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My name is Natalie Slayden. I am a Master’s student at Nova Southeastern University working in Dr. Tracey Sutton’s Oceanic Ecology Lab. I am studying the age and growth of deep-pelagic fishes, with case studies of meso- and bathypelagic species from the Gulf of Mexico.
All fishes have three pairs of otoliths. Otoliths are often referred to as ear stones and are located in the cranial cavity of fishes. Otoliths come in different shapes and sizes depending on the species. Therefore, otoliths can be used to identify fish species. Fishes have otoliths to help them detect sound & orient themselves in the water column. Otoliths can tell us a lot about a fish’s life history and they can also be used to determine age.
Left: Both sides of an otolith from the species Ceratoscopelus warmingii (Rivaton & Philippe, 1999). Right: Awesome picture of a Ceratoscopelus warmingii taken by Danté Fenolio.
Have you ever heard of tree rings? Trees have rings that can be counted to reveal how old they are. Otoliths have rings too! These rings can be formed daily, monthly, yearly, or during events such as feeding. Like tree rings, otolith rings can be counted to determine age. Most previous research has focused on aging coastal fishes. Now, I am working to age some mesopelagic (200 – 1000 m) and bathypelagic (deeper than 1000 m) fishes.
Above: The otolith rings of three different species (Gartner, 1991)
Fisheries have become interested in deep-sea fishes to utilize them as feed for aquaculture and as oil for omega dietary supplements. Since they are a target for fisheries, it is important that we understand how long these deep-sea fishes live. Some deep-sea fishes have rings that are formed daily. Most of these fishes with daily rings perform a daily diel vertical migration, meaning they swim from the depths up towards the surface waters at night to feed and then swim back down to the depths at dawn to avoid visual predators. Lanternfishes are one group of fishes that undergo this migration pattern and usually have an age of one year or less. We think that the daily rings are formed due to light or temperature changes that occur during their daily vertical migration. However, for fishes that do not vertically migrate and remain at depth, it is uncertain what their otolith rings represent. Are they daily or yearly? Could they represent a single meal?
So, for my thesis project I will attempt to determine what an otolith ring represents for a non-vertically migrating deep-sea fish. Second, I will be describing the otolith ring patterns and correlating those patterns to the life history of my case study fishes. Lastly, I will be providing age estimations for a number of mesopelagic and bathypelagic fishes.
Hello, everyone! My name is Kristian Ramkissoon, and I am a graduate student working in the Oceanic Ecology Lab with Dr. Tracey Sutton. As a member of the lab, I am currently studying the species composition, abundance, and vertical distribution of the deep-sea fish genus Cyclothone, whose combined numbers make it the most abundant vertebrate on the planet. This study of Cyclothone in the Gulf of Mexico is one of the first of its kind. So what are Cyclothone? The name Cyclothone refers to a specific genus of fish which includes a number of different species. They are more commonly known as bristlemouths. Below are some of the more common species that we have collected in the Gulf of Mexico.
From left to right:(Top Row) Cyclothone pseudopallida, Cyclothone braueri,
(Bottom Row) Cyclothone obscura, Cyclothone pallida
Bristlemouths are close relatives of another abundant group of deep-sea fishes, the dragonfishes, and can similarly be found within the meso- and bathypelagic zones of the ocean. Unlike their more infamous cousins, however, Cyclothone are much smaller in size and much less active (many of the Cyclothone we encounter on our cruises are hardly an inch long!)
Cyclothone pallida against a ruler and under the microscope.
Collectively, these fishes have a near-ubiquitous distribution, with various species found throughout the world’s oceans. This worldwide presence, along with their status as the most abundant known vertebrate, make understanding Cyclothone important for understanding the ecology of the deep sea. As a part of my research into the world of bristlemouths, I spent a lot of time learning the unique features that distinguish each species from one another. Some of the common traits that I used to distinguish between different Cyclothone species were skin color, tooth shape, and gill morphology. To date we have identified thousands of individual Cyclothone down to the species level, keeping close counts and measures of each!
Pigmentation found on the head of (A) Cyclothone alba, (B-C) Cyclothone atraria, (D-F) Cyclothone braueri, and (G-J) Cyclothone pseudopallida.
Body, pigmentation, and photophores of Cyclothone pseudopallida.
So far, my research has revealed quite a few interesting things about these tiny denizens of the deep! For one, we have confirmed that Cyclothone in the Gulf of Mexico, similarly to those elsewhere in the world, do not vertically migrate. Additionally, the taxonomic data collected, in combination with data from the MOCNESS (Multiple Opening Closing Net and Environmental Sensing System) seem to suggest that all six species commonly found within the first 1500 meters of the northern Gulf of Mexico occupy relatively tight and distinct depth ranges. This information tells us that Cyclothone, unlike many other deep-living predators who migrate daily, may subsist entirely on what is found at their respective depth ranges (in the deep, this can be very little!). In addition, we are attempting to assess the impact that hydrographic features such as the Loop Current and eddies formed by it may have on the distribution of Cyclothone within the Gulf of Mexico.
My name is Matt Woodstock. I am a master’s student at Nova Southeastern University studying under Dr. Tracey Sutton. My thesis project is about the trophic ecology and parasitism of mesopelagic (open ocean, 200 – 1000 m depth) fishes in the Gulf of Mexico.
Mesopelagic fishes are important consumers of small crustaceans (shrimp-like animals) and are prey of oceanic predators (e.g. tunas and billfishes). Some mesopelagic fishes undertake a diel vertical migration, meaning these fishes migrate up into the near-surface waters at night and then migrate back down into the deep, dark depths during the day. These fishes migrate so that they can avoid visual predators in the epipelagic (0-200 m) during the day but take full advantage of the abundant food supply there at night under the cover of darkness. Other mesopelagic fishes do not vertically migrate and remain deep at night. A lot of animals participate in this daily movement and it is regarded as the largest daily animal migration on Earth!
A hatchetfish (left) and a lanternfish (right). The hatchetfish does not undergo a daily vertical migration, but the lanternfish does. Images courtesy of DEEPEND/Dante Fenolio.
So what exactly do I study? My job is to dissect a wide variety of fishes and identify their gut contents and parasites. The gut contents obviously tell us what the fish has recently eaten, but the parasites I am interested in are transmitted through their diet. Certain parasites, called endoparasites, live within another animal (a host) and must go through different animals to complete their life cycle. If I find a lot of the same parasite in the same species of fish that means that fish has eaten the same prey item for the majority of its life. If I find a lot of different parasites within a species, then the diet of that fish may have shifted at some point in its life, or that fish may have a general diet where it eats many different types of prey. Results from this type of study allow us to make conclusions about the connectivity and stability of different ecosystems.
Two roundworms from fishes on DEEPEND cruises. On the left picture, notice the white, swirly looking object. This parasite is attached to the intestine, where it feeds on the digested nutrients of the host’s food.
The coolest part about my project is that many of the fishes I study have never been examined for parasites before. That means that I am the first person to see a parasite within that fish before (or I am at least the first person to write it down)! I am also studying the external parasites, called ectoparasites, of these fishes as I find them. These parasites are unique because they spend part of their lives searching for a host to latch onto, and then they attach themselves to a host for the remainder of their life (normally)! They also make for a great picture!
Two types of external parasites from fishes captured during DEEPEND cruises. These parasites will attach themselves to the host through the scales and feed on the host’s tissue or previously digested food.
My name is Rich Jones and I am a master’s student in Dr. Jon A. Moore’s lab at the Florida Atlantic University’s Honors College. Dr. Moore is an ichthyologist who has been working closely with DEEPEND since the beginning helping to identify some of the obscure and poorly studied deep-sea fishes collected from these depths. For myself, as someone who has always been excited about biodiversity, this work has been one of the greatest privileges of my life. Some of the fishes we have identified have only been seen by a handful of people before in the history of the world. The opportunity to study the habits of these rare animals with a comprehensive suite of data, let alone hold them in your hand, is a unique pleasure of working with DEEPEND. Some of the fishes we caught were less rare, but equally as mysterious in how poorly studied they are. One such obscure group entrusted to our lab were the Paralepididae, commonly known as “barracudina” due to their superficial resemblance to small barracuda (they are not related to barracuda). Samples collected by DEEPEND and NOAA cruises have presented a rare and unique opportunity to study these enigmatic little fishes, and I have spent the past few years getting to know them through my thesis research investigating their basic life history in the deep Gulf of Mexico.
Pictured here is a duck-billed barracudina (Magnisudis sp.) in its natural habitat, deep in the ocean. Duck-billed barracudina are some of the largest of the barracudinas and can grow to lengths of about one meter (3 feet). They are members of the sub-group known as “scaly” barracudina because they have more scales than the other varieties. This photograph is an extremely uncommon example of a live barracudina, taken by the NOAA Okeanos Explorer’s Remotely Operated Vehicle (or ROV) as it descended through the mid-water to survey the deep seafloor of the Gulf of Mexico.
At first, I knew nothing about barracudina. I wanted to focus on them for my master’s thesis research simply because they were so poorly studied. Once I began to get to know them, I learned that there are a lot of amazing and strange things that make these little fish special. Many of the smallest species are almost completely transparent in life, lacking all but a few scales. Some of those transparent species possess a unique type of bioluminescence along their bellies which is derived from their liver tissues. They use this bioluminescence to counter-shade their silhouettes against the dim light down-welling into the deep sea. They are all simultaneous hermaphrodites which means that they are both males and females at the same time throughout their entire lives. This type of reproductive mode is extremely rare among vertebrates but likely a useful quality in the deep-sea where encounters with potential mates are rare. They are very closely related to lancetfish (Alepisauridae) which are some of the biggest and baddest fish found in the deep pelagic. They can grow to lengths greater than 2.5 meters (8 feet)! Unlike barracudina, lancetfish are well studied because they are frequently caught as bycatch in pelagic long-line fisheries. So much so that they are often considered a pest to that fishery! The lancetfish’s smaller relatives, the barracudina, are not directly caught by the long-line fishers themselves but are frequently documented in the stomachs of those fishers’ targets, swordfish and big-eye tuna. In fact, several barracudina species were first described by science based on specimens found in the stomachs of fish bought at fish markets.
Pictured here is a juvenile javelin barracudina (Lestrolepis intermedia) collected during a DEEPEND cruise. This species is one of the “naked” barracudina, so called because they lack most scales and are highly translucent. This species has a unique bioluminescent organ that runs along its belly in a straight line and an additional photophore spot just in front of each eye. In life, these fish glow a faint yellow color. Observations from submersible expeditions in the 1950’s reported that this species exhibits a unique swimming behavior in which it orients itself vertically in the water column, rapidly switching its orientation from upwards to downwards.
Part of the reason barracudina are so poorly studied is because they are only infrequently captured in net trawls, and the specimens that are caught by nets are usually smaller representatives for their species. Given that they are infrequent and small in net sampling but frequent and large in the guts of certain top-predator fishes could mean that they are more common than we know and that they are just fast enough swimmers to avoid the nets. It could also be that barracudina are generally uncommon and just one of many important prey types to those deep-diving delicacies of the fish market. Either way, barracudina are under-appreciated, and as our impacts on the ocean increase, whether from industrial fishing, climate change, or oil spills, we will need to know more about the favorite prey of our favorite seafood to inform us about the sustainability of those treasured pelagic resources.
To that end, my work with barracudina has two main goals: (A) identify ecological patterns among the barracudina species in the Gulf of Mexico and (B) develop an easy to use key for identifying these often difficult-to-distinguish species. Regarding their ecology, I am asking some very basic questions: (1) What depths do the different species inhabit? (2) Do they vertically migrate? (3) How easily can they avoid the nets? (4) What do adult barracudina eat? And (5) Where in the water column are adults and juveniles found, respectively?
A picture of a typical sample from a MOCNESS tow that includes the common naked barracudina (Lestidiops affinis; center of photo) among other mesopelagic fishes like lanternfish and bristlemouths. While barracudina are not the most abundant, small swimmers of the deep sea, they are still relevant as they are a favorite food item for deep-diving tunas, billfishes, whales, and sharks.
What I have found is partly to be expected and partly surprising. It is not surprising, for example, that net avoidance is common among barracudina. The NOAA cruises immediately after the Deepwater Horizon oil spill utilized two different net types to sample the deep Gulf. One was a high-speed rope trawl and the other a multiple opening and closing net and environmental sensing system (or MOCNESS), which the DEEPEND cruises also employed. The mouth area of the MOCNESS is fairly small and because the net mesh size is only 3mm in diameter it cannot be towed very fast. This increases the potential for net avoidance by larger, faster swimmers. The rope trawl, on the other hand, had a much larger mouth area and could be towed much faster which made it more difficult to avoid. The rope trawl caught significantly more and significantly larger barracudina than the MOCNESS, which was to be expected.
Another unsurprising, but important, finding was that different barracudina species occupy distinctly different layers of the water column. It seems that there is a general distinction between where in the depths you find the “scaly” and “naked” barracudina types. The smaller, translucent or “naked” types are significantly more common near the surface in the lower epipelagic while the larger “scaly” types are almost exclusively found in the twilight zone of the mesopelagic. However, while the naked barracudina are much more common near the surface, they can be found throughout the water column all the way to the deepest, darkest depths. Comparing abundances caught at depth between day and night, there does appear to be a slight, but far from significant, amount of vertical migration in barracudina. I suspect that the reason there appears to be any vertical migration at all in these species may be that they are chasing their food, most of which does vertically migrate to the surface waters at night to feed.
Dietary habits also had a similar distinction between the two main types of barracudina. After dissecting the stomachs of several hundred adult specimens, I found that the naked ones seemed to be exclusively eating migrating mesopelagic fishes while the scaly types were eating mostly deep-sea shrimps. This is somewhat surprising because we would expect that small fishes, like barracudina, living in the deep sea would eat whatever they encounter and would not be very picky. It is likely that these differences in dietary habits and apparent selectivity are the result of a combination of their preferred habitats and their unique feeding behaviors, which continue to remain unclear. Rare observations from the voyages of the French submersible Bathyscaphe Trieste in the 1950’s reported that one barracudina species (Lestrolepis intermedia) indeed swims quite rapidly through the water column, “like silvery javelins”, occasionally halting to “float along like erect pieces of asparagus”, rapidly changing their orientation from looking upwards to looking downwards. It is unknown whether this is a unique hunting behavior or predator avoidance behavior or both. It is also unclear whether all barracudina species exhibit this odd behavior.
The apparent differences in distribution and diet I have found among the barracudina in the Gulf of Mexico could prove to be useful information as the different species appear to reflect distinct aspects of the deep-pelagic ecosystem where they live. The presence or absence of certain barracudina from a given area or large fish’s stomach could be used to help make inferences about the state of the greater pelagic environment. In managing an entire ecosystem, fishery managers rely on suites of different indicator species to inform them about the ecosystems that sustain our living ocean resources. For these suites of indicators to be effective, however, managers need to able to correctly identify them to their respective species. Many barracudina, especially the naked ones, are very difficult to identify to species and the keys that exist to diagnose them often require counting the number of vertebrae they have which is not an easy thing for most managers to do. As such, another goal of my research is to provide an easy-to-use dichotomous key that relies on simple measurements and illustrations of pigments to aid quick but accurate identification to species. Helping me to complete this goal is Ray Simpson, a post-doctoral researcher based at the Yale Peabody Museum, who is an excellent illustrator.
An illustration of the Spotback Barracudina (Uncisudis advena) by Ray Simpson
A picture of one of the largest (>15cm) ever recorded specimens of the Gulf of Mexico Bullis’s Barracudina (Stemonsudis bullisi). This endemic species had previously only been known and described from two juvenile specimens around 6cm long.
Like the DEEPEND consortium itself, the over-arching goal of my research is to contribute to a baseline of data that will inform future research and monitoring efforts in the deep Gulf of Mexico. In this way, even our simplest findings are superlative: three of the nineteen barracudina species captured in our samples represent first records for those species in the Gulf of Mexico, and the overall ranges of several other species have been expanded significantly thanks to our sampling efforts. We captured the largest specimens ever recorded for one species which is only known from the Gulf of Mexico. Hopefully publishing these results in an open-access outlet will provide useful information to managers when the next spill happens or when changes in deep-sea fisheries management need specific monitoring criteria. Regardless, it has been a real pleasure working with these odd little swimmers from the shadowy depths.
Check out Ray Simpson’s website here: http://www.watlfish.com/
It is an online outlet for Ray’s illustrations and an exhaustive list of Fishes of the Western North Atlantic which reads like a field guide.
My name is Ronald Sieber. I am a Master’s student at Nova Southeastern University working under Dr. Tamara Frank in the Deep Sea Biology Lab. I work with Dr. Frank as a graduate research assistant studying deep sea shrimp in the northern Gulf of Mexico. My work pertains to the general distribution and abundance of the deep sea shrimp family Benthesicymidae.
The family Benthesicymidae consists of 39 species across five genera, the most speciose of which are Gennadas (16 species) and Benthesicymus (15 species). Thus far we have collected two genera (Gennadas and Bentheogennema) consisting of six species. While the family in general can be identified by a blade-like rostrum and a bearded appearance due to the presence of setae tufts, the individual species can only be identified by the shape and structure of the genitalia. The structures are known as petasma (for males) and thylecum (for females).
Image of Bentheogennema intermedia displaying the truncate and blade-like rostrum typical of all members of the family Benthesicymidae. Adapted from Orrell and Hollowell, 2017.
Petasma (a) and thylecum (b) for Gennadas bouvieri adapted from (Kensley 1971) and Bentheogennema intermedia from (Perez Farfante and Kensley 1997). Petasmas are composed of three variously shaped lobes while thyleca are composed of various processes and flaps on the 6th, 7th, and 8th sternites that are species specific and easily identifiable.
This study is trying to establish a broader understanding of the Benthesicymidae assemblage in this region of the Gulf of Mexico. It will also look into potential abundance shifts for the individual species to see if there have been any increases or decreases in quantity over the seven years that samples have been collected. Also, this study is looking into the potential impact that the Loop Current poses to the vertical migration of the Benthesicymidae. This current, which is sporadically present in the region of study, causes an abrupt shift in water temperature that is unfavorable for these shrimp. While initial results show an impact in abundance due to Loop Current presence, further statistical analyses are required to show the potential migration shifts that the current poses.
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.
Hello, my name is Max Weber and I am a Masters candidate in Marine Biology at Texas A&M University at Galveston. I study deep-sea fish genetics in the lab of Dr. Ron Eytan. Genetics are a powerful tool that can reveal a lot about the fishes that inhabit the deep-sea. One of my areas of research involves the investigation of population size over time in a large number of deep-sea fish species.
We used to think that even though sea surface temperatures change a lot day to day and season to season, that deep-sea temperatures were very stable (cold, but stable!). However, recent long-term monitoring studies have shown evidence of rapid alterations in deep-sea temperatures and other studies on benthic deep-sea communities have shown that those communities are currently being altered as a result of climatic changes.
Historic changes in population size (the number of individuals of a given species in a population) often reveal the effects of major ecological events on the genetic diversity of a population or a species. These fluctuations can be inferred through the use of molecular data. Global climate conditions have varied greatly since the last glacial maxima, approximately 20,000 years ago, leading to changes in global currents, oceanic temperatures, and sea level. Several studies have recently uncovered sharp declines in population sizes of coastal marine fishes attributed to these changes in the marine environment.
My Master’s research focuses on whether fluctuations in the population sizes of deep-sea fishes mirror those found in coastal/shallower water. If I find evidence of recent population expansions in deep-sea fishes, it would suggest that the deep-sea environment is more volatile than previously imagined, however, if I find that the populations of deep-sea fishes are stable, it would suggest that the environment is stable as well. To answer this question, I am using several different methods of analysis to look at DNA sequence data. One method is the Extended Bayesian Skyline Plot (see example below). This presents a visual representation of population size going back in time. Some of my preliminary analyses have revealed major population expansions in recent history. These are exciting results and may help to give us a better idea of how the deep-sea habitat has changed over time.
This is a photo of the lovely hatchetfish, Argyropelecus aculeatus, which lives between 300-6,000 feet deep. It is one of the most common species we capture on our cruises.
This is an Extended Bayesian Skyline Plot (EBSP) showing the population size of Argyropelecus aculeatus over time. It shows that the population had a major expansion followed by continued growth. I am currently working to calibrate a molecular clock that will allow me to assign dates to these changes.
This is a deep-sea dragonfish, Echiostoma barbatum, collected during one of the DEEPEND cruises.
Howdy! My name is Corinne Meinert and I am a Master’s student in marine biology at Texas A&M University in Galveston studying biodiversity of ichthyoplankton in the Northern Gulf of Mexico. When you break the word ‘ichthyoplankton’ down you get ‘ichthyo’ which means fish, and ‘plankton’ which means drifter, so all together the word refers to fish eggs and larval fish that drift in the ocean with the currents. Studying the biodiversity of these little fish is important because it can tell us how healthy the ecosystem is where they live; in general, the higher the diversity of fish, the healthier the ecosystem.
To give you an idea of how small these fish are, below is a picture of a snake mackerel (Gempylus serpens) on my finger:
In the lab, we use microscopes to visually identify our fish samples to the family level. For some families, such as tunas, billfish, and dolphinfish, we use genetics to identify the fish to species level. Over the past two years, we have collected and identified over 18,000 larval fish and have found a total of 99 different families. The most abundant families we have found are lanternfish (Myctophidae) and jacks (Carangidae), when combined, these two families make up of 25% of our total catch. Below are a few pictures of different families of fish we have collected (note: the third one is a tuna with another tuna inside of its stomach!):
We still have a lot to learn about larval fish. Understanding how abundant they are and where they live can help us make better management decisions for the future. If you want to learn more about ichthyoplankton and biodiversity, here are a few good webpages and videos to get started:
Information on ichthyoplankton: https://swfsc.noaa.gov/textblock.aspx?Division=FRD&id=6210
Information on biodiversity: https://www.youtube.com/watch?v=GK_vRtHJZu4
A compilation of other fish (and one invertebrate!) caught during DEEPEND sampling:
Blog by Sebastian Velez, Master's Student at Wilkes Honors College, Florida Atlantic University, Jupiter, FL
When you walk into a restaurant and order sushi, or a fish dinner, do you ever contemplate the series of events that led to that fish arriving onto your plate? Probably not…you’re hungry, but the odds that that particular animal would make it to a harvestable size are astounding. I’ll give you an example. A 10-year-old red snapper in the Gulf of Mexico can produce approximately 60million eggs annually. Of those 60 million eggs, only 450 individuals will reach a size of 5cm. At this size they are still susceptible to predation, starvation, and advection away from suitable habitats. My name is Sebastian Velez and I’m a Master’s student in Biology at Florida Atlantic University, studying juvenile snappers and groupers in the Northern Gulf of Mexico collected during the DEEPEND Cruises. I am particularly interested in what happens to these organisms when they are wafted far out to sea, off the continental shelf in areas where depths can reach 1500m.
This is a juvenile Red Snapper, Lutjanus campechanus. This species supports multimillion dollar recreational and commercial fisheries in the Gulf of Mexico.
Now this concept of advection away from suitable habitat is something that occurs as a result of the life history of snappers and groupers. Both families form seasonal spawning aggregations, at which point the resulting larvae are wafted out to sea for 20-50 days, and begin settling on nearshore habitats. The currents responsible for this dispersal include; the Mississippi River Discharge Plume, The Loop Current, and a series of cyclonic and anticyclonic eddies. But every once in a while these larvae get wafted a bit too far offshore. Literally hundreds of kilometers away from their preferred habitats and so the question is; what happens to these animals when they are so far from shore?
The literature is very vague as to what happens with these expatriates, with most accounts only stating that this phenomena takes place and they most likely die as a result of starvation or predation. Thanks to the DEEPEND cruises, we have found that the biodiversity of these expatriates within both families was impressive, with some of the most notable species being; Goliath Grouper, Snowy Grouper, Nassau Grouper, Red Snapper, Vermillion Snapper, Grey Snapper, and Queen Snapper. Our study also suggests that a few members within these families have the ability to stall their settlement, specifically the Wenchman snapper. Individuals were often found ranging from 14-47mm in standard length, lengths usually attributed to newly settled individuals. We also found new depth records for Red and Wenchman Snapper down to 1500m, well past their normal distributions, most likely in an attempt to find suitable habitat where none exists.
This is an unidentified member of the Subfamily Liopropomatinae, Liopropoma sp. Another type of grouper with vivid colorations and often referred to as basslets, these are very popular in the aquarium trade.
These fishes represent multi-million dollar industries in the form of commercial and recreational fisheries. Understanding the biology and life history of exploited species is imperative in informing future management decisions. The pelagic stages of these species have historically been very hard to sample, thus leaving a gap in the associated knowledge. The processes by which these individuals are dispersed represent a potential mechanism in the connectivity between populations and could help managers forecast future drops in stock abundance.
An unidentified individual from Subfamily Epinephilinae. These are your classic groupers. Examples would be Nassau and Goliath Groupers.
Hey, have you ever heard of a heteropod? You may have heard that term associated with terrestrial spiders, but what I am talking about is a group of very special marine snails! Hi, I’m Kris Clark, a graduate student from the University of South Florida College of Marine Science, studying marine gastropod molluscs collected from the DEEPEND cruises. My little creatures are within the Superfamily, Pterotracheoidea. These floating sea snails, commonly called heteropods or sea elephants (albeit they are generally small), are found throughout the world’s oceans in tropical and subtropical waters where they have adapted to pelagic (open sea) living. I like the name sea elephant as it describes their resemblance to an elephant’s trunk. These animals have an extended proboscis or nose-like feature that terminates with their mouth. The term heteropod was coined for these little beasts back in the 1800’s when they were first realized. The term was used because of the evolutionary development of their swimming fin from their ancestral foot – hetero meaning “different” or “other”.
There are three family groups that are categorized by the type (or lack) of a shell. Atlantidae have a full shell where the animal can fully retract inside. Carinariidae have only a very tiny partial shell that covers their visceral mass and gills. And lastly, the Pterotracheidae lack a shell entirely. All heteropods have mostly transparent bodies, have an evolved foot that now serves as a swimming fin, have a mobile proboscis for feeding, and have spherically gelatinous eyes for locating prey. They feed on copepods, polychaetes, brine shrimp, salps, tiny crustacea, jellyfish, pteropods, and other heteropods.
Most people have not ever heard of heteropods. And that’s not surprising. This group of sea-life is still understudied, however more investigations are developing, including mine. One important and interesting finding about heteropods is that there are a lot of them in the oceans. And since they are found in every ocean and are very abundant it is estimated that these swimming snails are highly important to the ocean foodweb – mainly fishes rely on the heteropods to eat, and larger prey eat these fishes, and so on. So heteropods post an important position in the food hierarchy in the ocean system. Many other compelling attributes have been discovered about little heteropods… keep in touch with our future articles for more curious discoveries!
Want to learn more now? Check out these fun videos of swimming Pterotracheoidea…
Left to right: back: Jessica, Alex, Michelle, Cori, Travis, Jillian, and Nina; front: Jason and Rich
HAPPY 4th of JULY!
Scientists still get to celebrate while we’re out at sea! Check out our tattoos! :)
Today is our last day of sampling. We started bright and early again at 6am. It rained a bit, but it was accompanied by a full rainbow arching over the boat. Nice way to start off the morning!
You guys are probably wondering how we collect all of the larval fish I showed you on the last blog post. Well, we deploy a bongo net off the back of the boat and a neuston net off the side. Both nets are brought on board and the samples are washed down into the codends. The contents of the codends are rinsed/poured and put into our sample jars. The samples are brought into the wet lab for a closer look and a potential photo. Some of the larger specimens (e.g., tunas, swordfish) are frozen for genetic analyses.
I set up a GoPro around the boat to show you guys how we sample at each station. Let’s take a look of some of our scientists at work:
Bongo nets and the sunset last night. Neuston net.
Rich is collecting water for the YSI and for the food web study. Nina is reading the water's temperature, salinity, and dissolved oxygen.
Rich, Nina, Jillian, and Jason are retrieving the bongo nets. Everyone's rinsing down the nets, while Michelle is recording the
Jillian is pouring her plankton sample out of the codend. Jason and Nina are rinsing the bongo nets.
Nina and Jessica are putting the sample into the jar. Jessica is looking at a larval tuna under the microscope/taking a picture.
Alex and Cori just retrieved the neuston net. Jillian, Alex, Cori, and Travis are sorting the neuston net sample.
Jason and Travis sorting through Sargassum. Jason and Alex looking at our catch!
Dr. Michelle Sluis is the PI on the cruise. She is recording the data for each tow (e.g., start time, location, etc.) in the pictures above.
Hope you enjoyed the pictures!
Last night we cruised towards our southern transect. We arrived at our first station and began sampling at sunrise (6am). We've hit 10 stations so far today! We collected many of our targeted species and more!
On the boat, we use a camera attached to our microscope to help us take pictures of the tiny fish. Here's some of our catch:
Alex found a siphonophore.
Cori, Travis and Jillian on deck and ready for the next tow!
All smiles here!
My name is Nina Pruzinsky. I’m out in the northern Gulf of Mexico with Texas A&M sampling for fish larvae on the R/V Pelican. We’ll be out here from July 1-5th. The scientists onboard include: Dr. Michelle Sluis (TAMUG), Jessica Lee (TAMUG), Travis Richards (TAMUG), Cori Meinert (TAMUG), Jillian Gilmartin (TAMUG), Alex Southernland (TAMUG), Jason Mostowy (TAMUG), Richard Jones (FAU) and Nina Pruzinsky (NSU).
We left the port at LUMCON at midnight on June 30th and traveled to the first station (Station 48) during the night. We started our sampling around 10am yesterday. We finished nine stations during the day and did two night tows. During the day we are using a neuston net and bongo nets to sample for larval fish. The neuston net tows for 10 minutes at the surface and the bongo nets sample to about 100 m depth. At night, we only tow the neuston net. This way, we can compare the differences between day and night tows at the same station. Additionally, Alex is sampling for gelatinous zooplankton (jellyfish) for genetic analyses, Jillian is Gtowing another plankton net to look at the community structure of zooplankton, and Travis is collecting water samples in order to characterize the food web in the Gulf.
Yesterday we caught tunas, billfish, dolphinfish, flyingfish, eel larvae, remora, frogfish, triggerfish, pufferfish, rough scad, lanternfish (at night) and more! Check out the pictures below! As you can see, all of our fish are extremely small!
Today we started sampling at sunrise around 6am and have completed three stations. We already caught some tuna and dolphinfish larvae!
Stay tuned for more pictures and updates on the cruise!
R/V Pelican before depature.
Larval dolphinfish (mahi-mahi).
Michelle and Cori preparing the neuston net.
Jillian setting up the plankton net along with the bongo nets.
We also were able to dip net a juvenile tuna last night for my thesis!
Another day at sea – one of our last for this cruise.
My name is Laura Timm and I am a PhD student at Florida International University. This is my fourth DEEPEND cruise and the data we collect from it will contribute to the last chapter of my dissertation.
I work on crustacean genetics. Specifically, I use the DNA of a few shrimp species to describe diversity and characterize how (or if) it is moving within the Gulf. These two things, diversity and gene flow, provide a lot of insight into the health and resilience of these target species. Most of my work with DEEPEND has focused on three shrimp: Acanthephyra purpurea is a bright red color and produces a bioluminescent spew to scare off predators.
Systellaspis debilis is also red (though younger ones can look orange), but with tiny light-producing organs called photophores polka-dotting its body.
Sergia robusta can be dark red or even purple and has photophores around its mouth and tail.
To me, all three are uniquely beautiful.
My research focuses on questions related to genetic diversity, which is a good metric for species health. Where is the most diversity found? Has this changed since 2011? How is diversity distributed? Is some genetic diversity unique to certain places? Answers to these questions provide unprecedented insight into how the Gulf copes with disturbances.
Now, a little perspective.
We trawl with a MOC10 net. It is very large. Every person on the ship could go stand in the frame of the net. However, when compared to the size of the ocean, it is tiny – it has been described as the equivalent of investigating terrestrial diversity using just a butterfly net. Yet, we still catch thousands of shrimp. Of these thousands of shrimp, a few hundred are targeted (A. purpurea, S. debilis, S. robusta). Of these hundreds, 96 are sequenced (this is due to the sequencing process; I can only sequence 96 at a time). The genomes of these species have not been sequenced, so I target a few thousand base pairs of DNA. A few thousand base pairs out of billions of base pairs. About 100 shrimp out of hundreds, hundreds out of thousands, thousands out of every shrimp in the Gulf. This tiny amount of data (which, in the history of science, is unprecedentedly large) can tell us so much about the animals living in the Gulf and how they came to be there and whether they are likely to survive whatever comes next.
Written by Rosanna Milligan
It’s the end of another successful cruise and we’ve collected thousands of animals and taken hundreds of physical and chemical measurements across the northern Gulf of Mexico. My job is now to take these data, integrate them with the data from our previous research cruises, and analyze them all to try to find patterns in them that will help us understand how the deep pelagic fish communities are structured.
Understanding how animals are distributed through different environments is one of the key questions in ecology, because the answers can tell us important information about which areas might be particularly valuable. This might be because they contain particularly high biodiversity and are important to conserve, or they might be areas that might contain particularly high abundances of animals that we might want to target for fisheries or drug development for example.
While it’s easy to imagine different terrestrial environments, like deserts, forests or mountain ranges, it’s much harder to imagine what the different environments that might exist in the open oceans are, because, frankly, one patch of seawater looks much the same as any other at first glance. But, when we start looking with scientific instruments like CTDs, or using satellite imagery, we can start to see how the oceans are structured by gradients and boundaries in the physical and chemical properties of the oceans like temperature, salinity or water currents. However, we still don’t really understand is how much this environmental variability influences the animals that live in the deep pelagic oceans. Do they care about different conditions or are they happy to live anywhere? Are they just pushed around randomly by water currents or do they actively swim against them to stay in the best locations?
CTD Instrument used to measure the physical properties of water and to collect water samples from different depths.
Our work with the DEEPEND project is starting to disentangle some of these ideas. For example, we’ve been working hard to figure out how to identify different water masses in the Gulf of Mexico in an ecologically-meaningful way, and separate out how and why different water types affect different deep-sea animals and their distribution patterns. We’re working with teams of geneticists, chemists and oceanographers too, to match up all the different research strands into a coherent story. All of this will be really important in understanding how resilient or vulnerable different organisms might be to human impacts in the Gulf of Mexico, in case something like the Deepwater Horizon disaster ever happens again.
So all the work we do at sea is really just scratching the surface of the work we do when we get back. We’ve got lots more work to do and many more questions to answer!