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…

Pterotrachids:  https://www.youtube.com/watch?v=7CxGafI019E

Carinarids:  https://www.youtube.com/watch?v=GeBUbxSzJjw

Atlantids:  https://www.youtube.com/watch?v=ghFNGPGc7k8