Thesis Defense by June Shrestha – December 9th

 

"Fish pee in the sea: a surprising source of limiting nutrients in California kelp forests"
A Thesis Defense by June Shrestha

The Ichthyology Lab

MLML Live-Stream | December 9, 2020 at 12 pm

Growing up, June always loved being underwater. Long summer days were spent at the local pool in Virginia, where she swam along the bottom pretending to be a SCUBA diver and scouring the “seafloor” looking for treasure: forgotten toys, hair ties, and even a coin or two. Then on a fateful snorkel trip to the ocean with her family, 10-year-old June loved swimming with the fish so much, that she decided that she wanted to be an “Oceanographer Scientist” when she grew up! Mind you, she did not know exactly what an oceanographer did, but she liked that it had the word “ocean” in it, and “scientist” sounded impressive. 

From then on, all of her academic pursuits were focused on reaching her goal of becoming an “Oceanographer Scientist”. In high school, she crashed “Take Your Daughter to Work Day” events at NOAA, conducted extra science fair projects, and even studied Latin for four years in hopes that it would help her learn scientific nomenclature. In college, June majored in Biological Sciences for her B.S. degree at Virginia Tech and learned that she was actually more interested in ecology, not oceanography! She participated on any research project she could involving the words “water”, “fish”, or “snorkel”, and spent many days surveying streams for fishes in the mountains of Virginia.

Now, as June graduates with her M.S. in Marine Science from Moss Landing Marine Laboratories and CSU Monterey Bay, she can finally say that she accomplished her childhood dream. When not conducting research, you can find June SCUBA diving - for real now - within the kelp beds of California.

Thesis Abstract:

In marine systems, fishes excrete dissolved nutrients rich in nitrogen, a biolimiting nutrient essential for regulating primary production and macroalgal growth in the ocean. Often overlooked in attempts to explain the variability in kelp forest productivity, relatively little is known about the magnitude and patterns that drive nutrient excretion from fishes, especially in temperate kelp forests. I investigated the supply of nutrients excreted by the dominant fishes (30 species representing ~85% of total fish biomass) on nearshore rocky reefs in California. Using rapid field incubations, I measured the amount of dissolved ammonium (NH4+) released per individual (n = 460) as a function of body size and developed predictive models relating mass to excretion rates at the family-level. I then combined the family-specific predictive equations with data on fish density and size structure around the northern Channel Islands characterized from visual SCUBA surveys conducted from 2005-2018. Mass-specific excretion rates ranged from 0.01 – 3.45 µmol g-1 hr-1, and per capita ammonium excretion ranged from 5.9 – 2765 µmol per individual per hr. Ammonium excretion rates scaled with fish size; mass-specific excretion rates were greater in smaller fishes, but larger fishes contributed more ammonium per individual. When controlling for body size, ammonium excretion rates differed significantly among fish families with the highest excretion by surfperches (Embiotocidae). On an areal scale, the fish community in the northern Channel Islands excreted a substantial amount of ammonium to the kelp forest (mean: 131.3 µmol · m-2 · hr-1), and spatiotemporal variability (range: 59.84 – 247.9 µmol · m-2 · hr-1) was driven by the establishment of marine protected areas (MPAs), geographic and temporal shifts in the overarching fish community structure, and environmental and habitat characteristics. Results suggest that fish-derived nutrients may provide an important and underrepresented nutrient source to kelp beds, particularly during low-nutrient periods (e.g. seasonal or climatic events), and that fishing may interfere with these nutrient cycling pathways. Areal rates of ammonium excretion – consistent with those reported for tropical reefs, but among the first measured in temperate systems – reveal that fishes may play a critical role in supporting the resiliency of kelp forest ecosystems.

June Shrestha Presents: Fish pee in the sea: a surprising source of limiting nutrients in California kelp forests

Thesis Defense by Jacoby Baker – December 4th

 

"Maternal environment drives larval rockfish gene expression (Sebastes spp.)"
A Thesis Defense by Jacoby Baker

The Ichthyology Lab

MLML Live-Stream | December 4, 2020 at 4 pm

Jacoby has always had an affinity for the water. Even so, he tried to escape the calling of the water and started his undergrad career first in mathematics then moved into biochemistry. Eventually, he couldn't fight it anymore and received his B.S in Biological Sciences with a concentration in Marine Biology from San Jose State University. In his final year of undergrad he found himself interning at NOAA NMFS in Santa Cruz working on a large collaborative ocean acidification and hypoxia project that Dr. Scott Hamilton and Dr. Cheryl Logan were PIs on. Here, he cultivated his interest in researching the effects of climate change stressors on marine organisms, which led to his thesis project. Jacoby is now a Research Assistant at the Monterey Bay Aquarium Research Institute (MBARI) and is applying his molecular background on a project using environmental DNA (eDNA) to help identify organisms residing within Monterey Bay.

Thesis Abstract:

Global climate change is driving shifts in ocean chemistry, which combined with intensification of coastal upwelling, reduces ocean pH and dissolved oxygen (DO) content in the nearshore habitats of the California Current System. Physiological plasticity, within and across generations, might be especially important for long-lived, late-to-mature species, like rockfishes (genus Sebastes), that may be unable to keep pace with climate change via genetic adaptation. Rockfishes exhibit matrotrophic viviparity and may be able to buffer their offspring from environmental stress through early developmental exposure or transgenerational plasticity (non-genetic inheritance of phenotypes). I pre-exposed mother gopher (S. carnatus) and blue (S. mystinus) rockfish to one of four treatments; 1) ambient conditions, 2) low pH, 3) low DO, or 4) combined low pH/DO stressor during fertilization and gestation, followed by a 5-day larval exposure after birth in either the same or different treatment. I used RNA sequencing to determine how the maternal environment affected larval rockfish gene expression (GE). I found that the maternal exposure drove larval GE patterns regardless of sampling time point or treatment. Furthermore, the maternal environment continued to strongly influence larval GE for at least the first five days after birth. These data suggest that rockfish may not be able to buffer their offspring from environmental stressors, highlighting the important role of the maternal environment during gestation.

Jacoby Baker Presents: Maternal environment drives larval rockfish gene expression (Sebastes spp.)

🚨BREAKING NEWS🚨: Stressed graduate student studies stressed fish

By Alora Yarbrough, MLML Ichthyology Lab

What stresses you out? As a 24-year-old graduate student, I use the phrase “I’m stressed” at least once a day. I’m sure most readers can relate. Between classes, thesis deadlines, work, and rent, there are a lot of things that make my cortisol levels rise daily.

A blackeye goby next to its hole. Photo taken by Kristin Saksa at Stillwater Cove, Pebble Beach.

My personal stressors inspired me to study how stress affects a common Monterey Bay fish: the blackeye goby (Rhinogobiops nicholsii). I know what you’re thinking… what could possibly stress out a fish? Didn’t Sebastian from The Little Mermaid sing a whole song about how “life under the sea is better than anything they got up there?” Well, it turns out there are a lot of things that cause a fish’s heart to race and cortisol to spike. Anything from predators being nearby to a slight increase in temperature is enough to set off a full stress response.

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Survey Like a BOSS: A few highlights from a month at sea testing the Benthic Observation Survey System

By Ryan Fields, MLML Fisheries and Conservation Biology Lab Fields_Salmon_AK

Ryan Fields serves as lab technician to the Fisheries and Conservation Biology Lab (FCB lab), where he also studied for his Master's degree. As a technician Ryan continues to participate in lab projects that include California Collaborative Fisheries Research Program and the development of new video lander tools to improve fisheries management of Pacific rocky reefs.

 

This October, the Fisheries and Conservation Biology Lab completed a month-long research cruise along the California coast testing a new video camera tool designed to survey fishes. This was both a fantastic project and trip, and I want to share a few highlights from video we collected. The main goal of this project was to design, build, and demonstrate the feasibility of deploying a video lander tool at a scale that is useful for fisheries management agencies (i.e. a coastwide survey). We were very successful in meeting this first goal, and in 24 days we conducted 419 visual surveys across 295 miles of coastline between Half Moon Bay and Anacapa Island.

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MLML Students at the Forefront of Marine Science

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Will Fennie in the field collecting data. Photo Source: Will Fennie

Whether it be out in the field or inside the lab, conducting research is often what people imagine as the highlight of science. However, once that research is completed, then what? For many scientists, it’s the impact of their research that is viewed as a true career highlight. MLML alum, Will Fennie, had his first taste of this success when research from his Master’s thesis contributed to a well-publicized paper on juvenile rockfish and ocean acidification.

Species-Specific Responses of Juvenile Rockfish to Elevated pCO2: From Behavior to Genomics

For this study, Dr. Scott Hamilton, professor of Ichthyology at MLML, served as first author and his student, Will Fennie, served as third author.

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Tiny Giants

By Heather Fulton-Bennett, Phycology Lab

The Monterey Bay Aquarium recently welcomed a new Giant Sea Bass (Stereolepis gigas) to their Kelp Gardens exhibit. Unlike its name, this new addition isn't so giant - barely 4 inches long!

Juvenile Giant Sea Bass

Giant sea bass are found along the west coast from Humboldt Bay to Baja California, Mexico and can reach up to 8 feet long. While rarely seen in the Monterey Bay, they are recovering from overfishing and are being seen more in southern California. The aquarium also has a sub-adult in the Kelp Forest tank, and two adults in their Monterey Bay Habitat exhibit. You can see more of this little one here or head to the aquarium yourself!

The Monterey Bay Aquarium is free for residents of Monterey, Santa Cruz, and San Benito Counties through Dec. 13th, so go check out the new arrivals and old favorites!

Halloween’s Most Festive Ocean Creatures!

OLYMPUS DIGITAL CAMERABy Vicky Vásquez

Vicky Vásquez is a graduate student in the Pacific Shark Research Center and serves as Deputy Director of the Ocean Research Foundation.

 

Just in time for All Hallow’s Eve here’s a line-up of the ocean’s most festive Halloween animals! Check them out in all their ghastly horror, they’ve been waiting all year to get some haunting attention.

Halloween Crab (Gecarinus quadratus)

This list certainly could not begin without the arthropod waiting all year for its time to Trick and Treat. The Trick? Halloween crabs are not as beachy as you might think. They spend most of their lives in mangroves and rainforests along the Pacific coast of Mexico down to Panama. Since they have a planktonic larval stage, they only head to the ocean to spawn. The Treat? Racoons love them! Halloween crabs are an important food source in areas where the range of these two animals overlap.

Species: Gecarcinus quadratus Common name: Halloween Crab. Photo by E. Mena
Species: Gecarcinus quadratus Common name: Halloween Crab. Photo by E. Mena

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Tales from the Field in Antarctica: Post 3

By Jamie Sibley Yin

Dr. Valerie Loeb is an adjunct professor at Moss Landing Marine Labs. Currently, she functions as an independent Antarctic ecosystem research scientist collaborating with Jarrod Santora of UC Santa Cruz. In April, she headed out to sea with a new NSF funded project entitled "Pilot Study:   Addition of Biological Sampling to Drake Passage Transits of the 'LM Gould'".  The following are updates from the field by Jamie Sibley Yin who is in charge of communications.

 

April 19th, 2015 - Palmer Station and Ice Fish Project

A view of the Lawrence M. Gould (our ship) and Palmer Station.
A view of the Lawrence M. Gould (our ship) and Palmer Station.

When I woke up it was hard to believe we were in the same ocean as last night.  The water was glassy and glaciers cut with snow-capped black rock towered on either side of us.  We were due at Palmer Station in less than an hour.  Palmer was the final destination for some folks—but not us.  We were going with the ship, wherever she went.

This meant fishing in Gerlache Strait and recovering underwater gliders from Shackleton Ridge.

Palmer far exceeded my expectations for a station on an island off the coast of Antarctica.  It’s nestled between light blue glaciers and looks out to the rock-studded ocean.  The station feels like a ski cabin, fire roaring in thewood stove and floor to ceiling glass windows.  The facilities are excellent and include a sauna and outdoor hot tub.  After lunch we walked up the glacier behind the station (think gentle sloping glacier—nothing hard core).  We take a radio and write our estimated time of arrival on the board.  If you are not back by this time, the rescue team at Palmer must spring into action and come find you.  The Antarctic landscape is harsh and far from any medical facilities, thus, every precaution is taken to prevent and minimize injuries.

A large seal near the station.
A large seal near the station.

After our glacier jaunt, dinner was served at the station, everyone from the ship was invited to dine with the station dwellers.  All was merry and the food was spectacular: tacos with chile verde, seared fish, heaping bowls of guacamole and honeydew relish.  Who knew food could be so wonderful in Antarctica.

I was a bit sad to leave station after basking in its’ glory for only two days, but to sea again it was.  This leg of the journey was for the icefish group to catch their fish.  They are studying two groups of fish: Nototheniods, an endemic group of Antarctic fish, and Channichthids, also known as icefish.  Icefish are unique in that they don’t have hemoglobin, a vital oxygen-binding protein found in the blood of all vertebrates.  Their blood is therefore milky white.  They are studying the thermo-tolerances of these fish and how they will respond to warmer water temperatures, potentially modeling their response to climate change.

A gravid icefish in the lab at Palmer Station.
A gravid icefish in the lab at Palmer Station.

They have a lab set up at the station but first they must find their fish.  They use pot traps and benthic trawls to fish.  The boat goes to specific locations where they have had success catching their fish in previous years.  The trawling areas must have sandy bottoms (so the net doesn’t become snagged on underwater pinnacles).  The pots are deployed in strings of four.  They are left out for 24 hours after which we retrieve them and the fish inside.  The icefish are strange-looking creatures, with flat elegant mouths and large sentient eyes they look more like crocodiles than fish.

Kristin, one of the PIs of the icefish project getting ready to unload a fish.
Kristin, one of the PIs of the icefish project getting ready to unload a fish.

 

 

Our zooplankton sampling has been put on hold until the fish crew is done.  We are still sorting through our samples and attempting to identify all our critters, including some very small copepods that are barely a few millimeters in length.  It will be interesting to see how their composition changes when we sample closer to the continent.

Do you know where your seafood comes from?

By Jessica Jang

With oceans covering over 75% of Earth’s surface, nearly one billion people depend on seafood for sustenance. As more people continue to add seafood into their diets, our seafood resources are becoming depleted. Some seafood such as bluefin tuna are very valuable, resulting in unmanaged fisheries. To keep up with the demands and profits, products are purposely being mislabeled in hopes that the consumers will continue buying these products. Today, around 25 – 75% of the seafood we consume is mislabeled. This is an alarming issue, as seafood fraud encourages increased illegal fishing activities and impairs consumers right choices in seafood and can impact our health.

Seafood is an important source of food for many people, especially in Japan. Here is the famous Tsukiji Fish Market known for selling high quality bluefin tuna; photo credit to Japan-Guide

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MPAs we’re diving today!

By Scott Gabara

One of the great things about being a student at Moss Landing Marine Laboratories is going diving with your fellow students.  You get to see what they are studying and hopefully get some good karma or pay them back for helping you out.  I was able to get back in the water after a couple months of drying up on land and dive with Devona Yates.

DCIM101GOPRO
Devona Yates with a kelp headband that is becoming all the rage now.

She is interested in predator-prey relationships and how predatory fishes can have cascading effects on lower trophic levels as they consume invertebrate prey.  This cascading effect may differ inside and outside Marine Protected Areas (MPAs), as it appears MPAs may have different, larger, and more abundant predatory fish.  Devona is using tethering and survey methods to quantify mortality of these invertebrates and how that may vary as a function of MPA status.  It will be interesting and exciting to look at these MPA effects on the survival of these important prey sources for fishes.  We use MPAs as a way to protect and increase important ecosystem members we depend on for food and are necessary for maintaining ecosystem function.  Predator depletion and recovery may cause changes that were much more complex than we had thought.

DCIM101GOPRO
David sampling to estimate the number of small invertebrate prey in different habitat types.

(LOOK) Here is a link to a short video clip of the dive, even harbor seals are interested in science.