crash on the shore. But there is another type of water movement that is not as noticeable to someone standing on the beach: ocean circulation.
Ocean circulation has impacted humans for hundreds if not thousands of years. Deep, powerful currents such as the Gulf Stream have been instrumental for traveling among continents for centuries. Shallow—but just as powerful—currents control the distribution of fish along the coasts, determining where fishing occurs. And currents of all sizes distribute heat throughout the world, something that is especially felt in Europe (which would be as cold as Siberia without ocean circulation).
This summer, I am creating a computer-generated model of ocean circulation on the U.S. northeast coastal shelf. This is a region that extends about 225 km (~ 140 miles) off the coast from Maine to North Carolina. Its average depth is about 200 meters (~ 650 feet)—whereas the average depth of the ocean is almost 20 times deeper—so this region is controlled by shallow currents and upper ocean processes known as surface circulation. How the water moves in this region is primarily governed by changes in air temperature, ocean surface temperature, the strength of winds and tides, and how much fresh water is deposited on the coastal shelf from rivers. All of these factors are constantly changing, so the circulation of water in this region changes on daily, monthly, seasonal and annual timescales. Modeling ocean circulation on the U.S. northeast coastal shelf will allow us to visualize these changes in the form of pictures and animations.
Studying the circulation pattern of the U.S. northeast coastal shelf is important to many disciplines, fisheries being the most notable. Currents are what prompt the movement of young shellfish from their hatching areas to their nurseries. Currents then control where these shellfish settle as adults. Currents also affect the availability of nutrients throughout the ocean, which controls the rate of growth of all marine organisms and in turn the amount of food accessible for fish and shellfish. For regions that rely on fisheries as a primary source of income, currents control when and where fishing occurs. My research will help these communities better understand the patterns of how ocean water circulates, enabling more stable and sustainable fishing practices along the US northeast coast.
Can Drones Protect You From Toxins?
Scott Goldberg — Northwestern University
Algal blooms are created when excess nutrients enter a body of water causing a massive increase in algal growth. Some of these blooms are harmful (called harmful algal blooms or HABs), and some of these HABs produce toxins called cyanotoxins, which are harmful to animals and people. We need to monitor and manage these blooms to help keep people and livestock safe. This is especially important because people can come into contact with large concentrations of cyanotoxins through ingestion or swimming in contaminated waters.
Unfortunately, current methods of monitoring HABs are slow and imperfect. Many tests require taking nearshore water samples followed by laboratory analysis which only offers information about the specific time and place where the samples were taken. The issue with the “where” part of this story is that because only nearshore water samples are taken, researchers do not have a clear picture of the entire bloom. This becomes a bigger issue when the “when” comes into play; analyzing these samples often takes a while (around a few days) and because algal blooms are complicated and dynamic systems, things can change during that time. Because one also has a limited understanding of the entire system at the time of sampling, due to only getting samples from nearshore waters, it can be hard to predict the nature of the bloom days later once the results are back.
Hopefully, by expanding upon current research to utilize autonomous vehicles to observe HABs, we can rectify this situation. An autonomous kayak will be put on a lake so it can acquire samples from throughout the entire body of water. At the same location, our drone will utilize near infrared and visible light cameras to help tell us how much algae is in the body of water. The use of these autonomous vehicles should grant two advantages over traditional methods. One is that by combining data from water samples collected by the kayak throughout the entire body of water and images from the drone taken on the same day, we can help fill in the gaps from the sampling data, giving us a more holistic view of the observed HAB. The other advantage is that while the images alone are not enough to get a complete understanding of the HAB, they can be analyzed much quicker than water samples to allow for a rapid first response to HABs before samples are done being analyzed.
A HAB can last anywhere from a several days to a few weeks, so it is important to have an effective method of monitoring that can be done efficiently many times. It takes about an hour to physically collect samples from a beach with the dimensions of 600 ft by 200 ft, while a drone can fly over and take enough images to cover the entire area in about 6 minutes. This difference in time can assist not only a rapid first response, but also can allow more sites to be surveyed in a short period of time.
An important question with any engineering endeavor is why can we do this today, but couldn’t do it years ago. One of the main reasons is that until recently, these drones were not easily available for civilian usage, and were for military purpose only. Since drones have been available for civilian use, consumer demand had led to many advances in drone technology, and both federal and state regulations have facilitated the use of these vehicles for research. By expanding on existing sampling techniques and adding a new observation method, this work could greatly improve future monitoring and management of HABs.
Tremors in Alaska: A Path to Predicting Earthquakes?
Whitney Schultz — Colorado School of Mines
For a long time, researchers have been trying to predict when earthquakes will occur, and they might be getting closer now because of little things called tremors. Tremors are small vibrations – so small that there is no chance that they are felt by someone walking around, so at face value, it may seem like studying tremors has no broader impact on society. However, studying tremors might help researchers determine how much stress there is along a fault, which could help them determine when earthquakes are likely to happen.
What are tremors?
Tremors can be identified as separate from earthquakes because of the differences in the types of signals they produce which are recorded at seismic monitoring stations. Tremors start more gradually and last longer than earthquakes. Tremors can be difficult to identify because they are small and their signal can often be similar to the background noise level.
Where are these tremors?
The tremors I am looking at occur in the Aleutian-Alaska subduction zone in South Central Alaska, but tremors occur in other subduction zones around the world. Subduction zones form when two of the Earth’s crustal plates move towards each other and one plate is forced underneath
Earth’s crustal plates move towards each other and one plate is forced underneath the other. The downward forced, or subducting, plate and the overriding plate have a lot of friction between them. Earthquakes happen when this friction is suddenly released and the plates quickly slide past each other. The zone where earthquakes happen is called the “locked zone” because the two plates are locked together by friction most of the time. After the locked zone, there is a transition zone where slow slip events (SSE) occur. SSEs are a phenomenon that happens when the plates have a somewhat restricted movement past each other but still have a steady motion. Researchers believe that this restricted movement causes the very small earthquake-like events known as tremors.
My research this summer is helping to prove or disprove the relationship between the SSEs and tremors using data from around South Central Alaska. I am comparing the time period that a SSE happened with when the tremors happened in order to find the relationship between them. I am also locating some of the tremors and comparing their location to that of the SSE to either confirm or deny the relationship. This is a pretty new area of research so this project is an early stepping stone. There is a lot more work to be done before researchers will be able to identify when there is a high risk for earthquakes.
Can Tiny Fibers Sample an Emerging Threat?
Chris Vatral — Eastern Nazarene College
Perfluoroalkyl substances (PFAS) are a group of man-made chemicals that are polluting our water sources. These chemicals are found in many different products that we use every day including rain coats, firefighting foam, and nonstick pots and pans. The properties of these compounds that cause them to be water repellent, non-stick, and flame retardant are also what makes them harmful to the environment. These chemicals are absorbed into living creatures creating a food chain wide problem. The carbon to fluorine bond in PFAS (where they get their name, perfluoro alklyl) is extremely strong, meaning that PFAS are extremely stable and don’t degrade easily. Once PFAS get into the environment, they stay there.
A few specific chemicals in this group, the ones that have eight or more carbons, have been shown to cause health problems, including several different types of cancer. The hazards of PFAS in water and sediment were brought into the public eye when citizens in a town adjacent to a DuPont manufacturing site in West Virginia noticed their cattle were suddenly getting sick and dying due to PFAS contamination. Since then, manufacturers agreed to phase out PFAS with long carbon chains, but contamination is a persistent problem.
One effective way of sampling the environment for chemical pollutants is called passive sampling. Passive sampling involves placing a sampler, usually made of some type of plastic, in the water, air, or soil for a certain period of time. The pollutants will move from the water into the plastic sampler. Scientists can determine the concentration of pollutants in the plastic sampler, and then use it to figure out how much pollution is in the water, air, or sediment.
A passive sampler does not yet exist to sample for PFAS in the environment. My goal this summer is to test a new passive sampler that is a really thin fiber made of a plastic called polyacrylate to determine whether these fibers can sample PFAS and if we can use them to determine how much PFAS pollution there is at a suspected contaminated site.
Aqueous film forming foam, used to fight fires at airports and military bases, contains a mix of PFAS compounds and has been linked to contamination problems. We have gathered samples of this foam from military bases to test the new polyacrylate passive sampler fibers. We will use different amounts of the foam to figure out at what level of contamination the fibers are best at sampling.
After the fibers sample the foam, we will remove the PFAS that have accumulated in the fibers and use high performance liquid chromatography and mass spectrometry to separate the different PFAS and determine the amount of PFAS on the sampler. This information will allow us to calculate the level of contamination in the water source that we sampled.
Developing a way to sample for PFAS at contaminated sites will help communities assess the risks of groundwater contamination and make remediation plans to keep communities and the environment healthy and safe.
I am the founder of oceanbites, and a postdoctoral fellow in the Higgins Lab at Colorado School of Mines, where I study poly- and perfluorinated chemicals. I got my Ph.D. in the Lohmann Lab at the University of Rhode Island Graduate School of Oceanography, where my research focused on how toxic chemicals like flame retardants end up in our lakes and oceans. Before graduate school, I earned a B.Sc. in chemistry from MIT and spent two years in environmental consulting. When I’m not doing chemistry in the lab, I’m doing chemistry at home (brewing beer).