Reproductive Husbandry of the Weedy Sea Dragon

By: | Date: 07/04/2009 | 7 Comments |

Reproductive husbandry of the weedy sea dragon, Phyllopteryx taeniolatus, at the Aquarium of the Pacific in Long Beach, California

By Kristy L. Forsgren, Aquarium of the Pacific, Long Beach, California. Reprinted with permission.

Weedy Seadragon in the wild. Photo courtesy of saspotato via flickr.

Weedy Seadragon in the wild. Photo courtesy of saspotato via flickr.

Author’s Note: “They are a precious species that is best left in its natural environment.  In addition to the difficulty in obtaining them, they are extremely expensive to maintain and require an enormous amount of time!  When I took care of the seadragon collection at the Long Beach Aquarium, it was my full-time job caring for and maintaining their exhibits.  Often times I worked more than 40 hours a week and almost 15+ hours a day at one point once I was able to breed them!”

Abstract

The weedy sea dragon, Phyllopteryx taeniolatus, is a member of the family  Syngnathidae, which includes the seahorses, pipehorses, and pipefishes. The weedy sea  dragon is a monotypic species endemic to southern coastline of Australia. Male sea  dragons become pregnant after female sea dragons transfer eggs onto a specialized patch  of skin on the underside of the male’s tail. Due to the difficulty and cost associated with  maintaining sea dragons in captive environments, reproductive success and rearing of  hatchlings has never been documented. During the summer of 2001, two weedy sea  dragons became pregnant at the Aquarium of the Pacific. Embryos were incubate for 34
days (X + SD = 34 + 12.73, N=2) and hatched over a 13-day period (X + SD = 13.5 +  9.19, N=2). A total of 40 juveniles were raised, 35 were distributed to zoos and  aquariums throughout the United States, and the others are on exhibit with the adults at  the Aquarium of the Pacific. While there may be speculation regarding the effect of  seasonality on sea dragons, the Aquarium of the Pacific believes that their successful  breeding may have been the result of simulating natural environmental conditions.

Introduction

The weedy sea dragon, Phyllopteryx taeniolatus, is a monotypic species endemic to the southern coastline of Australian, from Sydney on the east coast to Perth on the west coast and to the tip of Tasmania and inhabit rocky reefs, seaweed beds, and sea grass meadows (Kuiter, 2000). These extraordinary fish have elaborate appendages on their head and body that resemble blades of algae (Kuiter, 2000). This camouflage allows them to ambush their planktonic prey of larval fishes and mysid shrimp (Kuiter, 2000).

Weedy Seadragon with eggs. Photo courtesy of saspotato via flickr.

Weedy Seadragon with eggs. Photo courtesy of saspotato via flickr.

Paternal brooding is a peculiar reproductive strategy characteristic of syngnathids in which the males incubate developing embryos. Females transfer eggs to a specialized  patch of skin on the underside of the male’s tail (Kuiter, 2000). Embryos are incubated for several weeks (Kuiter, 2000). Hatching is staggered and occurs over several days aiding in the dispersal of the offspring and thereby decreasing competition for food (Kuiter, 2000).

The difficulty involved with collecting sea dragons, and providing them with live food have contributed to the challenges associated maintaining them in public aquaria. During the summer of 2001, two weedy sea dragon successfully received eggs from a female. A total of 40 juveniles were raised, 35 have been distributed to zoos and aquariums throughout the United States making this the first transfer of aquarium-bred weedy sea dragons in the world. The remainder of the juveniles are on display with the adult population at the Aquarium of the Pacific. The reproductive success at the Aquarium may have been associated with simulating seasonality by changing the temperature and photoperiod of the exhibit on a monthly basis.

Methods

The Aquarium of the Pacific’s weedy sea dragon population consists of five males  and two females. The sea dragon habitat consists of a 1.2 m deep cylindrical exhibit tank  that contains 5200 liters of water with a calculated turnover of 40 minutes. The exhibit  bottom is covered with 1.3 – 2.5 cm Mexican Beach Pebble (Blue Daisy Cement  Products, Inc., Gardena, California). Artificial macro algae are cemented to dead rock  and artificial Sargassum floats at the surface.

The exhibit is lit with two 250-watt, 20,000 Kelvin metal halide light fixtures and  a 30-watt lamp used as a night-light when exhibit lighting is off. The life support  components include an ultraviolet sterilizer, a UMI barrel heat exchanger, a sand filter,  protein skimmer, and a bio-tower.

Water quality parameters were checked weekly and adjustments were made to  maintain healthy ideal conditions; salinity was kept at 33 ppt, pH was between 8.2 and  8.3, alkalinity between 2.5 and 3.0, and ammonia was below 0.05 mg/L, nitrite was  below 0.080 mg/L and nitrate were kept below 0.005 mg/L.

Water temperature and day length data for southern Australia were obtained from the Australian Oceanographic Data Centre, these data were converted into a schedule of  monthly seasonal changes (Table 1). The metal halides and heat exchanger were  manually changed to regulate seasonal variation within the exhibit.

In order to care for the pregnant males and hatchlings, a holding basket for  pregnant males, a modified tank for raising hatchlings, and an automatic feeding bucket  were constructed. A cylindrical basket (56 cm x 81 cm) was constructed using 100  micron screening and reinforced with 1.3 cm plastic mesh, this basket was hung at the  surface of the sea dragon exhibit.

An acrylic tank (37.9 liters) was modified and placed on the same filtration as the  sea dragon exhibit (Figure 1). A 2.5 cm bulkhead was installed into the top center of the  tank and an overflow drain was plumbed with 2.5 cm PVC. Silicone was used to attach  500 micron screening onto the inside of an acrylic frame that was placed at a 40o angle  over the inside of the bulkhead, a thin flexible plastic was glued into the bottom corners  of the tank, creating a rounded surface on the bottom. Three sides of the tank were  covered with a blue gel (Just Blue, #79, LEE Filters, Hampshire, England).

An automatic feeding bucket was made and programmed to feed the sea dragon  hatchlings (Figure 2). A 2.5 cm bulkhead was plumbed into the bottom of a plastic 7.6  liters bucket, a PVC thread to hose thread adapter connected the bulkhead to a  programmable garden timer and an adjustable hose valve was attached to the garden  timer and a barbed nipple with a piece of clear vinyl tubing was attached. The bucket  was hung above the modified juvenile tank and programmed per manufacture’s  instructions.

Food was supplemented prior to feeding the sea dragons. Brine shrimp nauplii,  (Artemia salina) were enriched with Selco (Inve Aquaculture, Belgium) 24 hours before  feeding. Mysids (Mysidopsis bahia) were enriched with Selco-ed Artemia nauplii and frozen Cyclop-eeze product (Argent Laboratories, Redmond, Washington). Frozen mysis  shrimp (Tropical Marine Centre Ltd., England) were supplemented with vitamins  (VitaFish, Marine Enterprises Intl., Maryland).

Results

Spawning occurred from May 2001 to late June 2001 resulting in two male weedy  sea dragons successfully receiving clutches of eggs. Incubation varied from 25 days to  43 days (X + SD = 34 + 12.73 days, N=2) and hatching varied 7 days to 20 days (X+SD  = 13.5 + 9.19, N=2). Of the first weedy sea dragon’s hatchlings, 68.1% survived and  65.8% of the second male’s young survived.

Juvenile Weedy Seadragons

Juvenile Weedy Seadragons

Discussion

Seasonal variations may have contributed to the weedy sea dragons successfully  breeding at the Aquarium of the Pacific in Long Beach, California by stimulating  reproductive behavior. Breeding occurred during the spring and early summer of 2001,  when water temperatures ranged between 16.1 C and 17.8 C and the photoperiod was  between 13 and 14 hours of daylight.

Seasonality was accomplished by altering the water temperature and photoperiod  each month according to a schedule based on southern Australia’s regional seasonality.  Breeding occurs in the wild between October and January when water temperature varies  from 18 C to 22 C and photoperiod is between 13-14 hours (Powell, 1999). Due to the  differences in seasonality between the northern and southern hemispheres, a direct  seasonality schedule of southern Australia would have resulted in the exhibit being dark  at times during the Aquarium’s open hours. Therefore, a few alterations had to be made  in order to adapt Australia’s seasonal changes to Long Beach, California. The day length  schedule and consequently the water temperature schedule, was adapted to meet guest  needs while still accomplishing seasonal fluctuations. No adverse affects were observed  due to these environmental changes.

Several aquariums have observed the weedy sea dragon’s mating behavior fewer  have witnessed egg transfers. The Aquarium of the Pacific is the first aquarium  worldwide to successfully raise weedy sea dragon hatchlings. Mating behavior and egg  droppings have been observed throughout the year in facilities that do not implement a  seasonality schedule similar to that of the Aquarium of the Pacific’s, several observations  resulting from life support malfunctions resulting in a temperature change (Powell,  1999). However, at the Aquarium of the Pacific, reproductive behaviors increase in  frequency and intensity associated with seasonal temperature increase and extended day  length.

Weedy sea dragon mating behavior observed at the Aquarium of the Pacific  involved several dragons swimming 2-3 cm apart with their tails curled outward. These  interactions have been observed between males and between males and females, but  never between two females. An interaction that has been frequently observed is one in  which the animals move their heads toward, then away from one another, a propulsion  similar to that of two opposing magnets being forced together. No physical contact  actually occurs and shortly after this behavior, the sea dragons separate. Although the  nature of these interactions are unknown, they may be related to territory disputes or mate  selection.

On the morning of May 5, 2001, a pregnant weedy sea dragon carrying  approximately 50 eggs was discovered. A second dragon became pregnant on June 23,  2001, with approximately 75 eggs. The males were placed in a floating basket that  remained in the exhibit for the duration of the pregnancy preventing the need to transport  or acclimate them to another location. The basket prevented physical contact with other  dragons thus protecting the eggs and made daily observations of the dragons and the  developing embryos possible.

Pregnant sea dragons refused to consume frozen mysids; therefore they were fed  only live mysids (Mysidopsis bahia) consuming nearly 1500 mysids per day for the first  four weeks. Later, the dragon’s appetite decreased to approximately 100 mysids per day,  and they discontinued eating while the young were hatching. The dragons were returned  to the exhibit after the young hatched and they began eating live mysids the following  day. Frozen mysids were consumed within a week.

Incubation of eggs has been estimated to be 6 weeks, although young began  hatching at an average of 34 days (34 + 12.73, N=2) after egg transfer and hatching of the  entire clutch averaged 13.5 days (13.5 + 9.19, N=2). The hatchlings were scooped out of  the male’s basket in a small container to avoid being netted or touched while transferring  them into the flow through tank. The first hatchlings were 2 cm in length and were born  curled around a large pink yolk sac. The hatchling’s mouths and fins were  underdeveloped at birth but began developing quickly as the yolk sac was being  absorbed. Sea dragons born later were more developed and had smaller yolk sacs.

At seven days of age, the first hatchling’s yolk sacs had been completely absorbed  and they began swimming and eating one-day old Artemia nauplii. Sea dragons that  hatched after this time were ready to swim and eat. In addition to continuous daily  feedings, an automatic feeding bucket was set to feed five times throughout the night.

Although it is not known how much food was actually consumed during the night, the  feeding bucket provided food during the evening and early morning. Artemia nauplii  were fed to the hatchlings until brine shrimp remnants no longer appeared in the dragon’s  fecal pellets. This occurred about 5 days after first eating nauplii at that point, the  hatchlings began eating one-day old mysids (Mysidopsis bahia). As the young sea  dragons grew, the size of the food they were eating was increased, allowing them to feed  more efficiently. The dragons began eating 2-day old mysids at 10-19 days old, 3-4 day-old mysids when they were 19-33 days of age, and 5-7 day-old mysids at 33-42 days of  age. Adult mysids were eaten when the juveniles were 12 weeks of age.

When the juveniles were five months old, several were shipped to other zoos and  aquariums within the United States. Each dragon was triple bagged with approximately  11.4 liters of exhibit water supersaturated with oxygen. Dragons were packed in a  styrofoam insulated container lined with plastic and a frozen gel pack, then shipped  overnight to their respective destinations.

It is important to continue sharing the knowledge gained from sea dragons in  public aquariums. The life cycle of the sea dragon is more attainable than ever before  and with continued research, the mysteries of the sea dragon can be unlocked. In  addition to fulfilling biological interest, the sea dragons amaze aquarium visitors each  day, making them increasingly important ambassadors to the sea in particular to the  waters of Australia.

Conclusions

Breeding success may be influenced by seasonal variations similar to those in  southern Australian waters. The fact remains that there is very little known about how  seasonality may influence reproduction in sea dragons. While there may be speculation  regarding the effect of seasonality on sea dragons, the Aquarium of the Pacific believes  that their successful breeding may have been the result of simulating natural  environmental conditions.

Table 1. Aquarium of the Pacific’s schedule of monthly water temperature (+/- 0.1 to  1.5o C in Adelaide, South Australia, Australia) photoperiod and day length changes for  the sea dragon exhibit.

Picture 4
Figure 1. Diagram of modified acrylic tank used to raise weedy sea dragon hatchlings at  the Aquarium of the Pacific.
Picture 5
Figure 2. Overnight feeding bucket used to raise weedy sea dragon hatchlings at the
Aquarium of the Pacific.
Picture 6

Acknowledgments

The generous support and enthusiasm of the Aquarium of the Pacific has made  the breeding and rearing of the weedy sea dragons was possible. I’d like to thank the  husbandry and life support staff for their assistance, patience and support. I would  especially like to thank Sandy Trautwein, Curator of Fishes and Invertebrates, who  always believed in accomplishing this unique event and to Charlie, my husband, who has  shared my devotion and enthusiasm for sea dragons.

References

Bielinger, Diane. 1990. Dazzling dragons. Sea Fronteirs. Sept-Oct. pgs?
Dawson, C.E., 1985. Indo-Pacific pipefishes Red Sea to the Americas. The Gulf Coast
Research Laboratory: Ocean Springs, MI.
Helfman, Gene S. Bruce B. Collette and Douglas E. Facey. 1997. The diversity of
fishes. Blackwell Science: Malden, MA.
Kuiter, Rudie. 2000. Seahorses, pipefishes and their relatives. TMC Publishing.
Chorleywood: United Kingdom.
MacKay, Bruce. YEAR? Seadragons in wild and captive environments. Today’s
Aquarist. Vol.7(1): 5-9.
Paxton, John R., Douglass F. Hoese, Gerald R. Allan, and Jennifer E. Hanley. 1989.
Zoological Catalogue of Australia. Vol. 7 Pisces; Petromyzontidae to Carangidae.
Brown Prior Anderson Pty Ltd.: Burwood, Victoria.
Powell, Paula. 1999. Update on seadragon reproduction activity and report on feeding
regimens among public institutions. AZA Annual Conference Proceedings. Minnestota
Zoo: Minneapolis, MN.
Rielinger, Diane M. 1990. Dazzling dragons. Sea Frontiers. Sept.-Oct.:10-11.


7 Responses to “Reproductive Husbandry of the Weedy Sea Dragon”

  1. Bob Says:

    what a beautiful creature, i can’t imagine how a species so fragile can exist in the wild, it must be pretty rare.

  2. weedyseadragonperson Says:

    hey i need more info on weedy sea dragons! anyone know where i can get any? NOT wikipedia! help!

  3. Gournoe Says:

    This is a beautiful creature, although the website needs more info!

  4. Twilight Luva Says:

    Does anyone know if ballast water affects weedy seadragons?

    P.S Twilight rox

  5. Cee Says:

    Have visited the LB Aquarium twice this month (school field trips) and was amazed at how incredible and precious the Sea Horses and Sea Dragons were. I loved each exhibit!!!

    Thank you for your contributions.

    Cheryl

  6. Jay-See Says:

    This is new to me. Honestly I was amazed knowing that the male seadragon are the one who carry them. Thanks for the tank information. It will helps anyone who plans to make seahorse as pet.

  7. CD Yost Says:

    I have learned that Seadragons are sensitive to changes in their environments. Looks like this aquarium did well in recreating most of the natural habitat conditions. I am still curious about some other variables. Did they do anything to deal with depth pressure variables? Was this also a Display tank? if so ,how did they resolve possible stress issues of human contact like close viewers, noise & vibrations etc? Do they feed local mysid shrimp?

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