NOAA Teacher at Sea
Karah Nazor
Aboard NOAA Ship Reuben Lasker
May 29 – June 7, 2019
Mission: Rockfish Recruitment & Ecosystem Assessment
Geographic Area: Central California Coast
Date: May 31, 2019
Game Plan and Trawling Line: Channel Islands San Nicolas Line
I am up on the flying bridge and I just saw two humpback whales spouting, an albatross soaring and a large Mola Mola on the sea surface. In this blog I will write about an amazing once in a lifetime experience that from last night- May 31, 2019. The first haul was called off due to an abundance of Pacific White-Sided Dolphins, Lagenorhynchus obliquidens, (as reported by the inside marine mammal watch prior to net deployment), so we motored on ahead to the second station, but dolphins chased the ship all the way there, too. One strategy to encourage marine mammals to leave is for the ship to stop moving with the hope that the dolphins become disinterested and vacate the area. This pod was intent on having a party at the ship so Keith Sakuma encouraged everyone to just go outside to observe and enjoy the dolphins!
Fishing on this survey takes place at nighttime (so the fish do not see the net) and Scripps graduate student Kaila Pearson and I stepped outside on the side deck into the darkest of dark nights. Kaila and I carefully placed one foot in front of the other because we couldn’t see our feet and where to step next. I was afraid I would trip. When I asked Keith Hanson if we should use a flashlight to safely make our way up to the top deck, he suggested that we stay in place for a few minutes to allow our eyes to adjust. Within 5 minutes or so objects around us started to present themselves to us within the black void. We could eventually see our feet, each others faces, the dolphins, and even the finer features of the sea surface.
Within a few minutes Ily Iglesias reported seeing bioluminescence, a type of chemiluminescence that occurs in living things, such as the familiar green glow of lightening bugs in the Summer in the South. This glow results from oxidation of the protein luciferin (present in photophore cells/organs) by the enzyme luciferase. It its excited state, lucifern emits light. This reaction is known to occur in some marine bacteria, dinoflagellates (single celled photosynthetic organisms), squid, deep sea fish, pyrosomes and jellyfish, and I am fortunate to have observed many of these creatures already on this research cruise (see photos below). Some animals have photophore organs and generate their own luciferin, while others are hosts to bioluminescent bacteria.
When dinoflagellates floating on the sea surface are agitated, they glow. At first when I was trying really hard to see this, I noticed a couple of tiny flashes of green light, sort of like lightening bugs, but it wasn’t anything super obvious. In time, I noticed clouds of faint light, sort of like a glowing mist floating the water’s surface, that moved up and down with the swell. I hypothesized that dinoflagellates on the sea surface were being agitated by the passage of waves through them and Ily suggested that it was caused by schools of anchovies.
Since the dolphins were intent on staying, we decided to head to the next station. I knew that as the ship began to move that the bow would be breaking through surface water that had previously been undisturbed, and I predicted the bioluminescence would be much more intense.
As we took off, the dolphins began to bow surf and, as I predicted, the dinoflagellates were activated and this time their glow was a bright white. As the dolphins surfaced to breath, their skin became coated with the glowing algal cells, creating an effect as if they were swimming in an X-ray machine. The dolphins were literally glowing white swimming in a black sea! We were so entranced and excited by the beauty, we screamed in delight. I am sure the dolphins heard us cheering for them. They too, seemed excited and could see each other glowing as well.
Next we saw the faint cloud of dinoflagellates caused by Northern anchovies (Ily was right) up ahead of us. As the ship encountered the school of small (~ 3-6 inch) fish, they also started to glow really bright and it was easy to see all of the individual fish in the school. The dolphins could also see the glowing fish and split off in different directions to hunt them. There were hundreds of fish that dispersed as they were being chased creating a pattern of short white glowing lines somewhat like the yellow lane markers on the highway.
The display was unlike anything I have ever witnessed. It was like the Aurora Borealis of the sea. Despite our best efforts, our cell phone cameras were unable to pick up the bioluminescent signal, however, we do not need photos because the patterns of light will be forever embedded in our minds. The dolphins eventually tired from the surf and chase and departed. Ily said the experience was “an explosion of light that overwhelmed the senses” while Flora said it was “better than fireworks.”
With no marine mammal sightings at the third station, we completed a five minute haul in the deep channel and collected a huge white bin of anchovies (see photo of Keith Hanson with this catch below). In this catch we found a few Mexican lampfish, 3 king of the salmon, a lot of of large smooth tongues, a lot of salps, a few pyrosomes and one purple striped jellyfish. The purple-striped jelly (Chrysaora colorata) is is primarily preyed upon by Leatherback turtles. Haul 2 was conducted over shallower water near San Nicolas Island and we only found salps and four small rockfish in the catch. After these two hauls, we called it a night and wrapped up at 4:15 a.m.
Scientist Spotlight: Ilysa Iglesias, NMFS SWFSC FED/ University of California Santa Cruz (UCSC)
Ilysa “Ily” is a doctoral student who works in John Field’s Lab at UCSC. She is studying the fish we are collecting on this cruise as part of her research. She is very knowledgeable about all of the survey research objectives. She is also one of the most positive and gregarious people I have every met. Ily grew up in Santa Cruz, CA, and enjoys surfing, hiking, gardening and raising chickens. Ily is a fan of early marine explorer Jacques Cousteau, who often wore a red beanie/toboggan and a blue shirt. Ily came prepared and brought six red hats (that she knit herself) for each of the members of the sorting team. Ily’s favorite fish is the hatchetfish. She was thrilled when we found on in the catch!
Ily obtained a Bachelor’s degree from UC Berkeley in integrated biology and a Masters Degree from the University of Hawaii in Zoology with a specialization in marine biology. Her thesis was on the function of intertidal pools as a nursery habitat for near-shore reef fish. She compared otoliths (fish bone ears) of fish reared inside and outside of tide pools and compared their growth rates. Otoliths can be used to the age of the fish much like counting rings on a tree and stable isotope analysis reveals information about where the fish were reared.
Ily, Flora and Kristin have all used otoliths in their research and taught me how to locate and collect the sagittal otolith from anchovies and myctophids. It is a tiny ear bone (one of three) that is positioned near the hindbrain of fish. See photos below of the otoliths we collected. This is a technique that I will definitely take back to my classroom and teach my McCallie students.
After obtaining her masters degree, Ily was Conservation Fellow for the Nature Conservancy in HI and worked in octopus fisheries before returning home to join NOAA’s salmon team and then the rockfish team as a Research Associate. Ily has just completed the first year of her doctoral work in the Field Lab and expects to complete the program within 5 years.
On this cruise, Ily is collecting small fish called Myctophids for her research. These are small bioluminescent fish that live at depths of 300 and 1,500 m in the bathypelagic zone. In this survey, we encounter these deep sea dwellers during their nightly vertical migration up to the edge of the photic zone at depths we are targeting. They are likely chasing their prey (krill) on this upward journey. It is amazing to me they are able to withstand the pressure change. Mcytophids are also known as lanternfishes and have bioluminescent photophores dispersed on their bodies. The fish sorting team analyzes the position of these organs to help distinguish between the different species. There are 243 known species of myctophids, making these little fishes one of the most diverse vertebrates on Earth. They are so abundant in the sea that they make up 65% of the ocean’s biomass, but most people have never heard of them!
In 2014- 2015 there was an anonymously high sea surface temperatures off of the Pacific Coast known as The Blob. Marine scientists are still elucidating the effect of the hot water had on fish populations and ecosystems. Ily explains that “atmospheric forcing caused changes in oxygen and temperature resulting in variability in the California current.” The water was less nutrient dense and caused a reduction in phytoplankton. This disruption of primary production propagated up the trophic cascade resulting in die offs of zooplankton, fish, marine mammals and birds.
Ily is using the catch records and acoustics data from the rockfish survey to study changes in distribution and abundance of myctophids from before, during and after The Blob (2013-2019). She aims to understand if and how their trophic position of myctophids was affected by the unusually high sea surface temperatures. Using elemental analysis isotope ratio mass spectrometry to analyze the Carbon and Nitrogen atoms incorporated into fish muscle, Ily can determine what the myctophids were eating each year.
