Hi everyone, after checking to make sure all gear, crew, and science team were onboard the R/V Point Sur, we left the dock just after midnight and we have arrived at our first station! Today, the team spent time calibrating the multibeam sonar and putting the nets onto the MOCNESS frame.  You will hear more soon from the acoustics team about the sonar and I will describe the MOCNESS for you now. 

Hello! 

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.

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.

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!  [embed=videolink]{"video":"https://youtu.be/IThAD5yKrgE","width":"400","height":"225"}[/embed]

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.