Posts in Category: Box of Slugs
Box of Slugs 2 Update
It has been quite some time since I have posted anything about Box of Slugs 2, the tank at home that is connected to a coral reef aquarium. There has been a lot of excitement, such as the appearance of several species of Sacoglossans that had ridden in with live plants. However, without large grazers such as urchins or snails, it has also been difficult to control the growth of algae, such that much of the tank was quite furry and subject to blooms of cyanobacteria (blue green algae, a.k.a. red slime).
The mass of hair algae may have had some benefits as food for growing Elysia, but it also created dead spots with poor circulation, and overwhelmed some of the desirable species of macroalgae.
After a few tweaks, and a little patience, the mass of filamentous algae has died back, and the macroalgae and seagrasses are thriving. I got rid of the large rock that impeded flow, started dosing vinegar as a carbon source for the plants, and assembled a filter to remove debris and increase circulation.
The tank is looking pretty good at this point. There is a variety of macroalgae (Penicillus, Udotea, Avrainvillea, Halimeda), along with some Bryopsis and turtle grass. A few gorgonians add a little variety. All the plant species seem to be growing well, and there is little sign of the plague algae coming back.
Box of Slugs 2, 8/29/15.
Floor of Box of Slugs 2, 8/29/15
Probably the most important change was the addition of this filter to increase circulation and remove some of the debris. It consists of a sponge sleeve over a perforated 1″ PVC pipe, connected to an Eheim 1048 pump.
Sponge filter below surface, 8/29/15
The pump is stuck to the wall of the tank with a magnet. The arrangement allows the pump to be partway out of the water to minimize heat transfer. The output goes through a Hydor Flo rotating deflector, which provides circulation throughout the tank.
Eheim pump driving sponge filter. Note the output through the Flo deflector. The sponge to the right covers the drain that returns water to the sump, and is not part of the filter. 8/29/15
The resident slugs are three E. crispata. I have decided to separate the larger Elysia species, with clarki in the hatchery at USG and crispata in BoS2. Each system also has a few smaller hitchhiking species. BoS2 has a few of the frilly presumed Cyerce, while BoS1 has some presumed E. papillosa.
The E. crispata seem quite happy, but are largely ignoring all of the macroalgae species in favor of a few small patches of Bryopsis.
E. crispata on Udotea, 8/29/15
E. crispata cruising Box of Slugs 2, 8/29/15
More Pikeblennies
They were less shy today.
Male Pikeblenny 8/21/15
Female Pikeblenny 8/21/15
Their eyes are quite entrancing. It must be nice look straight ahead when hunting amphipods.
Male looking straight at you.
Gearing Back Up
Between teaching on the other campus and taking a little vacation, I have been letting the colonies coast for a few months. The second generation of E. clarki have not been growing particularly quickly, so I have not seen eggs in quite some time.
It is time to get more serious for the fall. I got some new Bryopsis from Justin to refresh the stuff that has been growing in the tank for months. The good news for him, but not so much for me, is that he is finally defeating Bryopsis in his >500 gallon system, and it has dwindled to very little. Unfortunately, that means I will not have a backup supply if the current crop starts to die off.
More importantly, the newest infusion of broodstock arrived from KP Aquatics yesterday. I ordered 3 new E. clarki for the office and 3 E. crispata for home, plus about 20 Penicillus to try to stay ahead of their appetites.
The clarki have settled in, and are looking happy.
New E. clarki 8/20/15
E. clarki enjoying a meal 8/20/15
As always, the good folks at KP threw in a few extras, including this presumed E. papillosa. By the time I arrived this morning, she had already laid eggs.
Presumed E. papillosa and eggs, 8/20/15
In the ongoing effort to reduce the amphipod population, I am trying a pair of pikeblennies in the growout tank. The idea was that they would make a dent in the amphipods, then I would move them to Box of Slugs 2, at home, to be able to enjoy them more. Given their shyness and speed, I am now a bit dubious that I will ever be able to catch them. One is considerably larger and more colorful, and they have not tried to kill one another yet, so I am thinking they may be a male-female pair. They are so interesting to watch, like tiny snakes hunting in the undergrowth, that I am very much enamored with them. With a little time, I hope they settle down and let themselves be photographed in more flattering poses.
Larger pikeblenny, possibly a male. Peeking warily from a pile of algae. 8/20/15
Smaller, drabber, possibly female pikeblenny. Bolder and more aggressive humter. 8/20/15
When possible, I will post photos of the pretty new E. crispata.
Dosing Pump is Here
Although the slug system does not require much in the way of chemical supplementation, the plants do require a little input beyond the weekly replacement of about 25% of the artificial seawater in the system. Because there are no fish or other creatures generating nitrogenous waste for the plants, I am adding small amounts of potassium nitrate (KNO3). Plants also require phosphate as a major nutrient, but they consume it in much smaller quantities, and the presence of some cyanobacteria (blue-green algae) implies that there is at least a small amount. I am also monitoring calcium (Ca2+), which is used by some (e.g., Penicillus and Halimeda) but not all (e.g., Bryopsis) of the food plants. Possibly most important is bicarbonate (HCO3–), which acts as both a buffer for the system’s pH and as a carbon source for the growth of the macroalgae. For the moment, the goal is to maintain ~5 ppm NO3–, ~400 ppm Ca2+, and ~3.2 mEq/L HCO3–.
Up to now, I have been adding supplements as needed to maintain parameters, and it has been fine. However, being away from the office due to other obligations or short vacations can cause parameters to fluctuate. This can lead to slowing of the growth of food plants, enhanced growth of pest algae (defined as species the slugs won’t eat), or both. Plus, it might be nice to take an extended vacation.
In an effort to stabilize parameters, I have added a Bubble Magus BM-T11 three-channel dosing pump. It can add NO3–, Ca2+ and HCO3– independently, in whatever volumes and intervals I choose. As part of the kit, I also got a set of reservoirs, a small fitting to mount the tubing on the sump, and a set of three reservoirs to hold solutions. Always fun to open the box and set things up.
Pump and Accessories from Marine Depot, 7/20/15
Then it was time to assemble things, fill up the reservoir, and see how things go. The pump was remarkably easy to program, but each of the the reservoirs had a poorly sealed connection on one of the critical fittings. All it took was a little cleaning and silicone sealer, and we were good to go.
Dosing system, in place and working. 7/21/15
Now it’s time to put the feet on the desk, chomp a cigar, and let the pump do all the work. Now that the pump is adding supplements at a known and constant rate, it should be straightforward to adjust the doses up or down to optimize plant growth and slug health.
New Slugs!
One of the members of the Washington DC Area Marine Aquarist Society (WAMAS) recently posted on the club forum that he had an outbreak of small slugs. When I looked at the photos, I was pleased and amazed to see that his slugs looked like small Elysia. Amazed because his was a traditional coral reef tank, which, given the hazardous pumps and lack of appropriate food, are not conducive to survival, much less propagation of Elysia. Nonetheless, there they were.
Ryan, the slugs’ accidental owner was happy to meet up and hand off a few. It took a few weeks to find the right time, but he gave me a baggie of six little slugs yesterday. Meantime, most of the little guys had done what Elysia usually do in reef tanks, and had climbed or been blown into the filtration system to their doom.
Even a quick, unmagnified look at the slugs suggested that they were not the usual suspects (clarki, crispata, papillosa…). Once under the microscope, they were clearly unlike the other species that I have either purchased or been lucky enough to obtain as hitchhikers on live plants. They are quite small – about 7 mm – have reduced parapodia, stubby, tubular rhinophores, little white bumps, and squarish hearts.
Two unidentified Elysia. Total magnification 70X. 6/28/15
Unidentified Elysia. Ruler shows how tiny the slug is. 6/28/15.
Small unknown Elysia. Each mark represents 1 mm. 6/28/15
They are now in the growout tank of the hatchery system, where I hope they will find a species of algae to their liking. Of the species that fit the rough description on the Sea Slug Forum, Elysia serca, and Elysia flava, two western Atlantic species, or E. obtusa, from the Pacific seem, to be the closest fits. However, none of them seems perfect. The mystery species lacks the characteristic trio of white spots on the heart and parapodia of E. serca, as shown in the photo below, but the small body size, large head, and small rhinophores look like a fairly close match. E. flava and E. obtusa appear much more translucent in photographs, but the pattern of white specs strongly resembles E. obtusa. If they settle in and produce progeny, there should be some opportunities for proper analysis.
Elysia serca from the Sea Slug Forum
Elysia obtusa from the Sea Slug Forum
E. serca, feeds on seagrasses, such as Thalassia (turtle grass) and Halophila (tape grass), which are true vascular plants rather than the macroalgae that serve as food for most of the genus. The food plants of the other two candidate species do not appear to be known. In their new home, there are at least a half dozen species of macroalgae, plus some shoal grass plants (Halodule) that rode in with them, so there is a decent chance they will find something to eat.
It would all be made a lot easier if we knew where they came from. As far as Ryan knew, no plants or macroalgae were placed into his system, so there is no obvious way for the slugs to have ridden into the tank. At this point, we don’t even know which ocean they came from.
Here’s a final look, in their new home. Will she thrive or fade? We’ll see.
Mystery slug in growout tank. 6/29/15.
Going Old School
I have been using a variety of different lighting systems in the hatchery. The Broodstock tank, with the adults, larger juveniles, and plentiful food, is lit with an old Coralife 2X55 watt compact fluorescent (CF) hood, whereas the growout tank has two 20-watt Marineland “Reef Capable” LED fixtures. The macroalgae have been growing like weeds under the old Coralife fixture, whereas the Marineland fixture has not performed all that well.
I suspected that the problem was the spectrum produced by the LED lights. Although many high-end LED systems contain red and far-red LEDs, the Marineland lights had arrays of blue and white LEDS, which produced very little red light. On the other hand, “daylight” CF lamps produce light with a broader spectrum, including significant amounts of the red and blue needed by Elysia food plants.
The solution seemed obvious. It is relatively easy and cheap to assemble CF fixtures using surplus ballasts, endcaps, clips and reflectors, so why not just build one?
Step 1 was to find the right parts, a wiring diagram for the ballast (in this case a Workhorse 5), and to make sure the parts still worked. A quick and dirty assembly shows the ballast, lamps and endcaps are ready to go.
Do all the old parts work?
Next, it was time to cut an old reflector to the right length, and figure out the rough positions for everything.
Ready for soldering.
Although wire nuts would be faster, soldering and shrink-tubing the connections seemed best, given the moist, splashy location.
Soldered, ready for final assembly.
All that remained was to secure the ballast, power cord, and the clips for the lamps (bulbs) to the reflector. Bingo! A new fixture that will produce a spectrum more appropriate for aquatic plants.
New compact fluorescent light, ready for installation.
Frilly Slug Going Home
There has been a frilly sacoglossan (Cyerce?) in the growout tank, which presumably rode in with the last batch of algae. In an effort to focus on E. clarki in the hatchery, and because there is probably another one of these guys remaining in Box of Slugs 2, she is getting moved home tonight.
Frilly sacoglossan 060115
Despite the utter failure of the environmental system at USG (temperature 28 – 30 degrees C over the past few days), the hatchery has muddled along. Even got the first small batch of eggs from the second generation of E. clarki. Thought it might be useful to start providing a sense of scale of these things.
First batch of eggs from the second generation.
Hatchery in Progress
As described a while back, all steps in the culturing process seems to be going pretty well, except for one bottleneck. The adult broodstock is (are?) happy to lay eggs, the eggs hatch consistently, and the veligers settle. However, they will not develop much farther after settling in a controlled environment. Oddly, the settled veligers will develop if left on their own in a large tank full of algae. Although I have now reared E. clarki from egg to adult, it is not really possible to plan experiments based on when slugs may or may not decide to develop in a display aquarium. A more systematic approach was needed.
The hatchery is an attempt at making the juveniles happier during and after settling. Egg masses will still develop in glass crystallization dishes, but they will be placed in the new setup just before hatching. There were a few issues that may have impeded development, and they should be addressed by the new setup.
The tank is an acrylic “half-ten” from Glasscages.com. It is essentially a half-height 10-gallon tank (10″ W X 20″ L X 6″H). I had originally planned on using a standard 10 gallon, but it became clear that it would be clumsy and result in a lot of wasted space.
Acrylic “Half-Ten” tank from Glass Cages. 5/19/15
One problem that arises with free-swimming veliger larvae is that they are positively phototactic (attracted to light). This may not be a problem in the open sea or a large aquarium, but in the small dishes I was using for hatching, it meant that they would swim to the surface and promptly get stuck in the air-water interface. This would leave little rafts of veligers on the surface. These floaty veligers were capable of settling, so it was not a complete disaster, but it could not be good for them. Some authors (e.g., Dionisio et al, 2013) go so far as suggest rearing them in the dark. My solution is to illuminate from below. Marineland makes a nice little submersible LED light that can be used to keep the veligers swimming downward. Below are views of a prototype hatching chamber (2″ PVC pipe, with 50 micron nylon mesh to retain the veligers and larvae), showing the light coming from underneath.
Light from below, with prototype hatching chamber. Front view. 5/19/15
Light from below, with prototype hatching chamber. 5/19/15
Secondly, the presence of a relatively large food plant (large enough to be certain all of the little slugs can climb on) might have altered water chemistry, either through the process of photosynthesis (raising pH, e.g.) or by releasing chemicals that inhibit the slugs’ feeding or development. Continuously recirculating ASW (artificial seawater) from the larger system through their hatching chambers should reduce or eliminate this problem. In order to keep voracious invertebrates from entering the chambers, ASW will pass through a UV sterilizer before being distributed in the hatchery.
The manifold for distributing the ASW to the chambers is made from a few PVC pipe fittings. Once the cement has cured, it will be drilled to accommodate valves to control the flow to each chamber.
Components of the manifold. 5/19/15
Manifold, assembled but not drilled. 5/19/15
Naturally, water arriving in the tank needs to leave, so I drilled it and added a bulkhead to drain to the sump.
Tank drilled and bulkhead installed for drain. 5/19/15
Once the manifold is finished, and the UV unit arrives, it will be ready to hook up and accommodate the next available brood. Stay tuned.
New kids in the growout tank
The slug colony is squeaking along toward full function. The next batch of plants arrived from KP Aquatics this week, so the broodstock and growout tanks are smorgasbords of macroalgae.
With the growout tank ready, I added the first youngsters from Box of Slugs 2. This batch consisted of two medium-sized and one small girl, and all seemed almost jubilant once they entered the tank.
The two largest could be twins.
New girls in growout tank, 4/18/15.
The little one is keeping an eye on big sister.
Big and little sister in growout tank, 4/18/15.
Moving the next generation into the system here should take a little pressure off the fodder in BoS 2. At some point I should get a better idea of the algae requirements on a per-slug basis.
Box of Slugs 1.0 upgrade!
After months of planning and anticipation, the new slug facility is up and running at Shady Grove. The original “system,” if you could call it that, was a 20 gallon long tank with an Evergrow LED fixture to supply light and a Hydor Ekip thermopump to provide heat and circulation. It worked fine in terms of egg production, and the adults seemed quite happy. The new system has a separate growout tank for baby slugs, a sump for equipment such as the heater and an automated topoff system to make up for evaporation. It will also have a hatchery tank, in which the eggs and veligers will have constant circulation of fresh, pest-free water.
After the shelf was built and painted, the system was set up in one of the lab spaces (no carpet, spill kits at the ready). For this test, only the 15 gallon broodstock tank and sump were used.
Preliminary test broodstock and sump
Then water was added…
Wet test, broodstock and sump
The plumbing and hardware appeared to function adequately, so it was ready to be set up in the office. The rack was moved into place and the sump was filled from the Bryopsis growout tank (photo below). For the final fill, I waited until I could get started first thing in the morning, so that I would have most of a day to keep an eye on it in case of unanticipated redirection of flow (i.e., flooding).
Box of Slugs 1.1, ready to be filled with water and livestock.
Then it was time to commit. Water, sand, plants, and slugs all had to be moved in an orderly way. In an hour or so, everyone was settled in their new homes. The seahorse had been moved to Box of Slugs 2 to minimize her stress, but all of the adult slugs, the broodstock, took their place in the 15 gallon tank on top.
Box of Slugs 1.1, up and running.
So there it is. The main slug tanks, for adult broodstock and growing youngsters, now have dividers to keep the Bryopsis from completely overwhelming the other algae. Heater, topoff valve, and pump are in the sump, where they can’t bother the slugs. Flow from the sump to the rest of the system passes through a reactor filled with activated carbon, to prevent possible inhibition of slug growth by secretions from the algae. It should also reduce any odors produced by a system packed with seaweed. Having a sump makes it easier to dose with calcium, bicarbonate, nitrate and phosphate without worrying that some is getting dumped on the slugs’ heads. As an added bonus, the tank is not taking up valuable real estate in the middle of my office.
The slugs seem happy in their new home. They are exploring, feeding, and starting their mornings by basking in the sun.
E. clarki in new home, checking temperature
Elysia clarki greeting the morning sun in new home
Now that phase 1 of B.o.S 1.1 is finished, I will be adding more macroalgae and move some of the the E. clarki youngsters from Box of Slugs 2 into the growout tank. The final phase will be to get the hatchery on line, to have more control of the timing and numbers of baby slugs.
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