Monday, July 28, 2014

Golden Trevally

Figure 1. Golden trevally eggs near hatching.
We were excited to receive 20 mature golden trevally from SeaWorld Orlando nearly a year ago. We distributed 10 fish each into two large recirculating systems. We expected to have fish spawning within a couple weeks, but after nearly a month of no spawning activity we concluded the fish were likely regressing due to transport and handling stresses. We decided to forgo any more spawning procedures until earlier this year, once the fish had become better acclimated to their new setting and temperatures were in the range reported for spawning. This paid off in mid-April after daily ambient temperatures were averaging close to 26°C and conditioned females were verified through cannulation. We administered spawning hormones to all 10 fish within that tank and obtained three spawns occurring 48, 72, and 96 hours after hormone administration. The first spawn contained mostly sinking (unfertilized) eggs but the next two spawns each contained a majority of neutrally buoyant eggs (~0.7 mm diameter). Hatching occurred quickly (~18 hours) with roughly 60,000 larvae hatched from the second spawn and 36,000 from the third spawn.

Figure 2. 14 days post hatch golden trevally larva.
Larvae were stocked into multiple 104 L tanks supplied with flow-through seawater to exchange a minimum of two tank volumes of water daily. Larvae from the second spawn were stocked into three tanks at nearly 15,000 larvae/tank and larvae from the third spawn were stocked into two tanks at a density near 18,000 larvae/tank. Development was rapid and larvae had fully functioning mouthparts within two days post hatch (dph). We fed the larvae enriched (Ori-Green) rotifers at 10-15 rotifers/mL daily until 25 dph.  We also fed the larvae copepod nauplii (Parvocalanus sp.) at 2 naups/mL daily until 10 dph. By 11 dph, most larvae were able to feed on Artemia nauplii and were fed them at 4 Artemia/mL. We used green water techniques by inoculating larval tanks with live T-ISO (~100,000 cells/mL) up to 25 dph. We began weaning the fish onto a dry diet (Otohime B1-B2) around 15 dph, and after 30 dph fish were feeding solely on the dry diet. During these trials, swim bladder inflation began at 5 dph, fin ray branching at 9 dph, and flexion at 14 dph. The typical black bar pattern and gold coloration could be seen developing as early as 20 dph with all larvae having reached metamorphosis by 30 dph. We observed a mean survival to metamorphosis around 6.5% and obtained over 3,200 juveniles. We restocked them into recirculating systems and raised them for a couple more weeks before they were shipped off to SeaWorld at 45-46 dph around 3.8 cm fork length and 0.94 g.
Figure 3. 30 days post hatch golden trevally larva beginning
to display black bars.

On multiple occasions we’ve administered hormones to both tanks of brood fish and have observed spawning to occur 48-96 hours after administration every time. The quality of spawns has been somewhat variable. We believe golden trevally commercial scale culture to be highly feasible and could be further improved by defining larval culture requirements and optimizing brood fish spawning procedures. We look forward to receiving new species to work with and hope to overcome any difficulties that might inhibit their aquaculture potential.

Figure 4. 45 days post hatch golden trevally juveniles.
Aquaculture lab at the University of Florida Indian River Research and Education Center in Fort Pierce, FL (Dr. Cortney Ohs, Dr. Jason Broach, Bryan Danson, Dan Elefante, Scott Grabe, Andrew Palau, and Audrey Beany)

Tuesday, July 22, 2014

Rising Tide expands in Florida

The University of Florida’s Indian River Research and Education Center (IRREC) is the latest research facility to join our growing Rising Tide family.  Dr. Cortney Ohs heads up the Aquaculture Research and Demonstration Facility at IRREC and has made leaps and bounds in the realms of marine baitfish, marine live feeds, and brood nutrition research since joining UF in 2005.  His expertise and expansive facility will greatly enhance the progress desired in the world of marine ornamental fish research. 

Figure.  Golden Trevally grown at IRREC.  Eggs were spawned from
broodstock received from SeaWorld Orlando. 
About a year ago, Cortney began his involvement with a shipment of golden trevally broodstock from SeaWorld Orlando.  He has since raised 1000’s of them to the juvenile phase, the details of which will be presented in a future blog post.  More recently he has acquired funding that will bring green chromis broodstock to his facility so he and his team can begin to address the production protocols required to make this heavily imported species an aquaculture reality.  TAL and IRREC will be working together closely on this species as well as the Pacific blue tang.  Cortney is currently working on getting Pacific blue tang broodstock so we can double our research efforts and continue to understand the parameters necessary to make this fish a captive bred species as well.  In addition, he will also be receiving shipments of eggs from public aquariums, targeting specific species of interest.

I am personally excited to have Cortney added to the expanding list of Rising Tide research facilities as I obtained my master’s degree studying in his lab.  Try not to hold that against him though, as he did the best he could J.  It is truly an exciting time for Rising Tide as it continues to grow and the separate teams continue to work together, propelling the research forward.

Eric Cassiano and the Rising Tide team at TAL    

Monday, June 30, 2014

Emma Forbes update: Understanding Bacteria at OI

Figure 1. Culture of bacteria (Pseudomonas sp.??) on marine
agar isolated from larval rearing tanks at OI.
Aloha everyone!

It’s been a while since my last post, but it’s been a busy few months. Though it's the kind of busy you don't realize until you sit down and catch your breath. It’s been a lot of fun spending my days in the lab working with everyone learning new things.

Figure 2. Sample of Parvocalanus nauplii on TCBS agar that
was fed to yellow tang larvae.
Since we are still observing relatively high mortality just past first feeding, my work at the Oceanic Institute is focused on bacterial population analysis and application of probiotics to our yellow tang larval rearing tanks. The first month of summer was spent looking at the growth of our live feeds with the addition of probiotics, which appear to have no effect on their survival or growth. This is great news for us! We’ve started to culture our copepods in probiotic-enriched water for larval rearing trials starting July!

Figure 3. Gel electrophoresis of 12 different
bacteria isolated from systems at OI.
My thesis is looking at the identification of bacteria in our culture environments and live feeds and their impact on larval survival. Much of June has been spent practicing different plating techniques, isolating different colonies and running PCR. It’s been very exciting, as there are over 15 different colonies that I’ve isolated and am now working to identify them. This will hopefully give us insight into the bacterial communities in our rearing tanks and any possible pathogenic bacteria that may be affecting yellow tang survival.

In one of my first trials a bright pink bacteria was growing in the tanks. I was able to sample it and isolate it on marine agar. Hopefully in a week or so I will be able to sequence it and determine exactly what species is growing in our hatchery! The unanimous hypothesis is that it’s a Pseudomonas sp., so everyone is very excited to see if they are right! Bets have been placed.

I’m excited to continue larval rearing trials with the probiotics in July to see if they help us increase survival past first feeding!  Fingers crossed!


Monday, June 23, 2014

One small step….Pacific Blue tang update

Figure.  17 day post hatch Pacific blue tang larva.  Credit: Kevin Barden.
The newly revamped larval rearing room has been up and running since early May.  In truth, there are still a few things we’d like to add to the filtration system, but that hasn’t stopped us from stocking eggs into the system as we get them.  One of the first larval rearing attempts was performed with Pacific Blue tangs.  We got roughly 4000 eggs; which we then stocked into a 210 liter tank (55 gallons).  This worked out to a density of roughly 20 eggs / liter.  For the first three days the water flow entering the tank was 750 mL/min; which theoretically works out to ~5 tank turnovers per day.  At first feeding the flow rate was increased to 2.75 L/min; which works out to ~20 tank turnovers per day.  It was left at that rate for the duration of the trial.  This high water flow was inspired by Chad Callan’s recent success with yellow tang larvae.  We also instituted a moderate air flow with two air stones pumping ~250 mL/min each.  Both created a significant amount of water movement within and through the tank.  The larvae were also subjected to a photoperiod of 14 hours light and 10 hours dark.  Because of the high water flow we fed the larvae Parvocalanus nauplii (<100 microns) at a density of 2/mL twice daily; which is all we had left over after supplying Jon’s milletseed butterflyfish trials.  Although the water quality was not optimal as ammonia and nitrite were detected in the system (albeit low values), the performance of the larvae was greater than we have seen in previous attempts.  Typically we would lose the majority of the larvae by ~6 days post hatch.  During this trial the majority of the larvae made it through that bottleneck and survived until ~10 days post hatch, with the last surviving to 20 days post hatch.  From the picture of a 17 day post hatch larva (the last taken) you can see the beginnings of the hypural plates forming which would preclude flexion.  However, we can’t say for sure.  What we can say is that these results were promising and hopefully in the not-too-distant future as the system becomes more stabilized, the live feeds become more plentiful and nutritious (new microalgae production system….which we’ll talk about later…), and the list of parameters tested becomes smaller we will have more advances to talk about.  But for now it’s just one small step forward.     


The Rising Tide team at the Tropical Aquaculture Laboratory

Wednesday, June 4, 2014

Something A Little Different...

Figure1. The new larval rearing room at TAL; showing the
120 Ltanks used to grow octopi in.  We've also recently tested
 our fish species in them which we'll talk about next time. 
At the Tropical Aquaculture Lab in Ruskin, we’ve been running into lots of bottlenecks in the early larval development of some of the Rising Tide species we’ve been working on.  We believe these issues were exacerbated due to our current larval rearing systems being inadequate to provide the pristine water quality necessary for larvae to survive.  Because of this, we’ve spent the past several months upgrading our facilities, to what we believe will be an important step toward significant advancements in captive raised marine ornamentals.

Figure 2. 22 day old common
octopus paralarvae
Upon nearing completion of the new system, we were approached by Mote Marine Laboratory’s cephalopod specialist Brian Siegel; their common octopus (Octopus vulgaris) had spawned, and they were curious if we would be interested at giving them a go.  Rising Tide’s focus is primarily on the captive propagation of marine fish species, but we thought this would be a great way to test out our new larval rearing system.  Common octopi have been reared in captivity at several institutions around the world, but with very low survival, believed to be due to poor water quality and nutrition.  We’re hopeful the improvements we’ve made to our system will allow us to have some success with these challenging cephalopods.

Cephalopods have incredible abilities to adapt to their environment using chromatophores, which are pigment-containing and light-reflecting organelles found within their cells.  They allow the octopi to communicate as well as camouflage to their environment.  Even as paralarvae, these common octopi can create beautiful patterns with their chromatophores, as seen here:

Common octopus paralarvae have a voracious appetite for crustacean zoea in their natural environment, and have been successfully reared by substituting with Artemia nauplii as a prey item throughout development.  By providing them with a constant supply of pristine seawater along with microalgae and Artemia nauplii, we’ve reached 28 days post hatch today.  We’re hopeful they will remain strong enough to survive to settlement.

The Rising Tide team at the Tropical Aquaculture Laboratory

Monday, May 19, 2014

Colurella adriatica update

Figure.  Photos of Colurella adriatica;
a potential new live feed for both
marine and freshwater fish larvae.
This post is in response to requests for more information about Colurella adriatica.  As previously stated, we’ve examined salinity and found that although they tolerate a wide range, optimal performance is at 15-20 g/L (ppt).  For feeding marine fish larvae this is likely going to be the culture salinity as acute acclimation to full strength seawater is good and this will save on salt.  Colurella also grows well at 5 g/L and therefore when growing them for freshwater fish, this is the recommended salinity.  Thus far, attempts to grow Colurella in 0 g/L freshwater have yielded poor results.  The only other culture parameter tested so far has been diet.  An industry partner works as a microbiologist and isolates bacteria.  He had some freeze-dried bacteria that he wanted us to test.  When solely fed freeze-dried bacteria the Colurella populations survived.  When compared to those Colurella fed algae paste (Nanno 3600™; Reed Mariculture), the ones fed freeze-dried bacteria initially grew better than those fed paste.  However, after 4 days the Colurella fed paste had significantly greater growth.  The results of this trial are still being evaluated, as is optimal diet, but Colurella’s ability to be fed, and survive on, freeze-dried bacteria seems feasible.  Other culture parameters haven’t been tested yet, but we keep our populations at ~78° F with gentle aeration and can reach ~500 rotifers per mL with a population growth rate half of what is achieved with Brachionus sp. rotifers.  Hopefully, once we know more about this species we can increase the population density and growth rate.
As stated in a previous post, Colurella has been fed to and consumed by a number of marine fish larvae.  In fact, it is easier to mention the one that has not consumed it: green chromis.  Digestibility has been an issue for us when using Colurella as prey for marine fish larvae.  We've actually seen live, undigested Colurella being passed through the gut of marine fish larvae.  After talking with Patrick Sorgeloos, his suggestion was to feed less and increase the residence time in the gut.  We'd always fed high densities.  One of the unique attributes of Pacific blue tang larvae is their ability to survive heavy water movement (usually in the form of aeration), even to the point of being unable to feed (more on this in a future post).  One of the tests we’ve run to increase digestion was to feed them Colurella followed by periods of heavy aeration so they couldn’t feed.  What we found were digested Colurella in the gut of Pacific blue tang larvae.  The results were encouraging and recent tests have focused on ways to increase residence time of Colurella in the gut of marine fish larvae.  Digestibility of Colurella is not a problem for freshwater fish larvae.  To date, we've fed them to bala shark, dwarf gourami, lemon tetra, and red-eye tetra larvae and they've all survived.  Recently a population of Colurella was supplied to a freshwater fish farmer in the hopes of more advantageous results during larval rearing. 

Perhaps the most exciting information is that in the next few weeks we’ll be awarded a grant to look at the culture conditions and larval feeding of Colurella (and Oithona colcarva; our marine cyclopoid copepod).  Whether this will be in the form of hiring someone or promoting someone at our facility remains to be seen, but having someone focused solely on answering these questions will help us obtain valid information quickly.  

The Rising Tide team at the Tropical Aquaculture Laboratory

Thursday, May 15, 2014

Milletseed Butterflyfish Larvae Update

Figure 1. A 35 day old milletseed butterflyfish larva with more
pronounced dorsal spines.  During this recent trial, larvae displayed
greater development in a shorter period of time.
It’s been a while since our last milletseed butterflyfish post but, not to worry, I’ve been very busy conducting a variety of replicated experiments to better understand their larval requirements.  From those experiments, I’ve learned several important things about raising the milletseed butterflyfish.

From our previous examinations we knew that nauplii of the copepod Parvocalanus crassirostris could be used as a first feed, however, in clear water only about 50% of larvae were feeding.  After exploring the literature, I decided to test a variety of parameters including algal turbidity, prey density, prey selectivity, tank size, light intensity, and stocking density in order to increase feeding performance.

Figure 2. A 35 day old milletseed butterflyfish
larva with less dorsal spine development and
more elongate shape.
From these studies I initially learned that the milletseed butterflyfish do not identify rotifers (Brachionus plicatilis) as prey throughout larval development.  Additionally, testing revealed that different stocking densities, light intensities, and tanks sizes didn’t have a significant effect on feeding incidence or performance of the larvae.  However, what did enhance feeding was the addition of algae (T-ISO) to the tank; which increased the feeding incidence to about 90%.  Another interesting result was that feeding incidence was the same at 1 individual/mL as at prey densities up to 20 individuals/mL.

 While the rearing of milletseed butterflyfish to the juvenile phase has not been accomplished yet, this information is crucial for the optimization of culture methods of the milletseed butterflyfish. By improving early larval feeding we can increase early larval survival and promote development, increasing the likelihood of rearing larvae to settlement.

Jon-Michael Degidio