- Deep Sea Fauna
- Environmental Variability
- Consequences of DWHOS
- Student Research
- DEEPEND Publications
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.