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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.
Hello! My name is Ryan Bos and I am a Masters Candidate in Marine Science at Nova Southeastern University. Currently, I am doing an appraisal of microplastic ingestion in deep-pelagic fishes and crustaceans in the Gulf of Mexico (GoM) with Dr. Tamara Frank and Dr. Tracey Sutton.
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 comprise 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 is 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 fishes in our oceans, and most of these plastic particles cannot be seen with the naked eye!
Deep-sea micronekton are integral parts of pelagic ecosystems, as they serve as key intermediates in oceanic food webs, contribute significantly to overall abundance and biomass, make substantial contributions to carbon flux, and serve as links between shallow and deep-pelagic waters. Thus, they are exemplary targets for microplastic studies.
Microplastics, as the name implies are small pieces of plastic that range in size from 1 µm - 5 mm that are categorized as being a fragment, film, spherule, foam, or fiber. 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, of which none were found. To determine if a particle is a piece of plastic, we used the ‘hot-needle,’ or ‘burn-test.’ It is a rapid and cost-effective technique for plastic determination. When plastic is probed with a hot-needle it either leaves a burn mark, melts, or in the case of fibers, curls up and is repelled by the needle.
Regrettably, there are no previous estimates of microplastic ingestion by deep-sea fishes and crustaceans in the GoM, despite the commercial importance of this ecosystem. A total of 723 individuals (316 fishes and 407 crustaceans) from a combined 48 species and 11 families were dissected and visually inspected for microplastics. Plastic items were found in both fishes and crustaceans. A total of 263 microplastics were identified, with crustaceans and fishes consuming 146 and 117 microplastics, respectively. Total micronektonic crustacean and fish plastic ingestion was approximately 31 % (n = 190/618) while 16 % of euphausiids (n = 96) and 11 % of crabs (n = 9) contained at least one piece of plastic.
Interestingly, there were apparent differences in type and number of microplastics ingested by fishes and crustaceans, with crustaceans ingesting predominantly fibers, as opposed to fishes, which consumed a substantial number of fragments. Further, vertically migrating taxa of fishes contained more microplastics than non-migratory taxa, but the opposite trend was observed in crustaceans. In fact, non-migratory crustaceans consumed significantly more plastic than all other taxa. Curiously, the non-migratory crustacean taxon with the highest frequency of plastic ingestion, the Benthesicymidae, are all habitual consumers of marine snow. That, coupled with the smaller size classes of microplastics found in this study, may be indicative of marine snow’s importance in biogeochemical cycling of microplastics.
As commercial fishing efforts scale up to harvest the deeper layers of the ocean, these results will be important for assessing risk associated with consumption or indirect consumption by the deep-sea biota. Importantly, larger deep-pelagic crustaceans appeared to have more plastic in them than small conspecifics, but size was not indicative of plastic ingestion by fishes, and no significance was observed for either group of animals.
Empirical cumulative distribution functions of carapace length of crustaceans (A) and standard length of fishes (B) that did and did not ingest microplastics. Two separate (one for crustaceans, one for fishes) Kolmogorov-Smirnov tests generated p-values of 0.09 and 0.924, respectively.
Deep-sea food webs are largely understudied relative to coastal studies, but results to date suggest a great deal of complexity. Our data reveal that more scrutiny should be given to deep-sea ecosystems with regards to plastic ingestion. These food webs are understudied because of the enormous expense and difficulty of obtaining deep-sea samples, highlighting the importance of projects such as DEEPEND.
If you are interested in learning more about our work or how to aid in the fight against plastic, please get in touch with me by email: Rb1862@mynsu.nova.edu
A brilliant new way to aid in the fight against plastic by doing laundry: https://coraball.com/
A resource for learning more about plastic: https://marinedebris.noaa.gov/info/plastic.html
An article about how plastic is killing our oceans, by Wendy Lipscomb from the website 'It's a fish thing': https://www.itsafishthing.com/plastic-in-the-ocean/
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.