JISAO Intern Presentations 2020

Cook Inlet (CI) beluga whales (Delphinapterus leucas) were first listed as endangered in 2008 under the Endangered Species Act. In 1979 there were an estimated 1,300 CI belugas and that number continues to decline. As of 2018 there are estimated to be only 279 individuals. Assessing the extent of skin condition occurrence in CI belugas provide greater understanding as to whether skin conditions are related to the health of the whales, and whether life history attributes, such as survival or birth rates, are correlated with skin disease. Some beluga whales are known to have skin conditions potentially caused by diseases, such as the herpesvirus. Overhead photos (taken from a hexacopter UAS) and oblique photos from 2017, 2018, and 2019 field seasons were evaluated for presence of skin conditions and cross-referenced to the identification catalogue. Whales that had been photographed over multiple field seasons were assessed to determine if there had been progression or regression of skin conditions over time. Documenting the progression of skin conditions will help clarify and define the longevity and mark permanence to determine whether they can be used for photo-identification across seasons and years.

Katline Barrows

University of Puget Sound; NOAA Alaska Fisheries Science Center; University of Washington

Iron is an essential element to life, especially in the ocean. However, iron is a trace element, meaning it is only found in miniscule amounts in the environment. In the ocean, heterotrophic bacteria require the use of iron for respiration of other organic nutrients such as nitrate and phosphate. It is possible to have a low concentration of iron relative to nitrate due to bacteria having a high demand for iron in these low iron regions of the ocean. This project seeks to understand if the de-coupling between dissolved iron and nitrate is due to bacterial uptake of dissolved iron rather than abiotic scavenging for iron. Data was obtained from the GEOTRACES international data product (IDP) from different cruises and ran through a homemade python code to determine both the Nitracline and Ferricline throughout regions of the ocean with varying iron concentrations. The preliminary results demonstrate that in regions of low iron concentrations, bacteria tend to take in more iron in order to respire sinking organic matter used for energy.

Jesus Espinoza

University of California, Merced; University of Washington School of Oceanography

A simple, but important, measure of the ability of models to simulate cloud properties is whether the vertical structure of cloud occurrence in the model is consistent with that from data. Observed cloud occurrence profiles in the tropical western Pacific typically exhibit three peaks, one near the top of the boundary layer, one near the freezing level, and a broad peak in the upper troposphere. There is considerable variation in the overall probability of occurrence and the relative strength of these peaks. Here, we investigate the ability of a new generation of high-resolution models to simulate these profiles. The model runs were forty days long and come from the DYnamics of the Atmospheric general circulation On Non-hydrostatic Domains (DYAMOND) project. We compare five of these models to observations from the Department of Energy Atmospheric Radiation Measurement (ARM) program site in Manus Island, Papua New Guinea. The ARM profiles are obtained from a combination of millimeter radar and micropulse lidar data. Our study consists of a determination of local variability in cloud occurrence profiles. We make use of the extended ARM data series to construct profiles for each August in the data series. The ARM data are available at high frequency at a single location, but the monthly average profiles are influenced by local weather variation. This data set provides us with an accurate assessment of cloud occurrence and a measure of internal variability. We then compare the profiles from the models. The models are run at a resolution of a few kilometers and we evaluate profiles in a 1° x 1° latitude-longitude cell located over the Manus site. Our results suggest that the models simulate the rough structure of cloud occurrence but that there are large differences in the relative strengths of the peaks among the models and the overall probability of occurrence.

Haley Staudmyer

University of Washington Department of Atmospheric Sciences

Random sampling is a method used in enviromental science research where sampling in a controlled setting is not an option. Why choose random sampling over every other sampling method? Visualize a work day on a fishing boat, take into consideration the movement on that boat which would cause fish to constantly move. Also, think about the work pace and how fast observers must work to obtain samples, it would be simply impossible to count every single fish. Random sampling is the easiest and most beneficial sampling method when working in an uncontrolled, hectic, and in motion environment. This method is used to collect samples and data in commercial fisheries. There are many obstacles and factors to take into consideration when sampling on a commercial fishing boat such as available space, time, weather, etc. So how can we make sure that this data is as reliable and efficient as possible? We developed the M&M exercise to demonstrate sampling notions to observers during their training , although on a much smaller scale of a catch that would be seen on a trawl fishing vessel. This tool allows us to demonstrate how random sampling works and how it is implemented. Using this tool illustrates how taking more samples will result in less variance and less bias within the produced estimates from the collected data. The results from the M&M exercise show that the more samples taken, the more reliable and closer our estimates are to the true value. In conclusion, random sampling has proven to work and be an efficient sampling method that is used in various fields not just commercial fishing.

Yoana Torres

Heritage University; Applied Physics Laboratory, University of Washington; NOAA Alaska Fisheries Science Center

Copepods are a highly abundant taxa of zooplankton and an excellent food source for the many economically valuable fish of the Pacific Northwest. Calanus pacificus exhibit vertical diel migration - moving up the water column at night to feed on phytoplankton and travel back down during the day to hide from predators. Hypoxia (low oxygen, defined as <2 mg O2 L-1) is known to have extensive physiological effects on zooplankton. Hood Canal, a sub-estuary of Puget Sound, experiences seasonal hypoxia in the late summer and fall, as opposed to the South Sound, where such seasonal hypoxia does not occur. The hypothesis is that individual copepods will modify their behaviours to avoid low oxygen conditions resulting in aggregation in less stressful water. The objective is to quantify the small scale behavioural responses of marine copepods to low levels of oxygen in the water column using copepods that have been collected from two locations of differing ocean chemistry. Four 1-m tall tanks were randomized to have the bottom portion either normoxic, control tank, or hypoxic for each experiment. 20 C. pacificus were introduced to each of the tanks and filmed for 30 minutes to observe their behaviours in experimental conditions.Video analysis of C. pacificus swimming trajectories was performed using the software FOSICA. Then custom scripts and the Tracker3D algorithm in Matlab were used to perform analyses of copepod density and individual swimming paths in each tank. Initially all copepods swam to the bottom of the tanks. The 10-15 minute time period showed a clear behavioural difference between the control and hypoxic tanks: average depth was higher in hypoxic tanks. Behavior of copepods from South Sound differed between the two hypoxic tanks, showing less avoidance of hypoxia in one tank relative to the other.

Dina Zawadzki

Monterey Peninsula College; University of Washington School of Oceanography

Phytoplankton are primary producers and provide the basal resources in marine food webs. Phytoplankton depend on light availability, temperature, and nutrients in order to grow. Changes in salinity and temperature which stratify the water column often create nutrient limited surface waters and nutrient rich deeper waters which in turn impact phytoplankton growth. Phytoplankton blooms and their relationship to light, temperature, and nutrients were analyzed from data collected in the Northern Bering and Chukchi Sea in Spring (June) and fall (August-September) 2017. There were more subsurface blooms in fall than spring 2017 indicating that phytoplankton growth was limited by nutrient availability in surface water. For non-nutrient limited casts, phytoplankton growth was limited by light availability. Simple theoretical models based on light, temperature, and nutrient equations from literature supported our findings that nutrient limitation is often a primary regulator of phytoplankton growth in these waters. Better understanding the relationship between phytoplankton growth and nutrient dynamics in the Northern Bering and Chukchi Seas will improve our understanding of how future climate warming might impact these ecosystems.

Cassondra DeFoor

University of Nevada, Reno; National Oceanic and Atmospheric Administration (NOAA); University of Washington

Easterly waves are disturbances in the tropical easterly winds with a significant frequency of occurrence over the Atlantic, western Caribbean and far East Pacific. These waves are the precursors to the majority of tropical cyclones in the Atlantic and East Pacific and contribute to the seasonal rainfall over northern South America and Central America, however little is known about the interaction of these waves with land areas. This study uses surface meteorological data collected from 5 August – 9 October 2019 as part of the Organization of Tropical East Pacific Convection (OTREC) field campaign to document the modulation of the local environment and convection over Costa Rica by easterly waves. Meteorological instrumentation was placed at 16 geographically diverse areas to measure surface quantities including air temperature, relative humidity, surface pressure, and rainfall. Four sites additionally collected rainwater isotope data. Ocean (land) sourced rainwater and/or less (more) rainfall exhibits enriched (depleted) values of oxygen-18 (O18). Outgoing longwave radiation was used to composite the data by ridge, neutral, or trough wave phases. A key finding of this study is the observed strong modulation of the surface meteorological and O18 data by easterly waves, with the convectively active trough having higher relative humidity, cooler air temperatures and depleted O18 compared to the ridge phase. The Central Mountain site additionally shows that topographically forced afternoon thunderstorms during neutral wave conditions have a similar depleting effect on the 018 signature as organized convection associated with wave troughs. Future work will explore in more depth the modulation of convection across the surface network by the waves seen in this study.

Bria Goldade

North Dakota State University; OTREC; University of Washington

Oxygen is “the oceanographer’s canary bird of climate change" (Körtzinger et al., 2006). The purpose of this study was to investigate if data collected from Argo floats deployed by many different countries could be combined and used to observe changes of oxygen in the ocean, specifically in the North Pacific Ocean.

Zoë Stroobosscher

Calvin University; Applied Physics Laboratory, University of Washington

Mesoscale eddies, large rotating bodies of water, can trap and transport marine ecosystems for thousands of kilometers allowing beneficial foraging opportunities for marine predators. Some of these marine predators have been shown to forage on the large biomass of mesopelagic fish. Our project aims to investigate how mesoscale eddies structure the diversity of mesopelagic fish in the North Atlantic by using multivariate analyses to explain the relationship between net tow samples of fish community composition and eddy characteristics. Results suggested regional patterns of species composition as well as changes in composition from the core to the periphery of an anticyclonic eddy, and distinct community composition of a mode-water eddy.

Victoria Trejo

California State University, Chico; Applied Physics Laboratory, University of Washington

Eddies provide pathways that allow near-inertial waves (NIWs) to radiate energy into the ocean interior, but the fate of NIW energy once it leaves the surface mixed layer is not well understood. It is known that cyclonic eddies repel NIWs while anticyclonic eddies flush energy downward through “inertial chimneys”. The Mediterranean Sea can be considered a microcosm of the global ocean as it is a host of many similar dynamic features, such as deep-water mass formation, thermohaline circulation, NIWs, and eddy fields. Using model output simulating ocean circulation in the Gulf of Lion, this study focuses on the differences in dynamical features and interactions with NIWs for cyclonic and anticyclonic eddies at the surface, 500m, and 1500m. It was found that anticyclonic eddies propagated further than cyclonic eddies, and Rossby number (a measure of eddy intensity) for both types of eddies decreased by an order of magnitude at depth. Additionally, NIWs were found propagating to depth, suggesting the facilitation of an inertial chimney mechanism. Results from this study provide insight into eddy fields in the Gulf of Lion and support the current understanding of interactions between eddies and NIWs.

Mark Yamane

Eckerd College, St. Petersburg, FL; University of Washington CICOES, Seattle, WA; NorthWest Research Associates (NWRA), Redmond, WA