Reproduction and Movement Patterns of Sheepshead

Tags

Apalachicola, gulf of mexico, marine biology, marine science, sheepshead

by austin heil, fsucml graduate student

Notice the teeth of this Sheepshead caught on artificial reef near Dog Island, Florida.

In the Gulf of Mexico, the Sheepshead are famous (or infamous) for their human-like teeth. Their teeth produce a smile matched by no other fish species. Tourists and land-dwellers often marvel at the Sheepshead’s teeth when they first encounter them. Despite what their outward appearance may imply, Sheepshead are a tasty fish, frequently sought after by recreational fishers in the Gulf of Mexico. Unfortunately, Sheepshead are almost exclusively targeted during their spawning season. This could result in a potential problem. The fishing spawning populations has resulted in declines of other fisheries species. Although I must admit that Sheepshead teeth are quite a spectacle, I personally find their biology more fascinating and important.

Hundreds of Sheepshead caught during a fishing tournament hosted by Sanibel Island Fishing Club during March 2014.

The first part of my research examined the reproduction and movement patterns of Sheepshead in the NE Gulf of Mexico. The first step was to determine where Sheepshead were spawning. I used data collected from a previous study in our area, along with communication from the local fishing community, to choose my study sites. I ended up choosing three artificial reefs for my study near Dog Island, FL. I used a Go-Pro mounted drop camera system to monitor monthly Sheepshead abundance on these reefs from August 2015 to August 2016. I found Sheepshead were basically absent from these reefs during summer and fall. However, in January, hundreds of Sheepshead showed up on these artificial reefs. This was exciting! A healthy population of Sheepshead remained on these reefs until April, after which they completely disappeared.

Sheepshead aggregation on artificial reef. Over 100 Sheepshead were observed on each 20 second rotation.

Now, I needed to determine if Sheepshead were indeed spawning on my study sites. To do this, I sampled from each reef population from January-April. Using histology, a nifty technique that allows you to observe tissue in detail, I found presence of hydrated eggs and post-ovulatory follicles. These indicated a presence of actively spawning individuals on all three reefs. I found evidence of Sheepshead spawning aggregations!

In the past couple of months, I have been presented with an exciting opportunity to further investigate the movement patterns of Sheepshead. Dr. Chip Cotton of the FSUCML received a grant to deploy a number of acoustic receivers array in Apalachicola Bay. The receivers will be strategically deployed to block off any exit from the Bay to the Gulf of Mexico. This allows you to capture movement offshore. Luckily for me, Sheepshead spend the majority of their life cycle in estuaries (like Apalachicola Bay).

Austin Heil holding up a Sheepshead caught during Saturday at the Sea summer camp, hosted by the FSUCML.

Starting in late November 2016, I will be tagging 15 Sheepshead with an acoustic tag in Apalachicola Bay. These acoustic tags will transmit to the receivers and track the movement of each fish inside the Bay. Ultimately, I want to capture when Sheepshead start their migration out of the estuary to offshore habitats. By tracking their movement, I will be able to determine the triggers (e.g. tides, water temperature, etc.) that initiate their migration offshore.

You can help fund Austin’s Sheepshead research, by donating here!

Goliath Grouper in nearshore mangrove estuaries: researching effects and patterns of mercury toxicity

Tags

Goliath Grouper, grouper, marine biology, marine science, sampling, ten thousand islands, TTI

by Chris Malinowski, FSUCML graduate student

I just returned, along with a team of scientists and volunteers, from a successful research trip (May 15-23) to the Ten Thousand Islands (TTI), southwest Florida, where we were conducting research on juvenile Goliath Grouper (Epinephelus itajara)—the largest grouper species in the western North Atlantic (adults can exceed 3m in length and 400 kg in weight).

Juvenile Goliath Grouper in a holding chamber, with water being pumped over its gills.

Joining me on this expedition were: Dr. Robert Ellis, a recent graduate from the Coleman/Koenig reef fish ecology lab and current employee at FWC-Fish and Wildlife Research Institute (FWRI); Dr. Philip Stevens, research scientist at FWC-FWRI and catfish angler extraordinaire; Dr. Mauricio Hostim, visiting scientist from Universidade Federal do Espírito Santo, Brazil; and Robert Malinowski, fishing enthusiast and volunteer researcher from Wisconsin [who coincidentally happens to be my father].

Life History and research objectives:

Goliath Grouper are long-lived (surviving 37+ yrs) and tend to remain primarily in nearshore mangrove habitats as juveniles— until they mature and move offshore to join adults on reefs around ages 5-7, or around one meter in length. This predictable habitat shift from juvenile to adult life stages allows us to target adults and juveniles separately.

Chris Malinowski putting blood into an anticoagulant vial, after drawing blood from a juvenile Goliath Grouper.

The main objectives of this trip were to catch larger juveniles (~400 to 1000 cm total length), using a setline technique with a baited 14-0 circle hook, and to obtain various tissue samples (blood, muscle, liver) to be measured for heavy metal contamination (e.g., mercury) and health impacts. Goliath Grouper have some of the highest measured mercury levels of any grouper species in the western Atlantic and Gulf of Mexico, so we are trying to understand patterns of accumulation, including where they are getting it from and how they are impacted. Comparing results of juvenile heavy metal levels and resultant health effects with that of adults will give us a good idea of how size, age, and habitat differences factor into heavy metal accumulation patterns.

Details of the research trip:

The Ten Thousand Islands is a beautiful region of Florida, containing shorelines with relatively expansive and healthy mangroves, which provide essential nursery habitat for juvenile Goliath Grouper and many other fish species.

Dr. Phillip Stevens releasing a Goliath Grouper after sampling, measuring, and tagging was completed.

Throughout our seven days of sampling, we visited various sites throughout TTI that we knew from previous studies, and last year’s sampling, to have the highest local abundances of juvenile Goliath Grouper. Overall, we caught and sampled a total of 9 fish. Last year we sampled 16 fish from these sites, so this was a bit lower than we had hoped. Nevertheless, a very successful trip!

Our sampling methods are non-lethal, which is critical for research on a protected species of conservation concern, and because we are able to obtain important mark-recapture data. Such data provides us with details of how far the fish has moved since it was last caught, how much it has grown, and allows for mortality estimates. On this trip, four of our nine fish were recaptures from previous years of sampling. More importantly for the objectives of this heavy metal study was that two of these fish were individuals I had sampled last year for mercury toxicity. This is really exciting because I will be able to measure and compare mercury contamination in these individuals from one year to the next. Overall, between adults and juveniles, I now have about 15 individual fish that I have recaptured and sampled for mercury toxicity multiple times from one year to the next.

Other species we encountered:

Our fishing technique of using large hooks and bait (catfish or other live bait) can often attract other large predators, other than Goliath Grouper. We caught two bull sharks on our lines, measuring about 6 feet in length. The first one we caught really got our hearts pounding because we could see the mangrove limb, that the setline was attached to, from hundreds of feet away violently bouncing up and down. You never know what will be on the other end of the line, so it was exciting to see the action from so far away. Once we motored up to the line and realized it was a bull shark, we quickly cut the hook out of its mouth to set it free.

From top to bottom: Dr. Mauricio Hostim, Chris Malinowski, Robert Malinowski. Releasing a bull shark (Carcharhinus leucas) after it was caught on one of our setlines.

We also had bottlenose dolphins and multiple species of turtle (terrapin, loggerhead), and various bird species, from herons to spoonbills, visit us each day. We had one very large and curious loggerhead sea turtle following us around and coming right up to the boat to check us out for an entire day of fishing. It is a beautiful thing to be surrounded by mangroves and to see so much life around you. Visiting this place reminds me of how important it is that we maintain what is left of our mangroves, particularly because they are so critical to the health of this ecosystem—including the critical habitat they provide for the survival of so many species.

Partnership with Rookery Bay NERR:

We were fortunate to pair with Kevin Cunniff and Rookery Bay National Estuarine Research Reserve (NERR) for this trip. Our research crew was provided accommodations at the Shell Island Road (SIR) field station and we were able to keep our boat docked at the Goodland field station, which enabled easy access to our sampling sites each morning. The SIR field station was a great place to stay because we had a full kitchen, living area, and a full lab where samples could be processed each evening when we returned from the field.

To learn more about Goliath Grouper research in the Coleman-Koenig research lab at the FSUCML, click here.

Who lives on some substrate under the sea?

Tags

education, marine biology, marine science, research, sponges

by Katie Kaiser, FSUCML graduate student

Photo by Katie Kaiser

Sponges! Absorbent and colorful with many different irreplaceable functions! Sponges are one of the only organisms that can directly filter bacteria sized particles from the water column. They filter at incredible rates and efficiency, clearing at least 95% of bacteria from the water. Loss of sponges in Florida Bay has been linked to increases in phytoplankton blooms, which are devastating to sponges, fish, and many benthic invertebrates.

Photo by Kate Hill

Besides their awesome filtering abilities sponges are also involved in a myriad of interactions. Sponges can be considered “living hotels” to hundreds of species of tiny animals such as sea spiders, worms, crustaceans, and brittle stars. Some symbiont species use the sponge as both a refuge and a food source!

Photo by Katie Kaiser

Crustaceans can provide a mobile home for sponges, and in turn one species of hermit crab lives inside a sponge that completely covers its shell and then continues to grow as the hermit crab grows; and decorator crabs can choose to decorate themselves with sponges that camouflage them from their predators!

Photo by Katie Kaiser

Sponges growing on mangrove roots protect them from small crustaceans that bore holes in the roots, killing the tree. In turn, the mangrove roots provide a stable substratum for the sponges in a habitat with abundant plankton on which sponges feed.

Photo by Janie Wulff

Sponges glue corals onto reefs, and protect the vulnerable undersides of corals from organisms that bore holes in coral skeletons. Sponges also filter bacteria out of the water column, maintaining clear water required by corals.

Sponges and zooanthids can protect each other from predators. Zooanthids are tiny colonial anemones that embed themselves in the surfaces of sponges, living in close association for the rest of their lives as a sort of 2-species ‘super-organism’.

Photo by Tim Swain

Sponge predators include Hawksbill sea turtles, angelfish, starfish, and nudibranchs! Sponges have unique chemical defenses that deter most predators, but angelfish overcome this by eating small portions of each of many different sponge species. Sea stars will “taste” a sponge with their tube feet then, if they like it, they climb onto it and release digestive enzymes. Nudibranchs eat a crevice into the sponge and then remain tucked inside.

Venturing to the West Florida Slope: Deep-sea Research Cruise

Tags

cruise, deep-sea, marine biology, marine science, research

by Johanna Imhoff, FSUCML graduate student

We are having beautiful weather as we steam toward our first set of stations on the West Florida Slope. After we had stowed most of our gear securely, fellow FSUCML grad students, Bianca and Brian; UNF grad student Clark; and I sat at the galley table and prepared flagging tape with individual numbers to tag each fish when it comes on board, and vials with the same numbers for storing fin clips and muscle biopsy samples for genetics and stable isotopes research. When we start fishing, our first fish will be RA-16-001 (that stands for Restore Act, as in FL Restore Act Center for Excellence Program, 2016, and the first fish). Bianca also prepared syringes for collecting blood sample for her reproductive and stress physiology research. With the team working together, we got this done pretty quickly and we’ve had time to read, nap, work and acquire our sea legs.

Stay tuned for more information about our research cruise.

Turkey Wing Clams, epibionts, and flatworms. Oh my!

Tags

clam, epibiont, flatworm, marine biology, marine science

By Melissa Olguin, FSU undergraduate

An Arca zebra shell with many different types of organisms attached. The peach colored flatworm is probably in the family Stylochidae, which is common in shallow areas of the Gulf of Mexico, usually near oyster reefs.

If you have a thing for invertebrates, then this project will give you a shell of a good time. I’m Melissa, a fourth year undergrad working in Dr. Brooke’s lab. I’m looking at the epibiont communities forming on a local bivalve, the Arca zebra, commonly called the Turkey Wing Clam. In the field these shells often look like little more than small clumps of sediment. But upon closer inspection one can find a slew of colorful motile and sessile organisms calling these shells home. Each shell appears to have its own community of encrusting, branching, and crawling organisms. Currently I’m recording and identifying the organisms growing and living on each shell.

Two large Arca zebra covered in epibionts, including algae, coralline algae, tunicates and several cup corals called Phyllangia americana. We don’t know how long these bivalves live, but they must be quite old as these corals grow slowly.

This process has exposed me to a lot of taxonomical work and even revealed to me the amount of work still needed for the Gulf of Mexico. One such example is demonstrated in the photo showing a peach colored flatworm. Much of the literature on Atlantic flatworms is old, and my main resource on the Gulf of Mexico for flatworms only has depth records of only 4 m for most species. That puts my flatworm (collected at 12m) beyond its recorded depth. This finding shows that in understudied habitats like the Apalachee Bay nearshore reefs, a little exploration can produce valuable new information, such as depth extensions in the case of my flatworm.

Besides looking at what is living on these shells, I am interested in seeing the interactions going on between the epibionts and the Arca zebra. Epibionts have been found to deter predation on bivalves (Vance 1978) while the Arca zebra shells can provide the substrate necessary for many organisms to settle on (Scandland 1979, Avila et al 2013). I would love to explore this more and I’m looking forward to discovering more about these fascinating communities.

References:

Hernández-Ávila, I., Tagliafico, A., & Rago, N. (2013). Composition and structure of the macrofauna associated with beds of two bivalve species in Cubagua Island, Venezuela. Revista de Biología Tropical, 61, 669-682.

Scanland, T. B. (1979). Epibiota of Arca zebra and Arca imbricata– Community Analysis. Veliger, 21, 475-485.

Vance, R. R. (1978). A mutualistic interaction between a sessile marine clam and its epibionts. Ecology, 679-685.

To Mate or Not to Mate: Timing of Black Sea Bass Reproduction

Tags

marine biology, marine science, research, sea bass

By Ryan Mckenzie, FSUCML Graduate Student

Recently captured fertilized egg of Black Sea Bass (Centropristis striata) under a microscope

Holy Mackerel! Well, I guess Black Sea Bass (Centropristis striata) in this case. In the late afternoon hours on Tuesday, I observed some fishy behavior occurring in my Black Sea Bass observation tanks at the Florida State University Coastal and Marine Laboratory. This morning while checking my tanks, I discovered fertilized eggs floating on the surface of the water. This is great news for my current research into the reproductive ecology of the Black Sea Bass in the Northeastern Gulf of Mexico. For my research, I am looking into many aspects of reproductive ecology of the Black Sea Bass including the seasonal dynamics of reef populations and individual reproductive behavior. Now with some more luck, I will be able to directly observe and describe their spawning behavior at the FSUCML. Along with other data collected from field surveys, I will use these observations to determine when spawning occurs and if it is related to environmental factors correlated to spawning activity in other reef fishes such as moon cycle, time of day, and water temperature. Was this spawning event related to the recent full moon? Does spawning always happen in the afternoon? These are some of the questions I hope to answer during these behavioral trials in the next few months here at the FSUCML.

My summer internship at FSUCML: researching large fish from coast to coast

Tags

grouper, intern, internship, marine biology, shark

By Melissa Hruby, FSUCML Intern

My name is Melissa Hruby and I am currently a sophomore majoring in animal science at the University of Wisconsin-Madison. This week concludes a four-week internship at the Florida State University Coastal and Marine Laboratory (FSUCML). I was drawn to FSUCML by the interesting research being conducted on coastal fishes including reef fish and sharks. I am still at the beginning stages of deciding on which science career path to take and thought this internship would be an excellent opportunity to gain hands-on experience in marine research. Indeed, this internship has exceeded my expectations and has exposed me to a field of research I never before knew existed.

Goliath Grouper research

The main focus of my internship was to work with Chris Malinowski on his Goliath Grouper dissertation research. Throughout the duration of my visit, I was able to partake in two sampling trips—each in a different region of Florida. The first was a one-day trip off of the lab in the Gulf of Mexico, and the second a six day trip out of Jupiter, FL in the Atlantic Ocean. Working with Chris through the process of trip planning and preparation, the actual fieldwork, and post-trip sample processing and analyses, gave me a glimpse of many aspects comprising Chris’s research.

These trips were both instructive and personally rewarding. I learned a lot about the biology of this native species, which was once almost fished to extinction, and of the techniques and mechanics involved in collecting data. Above all else, I got to experience the thrill of pulling in one of the largest bony fish in the world. Although we caught many Goliath Grouper over the course of these trips, I managed to pull in the largest one, which measured 216 cm in length (estimated > 500lbs)! This was by far my favorite part, and is something I will never forget.

Coastal shark survey

I was also fortunate enough to tag along on a shark survey excursion near the end of my internship. I assisted Cheston Peterson and a few others in a coastal shark survey. I quickly learned how much work it takes to sample a single shark, and developed an admiration for Cheston’s persistence and passion for these creatures. From just one day in the field with Cheston, we sampled over 80 sharks from five different species. My favorite part of this trip was hauling the large sharks (> 7 ft) on deck. This gave me a chance to work with these beautiful and admirable animals up close and to view them in a light that many people don’t get the chance to.

 

Final thoughts on my internship

Participating in this internship has been especially beneficial to me in my search for a career path and as I explore life interests. There are scarce opportunities, if any, involving this type of research in Wisconsin, so I was extremely fortunate in getting the chance to help Chris and other students from FSUCML with their research projects. Although I may not make a career of catching 500lb Goliath Grouper or seven-foot sharks, I will definitely put my newly acquired knowledge and skills to use in the future. After working in the field, I have learned how important effective teamwork is for the success of large collaborative research projects. Getting vital and timely data from each and every fish would be nearly impossible without cooperative efforts form everyone aboard the boat. From the organizational complexity of the project to the art of catching these giant fish, the entire process is far from easy and the teamwork behind it is what makes it successful. I plan on using the knowledge and insights I’ve gained through this internship to further advance my learning and to educate others whenever I can.