- Deep Sea Fauna
- Environmental Variability
- Consequences of DWHOS
- Student Research
- DEEPEND Publications
My name is Nina Pruzinsky. I am a Master’s student at Nova Southeastern University, where I am working under Dr. Tracey Sutton. Also, I am a graduate research assistant in Dr. Sutton’s Oceanic Ecology Lab, where I am studying the identification and spatiotemporal distributions of tuna early life stages (larvae and juveniles) in the Gulf of Mexico.
Tuna are ecologically, economically and recreationally important fishes. You may know them for their large size, high speeds, and highly migratory behaviors. Fishermen enjoy catching these are fish because they average 2.5 m in size and 250 kg in weight!! They are top-predators in many coastal and oceanic environments, feeding on fish, squid and crustaceans.
Check out this video of tuna from the Blue Planet II series.
Several species have been placed on the IUCN Red List of Threatened Species. For example, Northern Atlantic bluefin tuna is listed as endangered, yellowfin and albacares as near-threatened, and bigeye as vulnerable. Several tuna species spawn in the Gulf of Mexico due to its warm temperatures and unique hydrographic features improving the survival of their eggs and larvae.
So what exactly am I studying for my thesis?
First, I am identifying features that describe the early life stages of different tuna species. The morphology (“the study of form” or appearance of physical features) of tuna early life stages is poorly-described. Collecting fishes at these small size classes (3-125 mm SL) is very rare due to limited sampling across their wide-range of habitats. However, it is extremely important because if we do not know how to identify a fish when it is young, we cannot protect it and ensure it lives to its adult reproductive stage. So, my first task was to create an identification guide for these small fishes. The key features used for identification include: pigmentation patterns, body shape, ratios of different body parts, and fin ray counts.
To date, I have identified 11 different tuna species. These include: little tunny, blackfin tuna, bluefin tuna, yellowfin tuna, frigate tuna, bullet tuna, skipjack tuna, wahoo, Atlantic chub mackerel, Atlantic bonito, and king mackerel. Pictures of these fishes are included below. You can see how differently their early life stages look compared to their adult stages.
Larval and adult little tunny.
Larval and adult blackfin tuna.
Larval and adult king mackerel.
Larval and adult wahoo.
The second part of my project is to identify the spatiotemporal distributions of larval and juvenile tunas. Once we know what species we have, then we can identify where it is found, in what season it spawns, what type of environmental features it prefers, and so on. Basically, I am gaining knowledge about its habitat preferences, so we can help protect future populations and increase recruitment levels.
There are some small tuna species such as little tuna and blackfin tuna that do not have stock assessments nor management plans currently developed. Thus, learning about the environmental conditions that affect their distributions is essential in assessing their populations. It is evident that we still have a lot of knowledge to gain about these size classes.
This summer, I participated in an ichthyoplankton cruise in the Gulf of Mexico. Left: Jason and I are collecting organisms from the bongo net. Middle: I am holding a juvenile frigate tuna collected with a dipnet. Right: I am identifying a larval tuna under the microscope in the lab onboard.
Howdy! My name is Ryan Bos and I am here to aid in the fight against plastic! I am a Masters Candidate in Marine Science at Nova Southeastern University working with Dr. Tamara Frank and Dr. Tracey Sutton. Currently, I am doing an appraisal of microplastic ingestion in deep-sea fishes and crustaceans in the Gulf of Mexico (GoM).
Each day, nearly every person on Earth uses plastic items. It is all around us. It is in our clothes, cosmetics, vehicles, and if you carry a smartphone around with you, odds are that it has a plastic component. As humans, we manufacture and use plastic at alarming rates, and take it for granted. Plastic production is projected to increase with increases in the human population, yet plastic pollution is already infesting our oceans and will continue to persist for hundreds to thousands of years because of plastic’s inherent resiliency. I want to put the plastic crisis we are facing into perspective. There are ~34,000 extant species of fishes with the most abundant genus of fish, Cyclothone, consisting of 13 species. These 13 species are comprised of an estimated 1,000,000,000,000,000 individuals. By the year 2050, the number of fishes in our oceans will be equal to the number of plastics. What’s alarming about this statistic other than the number of fishes and plastic particles being equal? There are 33,987 more species that contribute to the total number of individual fish in our oceans, and most of these plastic particles can’t be seen with the naked eye!
Microplastics, as the name implies are small pieces of plastic that range in size from 1 - 5 mm that are categorized as being a fragment, film, spherule, foam, or fiber. These five categories can be further broken down into subcategories known as mini-microplastics that range in size from 1 µm - 1 mm and are named microfragments, microfilms, microbeads, microfoams, and microfibers. Once ingested, an animal may experience pseudosatiation (the feeling that they are full but have not received any nutrition), obstruction of feeding appendages, decreased reproductive fitness, and death. Pictures of these categories are portrayed below *excluding foams*. To determine if a particle is a piece of plastic, we are using what’s called the ‘hot-needle, or burn-test’. It is a rapid and cost-effective technique for plastic determination. If plastic is probed with a hot-needle it either leaves a burn mark, melts, or in the case of fibers, curls up or is repelled from the needle.
Pictured from left to right: Fragment, film, spherule, fibers
Pictured from left to right: Microfragment, microfilm, microbead, microfibers
Deep-sea animals are integral parts of pelagic ecosystems, as they serve as the base of the food web, contribute significantly to the overall abundance and biomass, make substantial contributions to carbon flux, and serve as a link between shallow and deep-pelagic waters. Regrettably, there are no previous estimates of microplastic ingestion by deep-sea fishes and crustaceans in the GoM. We discovered that approximately 28% of fishes (69/245) and 28% of crustaceans (83/292) have been shown to ingest at least one piece of plastic with 7% ingesting two or more pieces! One individual Sternoptyx diaphana (diaphanous hatchetfish) and Stylopandalus richardi ingested five spherules and six fibers, respectively!
Pictured from left to right: (Left): Two beautiful deep-sea hatchetfish (Argyropelecus aculeatus) that use photophores (light-producing cells) to counterilluminate rendering themselves less visible to predators lurking below. (Middle): A stunning shrimp (Oplophorus sp.) that can produce a bioluminescent spew (vomit) as a defense to distract potential predators. The spew can adhere to predators, which makes them visible to any other predators in the area. (Right): A formidable deep-sea dragonfish (Idiacanthus fasciola) with a smile not just used for good looks! This dragonfish and many other deep-sea piscivores (fish eaters) possess recurved teeth for capturing prey and not letting them go!
Our data reveal that more scrutiny should be given to deep-sea ecosystems with regards to plastic ingestion. Deep-sea food webs are largely understudied and have a stunning complexity to them. These food webs are understudied because of the enormous expense and difficulty of obtaining deep-sea samples. This makes the DEEPEND Consortium incredibly important for gathering these data and beginning to develop a story of community dynamics in the GoM.
A resource for learning more about plastic: https://marinedebris.noaa.gov/info/plastic.html
A brilliant new way to aid in the fight against plastic by doing laundry: https://coraball.com/
Hi folks, welcome back to the blog! This edition of Master’s Monday will be brought to you by Mike Novotny. I am a Master’s candidate at Nova Southeastern University, working under Dr. Tracey Sutton in the Oceanic Ecology Lab, where I study the bathypelagic zone and the fishes that call this environment home.
The ocean is commonly divided into three layers based on sunlight penetration with depth. The midnight (aphotic/bathypelagic) zone is the deepest layer, which starts around 1000 meters. The bathypelagic zone receives no sunlight, has consistent near-freezing temperatures, contains pressures exceeding 100 times that found at the surface, and is the planet’s largest ecosystem! It is within the depths of the bathypelagic zone that you will find the very intriguing group of fishes that belong to the family Platytroctidae, known also as Tubeshoulders. Due to the rarity of specimens, there is very little information known about these fishes, which is where my research takes off!
Tubeshoulders get their name due to a unique tube-like structure that can be found in the shoulder region of all fishes in this family. This tube leads to an organ that contains a luminous blue/green fluid, which allows the luminescent material to be expelled, possibly, for a potential defense mechanism by temporarily distracting the would-be predator. Below is a great video about bioluminescence, but jump to 10:40 to see how platytroctids get their name!
Tubeshoulders have very large eyes, especially for a deep-sea fish! These large eyes are excellent at detecting low-level, point source light and distance ranging, suggesting they may be visual predators, however, the diet of tubeshoulders has yet to be examined. My thesis research addresses this crucial data gap by exploring the feeding behavior and documenting prey preferences of this bathypelagic fish family. Based on stomach content analysis these fishes seem to feed infrequently. I visually examined and identified the gut contents under a compound microscope, which revealed that members of this family tend to be generalist zooplanktivores, consuming a wide variety of taxa such as, copepods, ostracods, chaetognaths, gelatinous taxa, and even the occasional squid! This study represents the first investigation into the diet of this fish family, and adds to the sparse community data of the bathypelagic zone, by identifying nutrient pathways that connect this deep-sea ecosystem to the upper ocean.
Hello! My name is Richard Hartland, I am currently working on a Master’s degree in marine environmental science at Nova Southeastern University. I am a part of Dr. Tammy Frank’s Deep-Sea Biology laboratory. My thesis is focused on performing a taxonomic and distributional appraisal of the deep-pelagic shrimp genera Sergia and Sergestes of the northern Gulf of Mexico, in the area where the Deepwater Horizon oil spill occurred in 2010. The shrimp I study are important members of the oceanic community, both as consumers of zooplankton and as prey for higher trophic levels (e.g., tunas, mackerel, oceanic dolphins).
Left: Sergestes corniculum. Right: Sergia splendens. Images courtesy of T. Frank.
I will be examining the abundance (how many) and biomass (how much they weigh) of the shrimps in the Gulf, and whether or not these values have changed over the years, starting in 2011 (six months after the oil spill) and continuing from 2015, through 2016, and into 2017. The boxplot below shows changes in the patterns of abundance for the most abundant species, Sergia splendens. These data seem to show a sharp decrease in abundance between 2011 and 2015, while slowly increasing in the years to follow.
Boxplot of Sergia splendens abundance from 2011 through 2017.
What we are seeing is a reduction in the number of individuals caught from 2011 and 2015, then we see an apparent increase from 2015 to 2016 and into 2017. Although there appears to be a dramatic drop in the abundance from 2011 to 2015, we cannot state that this is due only to the oil spill in 2010, as there are many other reasons the numbers could be different. What we should do is continue to sample in the same areas and monitor how the population changes over time. I am also looking into how these shrimp move up and down the water column during daylight and nighttime hours. This daily vertical migration is one of the many ways that deep-sea organisms are important components of oceanic ecosystems – this movement takes carbon from the near surface (in the form of their food) and transports it deep into the ocean, thus helping mitigate the increases in atmospheric carbon due to the burning of fossil fuels.
Hello Everyone! My name is Devan Nichols, and I am a master’s student at Nova Southeastern University working in Dr. Tamara Frank’s deep-sea biology laboratory. Our lab specializes in deep-sea crustaceans (aka shrimp!) and my thesis focuses on a particular family of deep sea shrimp known as Oplophoridae. As we all know, shrimp are fairly small organisms in the grand scheme of creatures that live in the deep sea, so why is it important that we study them? Great question! The deep-sea shrimp that I study range in size from 2-20 cm in length. Organisms this small, are perfect prey for larger animals such as deep-sea fish, squid and marine mammals. This means that Oplophoridae make up the base of the food chain, and act as primary producers for many organisms that are higher in the food chain. When the base of the food chain is impacted, even in a small way, it can throw off the balance of an entire ecosystem. These little guys are important!
Two species of Oplophoridae; Systellaspis debils (left) and Notostomus gibbosus (right). Images courtesy of DEEPEND/Dante Fenolio 2016.
Very little is known about the effects of oil spills on the deep sea. When people think of oil spills what usually comes to mind are the impacts it has on the ocean surface. When these disasters occur, the deep sea is not often thought of. It is kind of an out of sight out of mind situation. The Deepwater Horizon oil Spill (DWHOS) occurred in the Gulf of Mexico on April 20th 2010 releasing an estimated 1,000 barrels of oil per day for a total of 87 days into the Gulf. This oil was released from a wellhead located approximately 1,500 m deep.
My thesis is unique in that I have the opportunity to examine data collected one year after the oil spill (2011) and compare it to data collected five, (2015) six (2016) and seven (2017) years after the Deepwater Horizon oil spill. I am looking particularly at oplophorid assemblages. This means that I am looking at how the numbers of shrimp may have changed (abundance) and how the weight of shrimp may have changed (biomass) over these sampling years. The boxplot shown below, shows the patterns that I am seeing so far in oplophorid abundance as time goes by. These data seem to show a sharp decrease in abundance in 2011 to subsequent years.
Boxplot of oplophorid abundances during the four sampling years.
Although we cannot attribute any of these changes to the oil spill directly because we do not have a baseline (data from the area collected before the spill), we can still monitor how this oplophorid assemblage has changed over time, and use this information as a baseline to monitor future changes in the Gulf of Mexico. Along with assemblage changes, my thesis will also provide information on whether or not certain species are seasonal reproducers, and if the presence of the Loop Current has any significant effect on oplophorid ecology. The deep sea is a mysterious place, and scientists still have a lot to learn about its complexity and the organisms found there. The picture below shows the net we use to catch these deep sea shrimp, and some of the equipment we use to lower the net into the deep sea!
A 10-m2 MOCNESS net being towed behind the RV Point Sur during a DEEPEND cruise.