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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.

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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.

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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.

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This is a deep-sea dragonfish, Echiostoma barbatum, collected during one of the DEEPEND cruises.

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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:

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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!):

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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:

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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.

 

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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.

 

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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.

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An unidentified individual from Subfamily Epinephilinae. These are your classic groupers. Examples would be Nassau and Goliath Groupers.

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Posted by on in News

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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! :)

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Posted by on in News

Hi all,

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:

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Bongo nets and the sunset last night.                        Neuston net.

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Rich is collecting water for the YSI and for the food web study.                 Nina is reading the water's temperature, salinity, and dissolved oxygen.

 

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Rich, Nina, Jillian, and Jason are retrieving the bongo nets.  
                     Everyone's rinsing down the nets, while Michelle is recording the
                                                                                                          flowmeter data.

 

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Jillian is pouring her plankton sample out of the codend.                           Jason and Nina are rinsing the bongo nets.

 

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Nina and Jessica are putting the sample into the jar.                                Jessica is looking at a larval tuna under the microscope/taking a picture.

 

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Alex and Cori just retrieved the neuston net.                                           Jillian, Alex, Cori, and Travis are sorting the neuston net sample.

 

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Jason and Travis sorting through Sargassum.                                          Jason and Alex looking at our catch!

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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!
-Nina

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